IMPROVED SCREEN FOR REAR PROJECTION VIEWERS

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP79B00873A002000010012-9
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 6
• Document Creation Date: December 28, 2016
• Document Release Date: November 8, 2012
• Sequence Number: 12
• Publication Date: June 15, 1965
• Content Type: REPORT

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Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
CONFIDETiu
CORNING GLASS WORKS
ELECTRO-OPTICS LABORATORY
RALEIGH, NORTH CAROLINA
IMPROVED SCREEN FOR REAR PROJECTION VIEWERS
Dated 15 June 1965
Technical Report No.: 1
Date: August 27, 1965
Period Covered: July 15,1965
to
August 15 1965
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Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
COMFMERITEM,
I. Accomplishments
1. Literature Search
a. Open Literature
The literature search commenced at the beginning
of this period. Two main areas of investigation
were defined; 1) articles directly related to
?projection screens and 2) articles concerned with
the theoretical aspects of Mie scattering and
laboratory measurements of the scattering properties
of materials. Our Technical Librarian, Mr. Burriss,
spent two days extending the search on screens, at
the Library of Congress, Washington, D. C. As
expected, only a minimum number of articles were
found. These were made up of 16 patent references
and 17 references to the open literature of which
5 are foreign. The foreign articles have both
title and abstract in English.
Contrasted to this are some 150 articles relating
to scattering, theoretical techniques, and laboratory
methods; all of which are directly related to
supporting future tasks. Because of astronomical
quantities of this type of literature only those
articles most closely related to specific tasks are
being collected for retention.
b. Patent Literature
A patent search of both domestic and foreign
literature from 1945 to date was initiated under
the direction of of our patent 25X1
department, Corning, New York. The actual search
has been assigned to an outside firm in Washington,
D. C. and have been instructed to complete the
search at the earliest possible date.
CONIFINKTIN
Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
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2. Preliminary Theoretical Investigation: Screen
Resolution
Projection screens are used to display large
quantities of densely packed information which
may be viewed directly or under additional
magnification. Therefore it is essential that
the display medium have sufficient resolution
to present the required level of detail to the
observer.
Modulation transfer function measurements have
been extensively used to evaluate the resolution
of optical systems and components over the last
few years. The modulation transfer function (MTF)
is a measure of how well the contrast of a part-
icular size detail is transmitted through an optical
system as a function Of detail size.
Detail size is given in terms of spatial frequency
in cycles or lines per millimeter of a pattern
whose transmission varies sinusoidally with distance.
In low resolution systems the contrast in the image
is lost at a spatial frequency around 10 lines per
millimeter while high resolution systems can
adequately reproduce detail from 100 to 1000 lines
per millimeter.
Many techniques have been developed for measuring
the modulation transfer function. With Only a few
exceptions most work has been on image forming
devices such as lenses, curved mirrors, telescopes,
microscopes, projectOrs, etc. Comparatively little
has be done to investigate non-imaging components
like transparent plates, flat mirrors, and of primary
interest, scattering materials. Because of the vast
difference between conventional imaging system and
scattering materials, these well established
techniques must be re-examined as to their applicability.
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Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
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Lenses are designed to be used at a given diameter,
object distance and magnification. They are usually
uniformly illuminated and almost all of the light
incident on them passes through forming an image in
one particular plane.
Quite a different situation is encountered when using
a projection screen. It can never be uniformly
illuminated if it is to display information. A
significant portion of the incident energy is back-
scattered toward the projector and that which passes
through is re-distributed over an appreciable solid
angle. All of the information displayed must be
observed from many different directions and varying
distances from the screen. Care must be taken because
of these unique differences when measuring the
modulation transfer function of scattering materials,
because different techniques will give a different
MTF for the material.
The following is a list of factors which can be
expected to influence the measured MTF of a projection
screen.
a. Micro structure of scattering material
b. Macro structure of scattering material
C. Angle at which surface is viewed
d. Distance from the surface
e. How the material is illuminated
f. Acceptance angle of measuring device
g. Measurement techniques
Devices are commercially available for measuring the
MTF of ordinary optical components but their applic-
ability to this specific type of material is questioned.
Theoretical studies are planned to properly define the
conditions; under which the modulation transfer function
of scattering materials can be validly defined and
measured. Thus the results of such a 'study must be
understood before any attempt is made' to acquire a
device for making such measurements.
COWPER-mum ,
Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
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Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
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3. Progress on a New Optical Fiber Screen Material
Conventional optical fibers consist of an inner core
and a surrounding outer cladding of a lower refractive
index material. The attenuation of light in a fiber
is a complex phenomena but for practical purposes
the internal losses are due to inherent properties
of the dielectric core and not on imperfect internal
reflections. A patent disclosure of a new type of
optical fiber has been submitted by Corning Glass
Works which is expected to largely circumvent this
problem. This proposal is to use a hollow tube with
a highly reflective inside wall. Losses are now
governed only by the reflective properties of the
coating, no longer by the loss tangent of the core
.r1c1 are therefore expected to be less than for an
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equivalent solid core fiber. This new type of optical
fiber is being fabricated at our Danville, Virginia,
facility. Re-drawing of the hollow Vycor brand glass
tubes into fibers and their subsequent internal
plating with Molybdenum has been started.
Techniques on how to assemble these individual fiber
tubes into a matrix is presently under study. It is
hoped these fibers can be bonded together in some way
to produce an experimental rear projection screen.
4. Instrumentation
A Beckman DK-2 spectrophotometer with a reflectance
attachment has been purchased by the Electro-Optics
Laboratory of Corning Glass Works. This device will
be used to measure the diffuse spectral transmittance
and reflectance properties of sample screen materials.
The integrating sphere and reference samples still
require a coating of Magnesium oxide which is taken as
the reference standard. The electronics have been
checked an are in working condition.
EGKELLNIAL
Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9
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The photometer attachment is on order and all
remaining maintenance is expected to be completed
prior to the commencement of any experimental work.
II. Next Period Objectives
1. Literature Search
a. Open Literature
The necessary remaining literature will be
collected during this period. Because of
the time required between having the literature-
in-hand and having it digested, a cut-off date
will be set. Material received after this date,
with a few possible exceptions, will have' to
be put aside until after the interim report.
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Translations of the most important foreign
articles will be started during this period.
b. Patent Literature
The report from Mr. Zebrowski covering the results
of the patent search is due. This will contain
only patent numbers and no patents as such.
Therefore upon receipt of this the patent liter-
ature will be ordered.
2. Familiarization with Corning Manufacturing Facilities
Trips are planned to manufacturing plants at Corning,
New York, and Danville, Virginia, to become familiar
with Soffe available Corning materials, techniques,
and the limitation of the various manufacturing processes.
Contacts will be made at each facility with those
personnel who can later be contacted to provide
additional information relating to Corning capabilities
and the fabrication of samples as may be required during
later phases of the program.
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Declassified in Part - Sanitized Copy Approved for Release 2012/11/08: CIA-RDP79B00873A002000010012-9