(Sanitized) VISIT TO NPIC ON 14 JANUARY 1964.

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP67B00558R000100130023-1
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 7
• Document Creation Date: November 16, 2016
• Document Release Date: January 27, 2000
• Sequence Number: 23
• Content Type: MFR

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25X1A
MEMORANDUM FOR THE RECORD
SUBJECT: Visit to NPIC on 14 January 1964.
25X1A
25X1A
25X1A
1. Enclosed are comments concerning
the performance of the microscope and viewing
conditions which he observed during his trip to
NPIC.
2. submitted this memorandum during
his visit to Headquarters on 25 February 1964.
25X1A
Executive Secretariat
Scientific Advisory Board
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25X1 D
MEMORANDUM FOR THE RECORD
SUBJECT: Comments on Trip to NPIC, 14 January 1964.
i
1. These are a part of my observations made at NPIC
during my visit of 14 January 1964. I asked to see materials
of the best quality. I was shown KH 4 samples,
including the resolution targets near 'Washington, D. C., and
other samples from the flights that occurred over Washington
on 26 December 1963, and a. number of the other best photographs
thus far achieved. My interest in the inspection of these
materials was not so much in the materials themselves as it
was in the performance of the microscope and the viewing condi-
tions. It seems to me that the end product of the whole recon-
naissance system is the light that enters the eye of the inter-
preter. It is his :interpretation of what he is able to see
that produces the final intelligence of value to our country,and
I am not convinced that everything has been done to maximize
his ability to extract the best possible retinal image from the
pictures.
2. This is a natural. interest of mine partly because I
have, since World War II clays, been a member of the Armed Forces-
National Research Council Committee on Vision, and partly
because all of my activities have been devoted exclusively to
visibility matters for many years. I was interested, therefore,
in looking at the microscope from the standpoint of the visual
performance achieved with it and the viewing conditions under
which the photo-interpreters presumably operate.
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3. I endeavored to ask questions concerning the way in
which the actual interpreters use the microscopes. I did not
meet any of the interpreters or see them in the performance
of their work. So far as I am aware, the interpreters use
the same type of microscope and presumably work under the same
sorts of conditions that I experienced during my visit on
14 January. From many things that have been said both in the
various presentations I have heard and. in the responses to the
questions I have asked, I realize that the Agency is well aware
of some of the shortcomings of the microscope and the viewing
conditions under which it is used. For example: I recall from
the briefings that studies have been made of means for increas-
ing the apparent luminance of the diffusing surface against
which transparencies are viewed. This is an important matter
because, at high power, the exit pupil of the microscope is
quite small and produces retinal illumination lower than is
desirable in the darker portions of the scenes. I am convinced
that any observer can obtain more information from the film at
high power if more light could be made available. I am prepared
to believe that the optical design of these constructions has
been. carefully considered and that a larger exit pupil is not
practicable. If this is true, there seems to be little recourse
except to increase the light available below the transparencies.
4. The performance of the observer can also be increased
by improving the contrast rendition of the microscope. No
one to whom I talked had any information concerning the contrast
rendition of the system as now exists. My impression is that
the system is far from being poor in this respect, but on the
other hand, I would be surprised if worthwhile improvement could
not be achieved rather easily. Quantitative measurements of
contrast rendition which I have seen on other high quality micro-
scopes indicates that improvement is almost always possible if
a small opaque stop can be introduced at the transparency. In
one installation with which I am familiar, a thin piece of metal
containing a hole only large enough to allow the microscope to
inspect the portion of the transparency corresponding to the
field of view of the scope was provided in order to prevent light
from other portions of the picture from reaching the microscopic
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objective lens. It produced a very noticeable improvement
in the apparent contrast o.- the photographs, particularly at
high power. Such a result, could be achieved automatically
if illuminated diffusing lass beneath the transparency is
replaced by a lamp housing from which light is emitted only
by a small area directly beneath the microscopic objective.
5. In the present instrument the large illuminated
diffusing glass produces a very distracting glare field into
which the observer is forced to look. I understand that some
operators make a practice of covering this illuminated area
with opaque material, such as cardboard, in order to diminish
this glare. I heartily endorse this practice and strongly urge
its adoption and extension. I understand also that the inter-
preters tend to turn off the lights in the room while looking
into the microscope. This also is a desirable practice. Unless
both of these precautions are taken, the observer will be
surrounded by enough room light to impair his visual performance
unless well fitted eye cups are provided.
6. The small plastic shields with which the present
instrument is provided are virtually useless and doubtless are
seldom used. A dramatic improvement in visual performance
can be effected simply by using ones hands to form eye cups
before the microscope. The full improvement is not experienced
until all of the stray light is excluded. I strongly recommend
that the existing microscope be fitted with very good soft
rubber eye cups. It would be desirable to have these specially
made for each photo-interpreter so that he can achieve a com-
fortable, tight fit. If such cups are provided, the glare
produced by the large illuminated diffusing glass will be negated,
except for the deleterious effect arrising from abrupt changes
in his adaptation which will occur when he lifts his eyes from
the eye cups and looks at the brightly lightly lighted field
beneath the microscope. Presumably it is necessary for him to
do this at frequent intervals. Despite the fact that adaptation
is a comparatively rapid process at high light levels, visual
performance will be degraded for periods of several seconds after
the eyes are returned to the eye, cups if there is any form of
glare source in the working envi.ornment. Glare-free viewing
conditions in the work space outside the microscope eye-piece
is highly desirable.
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7. My visual inspection of the microscope made me
believe that achromatigation conditions could be improved,
particularly at high power. It is possible that some of the
chromatic effects which I seemed to observe stem from the
spectral distribution of the light from the illuminating system.
It is possible that the spectral distribution of the light
from the diffusing glass has a very different composition than
that which was assumed by the lens designer who achromatized
the microscope. This might be worth reviewing. In any event,
reduction of chromatic effects in these microscopes could improve
visual performance on the part of the photo-interpreters.
S. The microscopes eye pieces have focussing adjustments
but these are not provided with diopter markings. The adjust-
ments for interpupillary distance, moreover, do neat ;a;,- ',? In
have a calibration scale. The photo-inlterpreter should not be
expected to operate eye piece adjustment's and make settings of
int;erpupillary distance by trial and error. Just as in the
case of military lookouts, his refractive correction and inter-
pupillary distance should be determined carefully by clinical
procedures, and he should set the diopter rings and the inter-
pupillary adjustment in accordance with clinical findings before
he attempts to look through the microscope. If the clinical
work is done properly and if the microscope is properly adjusted
and calibrated, the observer will have his eyes properly aligned
with the optic axis of the instrument and provided with the
optimum (spherical) correction. In no other way will he obtain
the best visual performance of which the microscope is capable.
9. The photo-interpreters should not wear spectacles
while looking through the microscope. These will not be necessary
unless he is inflicted by astigmatism or some other visual
defect for which ordinary eye piece focussing adjustments do
not provide a correction. Each photo-interpreter should be given
a very careful periodic opthalmic examination. Provisions should
be made in the microscope for introducing cylinders (and prisms
and if needed), tailored to the prescription of each man. Spec-
tacles will then not be necessary.
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10. I wish particularly to emphasize the loss in
visual accuity in the use of microscopes such as those now
employed by the Agency if the observer has uncorrected
astigmatism, even astigmatic defects so slight as ordinarily
to be considered as sub-clinical.. These can quite demon-
stratively impair his visual performance.
11. The effect of small amounts of the astigmatism
can be quite insidious, because the interpreter is ordinarily
looking at non-sharp images and must endeavor to discriminate
fine details buried in soft or grainy photographic images.
He has no way to know whether the unresolved image he sees
is truly representative of the film or whether part of the
apparent loss of resolution is created by astigmatic or other
defects in his own eyes. He should not be asked to make this
judgeme3it; rather, he should be subjected to frequent, care-
ful othaimic examinations and he should be provided v - z th -full
corrections on each eye piece. In fact, I would strongly urge
that the photo-interpreter on whose visual performance so much
depends should have very careful special eye examinations not
less frequently than once a month, primarily in order to detect
small changes in astigmatism which may develop. Experience
may indicate whether such tests should be done less frequently
or more frequently than monthly, but clearly a testing program
should be instituted by the Agency and should be mandatory and
not left to the discretion of the individual photo-interpreter
or his private opthalmologist or optometrist. No detectable
sub-clinical astigmatism should. go uncorrected.
12. It would be desirable to give careful consideration to
improving the comfort of the photo-interpreter while working
through the microscope. Professional attention to such items
as seats, arm rests, head rests, etc. should be given and these
should be tailored to the stature and requirements of each
photo-interpreter. The accoustical enviornment should also be
considered and everything done to eliminate distraction, dis-
comfort, and fatigue for these men.
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13. Visual performance varies with age. I understand
that the group of photo-interpreters used by the Agency
contains a wide spectrum of age. The visual capabilities of
the men should be considered and possibly measured. Critical
materials might profitably be :Looked at by more than one
individual, inasmuch as there maybe a trade-off between the
effects of age on visual performance and interpretation
capabilities.
14. Finally, a review might profitably be made of design
compromises of the microscope, primarily if it affects their
performance at high power. A different instrument with higher
power capability might reveal more information in some instances
than can be obtained with the present microscope. It was my
impression that more power would have been helpful in a few
instances.
15. A study might also be made of the color and the
spectral distribution of the lighting. Small second order
improvements might result from a change of lighting.
25X1A
Optics Panel
Scientific Advisory Board
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