DEAR MR(Sanitized)

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A000700050018-1
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 12
• Document Creation Date: December 28, 2016
• Document Release Date: March 28, 2002
• Sequence Number: 18
• Publication Date: May 12, 1966
• Content Type: LETTER

~2 May 1966
25X1A
Enclosed are three copies of Technical Report
No. 7 on the above-referenced contract.
25X1A
WB:aq
Enclosures: Technical Report No. 7 (3 copies)
cc:
uccessor Contracting Officer
TI A L
C " qtr p I
Declass Review by
NIMA/DOD
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Technical Report No. 7
Government Contract
I
a. Current Status of Work
The following areas have been worked on during this period.
1. The influence of limiting the target to 15 bars was
further investigated.
Consider an infinite number of transparent bars of
width w spaced w apart and having a transmission
bo + bl, which are superimposed on a background having
a transmission bo - bl. (Fig. 1)
-F ---
Fig. 1
The visability of this target is
VT
(bo + b1 (b b1) = bl
...(:Iso+b+ .(b0 - b1) b
0
GFQU"P I
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The Cosine Fourier Series representation of the
above target is
f (x) = bo + b1 cos(,rx )-3 rW bl cos 3 wx +
l \ JJJ
If harmonics higher than the first are neglected,
then the visability of the approximate "infinite"
target is
(b + 4b / 1) - (b - 4b /,V)= 4 b - 4 V
? 11-1r)
_l ~- 'b 0 - ;7- T
f (bo + 4b1/-7 ) - (b0 - 4b1/7)
Consider now an odd number, N, of similar bars. The
Exponential Fourier Integral representation of this
"finite" target is
F(x) _ (bo - b1) + J d'1.) ei2iTy/x GO) )
where
G ( I) = 2Nwb1
sin (2Ny7 w ) )
2N 7 w V cos ('7w jJ )
As the number of bars increases, the Spectrum Density,
G( ) ) becomes more sharply peaked at points which
approach the values + 1/2w, +- 3/2w, . . . Thus, if
a sufficient number of bars is considered, the above
function is approximately
F(X) .r (bo - b1) + b1 + 2b1G( o) cos`~x
`` w
where GNo) is the maximum of G( ) ) closest to
= 1/2w.
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The visability of this approximate "finite" target is
VF = 2G(1~0) 1'1 = 2G( p) o) VT.
b
0
In particular for N = 15, the Exponential Spectral
Density has been calculated and has yielded for the
approximate finite target (Fig. 2).
VF = 1.27376 V for = 0.4997w.
T
For the approximate infinite target one has
Vf c 1.27324 VT for I/ = 0.5000w.
In Fig. 3 we show the Fourier transform of a target
with an infinite number of bars.
2. During the investigation of the instrument we performed
the following experiment. The value of the transfer
coefficient i for one frequency was measured using
filters of different modulation in the eyepiece. Using
green light, the instrument gave the same value for 'C
however, repeating this measurement with red light showed
that for different visibilities of the filters different
values for '2 were measured.
First, the ''/4 plate was suspected. However, after
measurements in different wavelengths were made, the
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error in birefringency was found to be neglibible and
therefore could not be the cause.
The cause was found to be a property of the polarizers.
This will be discussed in Section 3.
3. Properties of Polarizers
First it was thought that the transmission of the
polarizers was not given by cos2' (where 4i is the
angle between the polarizers) for all wavelengths.
The results are shown in Table 1. The polarizers are
adequate in all wavelength regions.
These measurements were made with a spectrometer. 25X1A
It turns out that the light beam in this instrument is
partially polarized and it is therefore impossible to
get absolute values for the transmittance of the
polarizers at various wavelengths. We will, therefore,
use the values as published by l and shown in
Fig. 4.
If, for example, the two beams are properly adjusted
in the green (500 myt), we have for the transmission
in the target bundle 39%. In the flooding beam we
have 2(.39)2 cos , = 1/2 x .39; or cos Cp = .6414.
For red light (750 m,M) in the target bundle we have
a transmission of .42 and in the flooding bundle .226.
Instead of a 2:1 ratio we have a 1.858:1 ratio or an
error of over 14%. This can lead to an error of 28%
C11 7"V V i 1
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25X1A
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in the measurement of the transfer function.
There are two ways to correct this situation. The
first one is to place two polarizers in each beam;
in the target beam with an angle zero, in the flooding
beam with the appropriate angle. The second one is to
find another way to adjust the flooding beam.
The first method will automatically be adjusted for
wavelength, but will result in a light loss. The
second method will not result in a light loss, but
might be much more difficult to accomplish.
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TFICATION
171
C
Cos 2 ro
500 nMjr
550 n4
600&1,z,,
650,,,,cf
709t
3.5
99.6
99.5
99.5
99.0
99.5
99.2
8.5
97.8
98.1
98.1
98.5
97.2
97.7
13.5
94.6
95.2
94.8
95.0
94.0
94.0
18.5
89.9
90.5
90.5
90.5
89.5
89.5
23.5
84.1
84.8
84.8
85.1
83.9
83.5
28.5
77.2
77.1
77.1
76.1
77.1
77.1
33.5
69.5
69.0
70.5
70.6
68.8
69.5
38.5
61.2
61.0
61.9
61.7
61.0
60.9
43.5
52.6
52.4
52.4
53.2
51.8
52.3
48.5
43.9
44.8
44.3
44.3
43.6
44.0
53.5
35.4
35.7
35.7
34.3
33.0
35.3
58.5
27.3
27.6
27.6
27.4
27.5
27.3
63.5
19.9
20.5
20.0
20.4
19.7
19.9
68.5
13.4
13.8
13.8
13.4
13.8
13.4
73.5
8.1
8.3
8.1
8.5
8.3
8.3
78.5
4.0
4.5
4.0
3.7
4.2
4.1
83.5
1.3
1.4
1.0
1.2
1.4
1.1
88.5
0.1
0.5
0.0
0.0
0.0
0.0
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TIAL
G .OUP I
EXCLUDED FROM AUTOMATIC
DOWNGRADING ANT) DECLASSIFICATION
I t I J, to
o p O o
N
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b. Problem Areas Encountered
Problem areas have been discussed in Section a.
c. Projected Work for Next Monthly Period
1. Work will continue in the areas described in
Section a: 1, 2, and 3.
2. When we are satisfied that all problems are solved,
work on the second model will be started.
d. Status of Funds Expended
From the period of February 1, 1966 to April 30, 1966
was spent on subject contract.
This figure includes direct labor, materials, overhead
and G 8 A, and fixed fee.
e. Documentation of any verbal committments and/or agree-
ments with the Technical Representatives of the Con-
tracting Officer during the reporting period.
No verbal agreements'or committments were made.
f. Request
The delivery date in our contract extension dated
18 March 1966 (Amendment No. 1) cannot be met. The delay
in receiving the contract extension resulted in serious
scheduling problems..
We therefore request an extension of the delivery date
to December 31, 1966. (This refers to the "deliverable
items" - two prototype Field Sine Wave Test Devices.)
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o tiI I
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In discussions with your project personnel it was
stated that the first model of this equipment could be
used later on this year and we agreed that we would
make available a workable, although not final piece of
equipment for your use for a period of time, since it
would be to our mutual advantage to find any improvements
that might be suggested by actual field use.
25X1A
Submitted by
12 May
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