FIFTH LETTER REPORT ON EVALUATION (U) (15 MARCH 1966 TO 14 APRIL 1966)

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A002900030013-4
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 3
• Document Creation Date: December 28, 2016
• Document Release Date: June 19, 2002
• Sequence Number: 13
• Publication Date: April 14, 1966
• Content Type: REPORT

Approved ForIease 2002/07/10 : ClA-RDP78B04702900030013-4
FIFTH LETTER REPORT ON EVALUATION (U)
(15 March 1966 to 14 April 1966)
14 April 1966
DECLASS REVIEW by NIMA/DOD
Approved For Release 2002/07/10 CIA-RDP78BO4747AO02900030013-4
25X1
25X1
 Approved Forlease 2002/07/10 : CIA-RDP78B047002900030013-4
Letter Report on Evaluation (U)
I. Work for Reporting Period
Measurements of the degree of coherence of the object plane illumination
have been completed during this past month. The interferometer experiments
described in the last letter report were performed for both single mode and multi-
mode laser illumination. All measurements of the degree of coherence when the
ground glass is predent and rotating are in excellent agreement with what one
would predict on the basis of a finite incoherent source. Specifically, the degree
of coherence is found to be a function of coordinate differences only, independent
of the laser mode structure, and the visibility of the fringes agrees, well within
the experimental error, with the visibility predicted from the vanCittert-Zernike
theorem. The laser rotating ground glass combination is, therefore, acting as
an incoherent source of diameter equal to the diameter of the laser beam.
During the past month the computer program has produced numerical results
showing the expected image intensity distribution for edges of five different contrasts
ranging from 1.2 to -a nd for ratios of coherence interval to lens spot size of 1, 2,
and 20. The contrast of these edges is defined as C = Imax/'I min. Further data
.
is expected shortly for other ratios of coherence interval to spot size. Experimental
imaging of edges has begun in parallel with this analytic program utilizing the high
acuity edges mentioned last month.
Since the last letter report we have shown theoretically that when the objects
used are low contrast a partially coherent imaging;system is linear in intensity.
This is an extension to the general partially coherent case of the linearity for low
contrast coherent systems which was mentioned in the proposal. We have also
shown that at low contrast an intensity modulation transfer function can be found
for the system and a direct comparison can then be made with incoherent systems.
Approved For Release 2002/07/10 : CIA-RDP78BO4747AO02900030013-4
 Approved For lease 2002/07/10 : CIA-RDP78BO474ZA002900030013-4
Work on the imaging of various contrast edges is continuing. As soon as
this is completed we will examine the images of other targets, including the
I I
structure in partially coherent light. Upon completion of this imaging work we
will continue onto the next part of the evaluation program, i. e. , examination of
the spatial filtering capabilities of the enlarger.
III. Visits to Contractor
None.
IV. Changes in Personnel
has been added to the project staff.
V. Progress of Work
As of this reporting date approximately 31% of the contract funds have been
expended and 35% of the work program has been completed.
25X1
Approved For Release 2002/07/10 : CIA-RDP78BO4747AO02900030013-4
"L" targets, for comparison with computer predictions of the image