TECHNICAL REPORT NO. 6 GOVERNMENT CONTRACT (SANITIZED)

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A002000030034-0
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 9
• Document Creation Date: December 28, 2016
• Document Release Date: May 26, 2011
• Sequence Number: 34
• Content Type: REPORT

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Technical Report No. 6
a. Current Status of Work
The following areas have been worked on during the period
starting July 24, 1965.
1. Some Remarks about the Precision of the Sine Wave
Equipment.
During this period we tried to measure the precision with
which the L could be measured. For awhile we encountered
some real difficulties in getting the results to repeat
for different targets. This was traced to birefrigence in the
film strips used for the targets. It turns out that the
film base is birefrigent. In fact, the film base is so
bad in this respect that we are modifying our equipment
to take glass plates. The new plate holder is being tested
now.
The two beams in the target unit have to be balanced in
intensity. It is shown in our proposal that when the
target film is assumed to pass 100% of the light in the
light strips and 0% of the light in the dark strips and the
polarizers are perfect, the intensity in the target beam
should be twice as large as the intensity in the flooding
beam. In reality these conditions do not hold true. We
will discuss here the influence of these two effects.
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Let us define the following quantities:
I = intensity of beam illuminating the target
I' = intensity of beam illuminating the flooding
beam
Tb = transmission of the, clear bars in the
target
T = transmission of the dark bars in the
0
target
= the transmission of a set of crossed
polarizers that is not perfect
angle at which the polarizer which
changes the visibility is set.
It is easily derived that the visibility of our target
assembly is now given by
{l_l_)sin2
(T b -T o ) I
l
(Tb+To I 1-. l-,C sin g +2I 1- 1- f cos
We should remember that we still can adjust the ratio
I'
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When we adjust this ratio to
I' 1 (Tb + To)
I 2
Equation (1) then becomes
T -T 1 - ofs 2 O
V b o COS 2
Tb+To 1 + ?(
T - T
0
V --b
target Tb + o
with which we get for (3)
V
target 1 + vc L
It is therefore extremely important that the best
possible polaroids are used.
We will continue to try to further improve the precision
with which these measurements can-be made.
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2. Target Fabrication
In order to fabricate the 15-bar targets, we built
three special cameras to get all three target groups
on the film.
Camera No. 1 is shown in Fig. 1. This camera puts the
first target group on the film (1 - 10 lines/mm). The
film or the plate is held by a holder. The film-holder
is shown in Fig. 4, together with the three ball arrange-
ment on the cameras. This ensures that the film is securely
located on each camera. The plate holder uses the same
ball arrangement.
Camera No. 2 is shown in Fig. 2. The target group from
10 - 100 lines/mm is photographed with this equipment.
In Fig. 3, both cameras No. 2 and No. 3 are shown.
Camera No. 3 takes the target group from 100 - 1000 lines/mm.
The special arrangements to locate the film with the
three balls is extremely important here since the depth
of focus of this camera is only a fraction of a micron.
The focussing in cameras No. 2 and No. 3 is critical and
the lenses can be focussed by a set of parallelogram
springs. A close-up of this arrangement for camera
No. 2 is shown in Fig. 6. The same arrangement is used
in camera No. 3, but a differential spring arrangement
is added here to make extremely small focussing adjustments
possible.
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With camera No. 3 we made actual targets of 1000 lines/mm
which were clearly resolved.
Fig. 5 shows the focussing arrangement and the target
location arrangement of camera No. 3.
Fig. 7 gives actual samples of targets up to 100 lines/~:m.
Fig. 8 shows the breadboard sine wave tester on which the
preliminary precision measurements are made.
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