SPATIAL FILTER

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A002700020034-4
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 2
• Document Creation Date: December 28, 2016
• Document Release Date: June 26, 2002
• Sequence Number: 34
• Publication Date: May 22, 1964
• Content Type: MEMO

Approved For Release 2002/07/12 : CIA-RDP78B04747A002700020034-4
SUBJECT: Spatial Filter
FILE NO.:
CQ ~~1e
We have completed the making of a spatial filter., under
Several copies of the filter are enclosed.
STAT
STAT
STAT
Task III. STAT
The transmission vs. radius of these filters meet the specifications you
established. It is therefore concluded that spatial filters can be made by
photographic means, not only of this particular transmission vs. radius
relationship,, but also of nearly any desired function.
The transmission of these filters were measured with the microdensitomer
using:
1. A circular scanning aperture of an effective diameter of 83 microns,
2. An objective (light collection cone) with an f number of 5.0, and
3. White light, filtered with a (red) wratten No. 25 filter (light of
.6-.75 microns).
The film used to make these filters has an emulsion of a modified STAT
type., and therefore exhibits extremely fine-grain, resulting in very 1 tt e
scattering of light passing through the emulsion (i.e., the density measured
specularly is very similar to that measured diffusely).
The filters have two defects: images of dust particles and a central
portion (about lmm. dia.) which is slightly too light or dark. Both of these
defects can be corrected and are not due to any inherit characteristics of the
making-process. To eliminate these defects will require a more dust-free
making-environment and a moderately precision X-Y film positioning device.
Neither defects should., however., prove disturbing in your evaluation of the
filters as spatial filters.
One note of caution: handle these film filters carefully since finger-
prints or other marks are likely to be permanent.
Please let me know how these filters perform as spatial filters.
STAT
FS/jf
cc: REH
Declass Review by NIMA / DOD
Approved For Release 2002/07/12 : CIA-RDP78B04747A002700020034-4
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