DEVELOPMENT OBJECTIVES MODULATED-LIGHT FILM VIEWING SYSTEM

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A002500050025-3
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 4
• Document Creation Date: December 28, 2016
• Document Release Date: November 16, 2001
• Sequence Number: 25
• Publication Date: March 23, 1964
• Content Type: MISC

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23 March 1964
These objectives propose a,fea.sibility study which would investigate con-
cepts for light-modulating systems and develop the concept(s) most adaptable
STATINTL to two kinds of direct viewing. This would include: (1) contact or 1:1 view-
ing as is now done on basic light tables by means of transmitted light, and
(2) high-magnification, macroscopic viewing afforded, for instance, by a
=Zoom 70 mounted on the same basic table.
In the history of photo interpretation, one of the most necessary and basic
pieces of viewing equipment has been the direct-viewer light table.
In general format, the viewers are box-like, rectangular in shape, and
have either a. 10" x 20" or a 10" x 40" viewing surface (opal glass) evenly
illuminated from underneath by fluorescent tubes with continuously variable
intensity. Film spools and winding gear are located at either 9" end. Both-
sized tables are placed on support tables, specially designed, and are used most
often to view roll-film positives.
The P.I. uses the 9" x 18" table'primarily for contact viewing the
standard format films (which range to 9" x 18"): his technique involves first
scanning the exposure by naked eye and then studying details with a 7X or 12X
tube magnifier. So that the seated P.I. could lean into his work rather than
have to lean over it, the table wa.s designed to rotate and tilt on its pedestal:
its most familiar working position is at an angle 450 from vertical and away
from the seated P.I.
The 9" x 40" light table is more often used in a, natural horizontal position
(with a, long side nearest the P.I.) for larger format and. higher-resolu:tion films.
Viewing is frequently augmented by a stereomicroscope capable of 7X-60X
magnifications.
The illumination system in current models fulfills its basic purpose as
a. light source. However, a. more sophisticated, modulating-light system would
be of direct benefit to the intelligence retrieval process. It would not only
reduce the physiological strains involved for the human visual system but also
enhance the display of photographic information for more effective exploitation.
For example: with current, standard fluorescent illumination of trans-
parencies, there is no means of masking extraneous light or of attenuating light
under thin densities and providing adequate brightness under heavy densities.
At contact scale, when the P.I. searches for details in dense regions of a
transparency, his eye is affected (the iris closes down) by flare either
surrounding the transparency or passing through adjacent, thin-density image
areas. Particularly trying visual situations are presented by snow, clouds
and shadows, and occasionally by haze.
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In addition, a direct-viewer used with a microscope for detecting
magnified details often proves inadequate in total illumination level.
3. SCOPE.
Envisioned is a direct-viewer light table built around a modulating
illumination system capable of automatically and continuously responding to
film densities and spatial frequencies and regulating light accordingly.
The effect would be similar to that of a. printer.
All concepts with potential application should be considered: some which
were visualized in the course of the original project idea are:
3.1. CRT scanning systems.
3.2. Light-beam scanning systems.
3.3. UV-IR quenching systems.
3.4. Photochromic filter or masking systems.
3.5. Phototropic filter or masking systems.
3.6. Various combinations of the above systems.
3.7. It would be ideal if one concept.-- or at least compatible systems --
were applicable to both direct-viewing uses of the light table. On the other
hand, it might prove sensible to develop two entirely different principles and,
consequently, independent systems.
3.8. Further but secondary considerations should be given to rear-projection
viewers and the potential incorporation of light-modulating principles in such
equipment.
3.9. Proposals will be evaluated on the basis of the following:
3.9.1. Performance - the degree to which the contractor can assure the
customer of meeting the stated requirements.
3.9.2. Simplicity - an approach which implies fewer contingencies, broad
application and reasonable economy.
To a certain extent these factors are mutually exclusive; however, each is
so important that concurrent development of the most promising proposal for
each category is a distinct possibility.
4. REQUIREMENTS.
4.1. Physical Configuration. It is desired that this modulated light
system be suitable for packaging in a. mode similar to the conventional
10" x 20" or 10" x 40" roll-film viewers. If this is not feasible, then the
proposal should include a. description of appropriate packaging which will be
evaluated for its relative merits as a design concept.
4.1.1. Viewing Area.. The entire 10" x 20" or 10" x 40" viewing areas
should be illuminated by the modulating system; however, consideration will
be given to systems which utilize auxiliary illumination on either end and
confine the modulated illumination to the central portion. The minimum
acceptable size for the area, of the modulated illumination is 9" x 9".
4.1.2. Controls. Controls must be kept to a. minimum and should be
mounted directly on the viewer. If a. separate control console is unavoidable,
then it would be acceptable.
4.1.2.1. Modulated Illumination. Controls should be provided for adjust-
ing the degree of modulation in terms of intensity and/or spatial frequency.
There should be a. control for setting the unmodula.ted levels of intensity and
controls for setting the size and position of the area of modulated illumination.
25X1A
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4.1.2.2. Auxiliary Illumination. If auxiliary illumination is required
to cover the entire specified viewing areas it should be independently variable
and completely isolated from the modulated illumination. A means should be
provided for instantaneously extinguishing the auxiliary source and illuminat-
ing it to a. preset level.
4.1.3. Physical Interference. Physical obstructions which come between
the operator and his work and which would inhibit viewing or efficiency are
not acceptable.
4.2. Illumination Characteristics.
4.2.1. Brightness. Minimum acceptable level of brightness for the entire
illuminated area is 1000 foot-lamberts: a. level of 2000 foot-lamberts is
desired.
4.2.1.1. Brightness Modulation. Brightness modulation shall be a. function
of density and spatial frequency. Brightness shall be inversely proportional
to transmittance and directly proportional to the spatial frequency of the
transparency being viewed. These modulations shall be variable in range,
allowing for individual operator preference and for the requirements of magnified
viewing (5X - 60X).
4.2.1.2. Response Time. Since the viewer is to be used for scanning, the
response time of the modulation system must be such that no visually perceptible
effects such as flicker or smea.r are produced.
4.2.1.3. Reduced Field. If possible, masking or size-reduction of the
illuminated area. should result in a proportionate increase in maximum intensity.
4.2.1.4. Spurious Effects. No spurious effects such as those produced by
uni-directional scan, are acceptable. On the other hand, special, effects,.available
at the operator's option, are acceptable.
4.2.2. Color Temperature. Color temperature shall be in the 35000 -
5500?K range and shall not be appreciably changed by brightness attenuation.
4.3. Development Plan. This development shall be executed in two,
independent, successive phases: feasibility study and operation of prototype.
Contract award shall constitute tentative approval of both phases. No funds
will be approved for the operational prototype phase, however, until the
customer has given assent on the basis of feasibility studies and breadboard
demonstrations. It is the customer's prerogative to terminate without pursuit
of the prototype phase if he is not satisfied with the proof of feasibility.
4.3.1. Feasibility Study. This requires detailed documentation of the
study program, which should include investigation, analysis and breadboarding.
Successful breadboard demonstration must precede the prototype phase.
4.3.2. Operational Prototype. This requires production of a prototype
system which can be evaluated operationally with both 1:1 direct viewing and
5X - 60X magnified viewing. The prototype shall include detailed descriptions
of all aspects of the systems as well as ma.intenance and operating instructions.
5. SECONDARY REQUIREMENTS.
These requirements should be considered if they do not compromise those
stated in Section 4:
5.1. Masking. The modulated light area. should be continuously variable in
size. Size should be independently variable in X and Y; identical change in
X and Y would be acceptable. Increase in intensity -- in correct proportion
to reduction in area. -- is desired.
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5.2. Translation. The modulated light area, once reduced in size, should
be movable to any desired position within its original boundaries. This trans-
lation should be optionally controlled -- either manually (by a joy-stick) or
automatically (by the position of the viewing microscope).
5.3. Enhancement. Other special optical effects made possible by a
modulating light source should be considered.
5.4. Rear-Projection Viewers. If a similar light modulation technique
could be applied to rear-projection viewers, which have a magnification range
of 5X-50X and a. screen size of 30" x 30", there is interest in establishing
its feasibility.
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