DEAR MR(Sanitized)

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A000700050016-3
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 6
• Document Creation Date: December 28, 2016
• Document Release Date: March 28, 2002
• Sequence Number: 16
• Publication Date: March 8, 1967
• Content Type: LETTER

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Enclosed. are three copies of Technical Report
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Enclosures: Technical Report No. 9 (3 copies)
cc:
Successor Con rac i.ng ricer
(2 copies)
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CONFIDENTIAL,
Declass Review by
NIMA/DOD
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 Approt For Ra200*1'/0l R747A700050016-3
Technical Report No. 8
A. Current Status of Work
During this period the sine wave tester was completely
assembled and thoroughly tested. The tests were made
0
microscope objectives stopped down to very
small numerical apertures to make their performance
diffraction limited. This mode of testing is very
difficult since the amount of light available in the
final image is very small and visual settings become
very difficult. Under these conditions we also en-
countered the difficulty that the depth of focus is
very large, thus causing the grain in the ground glass
in the sine wave tester to become objectionable. To
To see if the equipment was otherwise working correctly
a great number of measurements were made and the results
averaged. This resulted in some startling information
and indicated that there was another factor influencing.
the results. For a long period of time this problem
remained unexplained. Tt was finely traced to two
causes: balancing of the two beams and scattering in
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CONFIDENTIAL
the polarizers. The balancing of the two beams could
easily be corrected after a better adjustment pro-
cedure was worked out. The scattering of the light
in the polarizers was a more fundamental problem.
Since we were already using the best polarizers
available, we could not really hope for a great im-
provement here. However, by carefully selecting
the nieces to be used from a large quantity of
polarizers some improvement could be made. Some
scattering will always be present, even with the
best selected polarizers. From theory it follows
that this would not be a serious difficulty, and
the result from theoretical computations indicated
that it could be callibrated out easily, resulting
in a slightly different curve representing the visihili.t
of the image produced by the tester as a function of
the angle of the polarizer. The greatest effect
would be a reduction in the maximum visibility for
an angle zero. Tnsteaad of a visibility of 1, we
would have a visibility of minimum .95. Many measure-
rnents were made to verify these theoretical results.
All our measurements indicate an agreement of mea.sure-
ments with theory.
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To improve the light i_ntensi ty, the illumina-
tion of the two beams was modified and condensing
systems were included. The light diffusers in the
two beams were also modified. Here we had the pro-
blem that in order to diffuse the light sufficiently
one must use ground glass of enough coarseness to
scatter the light properly; this, however, leads
to the problem that the structure of the ground glass
would become visible during the measurements on systems
with a large depth of focus. Moving the ground glass
far enough away from the target to overcome this pro-
blem would lead to a large reduction in the light in-
tensity in the two beams. To overcome this problem
we introduced a different type of light diffuser.
This diffuser consists of a glass plate ground on
both sides. One side is ground with an extremely fine
abrasive, which results in a structure that would not
be objectionable during the measurements, but would
by itself not diffuse the light sufficiently. The
other side of the glass is ground with a much coarser
abrasive. This provides the necessary diffusion, while
the first side provides the smoothness. This combina-
tion leads to a diffuser of the desired quality, both
in smoothness and high light intensities.
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Because of all the modifications made during
this period, we felt that the resulting sine wave
tester was too make-shift to be delivered as a final
instrument. It was therefore decided to build a new
one, incorporating all the new features. This re-
building is now in progress and should he completed
in the next few weeks.
We feel confident that we will now have an
instrument with the desired properties and precision.
B. Problem Areas Encountered
The problem areas encountered are described in
Section A.
C. Projected Work for Next Monthly Period
The final instrument will he finished and fully
calibrated. Then work will start on the second model.
D. Status of Funds Expended
From the period of August 1, 1966 to December 31, 1966
25X1A the sum ofl Iwas spent on subject contract.
This figure includes direct labor, materials, overhead
and G 9 A.
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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 during
this period.
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