(SANITIZED)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81-00120R000100010021-3
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 69
• Document Creation Date: December 22, 2016
• Document Release Date: December 8, 2003
• Sequence Number: 21
• Content Type: FORM

STAT Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
~e.~= Page( s) Next 5 Page(s) In Document Denied
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Sept. 2, 1969
H.. SCHMIDT
3't464,770
14
LASER TRANSMITTER
' ~ 13
Al . -.-[--~s F19. 1
2a LASER RECEIVER
29
Fig. 3
23
L~,b2a
20" ' 9 ~-2b
2/ 24 O
INVENTOR
Horst Schmidt
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Sept. 2, 1969 H. SCHMIDT 3,464,770
COMBINED SIGHTING MECHANISM AND LASER RANGE FINDER
Filed Oct. 21, 1965 2 Sheets-Sheet 2
Fig. 4
/7
LASER TRANSMITTER
~5
3
1
30, I 1 25a
I N VEN TOR
Horst Schmidt
c
ATTORNEYS
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
United States Patent Office
3,464,770
COMBINED SIGHTING MECHANISM AND LASER
RANGE FINDER
Horst Schmidt, Nauborn, Kreis, Wetzlar, Germany, as.
signor to Ernst Leitz GBH, Optische Werke, Wetzlar,
Germany
Filed Oct. 21, 19865, Ser. No. 499,346
Claims priority, applicaGan Germany, Nov. 7, 1964,
L 49,230; Sept. 3, 1965, L 51,552
Int. Cl. G01c 3/08; F41g 3/06; G02b 23/10
U.S. Cl. 356-4 9 Claims
ABSTRACT OF THE DISCLOSURE
Arrangement combining a laser range finder, including
transmitter and receiver, with a sighting mechanism, in-
cluding an ocular, for determining the distance of a
target and for adjusting the angle of elevation required
to fire a projectile at the target. The laser range finder
and the sighting mechanism have partially coextensive
beam paths. A divider mirror in the beam path of the
sighting mechanism directs received rays to the laser re-
ceiver and sighting mechanism ocular. A reticle plate ar-
ranged in front of the mirror is connected to an element
of an optical system provided in front of the laser trans-
mitter. The reticle plate and such element are displaceable
transversely to the optical axis of such optical system.
Means provided in the beam path to the laser receiver
block the rays reflected from the target to which the laser
receiver is sensitive, except for rays, which correspond to
the transmitted beam in divergence and direction and
which are within the visible portion of the spectrum; the
former being passed to the laser receiver and the latter to
the ocular of the sighting mechanism via the divider
mirror. Means are also coupled between the laser re-
ceiver and the reticle plate for displacing the reticle plate
and such element in response to signals from the laser re-
ceiver. By this arrangement, adjustments can be. made in
the elevation angle requited for a projectile to reach the
target.
3,464,770
Patented Sept. 2, 1969
nection between the adjusting device in the interior of the
vehicle and the rotating prisms located on the outside of
the vehicle.
Additionally, there is a further disadvantage in that
rotating prisms generally produce astigmatic distortions
and secondary chromatic aberrations. Furthermore, the
components can not be cemented together because of the
intense laser radiation and the resulting glass-air areas
cause disturbing reflections.
It is an object of the present invention to provide an ar-
rangement of a sighting mechanism coupled. with a laser
range finder which is of simple construction and economi-
cal to produce.
It is another object of the present invention to provide
a combined sighting mechanism and laser range finder
having a common optical system for a portion of the
beam paths.
It is a further object to provide a combined sighting
mechanism and laser range finder having an optical sys-
tem which is relatively free of distortions.
In accordance with the present invention, the afore-
described disadvantages of the prior arrangements are
overcome by providing in front of a chromatic divider
mirror mounted in a conventional manner in the beam
path of a sighting mechanism, a reticle plate, and connect-
ing the plate with an element of the optical system ar-
ranged in front of a laser transmitter, with the plate being
mounted for displacement transverse to the optical axis.
There is further provided in the beam path of a laser
receiver, optical means which block the rays to which the
laser receiver is sensitive, except for the rays which are
reflected from the target and correspond to the trans-
mitted beam in divergence and direction and for the rays
within the visible portion of the spectrum which are fed
to the ocular of the sighting mechanism via the divider
mirror.
. According to a feature of the invention, the blocking
may be accomplished by providing a coating on the re-
ticle plate, except for a small central surface portion, for
blocking the rays lying beyond the visible portion of the
spectrum to which the laser receiver is sensitive. Thus the
coating forms a diaphragm for limiting the beam of rays
used for measuring and which is united with the reticle
plate.
Although the arrangement including a coating as a dia-
phragm for blocking the rays is more economical than
prior arrangements, the coating increases the expense of
the arrangement. Therefore, according to another feature
of the invention, the diaphragm is separated from the re-
ticle plate and is mounted in a plane that is optically re-
lated to the plane of the reticle plate. There is further
provided means which ensure that the received rays that
are used for measuring and which are parallel to the
transmitted rays always enter through the center of the
diaphragm regardless of the position of the reticle plate.
The diaphragrm may be adjusted to correspond to the dif-
ferent positions of the reticle plate by means of a com-
plicated gear arrangement. However, the present inven-
tion provides a simplified arrangement wherein a two-
member optical system having a parallel beam path be-
tween the two-members is arranged in front of the fixed
diaphragm of the laser receiver. The reticle plate image is
then produced in the diaphragm plane, and the member of
the system which is adjacent the reticle plate is connected
to the reticle plate and is displaceable with the plate in a
plane transverse to the optical axis. The beam divider is
suitably arranged between the reticle plate and the mem-
ber of the two-member system which is arranged in front
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
The present invention relates to an arrangement where-
in a visual sighting mechanism is coupled with a laser
range finder and wherein the arrangement is provided with
a device which adjusts for the angle of elevation required,
e.g. for a weapon associated with the arrangement to fire
a projectile at a target.
A device of this type is known wherein the angle of
elevation for a weapon associated with the device is de-
termined by adjusting a rotating pair of prisms provided
in the beam path of both the sighting mechanism and the
laser transmitter. Since the rotating prisms must receive
each beam path in contradistinction to a single beam path,
the diameter of the optical systems for the pair of rotat-
ing prisms and also for the associated optical components
positioned in front thereof must necessarily be corre-
spondingly larger. It has therefore been suggested that
this disadvantage may be overcome by directing the beam
of rays of the laser transmitter within the region of the
beam path of the sighting mechanism. However, this is
impossible without limiting the field of a portion of the
beam required for the visual sighting device. Aside there-
from, the use of a rotating prism pair represents a sub-
stantial increase in the st of the device because the
prisms, of necessity, must be made of a complicated con-
struction in order that the prisms have good optical and
mechanical properties.
Another disadvantage t 1 the prior arrangements is that
when the mechanism is incorporated into armored ve-
h .,,.
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
3,464,770
3 4
According to a further feature of the present invention, shown in FIGURE 3, a prismatic cube. The reflective
there is provided a pancratic or zoom lens telescopic sight coating 12 prevents undesired rays from passing through
as the sighting mechanism, wherein the sight may be used the reticle plate for these would otherwise impair the
with the laser range finder or as an auxiliary system in measuring result.
place of the laser range finder. The laser beam range finding process is similar to a
Additional objects and advantages of the present in- radar distance measuring process in that the time interval
vention will become apparent upon consideration of the between the emission and reception of the transmitted
following description when taken in conjunction with the beam is an indication of the distance of the target. The
accompanying drawings in which: distance information is then fed to the computer 17, to-
FIGURE 1 is a schematic view of the combined sight- 10 gether with other values such as wind speed and direction,
ing and laser beam measuring device having the reticle target speed, etc. The computer processes this data and
plate coupled with the device for blocking rays. determines the elevation and lead angle for the target and
FIGURE 2 is a front view of the recticle plate of FIG- , transmits the result to the plate 9 via the connection 19.
'URE I with a target indicated thereon in dash-dot lines. The reticle plate 9 and the lens 13 are then shifted in
FIGURE 3 is a schematic view of another embodiment 15 accordance with the computer calculation to compensate
of the present invention having a pancratic telescope sight for the elevation angle necessary for a projectile to reach
and a deflection device. the target. However, the shifting of the plate and the lens
FIGURE 4 is a further embodiment of a combined 13 results in the target no longer being centered in the
Bighting and laser beam measuring device according to cross-hairs 10 of the plate 9 since the line of sight is no
the present invention having a reticle plate and a dia- 20 longer directed at the target and therefore the entire sight-
phragm that are arranged in different planes. ing arrangement and the weapon coupled thereto are
Referring now to the drawings, there is shown in FIG- shifted to again center the target. The movement of the
RE 1 a reticle plate 9 arranged in front of a chromatic weapon and the sighting arrangement thereby provide the
divider or semi-reflecting mirror 1 which directs a portion required elevation angle necessary for a projectile to
2a of the rays 4 coming from an objective 3 of the sight- 25 reach the target. The laser beam range finding process
mg mechanism to a laser receiver 5 and reflects a por- may then be repeated to check the target range without
on 2b via a field lens 6 and a mirror 7 to an ocular 8 having to return the entire arrangement to a basic set-
with the field of view plane 29 being arranged in the ocu- ting. However, any further changes causing a further shift-
ing of the reticle plate will also have to be compensated
`1R supports the mirror 1. As shown in FIGURE 2, the 30 for by a corresponding movement of the entire apparatus.
reticle plate 9 which is fully permeable for the visible In FIGURE 3, which is another embodiment according
portion of the spectrum carries the line configuration 10 to the present invention, there is shown a movable mirror
and is provided, outside of the central portion 11, with 20 provided behind the objective 3; whereby in case of
a coating 12 which is impermeable to laser rays, the size inoperativeness or non-use of the laser device, the re-
of the central portion 11 being determined by the scatter- 35 ceived rays are directed to a pancratic or zoom lens range
img angle of the laser transmitter and by the focal length finder 21 combined with the sighting mechanism. For this
of the optical system of the sighting mechanism provided purpose, a further deflection mirror 22 and an additional
in front of the reticle plate. The coating may be of any field lens 23 are provided in the beam path. Further-
suitable type such as a reflective coating effective only for more, the mirror 7 in this embodiment must be collap-
laser rays. The reticle plate is connected with the nega- 40 sible, i.e., capable of being swung out of the axis of the
tive optical member 13 of a two optical member Galilean pancratic system. The deflection system also includes a
system 14 and is displaceable with the member 13 in the range finding mark 24, arranged in the ocular S.
direction of arrow A transverse to the optical axis of the In the arrangement of FIGURE 3, the range finding
'two member optical system. procedure can be carried out by means of the pancratic
The 'Galilean system has an axis 15 which extends in 45 system 21 in case the laser device is inoperative, or as a
parallel with the center line of the objectives 3 and is supplement to the laser measuring process. However, in
arranged in front of a laser transmitter 16, whereby the order to use the pancratic system for range finding, the
negative member 13 which is connected to the reticle plate mirrors 20 and 7 must be moved into the position shown
causes a deflection of the transmitted laser rays. The dis- in solid line in FIGURE 3. This range finding is then
placement of the negative element has the same optical G0 accomplished by changing the enlargement scale of the
effect as the displacement of the reticle plate. The dis- pancratic system until the target configuration on the
placement can be done in two coordinates at right angles range finding mark 24 is adjusted to the size of the target
to the optical axis of the laser transmitter and at right so that the mark is rendered congruent with the target.
angles to the optical axis of the optical system provided The adjustment path for changing the magnification
in front of the divider mirror, respectively, i.e., in a plane g5 which is an indication of the range, can then be used to
transverse to the optical axis. A computer 17 is connected set the elevation angle of the weapon or the movement
via a cable 18, with the laser beam measuring device and of the lens system can be transferred to the reticle plate
transmits its commands to the reticle plate 9 via the con- 9 via means which are not illustrated, and the elevation
nection 19. The mechanical means for adjusting the sight- of the weapon carried out as discussed in connection
ing mechanism are not illustrated in the drawing. 80 with FIGURE 1.
The mode of operation of the arrangement shown in Thus, the zoom lens system may be used with the
FIGURE 1 is essentially as follows: At first, the sighting laser arrangement as a complementary system, or as an
procedure is carried out in the conventional manner auxiliary system in place of the laser arrangement for
through use of the visual sighting mechanism with the en- the purpose of range finding.
tire system including a weapon coupled thereto, being set 65 Furthermore, it is also possible to obtain an auxiliary
on the target with respect to height and direction. There- range finding without using a pancratic optic by provid-
after, the range finding process is carried out by means ing in the ray path of the visual sighting mechanism a
of the leaser beam device. In this process, the rays 15 conventional range finder comprising two mutually dis-
emitted by the laser transmitter 16 are received by the placeable sections. In this conventional arrangement, as
objective 3 after reflection at the target and pass through 70 well as in the arrangement using a pancratic system, the
the central aperture 11 of the reticle plate 9 to the divider range finding mark is positioned in the image plane of an
mirror I and to the receiver S. The sighting mechanism is intermediate image producing system included in the
provided with conventional protective devices which are auxiliary system. In order that only this measuring mark
actuated during the laser range finding. The divider mir- be visible in the field of vision, it is advantageous to cir-
ror 11 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3 nt image piano
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
5 v,zVZ ? 1 V
5 6
by means of a mirror arrangement similar to that of existing between the transmitted beams and the bore
FIGURE 3. However, if the range finding marks are ad- axis of the weapons coupled to the sighting arrangement
vantageously arranged, for example in such a manner only those received rays that enter parallel to the trans-
that they do not overlap one another, the feature of mitted rays are directed in the desired way through the
eliminating the reticle plate by deflection mirrors can be 5 center of the diaphragm 26 to the laser receiver 5 for
omitted. a true determination of the range.
In the arrangement shown in FIGURE 4, which is a Thus, it is seen from the afore-described embodiments
further embodiment of the present invention, there is that the present invention provides arrangements includ-
provided a further two-member optical system compris- ing laser beam range finders which directly adjust for the
ing lens 25a and lens 25h, a diaphragm 26 and a lens 10 angle of elevation by movement of the reticle plate. These
27 arranged in front of the laser receiver S. Reflected arrangements are economical to produce and are relative-
rays are directed to the beam divided mirror via the ob- ly free of distortion since the need for additional optical
jective 3 arranged in the optical axis 4 of the laser re- components of complicated structure is eliminated. As
ceiver, after passing through the reticle plate 9. The shown, the present invention also provides means for
beam divider 1 splits the received rays so that a portion 15 limiting the rays passed to the laser receiver, such as the
of the rays is fed to the ocular 8 of the sighting device coating on the reticle plate and the separate diaphragm
via the deflection mirror 7 and the other portion passes in a different plane from that of the reticle plate, in order
through the beam divider to the laser receiver via the to provide a true measurement of the target range.
two member system 25, the diaphragm 26 and the lens It will be understood that the above description of the
27, with diaphragm 26 corresponding to the coating 12 20 present invention is susceptible to various modifications,
as shown in FIGURE 1 for limiting the beam of rays changes, and adaptations.
used for measuring the range. What is claimed is:
The reticle plate 9 is arranged in the front focal plane 1. A combined sighting mechanism and laser range
of the lens 25a and the diaphragm 26 in the back focal finder arrangement for determining the distance of a
plane of the lens 25b of the system 25 which is con- 25 target from the arrangement and for adjusting for the
structed to provide collimated rays between the two angle of elevation required for a weapon associated with
lens members, whereby the image of the reticle plate is the arrangement to fire a projectile at the target, the ar-
produced in the diaphragm plane. The lens 25a is fixedly rangement comprising, in combination:
connected with the reticle plate 9 through a connecting a laser range finder including a laser transmitter for
member 30 and together with the plate is displaceable in 30 transmitting laser rays to a target along a beam path
a plane transverse to the optical axis of the system. The and a laser receiver for receiving reflected rays from
negative member 13 of the Galilean system 14, which is the target along a beam path;
arranged in the beam path 33 of the laser transmitter a sighting mechanism optical system having a beam
16, is also coupled with the reticle plate and is displace- path and including an ocular, said beam path of the
able therewith. The reticle plate 9 is controlled via the 35 sighting mechanism optical system and said beam
cable 19 from the computer 17 which evaluates the path of the laser receiver being at least partially co-
measuring results fed to it from the laser beam range extensive;
finder via cable 18. a divider mirror mounted in the beam path of said
The mode of operation of the device shown in FIG- laser receiver for transmitting received rays from the
URE 4 is as follows: As in the operation of the ar- 40 target to said laser receiver and for reflecting received
rangement of FIGURE 1, the range finding process is rays from the target for direction to said ocular of
first performed in a conventional manner by using the said sighting mechanism optical system;
sighting device, whereby the entire arrangement includ- a two-member optical system arranged in the beam
ing the coupled weapons is net on the target in height path of said laser transmitter;
and direction. The target line of the telescope, the trans- 45 a reticle plate mounted in front of said divider mirror
mitted laser beam, the received laser beam and the bore in the beam path of the laser receiver and the sight-
axis of the weapons are then arranged parallel to each ing mechanism optical system and coupled to one
other. The measuring of the range is then performed member of said two-member optical system for dis-
by means of the laser range finding device. The rays 15 placement in a plane transverse to the optical axis of
transmitted by the transmitter 16 are in a conventional 50 such two-member optical system, such displacement
way received by the objective 3 after having been re- adjusting the elevation angle required for a projec-
flected by the target and then reach the chromatic di- tile to reach the target;
vided mirror 1 after having entered through the reticle means for passing to said laser receiver that portion of
plate 9. The divided mirror separate the visible portion the rays reflected from the target which correspond in
of the rays and directs that portion to the ocular 8 of 55 direction and divergence to the transmitted rays and
the sighting device with the laser beams being passed to to which said laser receiver is responsive, and for
receiver 5 via the system 25 and the lens 27. The results passing to said ocular of the sighting mechanism op-
of the receiver are fed to the computer 17 for calculi- tical system that portion of the rays reflected from the
tion of the angle of lead and elevation which is then target which fall within the visible spectrum by way
transferred to the reticle plate 9 by displacing the same. 60 of said mirror, and for blocking the other rays to
The displacement of the negative member 13 and the which said la
i
i
ser rece
ver
s responsive; and
lens 25a with the reticle plate results in the target line means coupled between the laser receiver and the ret-
of the telescope as well as the transmitted and received icle plate and responsive to signals from said laser
laser beam being maintained. parallel to each other, but receiver for displacing the reticle plate and said one
forming as desired, an angle relative to the weapon cou- 65 member of the two-member optical system in said
pled therewith. The shifting of the reticle 9 and
g plate transverse plane thereby to adjust for the elevation
the sight line toward the target is then compensated for angle required for a projectile to reach the target.
by counter-steering the entire sighting arrangement and 2. An arrangement as defined in claim I wherein said
the weapons, thereby providing the elevation angle re- 70 reticle plate is fully permeable for the visible portion of
quired for a projectile to reach the target. the spectrum and said means for passing and for blocking
-The operation of the present embodiment is depend- the rays is a coating impermeable to laser rays provided
ent upon the displacement of the lens 25a with the reticle on said reticle plate having a small open portion of a pre-
plate. Due to the afore-described construction of the determined size at the center of said reticle plate for pass-
system 25, it is provided that in any angular position 76 Ing the rays to which the laser receiver is responsive, the
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
7
3,464,770
size of said open portion being determined by the scatter-
ing angle of said laser transmitter and by the focal length
of the optical system of said sighting mechanism.
'3. An arrangement as defined in claim 2 wherein the
coating provided on said reticle plate outside of the cen-
tral open portion reflects rays to which the laser receiver
is responsive.
4. An arrangement as defined in claim 1 wherein said
two member optical system is a Galilean system, said
member connected with said reticle plate being the nega-
tive lens thereof.
S. An arrangement as defined in claim 1 wherein said
sighting mechanism is a pancratic telescopic sight.
6. An arrangement as defined in claim 5 wherein said
pancratic telescopic sight is provided with a range finding
mark for auxiliary range finding in addition to the laser
range finder.
7. An arrangement as defined in claim 6 wherein said
pancratic telescopic sight includes an image-reproduc-
8
a reticle plate mounted in front of said divider mirror
in the beam path of the laser receiver and the sight-
ing mechanism optical system and coupled to one
member of said two-member optical system for dis-
placement in a plane transverse to the optical axis
of such two-member optical system, such displacement
adjusting the elevation angle required for a projectile
to reach the target;
means for passing to said laser receiver that portion of
the rays reflected from the target which correspond
in direction and divergence to the transmitted rays
and to which said laser receiver is responsive, and
for blocking the other rays to which said laser receiver
is responsive, said means for passing and for blocking
the rays being a fixed diaphragm mounted in front of
said laser receiver;
means coupled between the laser receiver and the reticle
plate and responsive to signals from said laser re-
ceiver for displacing the reticle plate and said one
member of the two-member optical system in said
transverse plane thereby to adjust for the elevation
angle required for a projectile to reach the target;
and
a further two-member optical system arranged in front
of said fixed diaphragm, one member of said further
two-member optical system being adjacent to said
reticle plate and connected therewith for displacement
transverse to the optical axis of a portion of the sight-
ing mechanism optical system, said further two-mem-
her optical system providing a parallel beam path
therebetwecn and producing the image of said reticle
plate in the diaphragm plane.
References Cited
UNITED STATES PATENTS
ing system and.said range finding mark is provided in 20
the image plane of said system.
8. An arrangement as defined in claim 1 wherein said
divider mirror is a chromatic mirror and a plane parallel
plate supports said mirror.
9. A combined sighting mechanism and laser range 25
finder arrangement for determining the distance of a target
from the arrangement and for adjusting for the angle of
elevation required for a weapon associated with the ar-
rangement to fire a projectile at the target, the arrange-
ment comprising, in combination:
a laser range finder including a laser transmitter for
transmitting laser rays to a target along a beam path
and a laser receiver for receiving reflected rays from
the target along a beam path;
a sighting mechanism optical system having a beam path 35
and including an ocular, said beam path of the sight-
ing mechanism optical system and said beam path of
the laser receiver being at least partially coextensive;
a divider mirror mounted in the beam path of said laser
receiver for transmitting received rays from the tar- 40
get to said laser receiver and for reflecting received
rays from the target for direction to said ocular of
said sighting mechanism optical system;
a two-member optical system arranged in the bcani
path of said laser transmitter; 45
9/1967 Pun.
RONALD L. WILBERT, Primary Examiner
F. L. EVANS, Assistant Examiner
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
April 7, 1970 G. W. BICKEL ET AL 3,505,528
RANGE FINDER WITH RADIATION SENSITIVE MEANS BEHIND REFLECTOR
Filed Aug. 16, 1967
INVENTORS
GARY W. BICKEL
JOHN J. FERRARA
By MARVIN L. LIPSHU,1Z
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3 3,505,528
L i1~l~dl &3L4LC5 J: 41c11L `..,111CU Patented Apr. 7, 1970
3,505,528
RANGE FINDER WITH RADIATION SENSITIVE
MEANS BEHIND REFLECTOR
Gary W. Bickel, Boston, John J. Ferrara, Acton, and
Marvin L. Lipshutz, Brookline, Mass., assignors to
Honeywell Inc., Minneapolis, Minn., a corporation of
Delaware
Filed Aug. 16, 1967, Ser. No. 661,069
Int. Cl. H01j 5/16; 11011 15100
U.S. Cl. 250-216 2 Claims
ABSTRACT OF THE DISCLOSURE
An integrated first-surface reflector and transducing
sensor, in a kinematic mount, for use in optical systems
such as laser range finders, the sensor being positioned be-
hind the reflector to use the small amount of light un-
avoidably transmitted therethrough.
BACKGROUND OF THE INVENTION
This invention relates to the field of optical instruments
and more expressly to laser range finders. It is frequently
desirable to provide an optical instrument with means for
making known the exact instant when a beam of light is
received or transmitted. One method of accomplishing this
has been to insert a fiber optics tap into the optical path,
but this has the disadvantage of reducing the available
light intensity by reducing the effective area of the beam.
SUMMARY OF THE INVENTION
Our invention may be used wherever the light path re-
quires a reflecting surface and where the light is of suitable
intensity. It comprises a photodiode mounted behind the
reflecting surface, to make use of the otherwise wasted
light energy transmitted through the reflecting surface,
which is typically a layer of metal on the surface of a
block of optical glass.
BRIEF DESCRIPTION OF THE DRAWING
In the drawing FIGURE 1 is a view enlarged of an as-
sembly embodying the invention and FIGURE 2 is the
section taken along the line 2-2 of FIGURE 1.
DESCRIPTION OF THE PREFERRED
EMBODIMENT
Our invention comprises an assembly 10 mounted in
an aperture 11 in the housing 12 of an optical instrument
such as a laser range finder by suitable means such as
screws 13. Assembly 10 includes a backing member 14
having a bore 15 to receive a photodiode 16 having ter-
minals 17 and 20, the sensitive surface of the diode being
within bore 15 which is enlarged at 21 to avoid occultation
of the sensor. Diode 16 is pressed or otherwise suitably re-
tained in bore 15.
A mirror 22 includes a block 23 of optical glass having
a first reflective surface 24, and is. received in a cap 25
having a flange 26 traversed by a plurality of mounting
screws 27 which pass through compression springs 39 and
which are received in thread bores 31 in member 14.
The rear surface of block 23 is engaged by the ends of a
plurality of adjusting screws 32. Screws 27 and 32 co-
operate with springs 30 to comprise a kinematic mount
for mirror 22.
Assembly 10 is so positioned with respect to housing 12
as to receiving a beam of light, specifically laser light,
which is shown at 33, and to reflect as large a portion as
possible of that light, as shown at 34. It is unavoidable
that a certain minor portion of the incident light is not
reflected but transmitted through surface 24, as at 35, to
impinge on photodiode 16.
2
OPERATION
Whenever light of suitable intensity is supplied at 33,
a portion thereof acts at 35 to energize diode 16, which
thereafter gives an electrical output. This output can be
used for any desired purpose: in one embodiment of the
invention the diode signal was used as an indicator of zero
time for a laser range finder, since it occurred at the in-
stant when a laser pulse was transmitted at 34 to emerge
from the output optics of the device.
forth details and advantages of its structure and function,
and the operation and the novel features thereof are
pointed out in the appended claims. The disclosure, how-
ever, is illustrative only, and changes may be made within
the principle of the invention, to the full extent indicated
by the broad general meaning of the terms in which the
appended claims are expressed.
We claim as our invention:
1. Apparatus for indicating the presence of a beam of
light comprising, in combination: a mirror comprising
a block of optical glass, having a plane front surface
coated with metal to form a reflector, and a flanged
mounting cap enclosing said block and apertured to ex-
pose said front surface reflector;
a backing member including adjustable spacing means
projecting therefrom;
means securing said mirror to said backing member
with the rear surface of said block in contact with
said spacing means, including means traversing the
flange of said cap and resiliently urging said cap
toward said backing member while preventing sig-
nificant lateral movement therebetween;
means for mounting said member so that said front
surface reflector is positioned to reflect radiant en-
ergy impinging thereon; and.
detector means comprising a photodiode mounted in
said backing member to receive a portion of the radi-
ant energy transmitted through said reflector and
said block.
2. Apparatus for indicating the presence of a beam of
light comprising, in combination: a mirror comprising a
block of optical glass, having a plane front surface coated
with metal to form a reflector and a flanged mounting cap
on closing said block and apertured to expose said front
surface reflector;
a backing member including adjustable spacing means
projecting therefrom;
means securing said mirror to said backing member
with the rear surface of said block in contact with
said spacing means, including means traversing the
flange of said cap and resiliently urging said cap
toward a said backing member while preventing sig-
nificant lateral movement therebetween;
means for mounting said member so that said front
surface reflector is positioned to reflect radiant en-
ergy impinging obliquely thereon; and
detector means comprising a photodiode mounted ec-
centrically in said backing member to receive a por-
tion of the radiant energy transmitted through said
reflector and said block.
References Cited
UNITED STATES PATENTS
65 2,547,545 4/1951 Strong ----------- 356-209 X
2,873,381 2/1959 Lauroesch ---------- 250-236
3,049,964 8/1962 Miller et al. _--_--- 356-209 X
WALTER STOLWEIN, Primary Examiner
U.S. Cl, X.R.
356-4
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
June 23, 1970 D. C. McKOWN ET AL Jraavr r -s.i
LASER RADAR SYSTEM
Filed Sept. 10, 1965
I Aqh/ Retvend!,
2
14star 13
J27
C. "-
r
?.*,,, .
//arwiti?-
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~ON.9.~b ?~C.IYOVYLeSt~''Y
.4 v, oA/r' ,P, ~OMMASO,
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-00120R000100010021 3, 16,743
Uniteci states ratent CC Patented June 23, 1970
1 2
3,516,743
LASER RADAR SYSTEM
Daniel C. McKown, Chino, Donald E. Howlett, River-
side, and Anthony Di Tomnsaso, Upland, Calif., as-
signors to General Dynamics Corporation, Pomona,
Calif., a corporation of Delaware
Filed Sept. 10, 1965, Ser. No. 486,507
Int. Cl. G01c 3108
U.S. Cl. 356-4 12 Claims
ABSTRACT OF THE DISCLOSURE
A compact optical system which changes the trans-
mitted output of a laser unit into a slender rectangular
beam which is scanned back and forth at right angles
to the length of the rectangle while, simultaneously, the
field of view of associated receiver optics is scanned
across a detector unit in synchronism with the scanning
motion of the transmitted beam.
FIG. I is a plan view of an embodiment of a trans-
mitter-receiver unit utilizing the optical system of the
invention; .
FIG. 2 is a schematic illustration of the inventive opti-
cal system; and
FIG. 3 is a perspective view of the drive assembly for
the optical system.
Broadly, the invention, as illustrated, relates to an
optical searching device comprising a laser, a transmitting
10 channel, a receiving channel and detecting means. Align-
ment of the transmitter and receiver in the searching
mode is accomplished by the use of a two sided scan
mirror, alternate sides of the mirror cooperating on the
one hand with the laser beam to scan a given area, and
16 on the other with detector cells to align their field of
view with the beam. Specifically, the system comprises
transmitting optics including a first lens and an adjust-
able mirror which deflects the laser output to beam shap-
ing optics comprising a projecting lens and a cylindrical
20 lens. In the receiver a single collecting lens is interposed
between the scan mirror and the reflected energy. A syn-
chronized drive assembly is utilized to operate the scan
Optical systems for tracking of laser-illuminated targets mirror.
are known in the art. Such systems include optical trans- Referring now to the drawings, the device illustrated
mitter and receiver combinations for transmitting energy 25 is the optical system of a laser radar. The optical sys-
and receiving echoes reflected back from target objects. tem consists of two main parts, the transmitting optics
In most of the known systems the transmitter and re- indicated generally at 10 -and the receiving optics indi-
ceiver are made separately and are used at spaced posi- cated generally at 11. These two parts are interlocked
tions so that the transmitted signal is reflected back through the scanning mechanism indicated generally at
through some angle from a target object to a receiver. 30 12, which causes the receiver 11 to be always looking at
Such devices present problems of accurately directing each whatever objects the transmitter 10 is illuminating.
transmitter and receiver for target object picked up and The transmitting optics 10 receives the output or beam
of coordinating the transmitter and receiver relation for 13 of a laser crystal indicated at 14, which is a beam of
object tracking. circular cross section, and forms it into a beam of rec-
Composite optical transmitter and receiver devices have 35 tangular cross section. In the process of transforming the
been developed that utilize annular transmitter and re- beam 13, the transmitting optics 10 reduces the beam
ceiver reflectors so that the signals are transmitted and divergence in one dimension and increases its divergence
received concentrically or coaxially to and from a target in the other dimension. This is done in two stages. A
object. 40 collimator comprising a first lens 15 and a projecting
The present invention utilizes optical transmitter and lens 16 is used to reduce the beam divergence in both
receiver devices which move in unison and .function to dimensions and then a cylindrical lens 17 is used to in-
transform the output of a laser crystal into a beam crease the divergence in one dimension.
whose cross section is a slender rectangle, and to scan The receiving optics includes a lens 18 which images
the rectangular beam back and forth in a direction at the target complex onto the detector cell or cells 19. The
right angles to the length of the rectangle while simul- 4u target is regarded as being at infinity because its distance
taneously scanning the receiver field of view across de- from the receiver collecting lens 18 is many times the
tector cells or an eyepiece in synchronism with the scan- focal length of the receiving optics 11. Scanning is ac-
ning motion of the transmitter fan beam. complished by the use of a single two-sided plane mirror
Therefore, it is an object of this invention to provide 60 20 oscillated by the mechanism shown in FIGS. 1 and
an optical system. 3. The light to be transmitted is reflected from one side
A further object of the invention is to provide an of the mirror 20, and the received light is reflected from
optical system having synchronized transmitting and re- the other side. Because both reflecting surfaces are de-
ceiving optics. posited on the same substrate, any rotation of the sub-
Another object of the invention is to provide an optical 66 strate will be faithfully converted into a proportional
system for a laser radar. rotation of both the transmitted beam and the receiver
Another object of the invention is to provide an op- field of view.
tical system for a laser radar where the transmitting and As shown in FIG. 2, the beam 13 of light from a
receiving optics are inter-related through a scanning laser 14 is first reflected by the scan mirror 20 onto the
mechanism which causes the receiver to be always look- 60 first lens 15 of the collimator which focuses the beam
ing at whatever objects the transmitter is illuminating. into a bright spot indicated at 21. Because of the oscil-
Another object of the invention is to provide an optical lating motion of the scan mirror 20, the focal point
system which transforms the output of a laser crystal into or bright spot 21 moves back and forth, thereby pro-
a beam whose cross section is a slender rectangle, and viding the basis for the scanning motion of the trans-
to scan the rectangular beam back and forth in a direc- 65 mitted beam, this being accomplished by the drive as-
tion at right angles to the length of the rectangle while sembly illustrated in FIGS. 1 and 3 described in detail
simultaneously scanning the receiver field of view across
a detector unit in synchronism with the scanning motion hereinafter. After passing through the focal point or
of the transmitter fan beam. bright spot 21, the rays diverge as they move toward
Other objects of the invention, not specifically set forth 70 a projecting lens 16 via an adjustable mirror 22. After
above, will become readily apparent from the following passing through the projecting lens 16, the rays are
description and accompanying drawing wherein: nearly parallel. The divergence of this, nearly parallel
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
3,516,743
3
beam is related to the divergence of the original beam
13 from the laser 14 as follows:
fle=frO
where:
fr-focal length of the first lens 15
fo=focal length of the projecting lens 16
6=divergence of the laser 14 output
O=divergence of output from projecting lens 16
Because the ratio of f p to f, would typically be 5 to 1,
the output beam divergence is only one fifth the diver-
gence of the input laser beam. This output beam diver-
gence is satisfactory for the narrow dimension of the
rectangular beam cross section, but the divergence is
not great enough for the longer dimension of the beam.
To broaden the beam in the long dimension, the di-
verging (negative) cylindrical lens 17 is inserted into
the optical path following the projecting lens 16. The
resulting long dimension of the beam is:
2
4,+2 are etu jc
where:
gyp=divergence of output from projecting lens 16
f c=focal.length of cylindrical lens 17
d=diameter of the bundle of rays falling on the
. drical lens 17
4
at 28 on the housing 29 of the optical system. Lever 27
is spring biased in one direction by spring 30 and in the
opposed direction by cam follower 31 driven by cam
32 which in turn is driven by a prime mover or motor
33 via a gear train indicated generally at 34, the gear
5' train 34 being mounted in a support member 35. The
motor 33 may be electric or other suitable type.
A potentiometer 36 is also driven through gear train
34 and functions to determine the angular position
10 (phase) of the cam 32 and thus providing a means
whereby the target location can be read out electrically
at the instant the target is registered by the detector
cell or cells 19.
Housing 29 is provided with a pair of slots 37 which
15 permits the drive assembly for lever 27 to be moved
toward or away from the scan mirror 20 whereby the
scan mirror 20 can be moved through different scan
angles to enlarge or decrease the field scanned due to the
cam follower action on different effective lever arm
20 lengths of lever 27. Screws or other attaching means in-
dicated at 38 serve to hold the support housing 35 of
the drive assembly fixed in slots 37.
It is thus seen that the present invention provides a
laser radar having an optical system which utilizes a
25 single scanning mirror to insure synchronism between
the transmitter and receiver functions. Also, the novel
use of the cylindrical lens to form a beam having a
rectangular cross section thereby provides an advance
The adjustable mirror 22 is used in the transmitted over the prior known systems.
beam path between the first lens 15 and the projecting 30 Although a rectangular beam cross section is utilized
lens 16 to change the direction of the rays and to pro- herein, the scan synchronizing technique is equally appli-
vide an adjustable capability which is accomplished via cable to other beam shapes such as multiple fan beams
adjustment screws indicated at 23 in FIG. 1. or V-beams, however the forming optics for such beams
The receiving optics 11 consists of the receiver col- would be different.
lecting lens 18 and the scan mirror 20. The receiver 35 By substituting an eyepiece and a human observer in
collecting lens 18 focuses the rays toward the detector place of the detector cell, the system could be used for
cell or cells 19 which is adjustably mounted by the visual scanning with illumination. This approach could
mechanism indicated at 24 in FIG. 1, the cell being be useful in directing a searchlight beam against an air-
omitted in FIG. 1 for clarity. Along the optical path craft, due to the observer's eye remaining fixed during
between the receiver collecting lens 18 and the detector 40 the scanning.
cell or cells, the rays are reflected by the scan mirror Although a particular embodiment utilizing the inven-
20 which changes their direction and imposes a scanning tion has been illustrated and described, modifications
motion on the image formed at the detector cell 19 will become apparent to those skilled in the art, and it
which lies in the image plane of the receiver collecting is intended to cover in the appended claims all such modi-
lens 18. This scanning motion is provided through the 45 fications as come within the true spirit and scope of the
drive assembly illustrated in FIGS. 1 and 3 and de- invention.
scribed hereinbelow. What we claim is:
The detector cell 19 remains motionless. It is desired 1. A laser radar comprising, in combination, a laser
that the detector cell 19 always receives the radiation unit, synchronized transmitting and receiving optics, and
indicated at 25 returned from the spot or target illu- 50 detecting means, said laser unit being operably disposed
minated by the scanning transmitted beam 26. There- to transmit a laser beam to an associated target via said
fore, the scene formed by the receiver collecting lens 18 transmitting optics; said receiving optics being operably
must be scanned across the detector cell 19 by exactly disposed to receive a laser beam reflected from said asso-
the right amount to keep the image of the moving illu- ciated target and to direct said reflected beam to said
minated spot or target centered on the detector cell. To 53 detecting means; said transmitting and receiving optics
achieve this degree of synchronism, the present inven- including a dual sided mirror-like scanning means opera-
tion makes use of the scan mirror 20 which is silvered bly disposed between said transmitting optics and said
on bpth faces for use by the transmitter 10 and receiver receiving optics for synchronizing said receiving optics
11. Thus, the common scan mirror 20 produces identical with said transmitting optics; and means operably con-
movements of the rays in the transmitting and receiving Ou nected to said scanning means for moving said scanning
portions of. the optical system. Because the projecting means; said transmitting optics additionally including an
lens 16 and the receiver collecting lens 18 have different adjustable mirror, a first lens operably disposed between
focal lengths, the necessary condition for synchronism said scanning means and said adjustable mirror for direct-
is that: ing said laser beam onto said adjustable mirror for reflec-
tion therefrom, a second lens operably disposed to receive
where: to diverge to a substantially parallel pattern, and a third
lens operably located adjacent said second lens to receive
r=distance of receiver image plane from scan mirror 20. tt said substantially parallel rays of said reflected laser beam
In practice, the distance r is varied systematically until and to broaden said beam in a long dimension; said scan-
synchronism is achieved. ning means being pivotally mounted for reflecting said
Referring now to the scan mirror drive assembly illus- laser beam onto said first lens while simultaneously re-
trated in FIGS. I and 3, a lever member 27 is oper- flecting the received beam onto said detecting means; the
?' corresponding
ativel Approved For Release 2009/04/10: CIA-RDP81-00120R000100010021-3-
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
3,516,743
5
changes in the direction of the respective beams reflected
from said scanning means.
2. The laser radar defined in claim 1, wherein said
receiving optics additionally includes a lens for collect-
ing the beam rays reflected from said associated target
and focusing the rays toward the detecting means via said
scanning means.
3. The laser radar defined in claim 2, wherein said
dual sided scanning means consists of a plane mirror
silvered on both faces which thus produces identical
movements of the rays being transmitted and received.
4. The laser radar defined in claim 3, wherein said
means for moving said scanning means includes a prime
mover, gear means drivingly connected to said prime
mover for movement by said prime mover, a cam op-
eratively connected to said gear means and responsive
to the movement of said gear means, a cam follower
operably disposed relative to said cam and responsive to
movements of said cam, a lever operatively connected to
said scanning means and to said cam follower, said cam
follower biasing said lever in one direction to move said
scanning means, and bias means operatively connected
to said lever and responsive to movements of said cam
and cam follower for biasing said lever in a direction op-
posed to that of said cam follower.
5. The laser radar defined in claim 4, wherein a po-
tentiometer is drivingly connected to said gear means.
6. The laser radar defined in claim 5, additionally in-
cluding means operably connected to said detecting
means for adjustably positioning said detecting means.
7. An optical system comprising: a source of light,
transmitting optics from transmitting light from said
source to a target, receiving optics for receiving light
returned from said target, and means operably disposed,
between said transmitting optics and said receiving optics
for synchronizing said receiving optics with said trans-
mitting optics; said synchronizing means comprising a
pivotally mounted dual sided mirror-like means, and
means operably connected to said mirror-like means for
oscillating said mirror-like means; said transmitting optics
comprising an adjustable mirror, a first lens operably dis-
posed between said dual sided mirror-like means and said
adjustable mirror, a second lens, said adjustable mirror
operably positioned between said first and second lenses,
and a third lens located on the side of said second lens
opposite said ajustable mirror; said pivotally mounted
6
mirror-like means reflecting the light from said source
onto said first lens while simultaneously reflecting the
returned light onto detecting means; the oscillation of
said mirror-like means causing corresponding changes in
the direction of the respective beams reflected from said
mirror-like means.
8. The optical system defined in claim 7, wherein said
receiving optics includes a collecting lens.
9. The optical system defined in claim 8, wherein said
means for oscillating said dual sided mirror-like means
includes a lever means operatively connected to said
mirror-like means, biasing means operatively connected
on one side of said lever means for biasing said lever
means in one direction, and means operatively connected
on the side of said lever means opposite said biasing
means for driving said lever means against said biasing
means.
10. The optical system defined in claim 9, wherein said
driving means includes a cam and cam follower.
11. The optical system defined in claim 10, wherein
said cam and cam follower are driven by a prime mover
via gear means operatively connected to said prime
mover and to said cam and cam follower for driving said
cam and cam follower.
25 12. The optical system defined in claim 11, addition-
ally including means driven by said oscillating means
for determining the angular position or phase angle of
said cam.
References Cited
UNITED STATES PATENTS
3,364,358
1/1968
Answorth ----------
250-219
2,750,836
6/1956
Fastie.
3,278,753
10/1966
Pitts et al.
3,293,438
12/19,66
Davis.
FOREIGN PATENTS
992,760 '
5/1965 Great Britain.
RONALD L. WIBERT, Primary Examiner
F. L. EVANS, Assistant Examiner
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Oct. 13, 1970 H. G. DE WINTER 3,533,696
LASER RANGE FINDER INCLUDING A LIGHT DIFFUSING ELEMENT
Filed July 8, 1966
1d 1r 16 15'
INVENTOR
adfflAc-14,eale tau
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
United States Patent Office 3,533,696
Patented Oct. 13, 1970
1 2
3,533,696
LASER RANGE FINDER INCLUDING A LIGHT
DIFFUSING ELEMENT
Iiermanus Gerardus de Winter, Enschede, Netherlands,
assignor to N.V. Optische Industrie "De Oude Delft,"
Delft, Netherlands, q corporation of the Netherlands
Filed July 8, 1966, Ser. No. 563,764
Int. Cl. G61c 3108
U.S. Cl. 356-4
ABSTRACT OF THE DISCLOSURE
A laser range finder device in which a small sample
of the pulsed light beam transmitted by the laser head
is fed back to the receiver optics along an optical path
including a light deffusing element.
placed at an angle to the beam, axis, whereas the surface
in the reflective beam is a diffusely reflective or diffusely
transmissive surface. In order to permit adjustment of
the intensity of the sample of radiation coupled back to
the detector, the angle of any of such surfaces, or of
both, relative to the respective beam axes may be made
adjustable.
A particularly simple embodiment is achieved by pro-
viding a rod-like element of a material which is trans-
parent to the laser radiation and one end of which projects
into the laser beam transmitted and is so shaped that a
portion of that beam enters the element and is guided
thereby toward the other end of the element which projects
into the reflected beam and has a diffusing exit surface
for the radiation. Suitably, such element is a straight rod
which is supported in a plane substantially perpendicular
to the laser beam axis so as to be rotatably adjustable
about its own axis, and has two beveled end faces one of
which at least has radiation diffusing properties.
The radiation diffusing surface in the device according
to the invention ensures that in all circumstances radia-
tion from the laser beam will be incident on the optical
receiver within the extremely small spatial angle from
which radiation is passed on to the detector, without
having to resort to delicate adjustments which other
The invention relates to laser apparatus and, more
particularly, to laser range finders and like devices which 20
comprise a laser transmitter to transmit a pulsed beam
of radiation toward a target, an optical objective system
for receiving a beam of reflected laser radiation from
such target and a detector for detecting such reflected
radiation. 25
Devices of this kind form an important field of appli- available means, such as mirors, would require. On the
cation for lasers. They may be used, e.g. in conjunction other hand it provides automatically the necessary weak-
with suitable electronic counters to measure the time ening of the radiant energy before reaching the detector.
lapse between the transmittal of a pulse by the laser and Since the zero pulse and the echo pulse are both produced
the reception of a reflected pulse from the target whereby 30 by the same detector and processed by the same electronic
the distance to such target can be determined. In addi- circuits, the intensities of the direct laser radiation and
the to range finders in the strict sense, e.g. optical radar e same order this on the detector should o be in the
systems fall into the category of apparatus to which the laser order and d th this may of, necessitate t 1 attenuation of ght
invention is applicable. aser beam by a factor of, e.g. 106 to 108. This is brought
In order to accurately define the zero point of the 35 about by scattering almost all of the laser radiation picked
time measurement a sample of the radiation pulse trans- up from the beam outside the small spatial angle which
mitted by the laser is directly fed to a radiation detector. we optical be in th sorter 1 passes on to the Further and milli
rad The electric pulse thus generated may be used to start by ah may the in tng angular positions of the di diffusing and/or
an electronic counter or utilized in any other manner 40 reflective surfaces su trfs in the device d sc the ditheir pa ens
according to the specific aces in the described, their apparent
g purpose of the device envisaged. area or their effectiveness in directing radiant energy
It has hitherto been common to provide a separate toward the detector can be controlled with a view to
detector for generating the zero pulse and such detector
wide limits the amount of energy incident
is placed beside the laser beam and receives a fraction on the varying o detector.
of the laser beam either from a small mirror projecting on tor.
45
into the laser beam or from a wire grid which is posi- The drawing illustrates
range fier constructed cpre in ac-
in ac
tioned in front of the laser and scatters some of the radia- cordance embodiment with the a invention. on. In finder
drawings:
tion thereof into the direction of the zero pulse detector. FIG. 1 shows t device in the longitudinal cross It is an object of this invention to provide simple means FIG. ws the device in longitudinal csection;
to guide a required amount of radiant energy from the FIG. 2 shows a partial front view; 50 FIG 3 shows the coupling element of the device at a
laser beam to the detector detecting the radiation reflected larger r scale.
by the target, so that the same is also utilized as zero In FIG. 1, the housing 1 of the device has two com-
pulse detector. It is a further object to provide such partments separated from each other by a light tight
means which permits the amount of energy from the partition. In the upper
laser beam that is incident on the detector to be easil compartment a devica 2 i-
Y 65 housed, whereas the lower compartment co laser contains a tele-
adjusted within wide limits. A still further object is to scope 3 diagrammatically shown as comprising an objec-
provide such means which does not require critical adjust- tive 4, a prism image inverting system 5 and an eye piece
ments to ensure that a sample of the laser beam is incident 6. The laser and telescope axes are parallel. In the focal
on the detector. plane of the eye
pi a is
permit
In accordance with the invention, broadly, means are 60 accurate sighting onca targctit e 7 distance toed to is provided to diffuse a portion of the radiation of the pulsed be the distance to which is to
be measured.
beam transmitted and to make such diffused radiation The laser
incident on the optical objective system so that a sample tion, which boderally will produce iubrared radios
thereof is detected by the same detector which detects has in the embodiment illustrated a ruby rod as its
the reflected radiation. In a preferred embodiment opti- is5 active medium, which is optically "pumped" by means of
cally active surfaces are placed in the laser beam trans- a helical flash lamp 9. High energy pulses of very short
mitted and in the reflected beam entering the optical duration are generated by means of a roof prism 10 which
objective system so that radiation from the laser beam borders the laser cavity on one side and can be rotated
transmitted is directed into the objective system via said very fast by driving means not specificially shown in the
surfaces, and at least one of these surfaces has radiation 70 drawing, a technique well-known in the art as Q-switch-
diffusing properties. More specifically, the surface in the ing. The resulting pulsed beam of monochromatic coher-
laser h-:,m tranamitt ri m',,, F.. _
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3 small spatial
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
V, V U U, V IJ,J
3
angle and is 'accurately parallel to the axis of the tele-
scope 3.
A parallel beam 12 of radiation which has been reflected
by the distant target is focused by the objective 4. In the
convergent' beam behind the objective a beam splitting
prism 13 is positioned which is preferably provided with
a dichroit surface 14 which, in well-known manner, is
virtually transparent for visible light but selectively reflects
infrared components of the incident radiation including
the laser radiation toward a prism 1.5. Through a narrow
pass-band filter 16 the laser radiation falls on a diaphragm
or field stop 17 which is positioned in the plane of best
focus and has a pin point aperture corresponding to the
target point to which the laser beam has been directed.
The radiation admitted by the aperture is detected by a
photomultiplier 18. Whereas through the eye piece 6 the
whole field of the telescope 3 may be observed the photo-
multiplier 18 receives only the reflected laser radiation
from a small target in the center of such field.
To derive a starting or zero pulse for the time meas-
urement a sample of the radiant energy of the laser beam
11 is coupled back to the photomultiplier 18 directly by
means of a rod 19 of a material which is transparent to
the laser radiation and which has one end projecting into
the laser beam whereas the other end projects into the
reflected beam 12. The manner in which the rod is mount-
ed appears best from FIG. 2, whereas FIG. 3 shows the
end portions of the rod on an enlarged scale.
The rod is cylindrical in shape and rotatably mounted
in a hole of a support 20 attached to the instrument hous-
ing 1. A milled ring 21 fixed to the rod 19 facilitates its
angular adjustment and a blade spring 22 maintains the
rod in the selected position.
. Both end surfaces of the rod 19 are beveled at 45? with
the rod axis (FIG. 3). Surface 23 is optically polished
flat and serves to deviate by total reflection incident radia-
tion from the laser beam entering the rod through its
cylindrical surface towards the exit surface 24. This latter
surface has been made diffuse, e.g. by grinding, such that
radiation reaching this surface is scattered in a wide spatial
angle, as illustrated by the bundle of arrows in FIG. 3.
Thus, an extremely small fraction only of this radiation
will enter the objective 4 at such an angle as to be ad-
mitted by the pin hole of the field stop 17 to the detector
18. On the other hand, the rod need not be adjusted to
any precision since the scattering at the diffusing surface
24 ensures that some of the laser radiation will in all
circumstances be within the small field angle which the
objective 4 focuses on the pin hole of field stop 17. The
amount of energy actually incident on the detector can be
easily adapted to the requirements of the detector and
its related circuitry by rotating the rod 19. Thereby the
angle at which the laser beam sees the surface 23 and
hence the apparent effective area of this surface is varied,
as well as the percentage of the radiation leaving the rod
at surface 24 which eventually falls on the detector 18.
The latter is true since, generally, the diffusion caused at
surface 24 will not be such that the intensity of the result-
ant radiation is equal in all directions.
Many modifications may be applied to the apparatus
shown and described without giving up its essential ad-
vantages and without leaving the domain of the invention
in its broader aspects.. As an example, it is within the
scope of the invention to utilize separate small reflectors
4
respect to the beam axes such that the reflector in the
reflected beam receives some of the radiation deviated
by the reflector in the laser beam. At least one of these
reflectors may have diffusing properties, or a separate dif-
fusing element, such as a ground glass, may be mounted
in the optical path defined by the reflectors. Alternative-
ly, a reflector in the laser beam may be omitted and a
diffusing element of any kind, such as a grid may be
provided therein, in combination with a mirror in the
reflected beam, to transmit some of the scattered radia-
tion to the optical receiver. Preferably, in devices for
military purposes it should be avoided, however, to use a
diffusing element in the laser beam that scatters radia-
tion in forward directions also since this would f1c'i t t
r
a
.
r
e
detclction of the range finders by enemy forces. Finally, it
will be understood that a rod-like element like the one
described, instead of being straight, could have curved end
portions and light entrance an exit surfaces perpendicular
to the beam axes of which at least one has light diffusing
properties.
What I claim is:
1. In a laser range finding device comprising a laser
transmitter to transmit a pulsed beam of radiant energy
concentrated in a narrow spatial angle toward a target;
an optical receiver including an objective for focusing a
parallel beam of radiant energy reflected from said target
in a focal plane, a pin hole field stop in said focal plane to
discriminate between reflected radiant energy entering said
objective within said narrow spatial angle and other radia-
30 tion, and a detector disposed behind said field stop for
detecting such reflected radiant energy; a mirror reflective
surface placed in said transmitted pulsed beam at an
oblique angle to the laser axis for deflecting a sample of
said transmitted pulsed beam so as to become incident on
35 said objective, and a diffusing surface placed in front of
said objective at an angle to the objective axis, for optical-
ly diffusing said sample before entering said objective,
whereby some of the radiant energy in said sample is
projected by said objective on the pin hole of said field
40 stop and received by said detector, the angle of at least
one of said mirror reflective surface and said diffusing sur-
face being adjustable.
2. The device defined in claim 1, wherein said mirror
reflective surface and said diffusing surface are beveled
45 end faces of a radiation transparent rod supported in a
plane perpendicular to the laser axis and rotatably ad-
justable about its own axis.
References Cited
UNITED STATES PATENTS
2,577,815 12/1951 Saunderson et al. ------ 88-14
3,150,363 9/1964 Finvold.
3,373,441 3/1968 Zadig.
OTHER REFERENCES
NEREM Record, 1962, session 3: Highlights of Army
Communications and Electronics R&D. Nov. 5, 1962.
RONALD L. WIBERT, Primary Examiner
V. P. McGRAW, Assistant Examiner
in the laser beam and in the reflected beam at angles with 65
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
April 3, 1951
M. SCHWARTZ ET AL
RANGE FINDER WITH LIGHT BEAM CORRECTION
Filed Feb. 28, 1946
ATTORNEY
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2,547,232
)G 4L/AMCASTED L1-0
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Patented Apr. 3, 1951
UNITED STATES PATENT OFFICE
2,547,232
-RANGE FINDER WITH LIGHT BEAM
CORRECTION
-Morris Schwartz and William Castedello, Stam-
ford, Conn., assignors to The Kalart Compan$
-Inc., Stamford, Conn.
Application February 28, 1946, Serial No. 650,927
7 Claims. (C1.88--2.7)
I
This invention relates to light beam projecting
range finders, particularly to range finders of the
type in which a source of light is positioned be-
tween two light deviating means or reflectors,
one of which is movable, and in which the-angular
position of the movable reflector relative to the
stationary one is employed, either to ascertain
the range of an object or to focus the lens -of a
2
change of the filament position relative to t
plane through or parallel to an axis between the
two reflectors Is automatically corrected.
Another object of the invention is to provide
means which correct a variation of the light
paths, as caused by a-change of the filament posi-
tion relative to a plane through or parallel to an
axis between the reflectors without requiring an
the latter type cf range adjustment of any component parts of the range
photographic camera
,
finders being sometimes referred to as "lens cou- 10 finder.
pled range finders." Another object of the Invention is to provide
The word "camera, ' as used'herein, is intended optical means which maintain the two beams
to include apparatus for the taking of photo- projected
the parallel to range
other for eel adjustments range finder always
find graphs as well as devices, such urgerpicture 16 requiring such parallelism of the light beams in--as proJejecrors. television cameras, enlarges, and the
dependently of a variation of the filament -posi-
like, o or in other words, any device comprising ; a a
lens to be focused on an object or screen. tion relative to the reflectors.
.In range. finders of the type above referred to, Other and further objects, features and ad-
the source of light usually comprises an electric vantages of the invention will be set forth,here-
lamp having an incandescent filament, two im- 10 Inafter and the novel features thereof defined
ages of which are viewable on the object. The by the appended claims.
relative position of these images -is varied by The present application is a continuation In
means of the movable reflector, and the two part of the co-pending application Ser.:No.
images are brought into a predetermined' posi- 495:,872, red on July 15, 1943, by Morris Schwartz
tion relative to each other which is indicative Af 25 and William Castedello and Issued as Letters
the range of the object. Patent 2,403,308 on :July 2, 1946.
As will be evident to a person skilled in the In the accompanying drawings several -now
art, the accuracy of a range finder of the type preferred embodiments are shown -by -way of
above referred to will be affected by a variation Illustration and not by way o limitation.
of the position of the lamp .filament, relative to 30 Fig. 1 is a diagrammatic view of -the -optical
the two reflectors because any variation of the components of a light beam projecting -range
filament positioh will cause the images to be finder according to the invention.
viewable on the object in a different relative posi- Fig. 2 is a plan view of a light beam projecting
Lion fora given range of the object. It has been range finder including an electric lamp -accord- .
found that in electric lamps, as commercially 35 Ing to the invention.
available on the market, the filament is not al- Fig. 3 is a diagrammatic -view of the :optical
ways in the same position. Furthermore, the components of a modification of a light- beam
lamp will not always be inserted in the socket in projecting range finder according to the inven-
the same position. As a result, when a new lamp tion, and
Is inserted, it may be found that the filament of 40 Figs. 4 and 5 are diagrammatic views of the
such new lamp is changed relative to a plane images produced -by a light 'beam :projecting
parallel to an axis between the two reflectors, range finder -according to the Invention on -an
and/or that the filament of the new lamp is object, the images being shown in different posi-
slightly tilted relative to a plane through the tions of adjustment.
filament of the old lamp. Either such change of 45 Refer- now to -the -figures'Indetail, -the op-
the filament position will result in altered light tical system of the -light -beam projecting range
paths finder, as shown .in Fig. 1. comprises an electric
An arrangement for correction of a tilting of lamp t 9 having a filament If. This lamp -directs
the lamp has been fully described and disclosed a beam of light toward a pivotal light deviating
In the co-pending application, Ser. No. 648,726, 50 mesas 12 s'ich ?as a fully -silvered mirror -or a
filed Fel'r' :!y 19, 1946, by Morris Schwartz and prism which re-directs'-the beam of light toward
William ' ? ?' cello. which application is now an object the range of which Is to be ascertained.
abandor' : The beam of light reflected by mirror 12 is passed
:"h[- r ,f this invention Is to provide through an image forming lens 13 so that ;aa
anon"- env inaecuracy caused by a 65 image of filament it 1 4s -viewable on the object.
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2,b47; 82
F-. 6
plane parallel to the optical adis'between mirror prising a light source, a first light deviating means
12 and pentaprism 15. receiving light from said light source and direct-
in order to facilitate the understanding of the ing a beam of light toward an object, and a second
invention, It be first assumed that pentaprism 15 light deviating means receiving light from said
be'replaced by a reflector such.as mirror 12. It S light source and directing a second beam of light
will then be evident to a person skilled in the art toward the object, said light deviating means
that a variation of the filament position in axial being constructed to be movable relative to each
direction. say a higher position of filament 11. other for varying the angular relationship of said
will result in two light beams that are no longer light beams, one of the light deviating means
parallel to each other when mirror 12 is placed 10 having constant 90? deviation characteristics.
in a position corresponding to the maximum 2: A light beam projecting range finder com-
measuring range of the range finder, thereby prising a light source, a first image forming lens
causing faulty indications throughout the entire means receiving light from said light source, a
measuring range of the range finder. Let it be first light deviating means receiving light from
now assumed that filament I I be in a higher posi- 15 said first lens means and directing a beam of
tion in a range finder according to the invention light toward an object, a second light deviating
In which light deviating means 15 consists of a means receiving light from said light source, and
means having constant 90? deviation characteris- a second image forming lens receiving light from
tics. As a result of a higher position of fila- said second light deviating means and directing a
ment 11 lh!Feh is indicated in Fig. 1 by dashed 20 second beam of light toward said object, said
lines, the light beam (shown in dashed lines), as light deviating means being constructed to be
reffected by mirror 12 will constitute an angle movable relative to each other for varying the
(a) with the light beam (shown in dashed-dotted angular relationship between said light beams.
lines), as reflected by mirror 12 when filament one of the light deviating means having constant
is in its original position, (shown In full lines). . 90? deviation characteristics.
The second light beam will also be reflected by 3. A light beam projecting range finder com-
prism 15 at an angle to the light beam as re- prising a light source, a first image forming lens
flected by the pentaprism when filament I I is in means receiving light from said light source, a
Its original position. Due to the constant 90? first light deviating means receiving light from
deviation characteristics of prism 15, this angle 30 said first lens means and directing a beam of light
will be always the same angle (a) as the angle toward an object, a second light deviating means
between the light beams reflected by mirror 12. receiving light from said light source, and a
Consequently, parallelism between the light beams second image forming lens receiving light from
as rrojected by the light deviating means will said second light deviating means and directing a
be maintained in any higher position of filament as second beam of light toward said object, one of
11. The same is true when the filament II is in said light deviating means being pivotal for vary-
any lower position, the only difference being that ing the angular relationship between said light
then the dotted light beams will be at the oppo- beams, the other light deviating means having
site side of the dashed-dotted light beams. constant 90? deviation characteristics.
It will of.course be understood that the correc- .i4. A light beam projecting range finder as de-
tive properties of pentaprism 15 are limited by the scribed is claim 2, wherein the light deviating
size of the pentaprism, but experience shows that means having constant 90? deviation character-
variations in the filament position are rarely if istics ccmprises a pentaprism.
ever beyond the corrective range of pentaprism 15. 5. A ;fight beam projecting range finder as de-
Fig. 3 shows a modification in which penta- 45 scribed in claim 2, wherein the light deviating
prism 15 is replaced by two stationary fully means having 90? deviation characteristics com-
silvered mirrors 15' and 15" arranged at a rela- prises a pair of mirrors mounted at a relatively
tively acute angle to each other. These mirrors acute angle to each other.
correspond to the reflecting surfaces of penta- 6. In a light beam projecting range finder In-
prism 15 and hence constitute a light deviating 50 eluding a light source, in combination a pair of.
means having constant 90' deviation characteris- images forming lenses and reflecting means for
tics. As a result, mirrors 15' and I5" will always directing a pair of images of the light source on
maintain parallelism between the reflected beams an object whose range is to be determined, one
independently of a variation of the filament posi- of said reflecting means being a movable mirror
tion, as previously described. 55 to effect coincidence of the images on the said
It should be understood that the invention is object, the other reflecting means comprising a
not and shall not be limited to the light deviating constant 90? deviation prism, whereby a slight
means, as herein disclosed but that other light displacement of the light source relative to the
deviating means may be provided having constant optical axis of the range finder will result in dis-
90? deviation characteristics. 60 placement of the images which are equal and In
Fig. 4 shows an object 50 on which two images the same direction.
II' and I I" of filament II are viewable. These 7. In a light beam projecting range finder. in
Images are shown separated from each other, combination an exchangeably mounted electric
thereby indicating that the angle of mirror 12 incandescent lamp having a filament, an Image
does not correspond to the correct range of the 65 forming lens and a reflecting means mounted
ob46ct. on either side of the lamp in an optical relation-
Fig. 5 shows the two Images in a super-imposed ship with the lamp filament for directing a pair
position, thereby indicating correct adjustment of of images of the filament to an object whose
the angular position of mirror 12 which in turn range is to be determined, one of said reflecting
will result in a correct focusing of the camera 70 means being a movable reflector to effect coin-
lens in case of a lens coupled range finder, as has cidence of the images on the said object, the
been explained in connection with Fig. 2. other reflecting means having constant 90? devia-
What is claimed as new and desired to be tion characteristics, whereby a slight displace--
secured by Letters Patent is: ment of the filament position relative to the opti-
1. A light beam projecting range finder corn- 74 cal axis between the reflecting means will result
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
7
8
in displacements of the said images that are equal
UNITED STATES PATMM
and in the same direction.
Number
Name Date
MORRIS SCHWARTZ.
889
625
Konig et a1
June 2
1905
WILLIAM CASTEDELLO.
.
1.062,166
. ___-.____
,
Konig May 20,
1913
REFERENCES CITED
6
1,489,838
Kohler -------------- Apr. 8,
1924
2,379,698
Tischer _____________- July 3,
1945
The following references are of record In the
2,401,706
Mihalyl ------------ June 4,
1946
file of this patent: .
2,403.308
Schwartz et al. ------- July 2,1946
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Feb..8, 1955 M. SCHWARTZ ET Ai. 2,701,500
RANGE FINDING UNIT, INC(.UDING A VIEWING RANGE -
FINDER AND A LIGHT BEAM PROJECTING RANGE
FINDER FOR PHOTOGRAPHIC PURPOSES
Filed March 9, 1951 2 Sheets-Sheet l
INVENTORS
- Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Feb. 8, 1955 M. SCHWARTZ ET AL 2,701,500
tANGE FINDING UNIT, INCLUDING A VIEWING RANGE
FINDER AND A LIGHT BEAM PROJECTING RANGE
Filed Barth 9, 1951
INVENTORS
zI.
..err?,~iv,~=s:~
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 Approved For Release 2009/04/10: CIA-RDP81-00120R000100010021-3
2,701,500
3 4
rib 42 for instance by a. scree: 44. Lever 41 is further 20 to reach prism 15 and to disturb thereby the observer
lever 41. It will be apparent that adjustment of screw tems of the range finders may further be shielded against
45 will vary the path of engagement between pin 39 and stray light by a shield 80 secured to base plate 10 by an
wedge surface 40 and, thereby, also the ratio of trans- ti ear 81.
mission between the rotation of shaft 22 and the angu- As will appear from the previous description, the
lar position of prism 13. One arm of a two-arm lever optical systems of the two range finders are disposed in
46 is pivoted to lever 41 by a pivot pin 47 and the other two different planes parallel one to the other. The only
arm of this lever is pivoted by a pivot pin 48 to an arm movable optical components of the two finders, namely
49. Lever 46 is pivotal about a pivot 50. Arm 49 is 10 the pivotal reflector, are combined in the single clement
pivoted to an arm 51 which in turn is fixedly secured to 13 so that the same moving means 21 can be used for
shaft 22, for instance by means of a screw 52. Springs the pivotal reflectors of both the finders. Furthermore,
53 and 54, secured on one end to base plate 10 and one of the image forming lenses is disposed between
and reflectors. Finally, the provision of the
on the other end to arm 51 and lever 41 respectively, load the r14 espective
the entire system so that wedge surface 40 is always 15 reflectors permits to view the two images of
based against pin 39 and a notch 55 is biased against a the viewing range finder in a position very closely adjacent
limiting edge 56 of lever 46. to the position normally occupied by the eye of the ob-
The entire hereinbefore described system of moving server when the observer uses the view finder of a
means 21 is mounted in the lower level or plane or camera of the type here in question. This view finder, as
closely adjacent to base plate 10. As will be apparent, 20 previously mentioned, may be visualized as being disposed
a certain angular rotation of shaft 22 will result in a in the compartment to the left of shield 30. As a result,
corresponding pivotal movement of prism 13, thereby only a slight shift of the eyeball of the observer is neces-
i
i
h
jointly varying the angular position of the pivotal re-
flecting surfaces of both the range finders.
Image forming lens 18 is secured to base plate 10 by
means of a mounting 60 which can be adjusted in the
direction of the optical axis of the lens by means of an
elongated slot 61 and a screw 62. Similarly, lens 19 is
secured to block 25 by means of a mounting frame 63
and can be adjusted in the direction of its optical axis by
means of an elongated slot 64 and a screw 65 engaging
a bracket 66 secured to block 25.
`A mask 70 on the lower half of prism 13 limits the
effective reflecting surface of this prism in accordance
with the diameter of lens 18.
Lamp 20 is inserted in a lamp holder of suitable de-
sign. This lamp bolder is shown as comprising a metal
sleeve 71 which is rotatably fitted in a wall 72 which
may be visualized as part of the camera casing. Sleeve
71 supports an insulation sleeve 73 in which is fitted a
metal sleeve 75 which serves to receive the base of lamp
20. The terminals of the lamp are connected in a con-
ventional mariner to a source of current, usually a battery
disposed within the camera casing. The entire lamp
holder can be rotated by means of a knurled head 85
accessible from the outside of the camera. To secure the
holder in a selected rotary position an insulation block
86 is secured by screws 87 to a bracket extending from
base plate 10 (not shown). The insulation block sup-
ports two springs 83 and 89 secured to block 86 by
screws 90. These springs engage frictionally sleeve 73
thereby holding the lamp holder in position. A pin 91
extending from sleeve 71 and engageable with a station-
ary stop 92 secured to base plate 10 or part of the
camera casing serves to limit the rotational movement
of the lamp holder.
The globe of the lamp extends into an axial bore 93
of a block 94 made of opaque material and secured to
base plate 10. Block 94 further includes two channels
or bores 95 and 96 extending from the central bore 93
and positioned in alignment with the lamp filament 74 and
the optical center axis between reflectors 11 and 13.
Lamp 20 is of the type having a filament 74 in form of
a substantially cylindrical coil and is so inserted in the
lamp ' holder that the long axis of the filament coil is
parallel to the aforementioned optical axis. As a result,
the two images of the lamp filament which are projected
by the light beams of the range finder appear as circles
which can be conveniently and accurately placed in a
superimposed position.
As previously mentioned, frame 27 'of the beam splitter
11 of the viewing range finder is mounted on the top of
block 2S. The position of the beam splitter can be ad-
justed by means. of a screw 76. Rotation of this screw
by means of a crown wheel 76' causes the.beam splitter
to be tilted slightly in its own plane for purposes of
adjustment.
The reflecting prism 14 of the viewing range finder is
also mounted on block 25 or more specifically on a
raised portion 25' thereof so that prism 14 is at the cor-
rect level relative to the beam splitter, as can best be seen
on Fig. 3. The.viewing prism 15 of the viewing range
finder is mounted on the same level as prism 14 by means
of a post 77 secured to base plate 10. A mask or screen
ng operat
on to t
e range
sary to switch from the view
finding operation.
25 The result of the aforedescribed structural arrange-
ment of all the optical and mechanical components of
the range finders is a very compact design which can be
conveniently mounted within the available space of a
camera casing without requiring an undue reduction of
30 the size of the individual components.
While the invention has been described in detail with
respect to a certain now preferred example and embodi-
ment of the invention it will be understood by those
skilled in the art after understanding the invention, that
35 various changes and modifications may be made with-
out departing from the spirit and scope of the invention,
and it is intended, therefore, to cover all such changes
and modifications in the appended claims.
What is claimed as new and desired to be secured by
40 Letters Patent is:
1. A photographic range finding unit comprising a
viewing range finder and a light beam projecting range
finder, the said viewing range finder including a semi-
transparent stationary reflector through which an image
45 of an object exterior to the said range finder is viewable,
'a pivotal reflector disposed in optical and spacial align-
ment with the stationary reflector so as to reflr';t a second
image of the exterior object to the stationary reflector,
and reflecting and viewing means optically associated
b0 with the stationary reflector for viewing the said two im-
ages; the said light beam projecting range finder includ-
ing a stationary reflector, a pivotal reflector, a holder
for a source of light disposed between the two reflectors
of the light beam projecting range finder, the said sta-
tit, tionary reflector, the said pivotal reflector and the said
holder of the light beam projecting range finder being
disposed in optical alignment an image forming lens be-
tween said light holder and the respective pivotal re-
flector in optical alignment therewith, and a second im-
age forming lens between the respective stationary re-
flector flector and said exterior object in optical alignment there-
with, thereby causing each of the two reflectors of the
light beam projecting range finder to reflect a light beam
emanating from a source of light in said holder toward
85 the said exterior object, respective reflectors of the two
range finders being disposed one above the other substan-
tially in alignment one with the other, the said pivotal
reflectors of the range finders being formed by a single
pivotally mounted reflecting member including a light
To deviating surface having a portion in optical and spacial
alignment with. the stationary reflector of one of the
range finders for the purpose aforesaid and a second
portion in optical and spacial al>nment with the sta-
tionary reflector of the other rar.L. finder for the pur-
75 pose aforesaid, and moving means coupled with said piv-
otal member for varying the angular position of the said
pivotal reflectors.
2. A range finding unit as defined in claim 1, wherein
the aforementioned components of one of said range
CO finders are disposed substantially in one' layer and the
aforementioned components of the other range finder
substantially in a second layer generally parallel to and
above the first layer, and wherein said light deviating
surface of the pivotal reflecting member- extends through
78 mov hw nrnvirt-A in nr,vant gtrav Huht from lamb 22 both said lavers.
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3. A range finding unit as defined in claim 2, wherein
the said pivotal reflecting member is a single prism elon-
gated to extend through bcth said layers having their
reflecting surfaces in the same plane.
Al. A range finding unit as defined in claim 1, in combi- u"
nation with a base plate on which said pivotal reflecting
member, a bracket having a side wall and a top wall,
said image forming lenses, said moving means, said re-
flecting and viewing means, and said light holder are
mounted, said bracket supporting on said side wall the
stationary deflector for the light beam projecting range
finder and, on its top wall the stationary reflector for
the viewing range finder.
5. A range finding unit comprising a base plate, a
viewing range finder and a light beam projecting range
finder mounted on said base plate, the said viewing range
finder including a semi-transparent stationary reflector
through which an image of an object exterior to the said
range finder is viewable, a pivotal reflector disposed in
optical and spacial alignment with the stationary reflector
so as to reflect a second image of the exterior object to
the stationary reflector, and reflecting and viewing means
optically associated with the stationary reflector for view-
ing the said two images; the said light beam projecting
6
range finder to reflect a light beam emanating from a
source of light in said holder toward the said exterior
object, the reflectors and the viewing means of the view-
ing range finder being disposed substantially in one layer
parallel to the base plate, and the reflectors, the lenses
and the light holder of the light beam projecting range
finder being disposed in a second layer situated between
the said first layer and the base plate parallel to the
first layer and the plate, respective reflectors of the two
10 range finders being disposed one above the other sub-
stantially in transverse alignment relative to said layers,
the said pivotal reflectors of the range finders being
formed by a single pivotally mounted reflecting member
including a light deviating surface having a portion in
16 optical alignment with the stationary reflector of one of
the range finders and a second portioi: in optical align-
ment with the stationary reflector of the other range
finder, both said portions being in one plane, and moving
means coupled with said pivotal member for varying the
20 angular position of the said pivotal reflectors, the said
moving means being disposed substantially in the second
parallel layer.
References Cited in the file of this patent
UNITED STATES PATENTS
range finder including a stationary reflector, a pivotal re- 2S
flector, a holder for a source of light disposed between
the two reflectors of the light beam projecting range
finder, the said stationary reflector, the said pivotal re-
flector and the said holder of the light beam projecting
range finder being disposed in optical alignment, an im- 30
age forming lens between said light holder and the respec-
tive pivotal reflector in optical alignment therewith, and
a second image forming lens between the respective sta-
tionary reflector and said exterior object, thereby caus-
ing each of the two reflectors of the light beam projecting 35
1,489,838
Kohler ------------------ Apr. 8,
1924
2,101,543
Henkel ---------------- Dec. 7,
1931
2,151,124
Leitz ---------------- Mar. 2!,
1939
2,376,982
Schwartz et al. _-___-____ May 29,
1945
2,379,698
Fischer ---------------- July 3,
1945
2,397,160
Schwartz et al. ___--__-_- Mar. 26,
1946
2,403,308
Schwartz et at. ____---_-_ July 2,
1946
2,547,232
Schwartz et al. ---------- Apr. 3,
1951
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Oct. 10, 1961 D. S. GREY 3,003,407
COMBINED RANGE FINDER AND VIEW FINDER
Filed Oct. S. 1956 4 Sheets-Sheet 1
Firs+ Image Plan.
FIG. 2
IN" R.
BY
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Oct. 10, 1961
Filed Oct. S. 1956
D. S. GREY 3,003,407
COMBINED RANGE FINDER AND VIEW FINDER
4 Sheets-Sheet 2
First Image Plane --
plN FJVTOR.
BY
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Oct.. 10, 1961
Filed Oot. 8, 1956
. D. S. GREY 3,003,407
COMBINED RANGE FINDER AND VIEW FINDER
4 Sheets-Sheet 3
Second Image- Plane x-'40
84 38 r' 1 34
First Image Plane
12 -; 32
FIG. 7
I rIOO
88 94
98
92-''
I
90 96 I
..FIG. 10
.., 201
FIG. 8
Mir
JNxFNTOR
ATTORNEYS
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Oct. 10, 1961 D. S. GREY 3,003,407
COMBINED RANGE FINDER AND VIEW FINDER
Filed Oct. 8, 1956
20
FIG. 13
4 Sheets-Sheet 4
INVENTOR.
8Y ?Y ..1~~
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 U Approved For Release 2009/04/10: CIA-RDP81-00120R000100010021-3,113,417
n.LL%. %4 %JL"L%.'a .L "L%.A1L l~lll`...C Patented let. 1?, 196l
3,003,407
COMBINED RANGE FINDER AND VIEW FINDER
David S. Grey, Weston, Mass., assignor to Polaroid Cor-
poration, Cambridge, Mass., a corporation of Delaware
Filed Oct. S, 1956, Ser. No. 614,716
15 Claims. (Cl. 95-44)
The present invention relates to a range finder and a
view finder for use in a photographic camera and more
particularly to a combined range finder and view finder
which employs the objective lens of the camera for rang-
ing and view finding, in addition to its imaging function
relative to the photographic exposure.
Various advantages are known to accrue to the employ-
ment of the camera objective in view finding systems, said
systems being generally either of a reflex type or one in
which viewing occurs along an eye-level axis which is
an optical image of the axis of the objective, either co-
incident with or laterally displaced with respect to that
of the objective. One principal benefit identified with
this type of view finder is avoidance of the need of cor-
recting for parallax, there being provided for viewing
purposes an accurate image of the photographic subject.
Furthermore, where the entrance pupil of the range and
view finder system is identified with the camera objective
rather than with a separate finder objective the same over-
lap of foreground with background objects occurs in said
system as in the photographic image. In addition, a posi-
tive and accurate framing of the field, irrespective of
frontal attachments or of the focal setting of the camera
objective is achieved.
Use has been made of the camera objective, or of a
:special objective, in a so-called split-field range finding
'system combined with a view finding system wherein the
\central area of the objective is employed for imaging
'the view finder field and marginal areas of the ob-
jective- are. used for imaging the range finder field. How-
ever, systems of the last-mentioned type have, it is be-
lieved, only found application relative to small cameras,
namely, cameras of the type employing 35 mm. film, skid
systems being entirely unsuitable for incorporation with
larger cameras such as those providing an image diagonal
gteater than approximately three inches.
In another known finder system, the image formed by
the camera objective is deflected by a mirror to a posi-
tion such that it can be viewed by a magnifier, either
simple or compound. In a camera which employs a
small image area, it is-feasible to follow this procedure
but if the image area has a diagonal dimension larger
than approximately three inches, the necessity for pro-
viding'an image to be viewed by the magnifier, together
with the requirement for a magnifier so constructed as to
collect light from this image necessitates an unwieldy,
bulky and costly system, especially if such a system is of
an eye-level type. The same considerations also apply,
perhaps even more strongly, to other known systems
which employ an auxiliary finder lens of the same focal
length as the camera objective instead of said objective.
The present invention is concerned with the provision
Of a compact, relatively simple and moderately priced
combined range and view finder system, utilizing the
camera objective and adapted to incorporation with
cameras of the larger type, hereinbefore mentioned.
An important feature of the present invention is the
2
construction in which an auxiliary or complementary
positive lens or its optical equivalent is inserted behind
the camera objective which, in combination with said
camera objective, forms, in effect, a lens of short focal
b length. Hence, the angular field of the camera objective
is imaged within a small area. There are two principal
variations of this arrangement as follows:
In one arrangement, a single auxiliary positive lens or
objective is employed, the positive lens being positioned
behind the camera objective and dimensioned to cover
an area which is generally coextensive with a strip-like
area extending substantially across the objective aperture
thus permitting the use of light which passes through
the edges or marginal areas of said aperture for range
Another arrangement employs two or more auxiliary
objective lenses having individual optical axes and being
behind the-camera objective, the separate axes being
subsequently combined by suitable light-deviating means,
such as optical wedges or reflecting means; so that they
have substantially coincident image planes. The sepa-
ration between the apertures of the auxiliary objectives
permits acceptance of light from marginal portions of
the camera objective and, accordingly, permits accurate
ranging.
One object of the invention is to provide a novel and
efficient combined split-field range finder and view finder
system for a larger type camera in which the camera
objective is employed as a component of the system and
in which focusing of the photographic image and of the
ranging and view finder images is obtained simultaneous-
ly through movement of the objective along its axis to a
correct position.
Another object is to provide and arrange a plurality
of reflecting and refracting optical components of given
characteristics in combination with a camera objective
of relatively large image diagonal so that light rays pass=
ing through the central area of the objective are used in
forming view finder image portions and light rays pass-
ing through marginal areas of the objective are employed
in forming ranging image portions.
A further object is to provide a range and view finder
system in a form wherein light-deviating and imaging
components may readily be moved into, operated with-
in, and withdrawn from the area defined by the angle of
view of the objective which is used for making the
photographic exposure.
Other objects are to provide systems of the character
described employing novel combinations of optical com-
ponents which result in improved imaging accuracy, de-
sired image magnification and reduction, contrast be-
tween ranging and view finding image areas, and correc-
tion for spherical and chromatic aberration; to provide
an eye-level range and view finding system wherein erect
images having unreversed left and right image portions
are produced and can be seen through a single viewing
aperture; and to provide a system in which photosensi-
tive materials positioned in the focal plane of the camera
are safeguarded from unwanted actinic light during oper-
ation of the ranging and view finding components.
Other objects of the invention will in part be obvious
and will in part appear hereinafter.
The invention accordingly comprises the product
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3 4
possessing the features, properties and the relation of is provided with an image-forming, concave, spherical,
components which are exemplified in the following de- specularly-reflecting surface 44a. A negative lens ele-
tailed disclosure, and the scope of the application of ment 48 is bonded to the upper planar surface of com-
which will bs indicated in the claims. ponent 44, as shown in greater detail in FIG. 4.
For a fuller understanding of the nature and objects of 5 Operation of the system is substantially as follows.
the invention, reference should be had to the following Assuming light lock 22 to be closed and composite ele-
detailed description taken in connection with the accom- ment 28 to be positioned as shown, the iris diaphragm
panying drawings wherein: to be open to its maximum diameter and the shutter
FIGURE 1 is a side-elevational view, in section, illus- to be open, light from the field of view which includes
trating diagrammatically a combined range and view 10 an object to be ranged is admitted to the combined
finder optical system of the present invention; range and view finding system. The image-forming light
FIG. 2 is a diagrammatic, side-elevational view, partly rays from the objective and incident upon composite
in section, of a camera showing incorporation of the element 28 are transmitted by prism component 42,
system of FIG. 1 therein; semi-reflecting surface 46 and component 44 to concave
optical wedge means of FIG. 1; component 44 to surface 46, are reflected upwardly
FIG. 4 is a diagrammatic view, in perspective, of a therefrom through lens component 48 and pass through
light-deviating and image-forming component of FIG. 1; field lens 32 to the first image plane. The objective 12,
FIG. 5 is a diagrammatic view, in perspective, of a or a component thereof, is moved axially to establish,
modification of the optical component of FIG. 4; 20 in conjunction with concave image-forming mirror 44a
:FIG. 6 is a diagrammatic side-elevational view, in sec- operating as an auxiliary or complementary objective,
tion, showing a modification of the combined range and correct focus relative to the first image plane. The
view finder optical system of ?IG. 1; concave mirror 44a in conjunction with negative lens
FIG. 7 is a view, similar to that of FIG. 6, of another 48 provides correction for spherical and chromatic aber-
combined range and view finder optical system of the 25 ration, said correction being of importance if ranging is
invention; to be accurate.
FIG. 8 is a diagrammatic side-elevational view of a The system has an exit pupil defined, for example,
modified portion of the optical system of FIG. T: by the image of the relay lens 38, and three distinct
FIG. 9 is a diagrammatic, top plan view, partly in entrance pupils each of which pertains to a separate
section, of the system of FIG. 7; 30 portion of the field of view. The principal entrance
FIG. 10 is a diagrammatic, top plan view, in section, pupil lies at or near the center of composite element
of another combined range and view finder optical sys- 28 and is conjugate to said exit pupil for light from the
tem of the invention; field of view which passes outside the area defined by
FIG, 11 is a diagrammatic view of the composite light- the deviating wedges 34a and 34b which are used for
deviating and image-forming element of FIG. 10 show- 3ti ranging. The two other entrance pupils located at each
ing surface areas in elevation; side of the central entrance pupil, are conjugate to the
FIG. 12 is a diagrammatic, top plan view of a modifl- exit pupil for light which passes through the respective
cation of a ranging wedges.
portion of the system of FIG. 10; and The deviating wedges 34a and 34b are located in
FIG. 13 is a diagrammatic top plan view of another the first image plane of the system composed of the
modification of a portion of the system of FIG. 10. 40
Referring camera objective 12, the composite element 28 and field
to FIG. 1, a combined range and view find- 32, said image plane having been established with
ing system of the invention is shown which incorporates lens the objective 12. set for an object at infinite distance.
the picture "taking" objective lens 12 of a camera 14, The deviating wedges provide a discontinuity of light
the camera being shown more fully in FIG. 2. The deviation in said image plane along the line of junction
objective lens 12, or a component thereof, is movable 45 of the two wedges. Hence, there is a discontinuity of
toward and away from focal plane 18 by conventional
s a
means, not shown, as indicated by the double-headed ered entrance pupil. pertaining t. In the
is a
other words, arrow 20. Camera 14 has, for example, a between- ed by by each the he wedges. c, there ere c
the-lens shutter and an iris diaphragm, not shown, posi- de12 viational discontinuity to incident light. objective
tioned at location line 16. and a focal plane 18, the 50 t lo a is s adjusted and if to the focus focus an object , located
the image a finite d di
e
latter being the image plane of objective 12 which is be formed ss s correct, mage of the
used for positioning and photographically exposing a object will e at said first image and the
object image portions, because they are e fotc plane
used at said
photosensitive film. It is to. he assumed that camera plane, will be deviated in coincidence by the wedges
14 is of a type larger than a so-called "miniature" and will provide alignment of split-field areas. If the
camera. A light lock 22 is mounted for positioning 55 image of the object is not formed at said first image
within and withdrawal from the area 24 defined by the plane the wedges will deviate the light rays from the
angle of view of objective 12. The light lock, at the object but they will not be in coincidence and the split-
closed position shown, serves to shield from actinic light field image portions of said object will not be aligned.
a film, not shown, which would normally be positioned This occurs because a wedge at an image plane will
for exposure at plane 18 when the range and view find- 60 not shift the apparent position of the image, but a
ing system is being used preparatory to said exposure. wedge outside the image plane will shift said apparent
The light lock is pivoted away from its light intercept-
that cor-
position when a photographic exposure is about to reef position of alignment the the image. split-field wi be understood portions
ing be made, as indicated by arrow 26. Other compo- eof the object
at the e focal image ocaal l plane
e
nents of the combined range and view finding system 65 of implies the ccamera. orrect imaging Whe the the camera object is focused, a ? composite light-deviating and image-form- the film
and
Ing element 28, movable, as indicated by arrow 30, in the wedges plane, the e composite 34b element
are kept the in fixed field lens r32 32 relation to
and out of area 24, as for example, by, pivotal or slid- each other r to o insure operation each of the system.
able mounting means, such as the pivotal means shown Images of the field of view and of the object formed
in FIG. 2, a field lens 32, ranging wedge means 34 com- 70 at the first image plane are twice reflected by prism 36,
posed of wedges 34a and 34b shown in detail in FIG. which may appropriately be a penta prism, and are
3, prism 36, relay lens 38 and eyepiece 40. Composite relayed by relay lens 38 to the second image plane
element 28 is composed of prism components 42 and for observation by eyepiece 40. Camera lens 12, field
44 bonded together and. having an intervening, semi- lens 32, relay lens 38 and eyepiece 40 constitute, in
transparent. reflectina surface 46. Prism comnnnent dd 116 effect a tprrpAtrial tPlacrnn. T6., fn... T "lions which
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
8,003,407
occur in elements 28 and 36 are mutually compensating
for ipvcrsion thus insuring an erect image.
In operating The combined range and view finder of
the invention relative to making a photographic expo-
sure, it is assumed that, preliminarily, the camera iris
diaphragm at 16 is completely open, the shutter at 16
is open, the light lock 26 is closed and the composite
elenlent 28, or other type of auxiliary objective to be
described below, is located immediately behind the
camera objective. A workable operational sequence for
making the photographic exposure would he as follows:
The shutter closes; the diaphragm assumes a preset open-
ing value; composite element 28 is removed from the
exposure area; the light lock closes; and the shutter
opens and closes. A focal plane shutter, not shown,
could also he employed and would probably obviate the
' necessity of providing the light lock.
The combined range and view finder system of FIG. 1
is shown in FIG- 2 incorporated with a camera of a fold-
ing type having a bellows 50. The camera objective lens
12 is moved axially by tan adjusting knob 52 which, when
moved arcuately, actuates mechanism, not shown, pro-
viding translational movement of the lens, or one or more
elements thereof, along its axis. The composite light-
deviating and imaging element 28 is mounted on a pivotal
arm 54 which permits the element to be moved to a posi-
tion put of the area 24 within the angle of view of the
objective, as indicated by the broken line. Other optical
elements of the finder system are shown mounted in tubu-
lar means 56 having a viewing aperture 58.
modification of the light-deviating element 28 of
FIG. 4 is shown in FIG. 5. The semi-transparent mirror
60, formed at the interface of prism elements 62 and 64,
terminates short of the extremities of the element. Clear,
light;-transmitting marginal areas 66 and 68 are thus lo-
cated adjacent each extremity. A concave reflecting sur-
face 64a, similar to surface 44a of element 28, is pro-
vided. In operation, marginal entering light from the
camera objective employed for ranging passes through
clear areas 66 and 68 of the prism interface and is con-
vergingly reflected by surface 64a to surface 60 whence
it is reflected upward to field lens 32. Light from the
central part of the objective forming other areas of the
field of view will necessarily have. to pass through the
semi-transparent reflecting area 60 before being twice
reflected by said surfaces 64a and 60 and a portion of the
light will thus be absorbed by said area 60. Accordingly,
ranging image areas will appear brighter than other areas
of the visible image and the heightened contrast thus pro-
vided between the image portions permits greater facility
in determining the alignment condition of the split-field
images during ranging operation. Other possible modi-
fications of clement 28 of FIG. 4 include: forming the
concave reflecting mirror on the bottom of the element
to utilize light which is deviated downwardly from semi-
transparent surface 44 thereto; forming said mirror on
the rear surface, as shown, and also on the bottom sur-
face to provide increased light for imaging purposes;
mounting negative lens 48 on the front surface of ele-
me
t 28
f
d
o
h
n
, or on b
th t
ront an
top surfaces.
e
1G. 6 illustrates a range and view finding system
which operates substantially similarly to that of FIG. I
but, which employs slightly modified components. A
light-deviating and imaging element 70 having portions
somewhat modified as to their relative size or arrange-
ment but otherwise similar to those of element 28 of
FIG. 1 deviates light from objective 12 obliquely upward
toward a modified prism 72. A pair of deviating wedges
34 is positioned between a field lens 32 and a face of
prism 72, the wedges preferably being bonded to at least
one. of the elements 72 and 32. Ranging and view find-
ing, considerations, adjustability of components, etc., are
similar to those described with respect to FIG. 1.
The. system of FIG. 7 emolovs a hair of nositive aux-
iliafy obit Approved For Release 2009/04/10 :
prisms or mirrors 80 to form deviating and imaging ele-
ments 82. A mirror 84 or a prism having a single re-
flecting surface is used in place of the twice-reflecting
prisms of FIGS. I and 6, only one additional reflection
5 being required to provide an erect image in conjunction
with the single reflecting surface of clement 82. Optical
wedges 34, of the type used in the systems above-shown,
are located at the second image plane. Other elements of
the system are essentially the same as those previously
10 described. In this system the ranging beams are main-
tained separate until incident upon the second image
plane, or approximately at this plane. It is therefore
necessary to insure exact alignment of all components be-
tween.the entrance pupils and the second image plane, or
15 ranging accuracy would be impaired. Dccentered lenses
may, alternatively, be used in forming the elements 82.
The deviating wedges 34 may be located at the first image
plane of the system, as shown in FIG. 8, if preferred,
or alternatively, they could even be positioned adjacent
20 the auxiliary objectives 78 of elements 82. It will thus
be seen that wide latitude is permitted in the placement of
wedge components which provides flexibility in the design
of the system and in its adaptability to mounting in a
camera. A generally similar system to that of FIG. 7 is
25 shown schematically in plan in FIG. 9, mirror surfaces
which open t relative to light traveling in a vertical
direction being omitted for reasons of clarity.
In FIG. 10 a modified system is illustrated which in-
cludes three auxiliary positive objectives, 86, 88 and 90,
30 mounted immediately behind the camera objective 12.
A composite prism element 92 having reflecting surfaces
94 and 96, and given reflecting areas of surfaces 98 and
100 which are shown in further detail in FIG. 11, is
positioned at the first image plane. Reflecting means of
35 the system which operate relative to light traveling in a
vertical direction have been omitted for clarity. Auxiliary
objective lenses 86 and 90 could, appropriately, have
relatively long focal lengths while auxiliary objective tens
88 could have a relatively short focal length. - Higher
40 magnification would thereby be produced in the central
ranging area than in the rest of the field. This arrange-
ment provides greater ranging accuracy but leaves a gap
in the object field between the area presented by the rang-
ing objectives and the area presented by the central ob-
45 jective. Reflecting surfaces 94 and 96 of composite
prism 92 are nonparallel with respect to surfaces 98 and
100, said nonparallelism of surfaces serving to deviate
light in a manner similar to that of the optical wedges 34
of FIG. 1. Accordingly, element 92 provides deviation
50 of the ranging light rays so that it may be said to consti-
tute the functional equivalent of the deviating wedges
34a and 34b, above described.
The modification of FIG. 12 illustrates placement of
a negative lens 102 in the optical path of light trans-
55 mitted by the central positive auxiliary objective 88 of
FIG. 10. Lens 88, with negative lens 102, constitutes
a telephoto lens and, accordingly, the three auxiliary ob-
jectives have substantially equal focal lengths. In FIG.
13, an alternate construction is shown for making the
00 focal lengths of all three auxiliary positive objectives, 86,
88 and 90 substantially equal. Glass components 104
and 106 are placed in the optical paths of the outer
auxiliary objective's and serve to increase the optical path
lengths between said objectives and the first image plane
65 with respect to optical path lengths in air which was
shown in FIG. 10. The glass components 104 and 106
are preferably bonded to the auxiliary objectives and to
the prism element 92, respectively.
70 It will be apparent that the systems described herein
could he modified in several ways. For example, the
deviating wedges could cover the entire field of view; they
could be omitted to provide a view finder only; or the
area around the deviating wedges' could be omitted to
CIA-RDP81-0012OR000100010021-3 deviating
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7
wedges, or the mirrors of prism 92, can be located at
either the first or second image planes of the system.
Since certain changes may be made in the above prod-
uct without departing from the scope of the invention
herein involved, it is intended that all matter contained 5
in the above description or shown in the accompanying
drawings shall be interpreted as illustrative and not in a
limiting sense.
What is claimed is:
1. In a photographic camera having an axially ad- 10
justable objective lens, a combined finder for viewing
and ranging a field of view through said lens, said finder
comprising composite light-deviating and imaging means
located behind said objective lens, said light-deviating and
imaging means being substantially coextensive with a pre- 15
determined area which extends transversely of the optical
axis of and includes opposite marginal portions of said
objective lens, said composite light-deviating and imaging
means including a first reflecting means for deviating light
from said objective lens to one side of the angular field 20
of said lens along a second axis disposed at a predeter-
mined angle with respect to said optical axis and also
including first focusing means which, in combination with
said objective lens, effectively constitutes lens means of
short focal length for focusing an image of the field of 25
view at a first image plane on said second axis, second
focusing means located on said second axis adjacent said
first image plane, second reflecting means for deviating
light transmitted along said second axis to a third axis
substantially parallel with said optical axis, third focus- 30
ing means positioned on said third axis for relaying said
image to a second image plane on said third axis, an
eyepiece located on said third axis for viewing said sec-
ond image plane, second light-deviating means compris-
ing at least two adjacent elements disposed at one of said 35
image planes for so splitting the field of said image into
separate and adjacent fields which correspond respectively
to light coming from each of said marginal portions of
said objective lens that said adjacent fields are continuous
when said image is coincident with said one of said 40
image planes and are discontinuous when said image'
is out of coincidence with said one of said image planes,
and means for moving at least said composite light-deviat-
ing and imaging means outside of the optical path ex-
tending between said objective lens and the focal plane 45
of the camera.
2. A combined range finder and view finder accord-
ing to claim 1, wherein the composite light-deviating and
imaging means comprises a semi-reflecting surface and a
concave. sphericai reflecting surface for reflecting and
focusing light coming from said objective lens and through
said semi-reflecting surface back to said semi-reflecting
surface.
3. A combined range finder and view finder according
to claim I, wherein the composite light-deviating and
imaging means comprises a semi-reflecting surface, a
concave, spherical reflecting surface for reflecting and
focusing light coming from said objective Icn' and through
said semi-reflecting surface hack to said semi-reflecting
surface, and a negative lens for correcting aberrations in (,0
light reflected from said semi-reflecting surface.
4. A combined range finder and view finder according
to claim I, wherein the composite light-deviating and
imaging means comprises a positive lens constituting an
auxiliary objective with respect to said camera objec-
tive, G.5
and means for deviating light transmitted by said
auxiliary objective.
5. A combined range finder and view finder according
to claim 1, wherein the composite light-deviating and
imaging means comprises a of i0
plurality positive lenses
constituting a plurality of auxiliary objectives with re-
spect to said camera objective, and means for deviating
light transmitted by said auxiliary objectives.
A
8
to claim 1, wherein said composite light-deviating and
imaging means includes a pair of reflecting surfaces, and
wherein said reflecting means for deviating light trans-
mitted along said second axis also includes a pair of re-
flecting surfaces.
7. A combined range finder and view finder accord-
ing to claim 1, wherein said second light-deviating means,
located at one of said image planes, comprises a pair
of optical wedges.
8. A combined range finder and view finder according
to claim 1, wherein said second light-deviating means
comprises a composite prism element having a plurality
of non-parallel surfaces which include given light-reflec:-
ing and light-transmitting areas.
9. A combined range finder and view finder according
to claim 1, wherein said composite light-deviating and
imaging means comprises means for forming an image
corrected for spherical aberration.
10. A combined range finder and view finder accord-
ing to claim 1, wherein said composite light-deviating
and imaging means forms two laterally separated image
planes at said first image plane, said images being pro-
jected for viewing at said second image plane.
11. A combined range finder and view finder accord-
ing to claim 1, wherein said composite light-deviating and
imaging means comprises a semi-reflecting surface, a
concave, spherically reflecting surface for reflecting and
focusing light coming from said objective lens arid
through said semi-reflecting surface back to said semi-
reflecting surface and a negative lens for correcting aber-
rations in light reflected from said semi-reflecting surface
along said second axis, and wherein said reflecting means
for deviating light transmitted along said second axis
comprises a penta prism, and wherein the last named light-
deviating means comprises a pair of optical wedges.
12. A combined range finder and view finder accord-
ing to claim 1, wherein said composite light-deviating and
imaging means comprises a concave, spherically reflect-
ing surface, a semi-reflecting surface having clear, light-
transmitting marginal areas coextensive with said mar-
ginal portions of said objective lens, light transmitted
through said marginal portions of said objective lens be-
ing passed through said light-transmitting marginal areas,
being convergingly reflected by said concave surface to
said semi-reflecting surface to increase thereby the rela-
tive brightness of light transmitted by said marginal por-
tions of said objective lens.
13. A combined range finder and view finder accord-
ing to claim 1, wherein said composite light-deviating
and imaging means comprises a positive lens constituting
an auxiliary objective with respect to said camera objec-
tive and means for deviating light transmitted by said
auxiliary objective, and wherein said reflecting means for
deviating light along said second axis comprises a plane
mirror, and wherein the last named light-deviating means
comprises a pair of optical wedges located at said second
image plane.
14. A combined range-finder and view-finder accord-
ing to claim 1, wherein said composite light-deviating
? nd imaging means comprises at least a pair of positive
lenses constituting auxiliary objectives with respect to
said camera objective. and a composite prism element
having a plurality of non-parallel surfaces which include
given light-reflecting and light-transmitting areas, said
surfaces constituting said second light-deviating means.
15. A combined range-finder and view-finder accord-
ing to claim 1. wherein s-id composite light-deviating and
imaging means comprises a pair of positive lenses con-
stituting auxiliary objectives with respect to said camera
objective, said auxiliary objectives being located to sub-
tend said marginal portions of said objective lens, and a
composite prism element located at the image plane of
said auxiliary objective, said composite prism element
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
$,003,407
given light-reflecting and light-transmitting areas, said
sucfaces constituting said second light-deviating. means,
said combined range-finder and view-finder including
optical elements positioned between said auxiliary objec-
tives and said composite prism clement for increasing
the optical path length between said auxiliary objectives
and said first image plane with respect to the optical path
length therebetween in air, and a positive lens constituting
an auxiliary objective with respect to said camera ob-
jective located on the optic axis of said camera objective
between the latter and said composite prism element.
g
to
References Cited in the file of this patent
UNITED STATRS PATENTS
2,341,410
Mihalyi -------------- Feb. 8,
1944
2,352,644
Linderman et al. -------- July 4,
1944
2,364,652
Pollock -------------- Dec. 12,
1944
2,887,019
Dodin ---------------- May 19,
1959
FOREIGN PATENTS
933,132
Germany -------------- Sept. 15, 1955
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 Approved For Release 2009/04/10: CIA-RDP81-00120R000100010021-3
May 6, 1969
A. B. PAGEL
AUTOMATIC FOCUSING SYSTEM
3,442,193
~Gr
ATTORNEYS
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
May 6, 1969
X235 F/G. 5
234
A. B. PAGEL 3,442,193
AUTOMATIC FOCUSING SYSTEM
237 '
Sheet _2 of 2
ARM/N B. PAGEL
INVENTOR.
W 1V...._
A T T QRNEYS
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United States Patent
'ki ce Patented 3,4 G2 19
May 1969
3,442,193
AUTOMATIC FOCUSING SYSTEM
Armin B. Pagel, Janesville, Wis., assignor to Eastman
Kodak Company, Rochester, N.Y., a corporation of
New Jersey
Filed May 31, 1966, Ser. No. 559,633
Jut. Cl. G03b 3/10
U.S. Cl. 95-44
ABSTRACT OF THE DISCLOSURE
An automatic focusing system for a camera in which
a beam of light is directed toward a subject from a light
source within the camera and a portion of the light beam
reflected from the subject back to the camera is sensed
by photoelectric means. The angle between the emitted
and reflected beams is translated into a mechanical move-
ment which is a function of the distance from the camera
to the subject. The projected and reflected beams are
focused in accordance with the distance to the point of
reflection and there is a mechanism providing for se-
quential operations which insures completion of various
adjustments prior to exposure.
2
photoresponsive sensing means; and translating the angle
so sensed into a corresponding mechanical movement.
The subject invention improves the basic Stimson range-
finding system by automatically focusing the projected
and reflected beams in accordance with the distance to the
point of reflection, thereby increasing the efficiency of
the range-finding portion of the apparatus, and by pro-
viding for completion of camera lens focus adjustment
prior to camera shutter actuation, the latter sequential
operations assuring that the light beam used for range-
finding purposes will be extinguished prior to actual pic-
ture-taking.
It is therefore an object of the present invention to
increase the efficiency of automatic range-finding ap-
paratus which uses a projected light beam.
It is a further object to focus bo:h the projected light
beam and its reflection, and to adjust such focus auto-
matically in accordance with the distance to the point
of reflection.
Another object is to increase the efficiency of automatic
range-finding apparatus for cameras by assuring that the
camera lens is focused and its projected light beam ex-
tinguished prior to operation of the camera's, picture-
taking shutter mechanism.
The novel features considered characteristic of the in-
vention herein are set forth with particularity in the
appended claims. The invention itself, however, both as
to its organization and method of operation, together
with additional objects and advantages thereof, will best
be understood from the following description of illustra-
tive embodiments and from the accompanying drawings
in which:
FIG. I is a schematic diagram of one embodiment of
a range-finder device according to the present invention,
including means for focusing the objective lens of an
optical instrument in response to the distance between
the instrument and the subject;
FIG. 2 is a schematic diagram of another embodiment
of a range-finding device according to the present in-
vention, in which the light beam projecting unit and the
reflected beam detecting unit are symmetrically disposed
on opposite sides of the axis of an axially adjustable lens
and are coupled for symmetrical movement, whereby the
detected point of impingement of the light beam on the
subject is located along such axis at all positions of the
25
This invention relates to automatic focusing apparatus
of the type described in the copending application for
Automatic Focusing System, Ser. No. 554,072, filed on
May 31, 1966, in the name of Allen G. Stimson.
The present invention relates to photographic cameras 30
or related optical instruments and, more particularly, to
such instruments embodying fully automatic means for
determining the distance from the instrument to the object
to be brought into focus.
Further, the present invention is an improvement re- 35
lating to the automatic focus apparatus disclosed in co-
pending U.S. application Ser. No. 554,072 filed in the
name of A. G. Stimson on May 31, 1966.
During the evolution of the modern photographic
camera, continuing attempts have been made to minimize 40
the numerous visual observations, subjective determina-
tions and manual operations usually involved in adjust-
ing shutter speed, lens aperture and focus of the lens to
achieve a photograph of optimum quality. Many cameras
now on the market incorporate light meter means which 45
response to the illumination of the scene to be photo- FIG. 3 is a schematic perceptive illustration of a pre-
graphed. However, although many present-day cameras ferred embodiment of the present invention, incorporated
incorporate devices which enable the operator to focus in a photographic camera to determine automatically
the lens properly by visually observing the quality or 50 the distance between the camera and the subject and to
composition of one or more images of the subject to be effect a corresponding setting of the camera lens;
photographed, no commercially successful device has thus FIG. 4 is a schematic diagram of still another em-
far been developed to adjust the focus of the lens auto- bodiment of a range-finder device showing an alternate
matically without necessitating any such visual obser- means for detecting the alignment of the reflected beam
vations. Accordingly, -many cameras, including some of 55 with the light sensing element thereof; and
relatively high price, are now provided with so-called FIG. 5 is an isometric view of yet another embodi-
universal focus lenses, which do not require focusing ment of a light-sensing means, comprising a galvano-
adjustment within the distance range usually encountered meter-type electrical measuring instrument adapted to
by the amateur photographer, Such lenses, however, are align itself with a light beam, and including means for
a compromise between eliminating focusing problems translating mechanically the aligned position of the mova-
and providing an image of optimum quality, and, there- ble portion of the instrument to establish the correspond-
fore, are not satisfactory under all conditions. ing position of a movable mechanical element.
The basic principle employed in the invention dis- Referring now to FIG. 1 of the drawing, element 10
closed in the Stimson application referred to above in- represents generally the lens system of a photographic
volves directing onto the subject a beam of light emitted camera or other optical instrument in which a lens sys-
from a light source positioned in predetermined relation tem is movable along its axis to focus, at an image-re-
to the camera; receiving, at a location spaced laterally cciving surface illustrated at 12, an image of a subject
from the emitted beam, a portion of the beam reflected located along the lens axis. The lens system is moved as
hack to the camera from the subject; sensing the angle 70 a function of the distance between the subject and the
between the emitted and the reflected beams by bringing lens system. For purposes of illustration, lens system 10 is
the reflected portion of the beam into alignment with shown mounted on mate 1'4 whG?h ? t
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3,442,193
3 4
attached to a Supporting surface, not shown, by pins 14, lion of gear 31, and hence the angular }~asition of the
which extend through parallel slots 15 to allow sliding light sensing system, correspondingly determines the posi-
movement of the plate along the axis 11, of lens 10. tion of lens 10 relative to image receiving surface 12.
A? second lens system, represented generally at 16, is While the drawing shows simply a circular cam 42
located in alignment with a light source 17 energized by adapted to increase the distance between lens 10 and sur-
a battery or other source of electric energy 18, and is 5 face 12 as the point of coincidence between axes 20 and
adapted to project a beam of light along the lens axis 20 25 move away from the instrument, or vice versa, in
which, in the illustrated embodiment, is located in fixed actual practice the cam could have a non-circular profile
parallel relation to lens axis 11. Thus, the beam of light determined by the relative positions of the various ele-
will impinge upon a subject located along axis 20, which 10 ments involved and their particular optical character-
subject would presumably present a frontal surface gen- istics.
erally transverse to the light beam and of sufficient width The operation of the illustrated device is initiated by
to also be in alignment with lens system 10, thereby con- closing switch 43, thereby electrically energizing light
stituting the object intended to be brought into sharp source 17, motor 33 and an electric transducer device 44
focu's by lens 10. Although not shown in the illustration, 15 connected to photocell 23 by leads 45 and 46. Transducer
it is' obvious that a conventional viewfinder device could 44 is adapted to supply current to energize solenoid 50,
be employed to establish the alignment of lens system 10 through output at leads 47 and 48, whenever photocell 23
with the subject. responds to the presence of a predetermined increase in
The light sensing system employed to detect the spot light intensity.
of light impinged upon the subject and at least partially 20 As soon as the motor is energized, the light sensing
reflected therefrom, : comprises a third lens system, de- system begins to scan axis 20 between points 37 and 38 and
picted generally at 21, which is mounted on a support continues to do so until the intersection of axes 20 and
member 22 in alignment with a photoelectric device 23, 25 coincides with a reflective surface, at which position
the light responsive portion 24 of which is disposed in a portion of the reflected light is focused on the photocell,
alignment with the axis 25 of the third lens system. 25 in response to which solenoid 50 rotates latch arm 51
(While the photoelectric device is represented in the about pivot 52 against the influence of spring 53 to open
drawing as a photoelectric vacuum tube, other types of switch 54, thereby deenergizing motor 33. To insure instant
similar devices, including photoresistive or photovoltaic response of the system independent of the inertia of the
solid state devices, can also be employed. Hence, the term motor and other moving parts, the latch arm may also be
photocell, as used herein, is intended to refer to any such 30 provided with a tooth 55 which, upon actuation of the
device which may be employed in connection with appro- solenoid, is interposed between two adjacent teeth of
priate circuitry to generate or control an electric signal gear 35 to effect an immediate and positive braking ac-
as a function of the illumination impinging on the de- lion, thus stopping the motion of all the movable ele-
vice.) Support member 22 is pivoted for arcuate planar ments of the device in appropriate positions as a function
movement on a fixed shaft 26 which, in the illustrated 35 of the distance of the subject from the instrument. This
embodiment, is axially aligned with the light responsive distance may also be related as a numeric value by a
portion of photocell 23. The opposite end of the support pointer member, as shown at 56, which is pivotally mount-
member is provided with a pin 27 and is thereby joined, ed at pivot 57 and movable against spring 58 by an arm
through connecting rod 28, to crank pin 29 which is 60 connected to support plate 22, such that the angular
eccentrically mounted on gear member 31 to move orbit- 40 position of the support plate may be translated into a
ally about the axis of gear shaft 32 as gear 31 is rotated direct distance reading by an appropriately numbered
by motor 33 through speed reduction gears 34, 35, and scale 61 in alignment with the pointer.
36. Although the foregoing description has used the term
When a subject is located along axis 20 in the path of "light" in a general sense in referring to the emitted light
the beam of light emitted by light source 17, the beam 45 beam and the light sensing means, it should be noted
will impinge upon the frontal surface of the subject and that to minimize the possibility of ambient light imping-
will be at least partially reflected. However, before a ing on the photocell and causing a spurious motion stop-
portion of the reflected beam can be detected by the ping signal, the associated electric transducer device should
light sensing system and generate a corresponding electric be so designed as to be responsive only to illumination by
signal, the axis 25 of the light sensing system must be 50 a range finder light source of greater intensity than the
positioned to coincide with the frontal reflective surface normally encountered illumination of the subject by other
of the subject along axis 20 to cause the illuminated area sources. Rather than simply providing an extremely in-
on the subject to be focused at the light sensitive portion tense source of visible light, however, it is preferable to
of the photocell. For example, with the light sensing sys- utilize a photocell which is responsive primarily only to
tem positioned as indicated in FIG. 1, its electric signal 53 light within a particular spectral frequency range which
will be produced only when the frontal reflective surface is not preponderant in normal ambient light, and to pro-
of the subject is substantially at point 37. vide a light source which emits primarily light within that
Thus, as the light sensing system is reciprocated arcu- frequency range. For example, a preferred embodiment
ately, it scans the portion of axis 20 between point 37 and of the range-finding device might employ light outside
point 38 and produces an electric signal responsive to the
focusing of reflected light onto the sensitive portion of 80 v the with nary th other rifreq sncytcom components ultra
the cell whenever axis 25 traverses a reflective frontal both violet) with frbgaecy dmpeegs being miimizee
surface along axis 20 between these two points. The dis- the appropriate eam oand ptical the lr. Alternatively, the
tance from the instrument of points 37 and 38 depends, of beam photocell by appr relatively intense monochromatic fromat Alternatively, a
course, on the particular design of the device. In the case 65 employed, for example, c use o of an opticbl light laser as might th he
of a camera, points 37 and 38 might correspond, respec- light for with a s use nn rowil e
tively, to the so-called h source, wjua corresponding
be-
nctian with the pith thpho oarc band fitter be-
yperfocal distance (beyond which ing used d in conjtocell.
further focusing adjustment is not normally required)
and to the nearest distance at which the camera is in- elements the foregoing eoperati n of thebds the essemay
tended to photograph a subject. ts and mode of operation of the device, it may
To effect the automatic focusing of lens 10 according accuracy of the device by insuring not only that the sub-ect
the member 13 is provided with a cam follower arm 40 which ject t in sharp focus at surface 12 all times, but also
that the lens system 16 and 21 are continuously adjusted
is resiliently biased by a spring 41 into engagement with so that the point of intersection between axes 20 and 25
a cam 42 (secured to gear 31) so that the rotative end. ,.
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5 8,442,193
6
and the photocell. To obtain this objective, the light beam 128 may be rotated in the manner just described, either
projecting lens 16 is mounted on a plate 62 which cor- by (1) a reversible electric motor 133 connected thereto
responds in structure to support member 13 of lens 10, through a speed reducing gear train 134, 135 and 136, or
whereby lens 16 may be moved along its axis 20 to vary (2) by simply rotating the accessible forward portion of
its position relative to light source 17. This adjustment of housing 125 manually, thereby rotating the motor through
lens 16 is effected by a bell crank 63 pivoted at 64, which the gear train.
moves plate 62 against the influence of spring 65 in ap- The light beam emitting device built into the camera
propriate relation to the movement of support plate 13 comprises an electrically energized light source 137
as a function of the profile of cam surface 66 thereon. mounted at the focal point of a lens 138, the axis 140
Likewise, lens 21 is also supported on support member 10 of which is parallel to the axis of the objective lens 121.
22 by a similar plate member 67 for movement along axis The light sensing device includes a mirror 141, angularly
25, with the distance between the lens and the photocell located on support arm 142 behind a third lens 143 and
being adjusted as a function of the angular position of movable about a vertical axis defined by pin 144 pivotally
member 22 by a curved tapered cam arm 68 fixed to a supporting arm 142 on the camera housing. The angular
stationary portion of the instrument at 70 and held in by 15 position of mirror 141 is determined by the axial position
a spring 71 in contacted engagement between lobe 72 at of the objective lens by means of a follower arm 145
the forward end of plate member 67 and a pin 73 fixed which is pivoted to the housing at 146. One end of the
to support member 22. follower arm 145 is held in resilient contact with the
Referring now to the embodiment of the invention back surface of gear member 128 by the contacting en-
shown in FIG. 2, the light beam projecting device, com- 20 gagement of the other end thereof with support arm 142
prising light source 81 and lens 82 and the light sensing under the influence of spring 147, whereby a forward
system, comprising photocell 83 and lens 84, are mount- movement of the objective lens moves mirror 141 in a
ed respectively on support plates 85 and 86 symmetrically clockwise direction, as viewed from the top, and vice
located at pivot points 87 and 88 on opposite sides of the versa. Photocell 148 is optically aligned with mirror 141
axis 90 of a lens system 91 of a camera or other optical 25 by means of fixed intermediate mirrors 150 and 151, which
instrument. Lens system 91, in turn, is supported by a serve to increase the focal distance between the lens 143
mounting plate 92 movable along axis 90 against the in- and photocell 148 and also to increase the optical distance
fluence of spring 93 by a cam 94 attached to a rotatable between mirror 141 and the photocell, thereby increasing
shaft 95, to vary the distance between the lens and the the movement of a focused spot of light at the photocell
image receiving surface depicted at 96. A symmetrical 30 in response to a given angular movement of the mirror.
cam follower member 97, positioned in contact with a Although each of the light sensing systems previously
second cam 98 attached to shaft 95 is also movable along described in relation to the embodiments illustrated in
axis 90 in response to the rotation of shaft 95 and is re- FIGS. 1 and 2 involves moving a lens relative to a photo-
siliently engaged by the respective arms 98 and 100 of cell to effect a scanning function, the same result is
plates 85 and 86 under the influence of springs 101 and 35 achieved in this embodiment by moving the mirror behind
102. In this construction, therefore, the axes of the light the stationary lens 143 while simultaneously carrying out
beam projecting device and the light sensing system at all a corresponding movement of the objective lens. For ex-
times converge at axis 90, such convergence point being ample, in the position shown in FIG. 3, the objective lens
kept in focus at surface 96 by lens 91. Such a system, in 121 is in its rearwardmost (hyperfocal) position, and, at
association with a drive mechanism and associated cir- 40 the same time, mirror 141 is positioned to focus at the
cuitry as shown in FIG. I would, therefore, eliminate en- photocell only such light beams as are reflected from a
tirely the lateral discrepancy between the sensed position subject located beyond the hyperfocal range of lens 121.
of the subject and the axis of the instrument, which might To take a picture with the camera shown in FIG. 3, the
constitute an unacceptable degree of parallax if, for ex- operator first brings the photographic subject into the field
ample, the device were to be used for accurate long range 45 of the viewfinder. Next, he depresses the shutter actuating
measurements in connection with surveying, weapon aim- button 120 to initiate the operation of the camera by mov-
ing, or the like. ing slidable member 153 downwardly, agains the influence
FIG. 3 illustrates a camera having a fully automatic of spring 154. When the camera is set for fully automatic
system responsive to depression of the shutter actuating operation, the downward motion of member 153 is limited
button 120, to first automatically focus the objective lens 50 by engagement of its shoulder 155 with stop member 156.
121 according to the distance between the camera and a In this position, the shutter release arm 157 of member
subject located along the axis 122 of the viewfinder com- 153 has not operatively engaged shutter-actuating trigger
prising lenses 123 and 124, and, thereafter, to actuate the 158. However, such downward movement of member 153
shutter mechanism to effect an exposure. closes normally open switch 160 in series with a battery
The embodiment illustrated in FIG. 3, utilize, . range- 55 161 to energize light source 137 and an electric transducer
finding system which utilizes the same gener.! >>,tnciple device 162 similar to the one described in reference to
of operation as that previously described in relation to the FIG. 1. Further, such movement of member 153 simul-
structure shown in FIG. 1. Objective lens 121 is mounted taneously actuates a double-pole double-throw switch com-
in a cylindrical housing 125, and is supported in the prising movable contact blades 163 and 164, moving such
camera housing, not shown, by a stationary ring 126. The GO blades out of contact with conductors 165 and 166, re-
rearward portion of lens housing 125 and the internal sur- spectively, and into contact with conductors 167 and 168.
face of ring 126 are provided with mating threads, as This causes moor 133 to be energized by battery 161 with
shown at 127, whereby the rotation of housing 125 in a the proper polarity to drive gear member 128 in a counter-
counterclockwise direction, as viewed from the front of clockwise direction, thereby axially moving lens 121 and
the camera, moves the lens forwardly away from the film, 65 causing the range-finding system to function as previously
not shown, and vice versa.. Attached to lens housing 125 described.
is a gear member 128 which is rotatable, through some- When the scanning movement of mirror 141 causes the
what more than a half revolution, between the illustrated reflected beam of light to impinge on the photocell 148,
position in which lug 130 at the periphery thereof is in transducer 162 energizes a solenoid 170 which, acting
contact with a stationary stop pin 131 and a second posi- 70 against the bias of spring 171, moves actuating arm 172
tion in which lug 130 contacts stationary stop pin 132. in a counterclockwise direction about its pivot 173, forc-
This rotation of housing 125 is sufficient to move lens 121 ing its tooth 174 between adjacent teeth of gear 136 to
axially through its entire range of focal adjustment as cause an immediate and positive stoppage of the drive
indicated by indicia shown on the front surface of the system. In this embodiment, however, the motor remains
housing adjacent the lens. As hereinafter described, gear 75 energized and is simply stalled by th1' htnrking of gear
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able member by means, not shown, corresponding to those
previously illustrated and described.
While photocell elements 212 and 213 were previously
described as being rectangular, it may be preferable to
utilize such elements having frontal profiles which de- r
crease in vertical dimension toward each other, whereby ''
the area upon which the vertical light beam impinges
is reduced as the system approaches alignment with the
illuminated area of the subject. By utilizing such an ar-
rangement, the motor energizing voltage can be reduced 10
gradually toward an apex (in this case "zero") output as
a function of the size of the illuminated area of the
photocell, thereby slowing the speed of the motor as the
system moves into alignment and reducing the inertia
of the drive mechanism which tends to carry plate 204 15
past the aligned position in which the drive motor is de-
energized.
FIG. 5 illustrates still another embodiment of a light
sensing system which may be incorporated in an auto-
matic range finder as previously described. In this embodi- 20
ment, the light sensing system utilizes a galvanometer-
type electrical measuring instrument comprising a mov-
able coil 230 pivotally supported by two jeweled bear-
ings, one of which is shown at 231, at opposite sides of a
permanent magnet 232, supported by a stationary sup- 25
port arm 233. In such an instrument, the angular de-
flection of the coil against the slight resistance of a hair-
spring 234 is a function of the amount of current flowing
through the coil. In this embodiment, such current is
produced by a photovoltaic-type cell 235 mounted on coil 30
230 in alignment with a vertical slit 236 between aperture
plates 237 and 238, which are also supported on the coil
and which define a narrow vertical scanning path illus-
trated by broken lines 240.
The light measuring system shown in FIG. 5 may be 35
mounted on a camera or other instrument in the same
manner as described in reference to the system illustrated
in FIG. 4. The scanning range of the system, is defined
by the limits of motion of needle 241, which is attached
to the coil for arcuate movement between legs 242 and 40
243 of step member 244, and so long as the subject is
located along the axis of the light source and within the
scanning range of the system, light reflected from a sub-
ject will always impinge on some portion of the photo-
cell. By profiling photocell 235 so that a maximum area
thereof is illuminated when path 240 is aligned with the 45
reflected spot of light at the subject, an apex (maximum)
current output is produced at the point of proper align-
ment, and the system can be made to align itself auto-
matically. With the illuminated spot reflected from the
subject being aligned with the maximum cell area, the posi- 50
tion of needle 241 is therefore determined by the distance
of the subject from the camera as may be indicated by
appropriate indicia 245 on stationary anvil member 246.
Alternatively, other means might be employed modi-
fying the embodiment shown in FIG. 5 to cause the elec- 55
tric signal of the photocell to change in a similar man-
ner as illuminated area moves either way from the aligned
central position. For example, instead of/or in addition
to varying the area of the photocell, a transparent filter
member varying in density toward each end might be 60
moved across the light path by the coil to vary the in-
tensity of the illumination of the photocell as a func-
tion of the position of the object. To stabilize such a self-
aligning galvanometer system and prevent undue oscil-
lation thereof, it is necessary to determine carefully the 05
desired profile of the photocell, the characteristics of the
hairspring, and other operative elements associated with
the instrument, as well as to provide appropriate damp-
ing means, but such considerations are within the province
of persons skilled in the electric meter art. 70
To translate the position of the needle into a corre-
sponding adjustment of the camera lens or some other
element, step plate 244 is slidably supported by stationary
pins 247 extending through parallel slots 248 and is pro-
vided with a series of steplike surfaces 250, whereby 75
needle 241 is trapped between one of such surfaces and
the lower surface of anvil member 246 to block further
movement of plate 244 as the plate is moved upwardly
by operating lever 251. Accordingly, the blocked posi-
tion of the plate, and/or the corresponding position of
operating lever 251, reflect the angular orientation of the
light sensing system and can readily be translated into the
desired corresponding mechanical movement needed to
focus the optical system.
FIG. 5 represents both the photocell and the associated
scanning path defining means as being movable with the
coil. However, it should be apparent that the coil might
carry only a mirror or some other single movable ele-
ment of the light sensing system as has been illustrated
by the various embodiments previously described. Al-
though the latter varieties necessitate flexible electrical
connections to the coil, they might nevertheless be pref-
erable to reduce the mass of the movable coil struc-
ture.
While the various embodiments of the invention herein
have been described with reference to instruments hav-
ing a movable lens or other element separate from the
elements of the range-finder device itself, it would also'
be possible to utilize the instrument lens for purposes of
focusing the light beam onto the subject or focusing the re-
flected beam onto the photocell. For example, to adjust the
projection lens of a projector as a function of the dis-
tance to the screen, an aperture plate could temporarily
be introduced to restrict the projection beam to illuminate
only a small spot on the screen for detection by the photo-
cell, and, after the lens was adjusted, the plate could be
removed to allow the projector to function in its normal
manner. Likewise, in a camera, a mirror could be inter-
posed temporarily behind the camera lens to focus the
reflected beam onto the photocell, and then removed after
the distance setting had been accomplished, in a manner
similar to that employed in the viewfinder device of a
single lens reflex camera.
The invention has been described in detail with par-
ticular reference to preferred embodiments thereof, but
it will be understood that variations and modifications
can be effected within the spirit and scope of the inven-
tion. Accordingly, the invention is not to be limited to
the specific details shown and described, but is of a scope
as defined by the appended claims.
I claim:
1. In a photographic camera having:
(a) exposure means for exposing an image receiving
surface within said camera to illumination from a
scene to be photographed in response to actuation of
said exposure means; and
(b) trigger means for actuating said exposure means,
the improvement comprising:
(c) rangefinder means including means
(1) for projecting a light beam toward a subject
to be photographed to impinge on the surface
thereof and
(2) for receiving a portion of said beam reflected
from said surface;
(d) beam disabling means for terminating the im-
pingement of light on the surface of said subject;
and
(e) coordinating means operatively connecting said
beam disabling means and said trigger means for
terminating said impingement prior to the actuation
of said exposure means.
2. A photographic camera according to claim 1 wherein
said beam disabling means includes light beam extinguish-
ing means for terminating the projection of said light
beam.
3. In a camera having:
(a) a film plane,
(b) actuatable shutter means for controlling the trans-
mission of light to said film plane, and
(c) actuatable rangefinding means including a mem-
ber positionable automatically as a function of the
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distance from said camera to a subject to be photog-
raphed;
the improvement comprising:
(d) trigger means for sequentially actuating said range-
finding means and said shutter means, whereby said 5
shutter means is actuated only after said member
has been positioned by said rangefinding means.
4. The camera structure according to claim 3 further
including: an objective lens, focusing means for varying
the distance between said lens and film plane, and means 10
operatively connecting said positionable member and said
focusing means for automatically adjusting said focusing
means to vary the distance between the lens and film
plane in accordance with the position of said member.
S. The camera structure according to claim 3 further 15
including indicator means responsive to said positionable
member for indicating the distance from the camera to
said subject.
6. The camera structure according to claim 5 further
including a viewfinder, said indicator means being visible 20
in said viewfinder.
7. In a photographic camera having:
(a) an image receiving surface;
(b) an objective lens;
(c) shutter means for exposing said image receiving 25
surface to an image formed by said objective lens;
(d) focusing means for adjusting said objective lens
to different focal positions varying the distance be-
tween said lens and said surface;
(e) a rangefinder system comprising:
(1) a light source unit including means for pro-
jecting a light beam to produce an area of il-
lumination on an object to be photographed
when said beam impinges thereon;
(2) a directional light sensing unit spaced from
said light source unit and including light respon-
sive means for producing a predetermined elec-
tric signal when said light responsive means and
said area are in alignment;
(3) drive means for moving at least one of said
units to bring said light responsive means and
said area into alignment by altering the angular
relation between said units;
(4) braking means responsive to said signal for
arresting said drive means when said light re-
sponsive means and said area are in alignment;
(f) adjustment means operatively connected to at least
one of said units and to said focusing means to posi-
tion said lens at a focal position corresponding to the
distance from the camera to said object as a function
of the spatial and angular relation of said units when
said drive means is arrested;
the improvement comprising:
(g) light control means for terminating the impinge-
ment of said light beam on said object;
(h) a trigger member; and
(i) actuating means responsive to movement of said
trigger member for sequentially actuating:
(1) first, said rangefinder system and said adjust-
ment means to adjust said lens according to the
distance from the camera to the subject,
(2) second, said light control means to terminate
the impingement of said light beam on said
object, and
(3) finally, said shutter means to expose said
image receiving surface. 65
8. A camera according to claim 7 further comprising:
(a) latching means operable to
(1) a first condition to retain said lens in its ad-
justed focal position when said braking means 70
arrests said drive means in response to said pre-
determined signal, regardless of subsequent al-
teration of said signal; and
(2) a released condition to permit adjustment of
the focal position of said lens; and 75
12
(b) means responsive to said shutter means for op-
erating said latch means to its released condition
upon completion of the exposure of said image re-
ceiving surface by said shutter means.
9. A photographic camera according to claim 7 further
comprising:
(a) a viewfinder; and
(b) indicator means visible in said viewfinder for in-
dicating the actuation of said shutter means.
10. A photographic camera according to claim 7 fur-
ther comprising: override means including a manually
operable override element movable from a first position
to a second position for disabling said actuating means
to allow said shutter means to be operated independently
of said actuating means.
11. A photographic camera according to claim 10 fur-
ther comprising:
(a) means for releasably retaining said override ele-
ment in said second position upon movement of said
element to said second position; and
(b) means for returning said element to said first posi-
tion in response to movement of said trigger means,
whereby said element must be moved manually to
said second position prior to each exposure to be
made independently of said actuating means.
12. A photographic camera according to claim 10 fur-
ther comprising:
(a) a viewfinder; and
(b) override indicator means visible in said viewfinder
for indicating the position of said movable element.
13. In the combination of a photographic camera having
an objective lens adjustable to different focal positions
and a rangefinding device having distance triangulating
means including:
(a) a light source unit adapted to project a beam of
light toward an object to be photographed to pro-
duce an illuminated area on said object when said
beam impinges thereon; and
(b) a directional light sensing unit spaced from said
light source means for producing a predetermined
electric signal when said light sensing means and
said area are in alignment;
the improvement comprising:
(c) adjustable lens means associated with at least one
of said units, said lens means being adjustable to
vary the position of a focal point thereof;
(d) drive means for moving at least one of said units
through a plurality of positions to bring said light
sensing means and said area into alignment;
(e) focusing means responsive to the position of at
least one of said units for adjusting said focal posi-
tion of the lens means during such movement as a
function of the angular and spatial relation of said
units;
(f) braking means responsive to said signal for arrest-
ing said drive means when said light sensing means
and said area are in alignment; and
(g) indicator means operatively connected to at least
one of said units to indicate the distance from the
camera to said object as a function of the spatial and
angular relation of the units when said drive means
is arrested.
14. The combination according' to claim 13 further
comprising: adjustment means responsive to said indicator
means for adjusting the focal position of said objective
lens as a function of the spatial and angular relation of
said units when said drive means is arrested.
15. A photographic camera comprising:
(a) an objective lens;
(b) means defining a surface upon which an image
formed by said lens will be in focus when said lens
and said surface are spaced by a first distance func-
tionally related to a second distance between said
lens and the object defining said image;
(c) movable means for adjusting said first distance
between said lens and said surface;
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
13
3,442,193
(d) a light lens means having an adjustable focal point
for projecting a beam of light from said unit along
a narrow first path to produce a localized illuminated
area on said subject when said first path is aligned
therewith;
(e) a light sensing unit including:
(1) photoresponsive means adapted to produce a
predetermined electric signal when in optical
alignment with an illuminated area; and
(2) a second lens means having an adjustable
focal point for defining a narrow second path
within which an illuminated area is in such
signal-producing alignment with said photocell
unit, said second path being engularly disposed
with respect to said first path and in intersecting
relation therewith;
(f) drive means for moving at least one of said units
to alter the angular relation of said paths and the
point of intersection thereof;
(g). rangefinder focusing means responsive to said drive
means for adjusting the focal point of at least one
of said first and second lens means as a function of
the position of said drive means;
(h) disabling means for arresting said drive means in
14
response to said signal when said point of intersection
and said illuminated area on said object are in coin-
cidence; and
(i) image focusing means operatively connecting said
drive means and said movable means for varying
said first distance as a function of the position of
said drive means.
References Cited
UNITED STATES PATENTS
1,866,581
7/1932
Simjian ------------ 352-140
2,701?,500
2/1955
Schwartz et al.
2,811,908
11/1957
Nerwin.
3,249,006
5/1966
Stauffer ------------ 352-140
3,264,935
8/1966
Vose -------------- 352-140
3,342,102
9/1967
Maxon ------------ 352-140
3,367,254
2/1968
Townsley ------------- 95-44
NORTON ANSHER, Primary Examiner.
C. B. FUNK, Assistant Examiner.
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-00120R000100010021-3
Oct. 7, 1969 R. H. STUDEBAKER 3,471,234
LASER BEAM PROJECTOR FOR SURVEYING OPERATIONS
Filed June 8, 1966
4 Sheets-Sheet 1
INVENTOIL
P.IJBSRT N~S`tvLBtitF~
Approved For Release 2009/04/10: CIA-RDP81-00120R000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Oct. 7, 1969
R. H. STUDL?AKER 3,471,234
LASER BEAM PROJECTOR FOR SURVEYING OPERATIONS
Filed June a. 1966
5
15$
FIG. 2
4 Sheets-Sheet
R,eCm r H,SUDEawm
BY W. A. JG~no~~ a
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Oct. 7, 1969 R. H. STUDE BAK R 3,471,234
1xvE~TOR
fir- H. S'sZUDeBFVC#R
BYW A.`JC~na-c~
`~ .aQ~Cy-.sti.Qna~,,.
LASER BEAM FRC,TECTOR FOR SURVEYING OPERATIONS
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
H S
R
Or-f- 7. 14f;;Q
.
, UDEE AKER
FIG. 4
LASER BEAM PROJECTOR FOR SURVEYING OPERATIONS
43b
FIG. 6
0.-I! 1,XJ4
4 Sheets-Sheet 4
VEx?oL
ice- I~ ~oEt~
BY W.A.Sc~na~cln`
cch~
Approved For Release 2009/04/10 CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
United States patent Office
1
3,471,2234
LASER BEAM PROJI CTOR FOR SURVEYING
OPERATIONS
Robert FL Studebaker, Dayton, Ohio, assignor. to Process
Equipment Company of Tipp City, Inc., a corporation
of Ohio
Filed June 8, 1966, Ser. No. 556,018
Int. Cl. GOlc 3100, 5100, 1/00
U.S. CL 356-3 8 Claims
3,471,234
Patented Oct. 7, 1969
2
a rotatable laser beam generator wherein a shadow may
be produced in the beam at a, -y one or more of a plu-
rality of precise angular locations around the rotational
axis of the laser beam, thereby permitting the measure-
ment or layout of angular displacements about the axis
of the rotating laser beam.
Still another object of this invention is to provide a
laser beam generator of the type producing a laser beam
rotating in a plane, characterized by the provision of ac-
curate mechanism for tilting the plane defined by the
laser beam to assume a desired inclination with respect
to the axis of rotation of the laser beam.
Other and further objects and advantages of this in-
vention will become apparent to those skilled in the art
from the following detailed description thereof, taken
in conjunction with the annexed sheets of drawings on
which a preferred embodiment of this invention is illus-
trated.
On the drawings:
FIG. I is a side elevational view of a planar laser
beam generator constructed in accordance with this in-
ABSTRACT OF THE DISCLOSURE
This invention provides a method and apparatus for
performing precise surveying operations relative to a
selected reference point by utilizing a laser beam. A 15
portable laser beam reference plane generator is provided
which may be set up in precise alignment with a selected
reference point and which produces a rotating laser beam
sweeping over the adjacent terrain. The generator may be
accurately adjusted to permit both elevation and angular 20
displacements to be measured at any point within the`
area tratersed by the rotating laser beam.
This invention relates to a precision surveying appara-
tus employing a laser beam as a reference plane, which
plane may be horizontal or at any desired angle relative
to the horizontal, and more particularly, to a portable
laser beam reference plane generator which may be set
up in precise alignment with a selected reference point
on any type of terrain and conveniently and accurately
adjusted to produce a laser beam rotating about an axis
passing through such reference point.
In my copending application Ser. No. 468,821, fired
July 1, 1965, now abandoned, and assi,,.cd to the assignee
of this application, I have disclosed and claimed a meth-
od and apparatus for utilizing a generated laser beam
sweeping through a preselected reference plane for de-
termining the relative elevation with respect to the refer-
ence plane of any ground surface point within the effec-
tive range of such laser beam. As pointed out in such co-
pending application, such system greatly facilitates sur-
veying operations and may also be utilized to simultane-
ously control earth working operations of a- plurality
of grading machines, scrapers, mining equipment, or the
like, each of which being provided with laser beam de-
tector means and suitable control arrangements respon-
sive to the laser beam for adjusting the elevation of the
implement to maintain such implement at a preselected
displacement relative to the laser beam reference plane,
irrespective of the. terrain variations.
In my copending application Ser. No. 474,684, filed
July 26, 1965, now abandoned, and assigned to the as-
signee of this application, I have disclosed a specific struc-
ture for a tripod-mounter laser beam generator. I have
now developed certain improvements in such construction
which provide even greater convenience and accuracy in
operating such laser beam- generator and further permits
the resulting laser beam to be utilized to not only deter-
mine elevation in surveying operations but also permits
angular displacements to be accurately laid out or meas-
ured over any type of terrain.
More particularly, it is an object of this invention to
provide a portable laser beam generator capable of pro-
ducing a laser beam rotating about an axis characterized
by the fact that the rotatable axis of the laser beam may
be precisely aligned with a ground reference point.
Another object of this invention is to provide an im-
proved method of surveying utilizing a rotating or oscil-
lating laser beam.
A further object of this invention is the provision of
vcntion.
FIG. 2 is a
of FIG. 1.
sectional view taken on the plane A-A
25 FIG. 3 is an enlarged scale perspective view of the top
portion of the laser beam generator of FIG. 1.
FIG. 4 is a partial vertical sectional view of the top
portions of FIG. 1.
FIG. 5 is a schematic plan view illustrating the utiliza-
30 tion of the laser beam generator of FIG. I in a survey-
ing operation for accurately determining angular dis-
placements.
FIG. 6 is a perspective view of a modified beam block-
ing member.
33
As shown on the drawings:
All of the elements of the laser beam generator shown
in FIG. I which appear below the section line A-A are
functionally identical to those disclosed and described
in detail in my said copending application Ser. No.
40 474,684, filed July 26, 1965 and hence reference should
be had to that application for a more detailed descrip-
tion of these elements. Briefly, there is provided a pri-
mary base or support member 10 which is of a circular
45 platelike configuration and has a plurality of depending
mounting brackets 11 welded around the periphery there-
of to provide a pivotal mounting for the bifurcated ends
of tripod legs 13. In this manner, primary base 10 may
be supported by the tripod legs 13 in a roughly hori-
zontal position on any terrain. Base 10 is further pro-
50 vided with a central depending circular boss 10a welded
thereto and. a similar boss 10b, formed in two semi-
circular pieces is secured to the top surface of primary
base 10 by a plurality of bolts (not shown). Bosses 10a
and 10b are centrally apertured and together define a
55 spherical segment internal bearing surface (not-shown).
A secondary base element 15 is provided which consti-
tutes a vertically extending hollow member. The lower
end of secondary base member is enlarged and ground to
60 produce an external spherical segment bearing surface
(not shown) which is cooperable with the inteiior spheri-
cal bearing surface of the primary base member 10 to
adjustably mount the. secondary base element in a gen-
erally vertical position relative to the primary base 10.
Near the middle portion of the secondary base elo-
as ment 15, a radially projecting integral flange 15c is pro-
vided which overlies the primary base 10 beyond the
perimeter of boss 10b. At equally spaced locations around
the perimeter of flange 15c, a plurality of threaded aper-
lures are provided which respectively receive the threaded
70 ends of depending adjusting pins 16. The adjusting pins
16 are each provided with an enlarged hand grasping col-
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
3)471,234
3 4
tar 16b and a flat head portion 16c which contacts the hollow hub 25 is rotatably journaled by suitable bearings
top surface of primary base'10. It is therefore apparent 26. The upper portions of hub 25 project above the radial
that the adjusting pins 16 permit the vertical position of enlarp~ment 17b and the top end 25a of hub 25 is solid.
secondary base 15 to be accurately pivotally adjusted rein- An inverted, cup-shaped cover 27 is mounted over the
tive to the primary base or support 10 to assume either 5 projecting portions of hub 25 and secured thereto by a
a true vertical position or a position at any desired in- bolt 27a. On the bottom edge of cover 27, a pulley 28 is
clination relative to the vertical, as indicated by means welded and a belt 29 connects pulley 28 to the motor
.that will be hereafter described. driven pulley 21b.
The top portion of secondary base 15 is axially slit to Near the top of hollow hub 25 an optical reflecting
define two opposed clamping flanges 15/ and a hand actu- 10 device 22 -is mounted which is arranged to receive the
ated clamping bolt 15e ii provided to draw such clamping upwardly directed primary laser beam Ll passing .`rough
flanges 15f together. Additionally, a spur gear 15k is the hub bore 25c and to reflect such beam in a fixed angu-
journaled between flanges 151 and is rotatable by a hand - lar relationship to the direction of the incident beam, for
crank 15) for a purpose to be described. example, at exactly 90? to the direction of the incident
As previously mentioned, secondary base element 15 is 15 laser beam L1. Thus, the reflected beam L3 will be posi-
hohow and defines a vertically extending cylindrical bore tioned in a fixed angular relationship, preferably 90?,
ISa (FIG. 2) extending completely through the second- with respect to the axis of tubular housing 17 and the
ary base element. A tubular support or housing 17 is pro- bore axis of the secondary base element 15. Optical de-
vided having a cylindrical portion 17a which is snugly vice 22 could be an accurate mirror positioned at a pre-
but slidaL.'y insertable in the cylindrical bore 15a of the 20 cise 45? angle with respect to the incident laser beam Li,
secondary base element 15. An axially extending rack but preferably comprises a device known as a pentaprism,
gear lie is secured to the outer wall of tubular support one type of which is currently manufactured and sold by
17 and passes through flanges 15f and cooperates with Brunson Instrument Company of Kansas City, Mo. and
spur gear 15k. A suitable axial slot (not shown) is pro- has the property of reflecting any incident light beam at
vided in the secondary base element 15 to accommodate 25 exactly 90? to the direction of the incident beam. Hence
the rack gear 17c. any eccentricity in the rotation of the hub 25 due to
It is therefore apparent that the relative vertical posi- bearing wear or misalignment will not change the angular
tion of the housing 17 with respect to the secondary base relationship of the reflected beam L3 relative to the pri-
element 15 may be conveniently adjusted by rotating hand mary beam U.
crank 15j and the housing 17 may then be locked in any 30 In the specific embodiment shown in the drawings, the
selected vertical position relative to the secondary base hollow hub 25' is provided near its top with a recess 25d
15 by tightening the clamping bolt 15e. Such adjustment, communicating with the hub bore 25c and correspond-
however, does not produce any deviation of the axis of ing in shape to the shape of the pentaprism 22. The re-
tubular housing 17 relative to the axis of the bore of cess 25d opens through the wall of the hub 25 so that the
the secondary base element 15, hence, in any selected ver- 35 pentaprism 22 may be slidably but snugly inserted in such
tical position, the axis of the housing 17 is shifted relative recess. A cover plug (not shown) is then inserted in the
to the vertical by manipulation of the adjusting pins 16. recess 25d to hold the pentaprism 22 in position.
In the lower portions of the tubular housing 17, a con- The pentaprism is of roughly pentagonal shape and is
ventional laser beam source 18 is suitably mounted so formed from optical quality glass. One side 22a of the
that a collimated primary beam Li produced by such 40 pentaprism receives the incident laser beam L1 and an-
laser source is upwardly directed and is coaxially aligned other side 22b, which is perpendicular to the first side
with the axis of housing 17. The laser beam source 18 22a, transmits the reflected laser beam U. The other two
may comprise any conventional gas laser such as the opposed angular sides 22c and 22d of the pentaprism
Model No. 5200 currently manufactured and sold by have a mirror coating applied to their outer surfaces, and
Perkin-Elmer Corporation of New Britain, Conn. The 45 ,!iise sides are accurately ground so that the incident
housing 17 is preferably formed from aluminum or any beam LI is internally reflected in the pentaprism 22 to
other metal which will shield the laser source 18 from follow the path indicated by the dotted lines to produce
ambient .electrical disturbances and which will readily the final output beam L3, which will always be at exactly
dissipate the heat generated by the laser source 18. Laser 90? to the direction of the incident beam U. The hub
Source 18 may be actuated by any source of electrical 50 25 is, of course, provided with a radial aperture 25e to
energy producing the required voltage and power. Permit the reflected beam L3 to pass out of the hub. The
I have observed that such laser beam sources actually cover 27 is provided with a suitable. aperture 27b in its
produce two oppositely directed beams, one beam being, side wall aligned with the radial hub opening of 25e, and
of course, the primary beam Ll and having the maximum hence with the path of the reflected laser beam D. Aper-
intensity, but a secondary beam indicated at L2 (FIG. 55 ture 25e may be covered by a suitable inserted window
1) is also emitted from the other end of such source 25f of glass or transparent plastic as desired.
in alignment with the primary beam U. Secondary beam The top surface 17m of the housing enlargement 17b is
L2 is of substantially reduced intensity, yet quite visible accurately ground to be precisely normal to the axis of
to the eye of an observer. In accordance with this inven- housing 17, hence normal to the primary lase; ream Ll.
tion, the secondary laser beam L2 is utilized to assure the 80 A pair of mutually perpendicularly disposed fluid bubble
precise vertical alignment of the primary beam Li with level indicators 24 are then mounted on, or in a selected
a selected ground reference point P. This can be very con- angular relationship with the ground top surface 17m
veniently accomplished by providing a central aperture and the indicating bubbles' of such level indicators may
17h in the bottom of housing 17 and covering such aper- be utilized to indicate when the surface 17m is exactly
ture with a transparent window 17j of glass or a plastic 05 horizontal with respect to gravity or in a selected angular
material that will readily transmit the laser beam L2. relationship therewith.
Referring now particularly to FIG. 3. it will be ob- In accordance with this invention, one of the level
served that the top portion of the tubular housing 17 is indicators 24 is mounted on a sine bar 30. The sine bar
provided with a radial enlargemen' indicated at 17b hav- 30 is snugly pivotally mounted at one end on a pivot bolt
lag a depending flange ;7d along one side. An electric 70 30a which is threaded into the depending flat side 17d
motor 21 is mounted on flange 17d in depending rela- of the enlargement 17b. The other end of the sine bar is
tionship to the enlargement 17b and has its shaft 21a raised or lowered relative to the top surface urn of hous-
projecting through an aperture 17e (FIG. 4) in the en- ing enlargement 17b by a micrometer actuated rod 31
largement 17b and mounts a pulley 21b thereon. Within which abuts against a transverse pivot pin 33 journaled
the top rArN,. A ..Q .L- a.-_ _r L____?_ ..
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
3,471,234
the ho'ising side 17d and such bracket is traversed by the
nucrorneter rod 31 and 1.,ounts in depending relationship
a conventional micrometer adjusting mechanism 33.
Mechanism 33 is provided with conventional calibrations
33a which are graduated to indicate the angular displace-
ment of the sine bar 30 relative to the ground top surface
17m, preferably in conventional surveying units of .01 ft.
vertical elevation per 100 ft. of horizontal distance. Ac-
cordingly, the sine bar 30 may be adjusted by-micrometer
mechanism 33 to a zero position where the top surface
30b of the sine bar 30 is exactly parallel to ;'ae ground
surface 17m of the housing enlargement 17b, or may be
angularly displaced upwardly or downwardly relative to
the ground top surface 17rn (hence, relative to the axis
of rotation of the laser beam L3) by a precise angular
amount by operation of the micrometer mechanism 33.
The last improvement accomplished by this invention
involves the provision of a support ring 40 which sur-
rounds cover 27 and is positioned in coaxial relationship
with respect to the axis of housing 17, hence in coaxial
relationship with respect to the primary laser beam Ll.
Ring 40 is supported in parallel relationship to the top
surface 17m by a plurality of posts 41 which are suitably
secured to the ring 40 and to the top surface 17m of the
housing enlargement 17b. The ring 40 is of shallow U-
phaped configuration, thereby defining an annular track
or channel 40a (FIG. 3). An indicating ring 42 is snugly
but rotatably mounted in the channel 40a. Ring 42 is
provided with angular graduations 42a on its top surface.
In accordance with this invention, one or more beam
blocking members 43 are provided which may be detach-
ably secured to the ring 40 at any desired horizontal
angular position relative to the axis of the primary laser
beam L1, assuming such laser beam to be vertical. Beam
blocking members 43 are provided with a properly shaped
recess 43a in their bottom portions to permit such mem-
bers to be snugly but slidably supported on the ring 40.
A radially disposed clamping screw 43b permits each
block 43 to be locked to ring 40 at any desired angular
position about the ring 40.
Preferably, one of the beam blocking members 43 is
constructed to have a transverse width in the plane of the
rotating laser beam L3 equal to the corresponding width
or diameter of the laser beam L3. The radial sides 43c
and 43d of each beam blocking member .13 are exactly
radial with respect to the rotational axis of the laser beam
13. If desired, additional beam blocking members 43'
(FIG. 6) may be provided whose cross-sectional con-
figuration in the plane of the rotating laser beam corre-
spond exactly to a fixed angle. In the case of the illustrated
beam blocking member 43', the angle is 90?.
The improvements in the laser beam generator hereto-
fore described contribute substantially to the flexibility
and utility of the laser beam generator. For example, in
all surveying operations, or operations involving the con-
trol of earthworking or analogous equipment by a laser
beam, there has to be first located in the working area
one or more reference points whose elevation is precisely
known. These reference points are commonly indicated
by a stake driven into the ground with an X on the top
of the stake indicating the precise reference point. It is,
of course, desirable that the rotating laser beam L3 be
aligned so that its axis of rotation passes precisely through
the desired reference point. This is accomplished with
Referring to FIG. 5, let us assume that it is desired to
lay out a line extending from the reference aoint P at
exactly 90? to another line passing through the reference
point. A beam receiving surveying rod 50, of the type de-
scribed in detail in my copending application Ser. No.
532,944, filed Mar. 9, 1966 and assigned to the assignee
of this application, is then set up at any desired distance
away from the reference point along the known line and
vertically adjusted to receive the laser beam L3. One of
the beam blocking members 43 is then moved around
ring 40 until the signal generated by the receiver on sur-
veying rod 50 is interrupted. At this position the survey-
ing rod 50 lies exactly in the shadow of the beam pro-
duced by the beam blocking member 43. Such member
43 is locked in this position on ring 40 by screw 43b. The
second be'tm blocking member (or the first one, if do-
sired) is then positioned exactly 90? away from the po-
sition of the first blocking member, as indicated by the
graduations 42a. The surveying rod 50 is then moved
by the rodman until it lies in the beam shadow S' pro-
duced by the second beam blocking member 43, and the
line drawn between the reference point and the second
location of the rod 50 will be exac'`y 90' with respect to
the known line. Of course, instead of utilizing two beam
blocking members 43, the single beam blocking member
43' having an angular extent of 90? could be mounted
blocking members for detecting or laying out horizon-
tWl angular relationships will be readily apparent to those
skilled in the art.
At any time it is desired to move the rotating laser
beam L3 in a plane that is inclined by a known amount
of degrees relative to the horizontal, the sine bar 30
and micrometer adjusting mechanism 33 may be em-
ployed. It is only necessary to set up the laser beam
generator so that the sine bar 30 is generally perpendicu-
lar to the horizontal axis about which the tipping of the
resulting laser beam plane is desired. Micrometer mech-
anism 33 is then actuated to displace the sine bar 30 by
the desired amount of angular inclination. Thereafter,
the adjusting pins 16 are operated to bring both bubble
level indicators 24 to their level indicating positions. The
resulting plane through which the rotating laser beam
L3 is swept will then be exactly parallel to the top sur-
face 30a of the sine bar 30, and hence will be inclined
relative to the horizontal by the amount indicated by
the setting of micrometer mechanism 33.
It will be undelctood by those skilled in the art that
many of the terms utilized in this specification and claims
are relative. Thrs, in describing the invention, emphasis
has been directed to conventional surveying operations
wherein the rotating beam is moving in either a horizontal
plane or a plane inclined at a slight angle to the horizon-
tal. Laser beam generators embodying this invention may
be applied to effect surveying measurements or utilized
as a surveying reference plane for structures or operations
requiring a vertical reference plane. In this case, the axis
of rotation of the rotating laser beam would be generally
horizontal, and supports other than the conventional tri-
pod legs would have to be provided for the primary base
member 10. Furthermore, for lack of an adequate generic
term, I have employed in the claims the term "surveying
reference apparatus." A.device embodying this invention
may obviously be utilized for setting up a laser beam ref-
the utmost dispatch by permitting the secondary laser 65 erence plane for surveying operations, but the same plane
beam L2 to project out of the bottom of housing 17 to may be advantageously utilized for controlling the vertical
impinge on the stake. Hence in setting up the lase beam movements of the working tool of various types of earth-
generator, the transit legs will be adjusted so that the sec- working implements; hence, the term "surveying refer-
ondary laser beam L2 is observed to be incident upon ence" is intended to include all utilizations of the refer-
tho center point of the reference marking on the top of 70 ence plane established by the rotating laser beam.
the reference stake. It is therefore apparent that a laser beam generator in-
In many surveying operations, it is desirable that a corporating the described improvements may be quickly,
horizontal line be laid out at an exact angular relation- conveniently and accurately set up on any terrain and con-
ship -'t-.:.._ -M:- ....... L_ -1;n?trA - prompt.. - 1, ,'r pram rotating or
acc< Approved For Release-2009/04/1 0 : CIA-RDP81-0012OR0001 sxactly aligned
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
3,471,23.1
7
with a known reference point. The elevation of the re- (3) r' ]ceding the upwardly directed beam at a known
suiting iaser beam pia:re may be conveniently adjusted and angle to the vertical; and
the inclination of the resulting laser beam plane relative (4) .'ctecting the reiected beam at a point horizontal
to the horizontal may be accurately and conveniently ly spaced from said reference point. _
adjusted to any desired angular relationship. Lastly, angu- 5. The method defined in claim 4 wherein said re-
lar displacements may be laid out, or the angular distance flected laser beans is continuously rotated or oscillated
between two unknown points on the terrain relative to a about the vertical axis of the originally generated laser
reference point may be quickly and accurately determined. beam, thereby defining a surveying reference plane having
As will he evident to those skilled in the art, modifica- a known elevational relationsnip to said reference point.
tions of this invention can be made in the light of the 10 6. A laser beam generator comprising a primary sup-
foregoing disclosure without departing from the scope of pert structure, a laser beam source producing two op-,
the appended claims. positeiy directed laser beams, a hollow tubular housing
I claim: constructed an-i arranged to receive said laser beam source
1. Laser beam surveying apparatus comprising: therein with said laser beams respectively directed patallel
(1) means for rotating a laser beam about a vertical 15 to the housing axis, means for mounting said housing on
reference axis; said support in a generally vertical position, said last men-
(2) an annular ring supported in coaxial relationship tioned means including means for angularly adjusting the
with said reference axis and axially spactd from the position of said housing to precisely position both laser
laser beam; beams in a true vertical position, whereby the down-
(3) At least one beam-blocking member mountable on 20 wardy directed beam impinges on the ground or other ref-
said ring in any selected angular position thereon, said erence surface to permit vertical alignment of the down-
beam-blocking member intersecting said laser beam wa-dly directed beam with a desired reference point, an
and having a width dimension in the plane traversed optical device capable of reflecting an incident laser beam
by the laser beam at least equal to the width of the at a known angle, means for rotatably mounting said opti-
laser beam, thereby creating a void ,r. the resulting 25 cal device in the path of said upwardly directed laser
laser beam reference plane at any selected angular beam, whereby rotation, or oscillation of said optical de-
position about said reference axis; and vice causes the reflected laser beam to sweep through a
(4) arcuate scale means for indicating the angular plane at a known angle to the true vertical.
position of said beam-blocking member. 7. The apparatus of claim 6 plus means for adjusting
2. 'f'he apparatus defined in claim 1 wherein said arcu- 30 the vertical position of said optical device relative to said
ate scale means comprises a second ring bearing degree primary support.
graduations, said second ring being rotatable relative to 8. Laser beam surveying apparatus comprising: (1)
said first mentioned ring and coaxial therewith. ` means for rotating a laser beam transversely about a
3. Apparatus for surveying angular relationships about vertical reference axis; (2) a beam-blocking member; (3)
a ground reference point comprising' 35 means for positioning said beam-blocking member to in-
(1) means for rotating a laser been about a vertical tercept?said beam at any selected angular position around
axis passing through the ground reference point; said vertical axis, thereby creating a void in the resulting
(2) a horizontal annular ring supported in coaxial re- laser beam reference plane at any selected angular posi-
lationship with said vertical axis and vertically spaced 40 tion about said reference axis.
from the laser beam;
(3) at least one beam blocking member mountable References Cited
on said ring in any selected angular position there- UNITED STATES PATENTS
on, said beam blocking member intersecting said laser 368,308 8/1887 Richardson 33-72
beam and having a cross-sectional configuration in
the plane traversed by the laser beam corresponding 95 1 1 9,92212,,791 793 3/1930 0 Bu iy
Bum 88-2.2 X
to the desired an l,, thereby creating an an ular glie
void in the resulting laser beam reference plane at 3,266,014 8/1566 Leotta ------------ 240-49 X
any selected angular position about the ground ref- 3,279,070 10/1966 Blount et al. 33-46.2
erence point. 3,335,285 8/1967 Gally et al.
4. A method of utilizirg a laser beam as a surveying 50 RONALD L. WIBERT, Primary Examiner
reference comprising the steps of:
(1) selecting a reference point in the area to be sur- J. ROTHENBERG, Assistant Examiner
veyed;
(2) positioning a laser beam source, of the type produc- U.S. Cl. 'X.R.
ing two oppositely directed laser beams, in a posi- 65 33-72, 331--94.5; 356-138
tion where the beams are vertical and the downward-
ly dire: ed one of said beams impinges on said ref-
erehue point:
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
July 7, 1970 G. PRADEL ET AL 3,519,829
OPTICAL SYSTEM FOR RADIATION SENSITIVE RANGR['INDLR
Filed Oct. 10, 1967
01
I
0,2 Fig.1
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 U Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
niteci zntates Patent Uffice 3,519,829
Patented July 7, 1970
3,519,829
OPTICAL SYSTEM FOR RADIATION
SENSITIVE RANGEFINDER
Georg Pradel, Heinz Richter, and Rolf Roder, Jena, Ger-
many, assignors to VEB Carl Zeiss Jena, Jena, District
of Gera, Germany
Filed Oct. 10, 1967, Ser. No. 674,710
Int. Cl. G01c 3/08
U.S. Cl. 250-216
ABSTRACT OF THE DISCLOSURE
An electro-optical rangefinder has two optical systems
and two light-sources. The one light-source through one
of the optical systems emits intensity-modulated invisible
light for measurement The other light-source emits visible
light and together with the other of the two optical sys-
tems makes up into a searchlight. Said other light-source
lies at such a focus of said one optical system as corre-
sponds to the medial wave-length of the light it emits. To
the optical system not emitting visible light is coordinated
an eyepiece for visual reception of the visible light. The
two optical systems may be coaxial with each other.
This invention relates to electro-optical rangefinders
comprising a radiation source emitting invisible light of
modulated intensity and two optical systems for respec-
tively transmitting and receiving this light.
Some known electro-optical rangefinders have a radia-
tion source emitting visible light the beam' of which is
modulated in intensity and then transmitted through an
optical system that serves at the same time for spotting a
distant reflector. Other such rangefinders with radiation
source emit and receive invisible light. Locating a remote
reflector by means of an electro-optical rangefinder of
that kind presents considerable difficulties, which can only the optical system o make-up-
ake up into a sighting telescope. If
be obviated by the simultaneous use in the measuring the mirror 4 and the mirror 40 respectively assume the
process of a separate search light. This separate search- 40 positions 4' and 40', the light of the light-source 2 is di-
light and the orientation it is required to impart to the rected through the optical system 1 and reflected by the
electro-optical rangefinder, incur considerable material ex- remote reflector, whereupon it enters the sighting tele-
penditure and complicate the measuring process. scope 5, 8, 9, 10 and, if accurately oriented and focussed,
The present invention aims at providing an electro-op- forms on the plate 9 an image of the reflector. When,
tical rangefinder using invisible light for measuring which 45 and not before, the image of the reflector lies at the cen-
is equipped with a searchlight that involves only a mini- ter of the graduated plate 9, the folding mirrors are to be
mum of material and technical complexity. tilted into the positions 4 and 40, whereupon the distance
To this end the invention consists in an herein can be measured by means of the receiver 7 and the mod-
rangefinder of the foregoing kind wherein a light-source ulated light striking it, this light being converted for range
emitting visible light is located at such a focus of one 50 display. The simultaneous tilting of the two mirrors may
be operated by a suitable
e
length of its light beam. If this optical system is a sur-
face mirror, the position of the focus is of course inde-
pendent of wave-length. On principle, the light-source sup-
plying visible light may be conjugate to the transmitting 55
or to the receiving optical system of the electro-optical
rangefinder. However, it is very often advisable to co-
ordinate the source of visible light to the optical system
emitting the intensity-modulated beam. A further simplifi-
cation in the set-up of such rangefinders can be obtained 60
by providing that the optical system not serving as search-
light is in the form of a sighting telescope. Advantageous-
ly the beam of the light-source emitting visible light and
that of the radiation source emitting invisible light are
face reflects to the transmitting optical system either the
2
rotatable about a horizontal and a vertical axis, both rota-
tions being measurable.
In order that the invention may be more readily under-
stood, reference is made to the accompanying drawings
which illustrate diagrammatically and by way of example
two embodiments of an electro-optical rangefinder, and
in which:
FIG. I shows the optical parts of an embodiment with
separate optical systems for transmitter and receiver, and
FIG. 2 shows the optical parts of another embodiment
with coaxial optical systems for transmitter and receiver.
In the embodiment shown in FIG. 1 a light-source 2
emitting visible light and a radiation source 3 emitting
invisible light are located respectively in two foci of a
transmitting optical system 1. The source 2 lies in the
optical axis 01-01 of the system I. The source 3 lies
at one side of this axis, its light being directed to the
system 1 by means of a folding mirror. The mirror 4
is so tiltable into two positions that a remote reflector 39
receives either visible spotlight (position 4') or invisible
measuring light (position 4).
A receiving optical system 5, equal to the transmitting
system 1, has an optical axis 02-02 parallel to the axis
O1-01. The focus of the system 5 lies in a diaphragm 6
25 coordinated to an electric receiver 7. The modulated in-
visible light of the radiation source 3 reflected by the re-
mote reflector, traverses the optical system 5, is reflected
by the remote reflector, transverses the optical system 5,
is reflected at a folding mirror 40, arrives at the dia-
30 phragm 6 outside the optical axis 02-02 and enters the
receiver 7. The center of the diaphragm 6 and that of
the radiation source 3 lie in an axis X1-X1 which is at
right angles to the optical axes O1-01 and 02-02 and
is the common axis of rotation of the two systems 1 and 5.
35 The optical axis 02-02 contains a focussing lens 8, a
m
c ansm.
In the embodiment shown in FIG. 2 of the drawings,
two supports 12 and 13 are mounted on an alidade 11
rotatable about an axis Y-Y at right angles to the plane
of the drawing. A telescope 14 is rotatable about an
X2-X2 by means of two hollow trunnions 15 and 16
extending into the supports 12 and 13. The telescope 14
contains a concave mirror 17 for light projection. A radi-
ation source 18 supplying modulated invisible light is
provided near the apex of the mirror 17. A visible-light
source 19 iia the trunnion 15 and the invisible-radiation
source 18 are both located at foci of the concave mirror
17. A right-angled prism 20 is so disposed in the telescope
14 that its cathetus surfaces 21 and 22 are respectively
conjugate to the light-source 19 and the radiation source
18. The cathetus surface 22 is selectively silvered, so that
the divergent li
ht ra
f
h
g
ys
rom t
e radiation source 18
invisible or the visible light and lets the other pass un- are reflected to the concave mirror 17. The divergent
obstructed. rays of the light-source 19 are reflected by the hypotenuse
Advantageously the transmitting and the receiving op- 70 surface 23 in the prism 20. They traverse the selectively
tical system have a common optical axis. According to a silvered cathetus surface 22 and arrive at the concave
further feature of the invention, both systems are jointly mirror 17, which directs then n z hen- of parallel rays
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3,519,829
3
to a remote reflector similar to the reflector 39 of FIG.
2. The light-source 19 and the radiation source 18 can
alternately' be switched on and off.
The telescope 14 also contains an optical receiving
system comprising an objective 24 and a focussing lens
25, the optical axis 03-03 of this system coinciding with
that of. the concave mirror 17. Whereas the objective 24
is rigidly connected to the telescope 14, the focussing lens
25 in the telescope is displaL.eable along the directions of
the arrow A.
The trunnion 16 contains a plane mirror, 26 which is
rotatable about an axle 27 at right angles to the plane
of the drawing. A tube 28 fast with the trunning 16 con-
tains a graduated plate 36 and an eyepiece 37 which to-
gether with the optical system 24, 25 make up into a
sighting telescope.
The support 13 contains a diaphragm 29 conjugate
to a photoelectric receiver. The diaphragm 29 and the
receiver 30 are so located that their centers lie in the
axis Xa--X2. The diaphragm 29 and the cross line on the
graduated plate 36 in the tube 28 lie within the image
distance of the optical system 24, 25. A beam 34 of
parallel light rays reflected by the remote reflector tra-
verses the optical system 24, 25 and is transmitted as a
converging beam to the hypotenuse surface 23 of the
prism 20, whence this beam is directed either to the plane
of the graduated plate 36 or to that of the diaphragm 29,
depending on whether the light is of the visible or the
invisible kind and according to the respective position
of the mirror 26. A range is determined by the modulated
light that emanates from the radiation source 18 and
which in a similar manner to FIG. 1 is so reflected from
the remote reflector as to travel through the optical sys-
tem-24, 25, 23 to the plane of the diaphragm 29, and by
the receiver 30 which the impinging light signal causes to
display the range..
In the embodiment shown in FIG. 2, the light-source
19 emits visible light via the prism 20 and the concave
mirror 17, which serves as spotlight projector. The light
4
The embodiments of the invention particularly de-
scribed are represented merely as examples of how the
invention may be applied, many modifications being pos-
sible in the constriction and relative positions of the
optical systems and the light-sources.
We claim:
1. An electro-optical rangefinder comprising:
a radiation source supplying invisible modulated light,
an optical system for transmitting said modulated light
subsequently to reflection by a remote reflector,
a photo-electric receiver receiving said modulated light,
a light-source supplying visible light,
said light-source being disposed at such a focus of one
of said two optical systems as corresponds to the
medial wavelength of the visible light,
said one optical system emitting the visible light,
the other of said optical systems receiving the visible
light reflection of same at said reflector,
and an eyepiece system coordinated to the optical sys-
tem receiving the visible light,
said eyepiece system being for visual observation of the
visible light reflected by said reflector.
2. An electro-optical rangefinder as claimed in claim
1, wherein the optical system traversed by said modulated
25 light is in the form of a sighting telescope.
3. An electro-optical rangefinder as claimed in claim
1, wherein the source of visible light in coordinated to the
optical system emitting the intensity-modulated beam.
4. An electro-optical rangefinder as claimed in claim
30 1, wherein the optical systems have a common optical
axis.
5. An electro-optical rangefinder as claimed in claim
1, wherein said reflector is coordinated to a right-angled
prism, the cathetus surface of the prism which faces the
35 reflector being selectively silvered.
6. An electro-optical rangefinder as claimed in claim 5,
wherein both systems are jointly rotatable about a hori-
zontal and a vertical axis.
returned by the remote reflector travels by way of the 40
objective 24, the focussing lens 25, the hypotenuse sur-
face 23, the mirror 26 and arrives in the optical system in
the tube 28, which serves as sighting telescope.
In the support 13, a vertical graduated dial 31 is fast
with the trunnion 16. The readings on the dial 31 can be
taken by means of a mirror 32 on the support 13, an
aperture 35 in the support 13 and a reading microscope
33 fast with the trunnion 15. The microscope 33 can also
be used for reading the values of the rotations of the
telescope 14 about the axis Y-Y.
References Cited
UNITED STATES PATENTS
2,966,090
12/1960
Scholdstrom ----------- 356-5
3,035,176
5/1962
Kis et al. ---------- 365-3 X
3,146,446
8/1964
Novitsky -------- 250-220 X
WALTER STOLWEIN, Primary Examiner
U.S. C1. X.R.
356-4
60
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 T 1-St _ J CIA _ . _ V%
Approved For Release 2009/04/10: CIA-RDP81-00120R000100010021-3 111 395299528
[721 Inventor Ludwig Leitz
Wetzlar, Germany
[21 J Appl. No. 687,650
(221 Filed Dec.4, 1967
(45) Patented Sept. 22, 1970
(731 Assignee Ernst Leitz GmbH,
Wetzlar, Germany
1321 Priority Dec.6, 1966
[33) Germany
(311 L55,208
[541 PHOTOELECTRIC PRECISION CAMERA RANGE
FINDER WITH OPTICAL VERIFICATION
6 Calms, 4 Drawing Figs.
[52) U.S. CL ....................................................... 95/44,
350/46, 355/55.356/4
1511 last. CL ................................................... G03b 3/00
[50) Field of Searcb ............................................ 95/44,44C,
45; 355/55,61; 350/46, 76, 77; 353/101; 356/4
References Cited
UNITED STATES PATENTS
1,847.010 2/1932 Koppe .......................... 355/61
2,968,994 1/1961 Shurcliff ....................... 350/46
2,983,208 5/1961 Sapp ............................. 95/44
3,185,059 5/1965 Durst.. .......................... 95/44
3,270,647 9/1966 Jakob et al .................... 95/44
3,274,914 9/1966 Biedermann et al.......... 95/44
Primary Examiner-John M. Horan
Assislant Examiner-Richard L. Moses
Attorney.' - Krafft and Wells
ABSTRACT: A range finder device for cameras comprising an
optical range finder for coarse visual control of the camera
range setting as well as a photoelectric range finder for a
precise reading of the range setting, the optimal setting being
indicated when both readings simultaneously indicate their
optimal value. The optical range finder is either of the triangu-
lation type, split image type, or of the ground glass type, while
the photoelectric range finder uses two photo-resistors in a
differential balance type circuit supplied by an AC-current.
The arrangement is suitable for adaptation to "range finder"
cameras as well as to single lens reflex cameras.
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Patented Sept. 22, 1970 3,529,528
Shoot I of 2
Fig. 2
I 24 32
2J4III141-
25
L
j
/8a
/6a 3I a
17g I 19a
16--t1 A1 U U L#-20
34
INVENTOR
BY Ludwig Leitz
ATTORNEYS
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
Patented Sept. 22, 1970
3,529,528
Shoot ti of 2
Fig. 3
80a
/12
Fig. 3 a
/3
Bob
BY
INVENTOR
Ludwig Leiter
by WAl,
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3 YS
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
3,529,528
1 2
PHOTOELECTRIC PRECISION CAMERA RANGE FIG. 3 is a sectional view of a single tens reflex camera with
FINDER WITH OPTICAL VERIFICATION a photoelectric range finder,. showing a different embodiment
CROSS-REFERENCE TO RELATED APPLICATIONS
Reference is made to applicant's co-pending application
Ser. No. 686.569, filed Nov. 29, 1967, now U.S. Pat. No.
3,529.527.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to range finding devices in
photographic cameras, and more particularly to photoelectric
range finding devices.
2. Description of the Prior Art
It is well known to those skilled in this particular art to guide
the two light beams of, for example, a. coincidence-type range
finder to two photoelectric receivers. These receivers consist
each of an arrangement of elongated photosensitive elements
on which the light beams are simultaneously incident. An elec-
tric circuitry is provided for comparing the voltage difference
of the signals generated in the elements by said two light
beams, which means comprise a measuring instrument having
an indicating needle. Range finding is accomplished by adjust-
ing the optical elements of the range finder until the deflection
of the needle of the measuring instrument is a minimum.
However, it was found that minimum needle deflection may
result, even though the range finder has not yet been adjusted
to the correct distance. Such erroneous adjustments occur
primarily when the objects whose distance is measured are
surrounded by an object space of periodic structure contain-
ing a plurality of similar objects located side-by-side, such as,
for example, a row of trees or of uniformed persons. From
such periodic structure equal light fluxes can originate which
may not come from the object itself but from other object
space portions, from which by sheer coincidence a light flux
may emerge which equals in intensity the light flux impinging
on the photoelectric receivers from the object. This, however,
may not be noticed by the operator.
It is therefore an object of the present invention to provide a
range fader device where the degree of adjustment is in-
dicated as a photoelectric precision reading as well as in an
optical range finding image. so as to avoid erroneous adjust-
ments.
This object is attained by combining in a photographic
camera a photoelectric precision range finder and an optical
range finder. The latter then serves as a coarse adjustment in-
dicator, while the photoelectric reading is used only for the
fine adjustment reading within a range where the above-
described problems of spatial periodicity is no longer present.
During the initial adjustment, the object itself is observed
through a split-image-type, or coincidence-type, or ground-
glass-type optical range finder. The subsequent "corrective"
fore adjustment is made while observing the reading of the
photoelectric range finder, which may be shown by a moving
instrument needle. The basic idea of the new device is to per-
mit a coarse lens setting sufficiently close to the correct posi-
tion by-means of the optical range finder so that the axes of the
two range finder beams are already generally directed to the
object to be measured, consequently eliminating the danger of
one of the photoelectric receivers being exposed to light rays
of object intensity, which actually do not result from the ob-
ject.
DESCRIPTION OF THE DRAWINGS
The invention will be more fully comprehended from the
following description when taken in conjunction with the ac-
companying drawings wherein
FIG. I is a perspective sectional view of a range finder
camera in which an optical and a photoelectric range finding
device are incorporated,
FIG. 2 shows schematically a
photoelectric range finder,
Approved For
FIG, 3a Is a partial rear view of the penta prism and the
photoelectric receivers of the embodiment of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1 the camera 1 is provided with an
optical range finder of known design. This range finder com-
prises two objective lenses 2 and 3 and one ocular 4. Objective
lens 2 and ocular 4 form at the same time the view finder of
the camera.
In the path of the view finder light beam between objective
6 at an angle of 45? to the optical axis. By said mirror the
second range finder light beam impinging from objective lens
3 via a mirror 5 is reflected into the ocular 4. Mirror 5 is
mounted on a pivotable shaft Sa which is in rigid connection
with a lever Sb. A spring 7 exerts a force on lever Sb thereby
keeping the free end portion of lever Sb in operative connec-
tion with a cam 8. The latter is part of the camera objective
lens 70 and is rotatable with said lens for distance adjustment
purposes.
The above described elements by themselves constitute a
known optical range finder of the split-image type or coin-
cidence-type.
The camera I is further provided with two semi-transparent
mirrors 10, 11 which are arranged, one in the path of each
range finder light beam. By said mirrors 10,11 a portion of each
beam is reflected to separate photoelectric resistors 12, 13
through field lenses 12a, 13o. The photoelectric resistors are
elements in a Wheatstone bridge circuit, as shown in FIG. 2,
which further comprises the ohmic resistors 14, 15, further
ohmic resistors 16, 17, 18, 19, 20 and current rectifiers 16a,
17a,18a,19a, 20a.
The photoelectric resistors are of identical design, shape
and electrical properties. Each one consists of. signal elec-
trodes 21, 22, 23, 24, 2S and 31, 32, 33, 34, 35 respectively
which are electrically separated from each other and are ar-
ranged in parallel. One common electrode 29 and 39 respec-
tively is provided in each photoelectric resistor. The signal
electrodes 21 through 25 and 31 through 35 are connected in
pairs and each pair is connected to a series arrangement of
one current rectifier 16a through 20a and one ohmic resistor,
the ohmic resistors being connected in parallel to terminal D
in the circuit.
The Wheatstone bridge is supplied with an AC current at
the. terminals A, B and the measuring instrument 60 is con-
nected between the terminals D and C. The field lenses 12a,
13a are arranged in front of the photoelectric resistors.
The above described elements constitute a photoelectric
range finder which functions in the following manner: If, on
the photoelectric resistor 12, light beams are incident from the
details of a certain object to be measured, the different
photosensitive elements between the signal electrodes 21
through 25 will assume different resistance values according
to the intensities of said light beams originating from said ob-
ject details. Equal resistance values will be assumed by the
photosensitive elements of resistor 13 if the pivotable mirror S
in front of the resistor 13 is adjusted to a position wherein it
reflects on the resistor 13 light beams emitting from the same
object details as the light beams. which are incident on the re-
sistor 12. Under this condition of adjustment the bridge is
balanced. At the terminals "a" through "e" half of the supply
voltage can be measured. If, however, the object details
the voltage of at least one of the terminals "a" through "e"
will be different from the half supply voltage. The current
ing instrument 60 to be deflected. As is well known to those
skilled in the art, range finding with photoelectric range
finders is accomplished by directing the one of the photo-
 3 4
dlec Approved For Release 2009/04/10: CIA-RDP81-00120R000100010021-3_j in said camera
ri gidly arranged to the object to be measured. Then the including a first light flux sensing element located in the
electric resistor are pivoted until the needle deflection in the
measuring instrument is a minimum. The position of the 5
pivotable optical elements can be read against a scale
which may be calibrated in distance units, e.g. in feet or
meters.
The novel range finding device according to the invention is
operated in two steps, by first adjusting the camera objective to
tens 70 by manually rotating said lens while viewing the image
of the optical coincidence-type or split image-type range
finder through ocular 4. After the objective lens 70 has thus
been set coarsely to the object distance, the second step, 15
which is the corrective fine adjustment of the objective lens to
the object distance, is performed also by manually rotating
lens 70, however, this time while observing the deflection of
the needle of instrument 60, for example, through an auxiliary
ocular 4a. 20
Emphasis is put on the fact that the novel range finding
path of said first light flux and a second light flux sensing
element located in the path of said second light flux, said
two light flux sensing elements connected to indicator
means responsive to differential changes between the two
light fluxes, thereby discriminating between the condition
when the light fluxes originate from unequal object areas
and the condition when the light fluxes received are
identical in that they originate from a common object
area or from separate light flux equivalent object areas;
and
means in said housing for simultaneous viewing of said indi-
cation of the camera range setting and said indicator
means whereby further discrimination is obtained
between the condition when the identical light fluxes
originate from a common object area and the condition
when they originate from separate, light flux equivalent
object areas whereby the optical range finder means gives
a coarse visual control of the camera range setting and
art usually are termed "range finder" cameras. The new reading of the camera range setting.
device can equally advantageously be employed with so-called 2. The device as defined in claim 1, wherein the photoelec-
tric range finder means further includes a power source sup-
single lens reflex cameras, if said cameras are additionally pro- 25 plying alternating current to its circuitry which is of the dif-
vided with a photoelectric range finding device as described ferential-balance-type, two identical photo-resistors in this cir-
above. cuitry serving as the light-flux-sensing elements, and optical
Particularly satisfactory results are obtained if the means directing, the light flux originating from at least a por-
photoelectric resistors 12 and 13 are disposed in the place tion of the object area to said resistors, whereby the portion of
where in applicant's co-pending application Set. No. 686,569, 30 the object area received by at least one of the resistors shifts in
filed Nov. 29, 1967, the deviating wedges are located. FIGS. 3 response to Changes in the camera range setting.
and 3a show the resistors 12 and 13 arranged to the rear side 3. The device as defined in claim 2, wherein the optical
of the camera and beneath the entering surface of penta prism range finder means are of the triangulation-type and include
W. In this place the resistors are particularly adapted to be il- 35 two spaced image receiving means for viewing of at least a
luminated by light beams from large aperture image portions portion of the object area through each of said means, and
of the objective lens 81, after reflection of said beams from the mirror means to combine the two images thus received into a
silvered and inclined rear surface portions S0a and 80b of the coincidence-type comparison image, the mirror means includ-
penta prism 80. The photoelectric range finder incorporated ing orientable means for the shifting of at least one of the ob-
in the single Lens reflex camera makes thus use of a con- 40 ject area portions viewed in response to changes in the camera
siderably, enlarged base line in substantially the same manner range setting; and wherein
as the optical coincidence-type or split image-type range the photoelectric range finder means further include
finder which is disclosed in my above-mentioned co-pending optical means in the path of each of the two images
application.
Below the main ocular 82 the camera has a second ocular 45
84 through which the photoelectric indicator 60 can be ob-
served. The electric circuitry is the same for both embodi-
ments shown.
Range finding with a single lens camera as illustrated in and
described with reference to the FIGS. 3 and 3a is accom- 50
plished in much the same way as is done with range finder
cameras. It involves an initial coarse adjustment of the lens 81
to the object distance while viewing an intermediate image of
the object through the ocular 82 on the viewing screen or
ground glass 83, followed by a "corrective" fine adjustment by 55
observing the needle deflection in the instrument 60 through
ocular 84.
Instead of being provided with the resistors 12, 13 the reflex
camera may of course have a conventional central split image 60
range finder comprising two deviating wedges in the central
ground glass or viewing screen portion. The two bundles of
light emerging from the wedges may be divided into two por-
tions each, with one portion of each bundle being reflected to
the ocular and the other portions being conducted to the
photoelectric receivers. The light rays emerging from the
deviating wedges are thus used both for coarse and for fine ad-
justment.
I claim:
1. In combination with a photographic camera having a
housing, a range finder device comprising:
optical range finder means mounted in said camera and
responsive to first and second light fluxes originating, from
object areas having an indication of the camera range
deflecting a fraction of the light flux from the two images
to the two photo-resistors for simultaneous optical and
photoelectric comparison of the two images received.
4. The device as claimed in claim 3, wherein one of the
image-receiving means also serves as a view finder means and
includes a view finder/optical range finder ocular, the coin-
cidence-type comparison image being a part of the view finder
image; and wherein
the photoelectric range finder means further includes as in-
dicator means a movable needle, and further includes a
second ocular located adjacent to the view finder ocular
for visual reading of the needle position.
5. The device as defined in claim 2, wherein the optical
range finder means include, in combination with a single lens
reflex camera, a movable mirror, a horizontal imaging screen
for the reception of an intermediate image, a field lens above
the screen, a pentaprism thereabove,'and arl ocular serving
both as a view finder ocular and optical range finder ocular;
and wherein
the photoelectric range finder means include mirror means
located on the back side of the pentaprism ahead of the
ocular and laterally outside the image field; the two
photo-resistors being located between the field lens and
the pentaprism outside the image field and arranged side-
by-side in the form of parallel, elongated parts tilted in
opposite directions around a common transverse surface
line, wherein the last-mentioned mirror means reflect a
portion of the intermediate image from the screen onto
the photo-resistors, which latter register identical light
fluxes when the intermediate image is in focus and dif-
ferent light fluxes when it is out of focus.
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 S J J L 7, J L0
6. 1 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
???- - !1.11.. &ne pnuiocicc sic range nnaer means further includes as in-
range finder means are of the ground-glass-type, the inter. dicator means a movable needle, and further includes an
mediate image created on the imaging screen being visible in ocular located adjacent to the view finder ocular for
the view finder/optical range finder ocular; and wherein visual reading of the needle position.
5
30
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
kJ nitea states ratent (1 l l 3,558,894
1721 Inventors Giovanni Odone
La Rosiaz, Lausanne;
Jesus DeAndres; Virgilio Cossetta,
Yverdon, Switzerland
(21) Appl. No. 686,554
[221 Filed Nov. 29, 1967
[451 Patented Jan.26,1971
173 ] Assignee Paillard S. A.
Vaud, Switzerland
a company of Switzerland
1321 Priority Dec. 15, 1966
[33] Switzerland
[311 18117/66
[541 TELEMETER CHIEFLY INTENDED FOR
PHOTOGRAPHIC PURPOSES
10 Claims, 3 Drawing Figs.
[521 U.S. Cl ........................................................ 250/216,
250/210,250/235,350/101,350/294,356/4
(51) Int. CI ......................................................... H01 j 3/14
[501 Field of Search ............................................. 95/44,45,
44C; 88/1 HF, I U; 250/234, 235, 210, 217, 2.4;
350/101, 294; 356/4
References Cited
UNITED STATES PATENTS
3,333,105
7/1967
Kossakowski ................
250/210
3,336,851
8/1967
Warshawsky .................
88/1HF
2.897,722
8/1959
Gunter. Jr. et al............
250/204X
3,385,159
6/1968
Bliss et al ...................... -
356/4
FOREIGN PATENTS
1,121,838
1/1962
Germany ......................
95/45
1,213,229
11/1963
Germany ......................
95/44
486,484
9/1952
Canada ........................
356/4
OTHER REFERENCES
Horman, M., " The Determination of Atmospheric Trans-
missivity by Backscatter from a Pulsed Light Separated
System," Armed Services Technical Information Agency,
Doc. No. 243,930, Oct. 1958.
Primary Examiner-James W. Lawrence
Assistant Examiner-C. M. Leedom
Attorney-McGlew and Toren
ABSTRACT: A compact telemeter measuring comparatively
short distances, chiefly for photographic purposes, comprising
a projector sending a beam of substantially parallel rays of
light onto an object the distance of which is to be ascertained,
an optical system receiving said beam after reflection on said
object and the axis of which'is directed in parallelism with the
axis of the projector and means sensitive to the location of the
point of convergence of the beam of light after it has passed
through the optical system. Said means are advantageously
constituted by two photocells lying on the axis of the optical
system and the relative illumination of which depends on the
location of said point of convergence along said axis. This
relative illumination controls an electric circuit shifting the
cells into a position of equal illumination defining the distance
to be measured.
2,339,780 1/1944 Huitt ............................ 95/44
2,490,052 12/1949 Harris .......:................... 350/294
2,968,994 1/1961 Shurcliff ....................... 88/56
3,185,059 5/1965 Durst ............................ 95/44
3,218,390 11/1965 Bramley........................ 350/294
3,218,909 11/1965 Fain ............................. 250/235
3,224,319 12/1965 Robert .......................:. 88/1 U
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
PATENTED JAN261971
f/G. 3
Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3 ATTORN1 YS
BY *4 A.wO&
3,558,894
. F//. 2
INVENTOR 5
GIOVRNNJ ODONE
JESUS DE RrroRE 5
VlRGIIIo C055ETTH
 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
1 7-
1 2
TELEMETER CHIEFLY INTENDED FOR
PHOTOGRAPHIC PURPOSES
The present invention has for its object a telemeter, chiefly
intended. for photographic purposes. Such a telemeter serves
mainly for measuring comparatively short distances, generally
less than about 10 meters.
Arrangements have already been proposed for measuring
distances by means of infrared rays for instance. Such prior
known arrangements are adapted for measuring comparative-
ly large distances and their execution is based on the same
principle as optical telemeters. In practice, the distances are
measured by the angle within which a receiver collects in-
frared rays issuing from a source lying at a location remote
from said receiver and reflected by the object of which it is
desired to measure the distance.
The arrangements known hitherto allow measuring accu-
rately comparatively long distances, of a magnitude of about
several times 10 meters, but they are on the other hand bulky
and require a comparatively considerable spacing between the
receiver and the transmitter constituted by the source of in-
frared rays.
The present invention has now for its object a telemeter to
be used chiefly for photographic purposes, which telemeter in-
cludes a projector supplying a narrow luminous beam and at
least one convergent optical receiving system of which the op-
tical axis is directed in substantial parallelism with that of the
projector so as to collect the rays of the beam which are
reflected by the object of which it is desired to measure the
'distance, while one or more devices are provided, which are
sensitive to the distance at which the rays collected by the
receiver converge.
. The accompanying drawing illustrates diagrammatically
and by way of example two embodiments of the invention. In
said drawing:
FIG. I is a sectional view of a telemeter according to the
first embodiment.
FIG. 2 is a wiring diagram for said embodiment.
FIG. 3 illustrates a second embodiment.
The telemeter illustrated in FIG. 1 is enclosed in a casing 1,
the rear end of which is closed by a flange 2 screwed inside the
body of the casing 1. Said flange 2 carries an electric motor 3
driving into rotation through its shaft 4 a screw 5. The latter
engages a threaded opening 7 formed in a member 6 adapted
to slide over the inwardly projecting portion of the flange 2,
which encloses the motor 3. Said member 6 carries optical
parts to be described in detail hereinafter.
The front end of the casing 1 is adapted to carry a ring 8
provided with an annular series of openings 9 which allow
light to enter the casing 1. Said ring 8 includes an inwardly
projecting cylindrical section 10 of a reduced diameter form-
ing a shoulder or bearing surface 11 for a concave reflector
12. The latter is held in position by a coaxial tubular member
13 screwed into the ring 8 and enclosing a support 14 for a
central sleeve 16 carrying a bulb 15. The rim of the support 14
is connected with the central sleeve 16 by radial arms 17 so
that the bulb lies on the optical axis 18 of the reflector 12.
The luminous rays passing out of the bulb 15, of which the
filament or the arc ,forms substantially a pin point, are
reflected by the reflector 12 and through the front opening of
the tubular member 13 in the shape of a beam the rays of
which are parallel with the optical axis 18.
The bulb 15 and reflector 12 forms thus a projector supply-
ing a compact beam directed towards the object of which it is
desired to ascertain the distance with reference to the teleme-
ter, which latter is generally associated with a photographic or
kinematographic camera.
Preferably, the light supplied by the projector 12-15 is
modulated at a comparatively low frequency, for instance of a
electromagnetically energized vibratory blade extending in
proximity with the bulb 15 across the path of the rays directed
towards the reflector 12.
A fraction of the rays reflected by the distant object enters
the casing I in the shape of an annular beam defined by the
gap between said casing I and the tubular member 13. Said
rays pass in fact through the openings 9 of the ring 8 and
thence through an annular optical glass element 19. The latter
shows on one side a substantially flat surface and on the other
side a tore-shaped surface coaxial with the projector. It acts
thus as a convergent cylindrical lens incurved so as to assume
an annular shape.
When said element 19 receives the rays passing out of a lu-
minous point located on the axis 18 of the optical system in-
eluding the projector and the element 19. it produces a real
image of said point in the shape of an annulus concentric with
the element 19, the axial spacing between said element and
said annular image depending of course on the distance
between the luminous point and said element 19. When the lu-
minous point is shifted along the optical axis 18, the real image
of said point is constituted by a circle moving similarly along
said axis 18 while its diameter increases as the point of conver-
gence of the incoming rays moves further away to the rear of
the element 19. Thus, the annular images corresponding to the
different possible positions of the luminous point along the
axis 18 move over a conical surface. On the other hand, the
rays collected by the element 19 are received at the rear
thereof by an annular mirror 20 in the shape of a frusto-cone
the apical angle of which is selected in a manner such that the
rays reflected by it converge onto a cylindrical surface 21,
coaxial with the axis 18 and located between the planes
defined by 19 and ZO, the reflected rays impinging on said sur-
face 21 whatever may be the distance separating the element
35 19 from the luminous point.
The cylindrical surface 21 is formed on two cones 22, 23 of
a transparent material, carried by the adjustable member 6.
The two cones 22,13 form guides for the light received on the
surface 21 and guide the light towards the corresponding
40 photosensitive cells 24, 25 carried by their apices.
Thus, the point of convergence of the rays reflected by 20
onto the surface is-shifted axially as a function of the distance
of the object, the distance of which is to be measured. Accord-
ing to the distance of said object and to the position of the
45 member 6 carrying the two cones 22 and 23, the intensity of
the light collected by the cell 24 varies with reference to that
of the light collected by the cell 25. Said difference in light in-
tensity generates a difference between the electric conditions
of the two cells, which latter difference may serve for con-
trolling trolling the motor 3 and causing it to rotate in a direction such
that it shifts the member 6 with the cones 22 and 23 until the
two cells 24 and 25 are subjected to equal luminous intensi-
ties.
55 To each distance between the object of which it.is desired to
ascertain the distance and the telemeter, there corresponds
consequently a predetermined position for the member 6.
Thus, the position of equal illumination for the cells 24 and 25
allows defining the distance of the object by noting the posi-
60 tion of the member 6. Said distance may, for instance, be read
by means of an index, not illustrated, actuated by a rod 6a car-
rying an arm 6b urged elastically into contact with the member
6. Said rod 6a may furthermore serve for the mechanical ac-
tuation of the ring controlling the adjustment of the ranges on
65 a camera coupled with the telemeter described.
Obviously, the telemeter described can be operative only if
at least one of the cells 24, 25 actually receives a fraction of
the rays reflected by the object, the distance of which is to be
measured. The cylindrical surface 21 should therefore have a
length sufficient in a direction parallel with the optical axis 18
for one of the cells 24, 25 to be energized by the rays sent by
the object into the telemeter, when the object lies at one limit
of the range of measurements allowed by the telemeter, while
the instantaneous adjustment of the member 6 corresponds to
the opposite limit of said range.
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magnitude of a few 10 cycles per second, so as to allow dif-
ferentiating the luminous rays produced by the projector when
reflected, from any parasitic luminous rays. Said modulation
of the light may be obtained in a simple manner by successive
interruptions of the current feeding the bulb 15, but obviously
it is possible to resort also to other means, for instance to an
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J,JJ8,2Sy4
3 4
If, for structural reasons, it is not possible to give the cylin- The rays reflected by the reflecting surface 31 may he cut
drical surface 21 a sufficient length, for instance because it off by a circular rearwardly facing mirror 32 located between
may be of interest to provide a very broad measuring range for the two cells 34 and 35. If the convergence of the reflected
the telemeter, the telemeter should be provided with a rough rays is larger than that illustrated in the drawing for the focus
manual preliminary adjusting mechanism adapted to bring 5 0. the reflected rays are cut off by the mirror 32 and are sent
said surface 21 into a position where it may receive the light back onto the cell 35. If, in contradistinction, the convergence
reflected by the distant object. of the rays is less, the totality of the latter reaches the cell 34
If the cylindrical surface 21 has a length sufficient for it to without being cut off by the mirror 32. It is therefore possible
receive the rays reflected by the object throughout the range to shift the mirror 32 and to bring it into a position such that
of measurements of the teleni:ter, it is of advantage to provide 10 the two cells 34 and 35 are equally illuminated, which allows
the latter with an arrangement for the automatic return to the defining the distance of the object as a function of the position
infinite when neither of the two cells 24, 25 produces a signal occupied by the mirror 32 corresponding to equal illumination
corresponding to the reception of the reflected beam. As a of the two cells 34 and 35.
matter of fact, if the object of which it is desired to ascertain 15 It is well-known in the art that the sources of light are never
the distance is too remote, the energy of the reflected lu- perfectly pinpoints and consequently it is not possible in prac-
minous beam is too weak for it to make the cells 24, 25 tice to obtain, with the projector described, a beam with per-
produce a perceptible output signal. It is therefore of interest fectly parallel rays. Consequently, the reflector 12 forms on
in such a case for the telemeter to indicate a very large the object an image of the luminous source or bulb 15, said
distance which may be considered as equivalent to the infinite. 20 image being generally blurred because it is not focused. If it is
FIG. 2 illustrates diagrammatically means connecting the desired to obtain an excellent accuracy with the arrangement
two cells 24, 25 when the latter are photoconductive cells. described, it is an easy matter to provide a mechanical
One electrode of each of the two cells 24. 25 is connected with coupling between the member 6 and the bulb 15 or the reflec-
a common terminal a showing a difference in voltage with tor 12. Thus, at the beginning of the measurement, when the
ground. The other electrode of each of said two cells is 25 luminous image is blurred, the conjugated image of the latter
grounded through the agency of a resistance R. The two re- is formed by an annular blurred luminous line on the cylindri-
sistances R have the same value. Furthermore, the grounded cal surface 21. However, said blurred line is sufficiently
electrodes of the cells 24, 25 are connected with each other spaced with reference to the line separating the cones 22 and
through the primary winding 26 of a transformer 27. Said wir- 23 for a sufficient difference in illumination to be obtained
ing diagram constitutes a bridge of which two arms are formed 30 between the cells 24 and 25, so that the motor 3 is driven into
by the photoconductive cells 24, 25, the two other arms being rotation in the direction urging said separating line towards
formed by the resistances R. Since the light defining the the annular luminous line.
distance of the object is modulated by reason of the modula- While said displacement is being produced, the motor 3 also
tion of the beam produced by the projector, the cells 24, 25 adjusts the distance between the bulb 15 and the reflector 12,
supply a variable electrical magnitude showing a component 35 which ensures the, accurate focusing of the conjugated image
the modulation of which corresponds to that of the projector. of the bulb 15 for a distance equal to the that corresponding to
Consequently, the primary 26 is fed by an alternating current the actual position of the member 6. Thus, as the member 6
whenever the two cells 24, 25 do not receive the same amount moves nearer the position corresponding to the distance to be
of modulated light and this produces an output voltage across measured, the focusing of the image of the bulb 15 on the ob-
the terminals of the secondary 28 of the transformer 27. Said 40 ject is improved and when the member 6 reaches this position
output voltage serves for starting the motor 3 in the direction corresponding to the actual distance, the focusing is excellent.
required for shifting the member 6 with the two cones 22, 23 Thus, the rays collected by the element 19 form on the surface
until the line separating the latter registers with the annular il- 21 a clean luminous line which registers with the line of
lumination produced by the rays reflected by the reflecting separation between the cones 22 and 23. The apparatus en-
surface 20. The direction along which the motor 3 is to be 45 sures in this manner a very high accuracy.,
driven is detected readily by comparing the phase of the cur- It should be noted that the telemeter described may be sub-
rent supplied by the secondary 28 with the modulation of the jected to various modifications within the scope of the accom-
projector beam. panying claims. In particular, the reflecting surfaces or mirrors
Obviously, the two cells 24, 25 can receive luminous rays 50 may be replaced by lenticular systems.
other than those produced by the bulb 15, but since said other It is not essential for the projector and the optical receiver
rays are not modulated, they cannot produce any induced al- to be coaxial, since the telemeter may still operate normally in
ternating voltage in the secondary 28 of the transformer 27. the case where the optical axes of the projector and of the op-
However, an error may occur if a comparatively important tical receiver are slightly shifted transversely with reference to
difference in illumination due to parasitic rays arises between 55 each other, in principle by a distance less than the diameter of
the two cells. To reduce such an effect and to increase the ac- the luminous spot produced on the object of which it is desired
.curacy of the telemeter, it is of interest to provide a luminous to ascertain the distance.
source inside the casing 1, so as to produce an unvarying com- We claim:
paratively important illumination for said cells. Thus, the 1..A telemeter, useful in measuring distances to an object,
characteristic properties of both cells are practically similar 60 chiefly for photographic purposes, comprising projector
for the modulated rays they receive. means arranged to transmit a beam of substantially parallel
In FIG. 1, said auxiliary source of light is constituted by a rays of light to the object the distance of which is to be mea-
bulb 29 carried inside a small casing 30 opening towards the sured, a convergent optical receiving system arranged to
cylindrical surface 21 formed on the cones 22 and 23. Thus, receive a reflected beam from the object and the axis of said
both cells 24 and 25 receive a continuous luminous com- 65 system being disposed in substantially parallel relationship
ponent of an intensity which is much larger than that of any with the axis of said projector means, means sensitive to the
external parasitic rays liable to alter the accuracy of the mea- location of the point at which the rays of light of the reflected
surements. The action of such parasitic, rays becomes con- beam passing out of said optical system converge on the axis
?equently quite negligible. of said optical system, and said projector means comprising a
FIG. 3 illustrates a modification according to which the bulb 70 reflector positioned forwardly of said optical receiving system
15 supplies a beam of parallel rays as provided by the reflector in the direction of the object to be measured, said reflector
12, the rays returning after reflection by the body being col- having a concave face directed toward the object, a substan-
lected by the reflecting surface 31 which causes them to con- tially pinpoint source of light located at the focus of said
verge onto the optical axis 18. The point of convergence for reflector, said optical receiving system comprising an annular
the rays, when perfectly parallel, is designated by Q. 75 convergent lens forming member coaxial with said reflector
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 Approved For Release 2009/04/10: CIA-RDP81-0012OR000100010021-3
5 6
and having its outer diameter larger than the diameter of said separate beams with the proportion of the luminous fluxes
reflector, two rearwardly flaring cones of transparent material forming the two beams being dependent on the position of
nested one within the other, said cones being coaxial with said said separator clement with respect to that of the image, said
lens-forming member and the rearwardly facing surface of optical system comprising convergent lens-forming means ar-
said cones forming a cylindrical surface coaxial with said 5 ranged concentrically about the optical axis of said optical
cones, and means for directing the rays of light of the reflected system for collecting the luminous flux reflected from the ob-
beam passing through said lens-forming member onto said ject and for directing the luminous flux to said separator elc-
cylindrical surface for passage through said cones to the ment, photoelectric means designed to measure and compare
apices thereof, and said sensitive means comprising a pair of the intensity of the luminous fluxes of the two beams, and
closely spaced photocells adjacent the apices of said cones to 10 means in operative communication with said photoelectric
be illuminated by the rays of light of the convergent beam to means for displacing said detector device along the optical
an extent varying with the location of the point of convergen- axis for bringing said detector device into the position for
cy with said optical axis. which the ratio of the two luminous fluxes measured by said
2. A telemeter, useful in measuring distances to an object, photoelectric means assumes a given value.
chiefly for photographic purposes, comprising projector l5 6. A telemeter, useful in measuring distances to an object,
means for transmitting a beam of substantially parallel rays of chiefly for photographic purposes, comprising projector
light to the object the distance of which is to be measured, a means for transmitting a beam of substantially parallel rays of
convergent optical receiving system having an optical axis in light to the object the distance of which is to be measured, a
substantially parallel relationship with the axis of said projec- 20 convergent optical receiving system having an optical axis in
tor means and arranged to receive a reflected beam from the substantially parallel relationship with the axis of said projec-
object being measured, said optical system arranged to con- tor means and arranged to receive a reflected beam from the
verge the reflected beam received from the object, photoelec- object being measured, said optical system arranged to con-
tric means arranged for receiving the reflected beam from said verge the reflected beam received from the object, photoelec-
optical system, wherein the improvement comprises said 25 tric means arranged for receiving the reflected beam from said
photoelectric means comprising at least two sensitive portions optical system, wherein the improvement comprises said
spaced with respect to the locus of the possible convergence photoelectric means comprising at least two sensitive portions
of the reflected beam, said optical system comprising annular spaced with respect to the locus of the possible convergence
convergent lens-forming means arranged concentrically about of the reflected beam, said optical system comprising a con-
the optical axis of said optical system for collecting the rays of 30 cave mirror reflecting surface arranged coaxially with the op-
the.reflected beam and for directing the reflected beam to said tical axis of said optical system for collecting the rays of the
photoelectric means, separator means disposed between said reflected beam and for directing the reflected beam to said
annular.convergent lens-forming means and said photoelectric photoelectric means, separator means disposed between said
means for separating the reflected beam into two portions reflecting surface and said photoelectric means for separating
with each portion being directed to a different one of said sen- 35 the reflected beam into two portions with each portion being
sitive portions of said photoelectric means, a drive member for directed to a different one of said sensitive portions of said
displacing said photoelectric means within the range of possi- photoelectric means, a drive member for displacing said
ble locations of convergence of the reflected beam, and means photoelectric means within the range of possible locations of
interconnecting said drive member and photoelectric means convergence of the reflected beam, and means interconnect-
for actuating said drive member when said sensitive portions 40 ing said drive member and photoelectric means for actuating
-of said photoelectric means are receiving unequal intensities said drive member when said sensitive portions of said
of .light from the reflected beam for positioning said photoelectric means are receiving unequal intensities of light
photoelectric means until it receives equal intensities of light from the reflected beam for positioning said photoelectric
from the reflected beam. means until it receives equal intensities of light from the
3. A telemeter, as set forth in claim 2, wherein said sensitive 45 reflected beam.
portions of photoelectric means comprises a pair of spaced 7. A range finder for measuring the distance to an object,
photoelectric cells each exposed to a different one of the two particularly for use in photography, comprising a projector
portions of the reflected beam received from said optical means for directing a narrow light beam to an object whose
receiving system after its division by said separator means. distance is to be measured, a convergent optical receiving
4. A telemeter as set forth in claim 2 wherein said sensitive 50 system capable of forming an image of the portion of the ob-
portions of said photoelectric means comprising a pair of ject lighted by the light beam, and detector means displacea-
closely spaced photocells arranged on the axis of said optical ble along the optical axis of said convergent optical receiving
system for receiving separate rays of light from the reflected system, wherein the improvement comprises said convergent
beam to a varying extent, and said means interconnecting said 55 optical receiving system including optical means arranged to
drive member and photoelectric device comprising an electric form a substantially plane linear image of the portion of the
circuit fed differentially by said photocells according to the lo- object lighted by the light beam, said detector means com-
cation of the point of convergence of the reflected beam on prises a separator element movable with said detector means
the optical axis and consequently to the distance to be mea- along the optical axis of said convergent optical receiving
sured, and means for modulating the reflected beam passing 60 system to keep substantial coincidence with the surface
through said optical system, and an auxiliary source of light ar- generated by the linear image when the distance of the object
ranged to produce a permanent illumination of said to be measured is varied within the useful range of the range
photocells. finder, said separator element separating the I luminous flux
S. A range finder for measuring the distance to an object, forming the image into two separate beams with the propor-
particularly for use in photography, comprising a projector 65 tion of the luminous fluxes forming the two beams being de-
means for directing a narrow light beam to an object whose pendent on the position of said separator element with respect
distance is to be measured, and a convergent optical receiving to that of the image and said detector means comprises
system capable of forming an image of the portion of the ob- photoelectric means designed to measure and compare the in-
ject lighted by the light beam with the image formed by said tensity of the luminous fluxes of the two beams.
convergent optical system being shifted parallel to itself along 70 8. A range finder, according to claim 7, wherein the sub-
the optical axis of said optical system in dependence on the stantially plane linear image formed by said optical means in
distance of the object, wherein the improvement comprises a said convergent optical receiving system provides a generated
detector device capable of being displaced along the optical surface which is substantially a cylindrical surface whose
axis, said detector device comprising a separator element for generating lines are parallel to the optical axis of said conver-
separating the luminous flux forming the image into two 75 gent optical receiving system when the distance of the object
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7
to be measured is varied with the useful range of the range
finder.
9. A range finder according to claim 8 wherein said optical
means in said convergent optical receiving system comprise an
annular convergent lens-forming member and a frustoconical
annular mirror member, with both said members being coaxi-
al.
10. In a range finder for measuring the distance to an object,
particularly for use in photography, comprising a projector
means for directing a narrow light beam to an object whose
distance is to be measured, the improvement comprising, in
combination, an optical receiving system forming a substan-
tially plane linear image of the portion of the object lighted by
the light beam, this image being in the form of symmetrical are
i
l
ca
portions of a circle centered on the optical axis of said opt
receiving system, a detector device comprising separator
means displaceable along said optical axis to a position where
said separator means coincide with symmetrical parts of the
linear image, said separator means separating the luminous
fluxes forming each of the symmetrical parts of the linear
image into two separate beams and said detector system com-
10 prising photoelectric means designed to measure and coin pare
the intensity of the luminous fluxes of the two separate beams.
70
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June 13, 1972 W. J. RATTMAN Et' AL 3,669,540
OPTICAL DEPTH FINDER AND ELEMENTS THEREFOR
Filed Aug. 31, 1970
F/6 2
IN VEN TORS
W/LL/AM J. RATTMAN
FRANK R. WASSON, /R.
GORDON C. MacKENZ/E
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U[LCU. tULCS ratent Uft1Ce 3,669,540
Patented June 13, 1972
3,669,540
OPTICAL DEPTH FINDER AND
ELEMENTS THEREFOR
William J. Rattman, Needham, Frank R. Wasson, Jr.,
Chelmsford, and Gordon C. MacKenzie, North
Billerica, Mass., assignors to Raytheon Company, Lex-
ington, Mass.
Filed Aug. 31, 1970, Ser. No. 68,206
Int. Cl. G01c 3/08; G02b 27/28
U.S. Cl. 356-4 7 Claims
ABSTRACT OF THE DISCLOSURE
An improved optical depth finder, and elements there-
for, for depth sounding and detection of submerged targets
from an airborne vehicle. The disclosed system uses a
coherent beam of polarized light from a laser directed
downwardly toward the surface of a body of water and
processes the polarized surface specular reflected energy,
energy reflected by submerged targets within the beam,
and energy reflected by the bottom of the body of water
to derive the desired information. Means are provided
selectively to attenuate the reflected energy in accordance
with the particular source thereof so as to permit the
dynamic range of the processor of the reflected energy
to be reduced and the system to be used when the height
of the airborne vehicle changes or condition of the water
varies.
2
saturation phenomenon occurs if a photodiode-amplifier
combination is used as the receiver photodetector.
One approach to the solution of this problem has been
"range gating," that is, a plurality of photodetectors are
employed, each one of such photodetectors having a differ-
ent sensitivity, in combination with gating logic wherein
the photudetector of proper sensitivity is activated at the
proper time to thereby detect the various returns. Such a
system is complicated and expensive.
A second approach to the solution of th'
s problem is to
place an optical filter in the focal plane of the receiver,
the center portion of the filter being of sufficient optical
density to greatly attenuate the relatively large power of
the reflected returns from the ocean surface. However, be-
cause of the density required of such center portion, the
measurement of shallow ocean depths may be prevented.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide an
improved laser depth sounding system.
It is another object of the invention to race fl
energy of a laser depth sounding system so that specular
reflections from the surface of the measured medium are
selectively attenuated.
It is another object of the invention to provide a filter
to attenuate more greatly backscatter reflections from
points nearer the surface of the measured medium than
backscatter reflections from points near the bott
The invention herein described was made in the course 30
of or under a contract or subcontract thereunder, with the
Department of Defense.
BACKGROUND OF THE INVENTION
35
measured medium. om of inc
These and other objects of the invention are generally
accomplished by combining means for directing a beam
of coherent polarized light from a laser and means, in-
cluding a polarized filter in cross-polarized relationship to
the substantially polarized energy resulting from specular
reflections from the ocea
f
n sur
ace, for selectively attenuat-
This invention relates generally to laser depth measur- ing such surface specular reflections prior to their detec-
tion by the receiver photodetector. In addition, an optical
receivers of such systems. wedge is disposed in the path of the reflected energy, the
Laser depth measuring systems using pulses of light are optical density and related energy attenuation factor of
known for the rapid accurate sounding of the depth of a 40 such wedge decreasing from its center portion to its
body of water, as the ocean, and for the detection of sub- peripheral section so as selectively to attenuate reflections
merged objects. The depth of the ocean or of the sub- form points nearer the ocean surface to a greater degree
merged object is generally determined by measurement than reflections from points nearer the ocean bottom.
of the interval between the detection of the energy re- 45 BRIEF DESCRIPTION OF THE DRAWINGS
Betted from the ocean surface and the energy reflected
from the ocean floor or from the submerged object. When For a better understanding of the present invention ref-
such a system is displaced from the ocean surface, as erence should now be made to the following description
when it is used on board a helicopter, the altitude of such taken in connection with the accompanying drawings in
helicopter is determined by measurement of the interval 60 which:
between the time of transmission of each laser pulse and FIG. I is a presentation of an airborne laser ocean
the time of detection of the resulting energy reflected depth sounding system greatly simplified in order to show
from the ocean surface. the principles of the invention; and
The power of the reflected return varies greatly in FIG. 2 is a sketch of a polarized optical wedge, par-
magnitude as the transmitted pulse is first reflected by the Cis tially broken away and somewhat distorted, to show the
ocean surface, then ocean medium and any submerged construction thereof.
target therein, and finally the ocean floor. While the ab-
solute magnitude of such power varies with aircraft alti- DESCRIPTION OF THE PREFERRED
tude, ocean surface roughness and ocean depth, under EMBODIMENT
any condition an extremely large relative difference in 00 FIG. I shows a laser depth s amplitude of reflected energy is encountered. For ex- within an airborne vehicle 11, hereounding
hownYaseahel cop-
ample, the predominantly specular reflections from the ter, for use in oceanographic survey. The depth sound-
ocean surface produce signals which may 70 db greater ing system comprises a laser transmitter 12, a laser re-
than signals resulting from reflections from points im- ceiver 13 and a utilization device 14. The laser transmit-
diately below the ocean surface and may be 90 db greater 65 ter 12, here a Q?switched frequency doubled yttrium alu-
than signals caused by reflections from the ocean floor. minum garnet device of sufficient power considering the
These characteristics place stringent requirements on the depth of the ocean, produces a linearly polarized coher-
dynamic range of the receiver. In particular, if a photo- ent laser beam (not numbered) of transmission wave-
multiplier is used as the photodetector of the receiver, length 0.531A, such wavelength being near the peak of
reflections from the ocean surface may saturate the photo- 70 the ocean transmission "window." Such laser beam is re-
multiplier, thereby preventing soundings from being made flected by transmitter mirror 15 so that it is transmitted
or submerged targets from being detected. This equivalent along a path substantially orthnvnn.l
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3,669,540
3
face. Such orthogonal attitude is maintained by mount-
ing the laser transmitter 12, the transmitter mirror 15
and the laser receiver 13 on a common platform (not
shown), such platform being gimballed with respect to
airborne vehicle 11 by gimbal system 16. The transmit-
ter mirror 15 is disposed in proper orientation to the
receiver boresight axis 17 so that the laser beam (after
reflection from transmitter mirror 15) and the receiver
boresight axis 17 are essentially coaxial. The transmit-
ter mirror 15 is small relative to the receiver collecting
aperture.
The energy in the transmitted beam is partially re-
flected first by the ocean surface, then the ocean medium
(including any submerged targets, not shown) and fi-
nally by the ocean floor. The maximum field of view of
the receiver 13 is herein represented by lines 18. In or-
der for detection by receiver 13 of subsurface backscat-
ter reflections occurring at depth D, and greater depth
D2, such subsurface reflections must propagate towards
the receiver and be refracted by the wave facets at the
ocean surface so as to be within the field of view of the
receiver. While such backscatter reflections propagate in
many directions, the reflection at depths D, and D2 which
are within the maximum field of view of the receiver are
represented by lines 19 and 20 respectively. It is noted
that the amount of refraction at the ocean surface re-
quired for backscatter reflections at depth D, to be with-
in the maximum field of view of the receiver is larger
than that amount of ocean surface refraction required
at greater depth Dz. Since large ocean surface refraction
will occur with large wave facet slopes, and since the
probability for smaller wave facet slopes is greater, the
greatest amount of reflected energy from shallow targets
is collected at the receiver near the receiver boresight
axis 17, while a correspondingly greater percentage of
reflected energy from greater depths will be collected
further off the receiver boresight axis 17. That is, the
field of view in the focal plane of the receiver is smaller
for subsurface backscatter returns occurring near the
ocean surface as compared with reflections near the
ocean bottom.
It is also noted that the polarized transmitted pulse
reflected by the ocean surface remains also essentially
polarized. In other words, the specular surface reflections
are substantially linearly polarized energy. The backscat-
ter reflections occurring immediately below the surface of
the ocean are essentially non-polarized.
The various reflected returns, as described in detail
above, are collected by the receiver collecting optics 21,
herein represented by a lens, whereby such reflected re-
turns are focused at the receiver focal plane. An optical
'filter 22, such filter being described in more detail here-
inafter, is disposed in such focal plane as indicated. The
filtering surface of the optical filter 22 is disposed es-
sentially orthogonal to the receiver boresight axis 17,
such boresight axis passing through the center portion
of the filtering surface. The function of optical filter 22
is to compress the dynamic range of the various reflected
returns. The center portion of the optical filter is used to
greatly attenuate specular reflections and subsurface back-
scatter reflections from immediately below the ocean sur-
face since such reflections predominate the center por-
tion of the filter. Subsurface backscatter reflections from
nearer the ocean floor are less greatly attenuated by the
optical filter 22 than those reflections from near the ocean
surface.
Field lens 13 converges the reflected returns filtered by
optical filter 22 on the photomultiplier 24. A narrow band
filter 25, of conventional design, passes only electromag-
netic energy in a narrow spectrum centered at the laser
transmitter wavelength, herein 0-53?. The electrical sig-
nal developed by photomultiplier 24 is transmitted to
utilization device 14 by transmission line 26. Utilization
device A
4
art. By measuring the time interval between the initial
signal it receives from the photomultiplier 24, represent-
ing ocean surface reflections, and the termination of the
signal from the photomultiplier, the ocean depth can be
determined since the speed of the laser energy in the
ocean medium is about 2.72 ns./ft. for a 0.53? operat-
ing wavelength. Utilization device 14 also receives a sig-
nal from laser transmitter 12, such signal occurring at
the initiation of the transmitted pulse and such signal be-
ing transmitted to utilization device 14 by transmission
line 27. The interval between the signal from the laser
transmitter 12 to the utilization device 14 and the begin-
ning of the reflected signal is used to determine the al-
titude of airborne vehicle 11.
FIG. 2 shows optical filter 22. Optical filter 22 is a disc-
shaped element comprised of a photographic film 33 sand-
wiched between glass plates 34 and 35. Cemented to the
outer portion of glass plate 35 is a disc 32 of linearly
polarized material. The photographic film 33 has formed
thereon a plurality of concentric rings 28, 29, 30 and
31, each such ring being less dense so that the film has
a greater optical density at its center.
In reference to FIG. 1, the linearly polarized disc 32
is oriented in cross-polarized relationship to the linearly
polarized energy resulting from specular reflections at the
surface of the ocean.
It will be obvious to one of ordinary skill in the art
that the graded optical density of the photographic film
need not be made up of a plurality of concentric rings
but can be a continuous graded density. It is also noted
that a polarized material could be formed with a more
optically dense center portion than the peripheral por-
tion to thereby form optical filter 22 in one unit. Also,
the polarizer could be separate from the graded density
filter. In any practical deployment a series of polarized
optical filters, as herein described, would be on board
the aircraft, each one suitable for a particular set of pos-
sible wind, altitude and ocean conditions. It is therefore
understood that the invention is not limited to the specific
embodiment as shown, but only by the spirit and scope
of the appended claims.
What is claimed is:
1. A unidirectionally polarized optical wedge.
2. For use in a laser depth measuring system wherein
substantially polarized electromagnetic specular reflec-
tions from the surface of a body of water are collected
within a receiver, the combination comprising:
(a) a disc fabricated from a polarized material, such
disc being disposed in the receiver to attenuate the
polarized electromagnetic specular reflections; and
(b) a photodetector responsive to such attenuated re-
flections.
3. For use in a laser depth measuring system wherein
electromagnetic reflections from a body of water are
collected within the field of view of a receiver, such col-
lected electromagnetic reflections being comprised of sub-
stantially polarized electromagnetic energy resulting from
specular reflections at the surface of the body of water,
such substantially polarized energy being concentrated
at the center of the field of view of the receiver, and sub-
stantially nonpolarized electromagnetic energy resulting
from backscatter reflections beneath the surface of the
body of water, the intensity of such substantially non-
polarized energy decreasing from the center of the field
of view of the receiver to the periphery thereof, the com-
bination comprising:
(a) an optical wedge, such optical wedge having a
greater optical density at the center portion than
at the peripheral portion, such center portion being
70 disposed at the center of the field of view of the
receiver, for selectively attenuating the intensity of
the nonpolarized energy;
(b) a disc, fabricated from a polarized material, such
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3,669,540
(c) a photodetector responsive to the selectively filtered
nonpolarized electromagnetic energy and the atten-
uated electromagnetic energy.
4. For use in a laser depth measuring system wherein
electromagnetic reflections resulting from illumination of
a body of water by a polarized beam from a laser are
collected within a field of view, such collected electro-
magnetic reflections being comprised of substantially
polarized electromagnetic energy specularly reflected from
the surface of the body of water, such substantially polar-
ized energy being concentrated at the center of the field
of view, and substantially unpolarized electromagnetic
energy backscattered from points beneath the surface of
the body of water, such unpolarized energy being con-
centrated in the peripheral portion of the field of view,
the combination comprising:
(a) a disc, fabricated from a polarized material, such
disc being disposed in the field of view selectively
to attenuate the intensity of polarized energy and
6
6. A polarized optical wedge, such wedge having a
unidirectionally linear polarization, and having an optical
density which decreases from its center portion to its
peripheral portion.
7. A unidirectionally polarized optical wedge, such
wedge having a linear polarization and formed thereon
a series of concentric rings, the optical density of each
one of the series of rings decreasing from the centrally
disposed ring to the peripherally disposed ring.
References Cited
UNITED STATES PATENTS
3,437,401
4/1969
Siksai ------------- 350-153
3,446,555
5/1969
Kahn --------------- 356-5
3,409,368
11/1968
Fernandez ----------- 356-5
3,465,347
9/1969
Hudson ------------ 350-314
OTHER REFERENCES
Sears, optics, 1949, 3rd edition, pp. 39-43.
BENJAMIN A. BORCHELT, Primary Examiner
S. BUCZINSKI, Assistant Examiner
to pass, substantially unattenuated, the unpolarized 20
electromagnetic energy; and,
(b) a photodetector responsive to the portion of the
electromagnetic reflections passed through the disc.
5. A unidirectionally polarized optical wedge, such
wedge having an optical density decreasing from its center 25
portion to its peripheral portion and a linear polarization.
U.S. Cl. X.R.
350--153, 314; 356-3, 5, 119
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