IMPROVED SCREEN FOR REAR PROJECTION VIEWERS

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP79B00873A001900010050-9
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 14
• Document Creation Date: December 28, 2016
• Document Release Date: September 6, 2012
• Sequence Number: 50
• Publication Date: September 13, 1968
• Content Type: REPORT

Declassified in Part - Sanitized Copy Approved for Release 2012/09/06: CIA-RDP79B00873A001900010050-9
STAT
CORNING GLASS WORKS
ELECTRO-OPTICS DEPARTMENT
RALEIGH, NORTH CAROLINA
IMPROVED SCREEN FOR REAR-PROJECTION VIEWERS
Technical Report Nb. - 32
Date - September 13, 1968
Period Covered - August 16, 1968
to
September 13, 1968
Declassified in Part - Sanitized Copy Approved for Release 2012/09/06: CIA-RDP79B00873A001900010050-9
STAT
Declassified in Part - Sanitized Copy Approved for Release 2012/09/06: CIA-RDP79B00873A001900010050-9
ABSTRACT
This report contains a review of rear-view screen specifi-
cations based on our past and continuing theoretical and ex-
perimental research in this field. The objective is to present
what we consider to be desirable and attainable specifications
for a relatively well-defined projector-observer system. Both
subjective and objective criteria are considered and lenticular
as well as scattering screens are treated. It is assumed that
the screen will be used for scanning of large quantities of
film, while careful studying of details will be performed by
the use of a direct magnifying device which will bypass the
screen. In this context preservation of contrast at all levels
of local screen brightness is judged to be of prime importance,
followed by resolution and the comfort of the observer. These
considerations lead to the following specifications. Resolution:
At 14 inches, screen should not appear to limit resolution,
MTF a 0.7 at 10 mm -1. Specular Reflection: Reflected images
should not be distracting, reflectance less than 0.5% at all
viewing angles. Diffuse Reflection: Should not unduly restrict
ambient light level, reflectance < 5% for scattering screens.
Less for lenticular screens. Brightness Variation: No "hot
spots" and operator should not be forced to change head position
to compensate, variation no more than ? 25% over the screen,
gradient no more than 2% per inch. Efficiency: Diffuse trans-
mittance into 45? semi-angle cone 20-30% for scattering and
60-80% for lenticular screens. Color effects, including non-
white screen transmittance spectrum, color variation with bend
angle, diffraction spectra, and scintillation, should not be
strong enough to be a distraction.
Declassified in Part - Sanitized Copy Approved for Release 2012/09/06: CIA-RDP79B00873A001900010050-9
Declassified in Part - Sanitized Copy Approved for Release 2012/09/06: CIA-RDP79B00873A001900010050-9
L.)
TECHNICAL REPORT NO. 32
I. INTRODUCTION
As a first step in the production of usable rear-view
screens in actual projectors we have undertaken a thorough
review of screen specifications.
In order to give proper weight to the various screen
parameters, we have taken a more careful look at the
complete viewing system, including the operator. While
we have attempted to put these specifications into quanti-
tative form wherever possible, it is recognized that for
some characteristics a qualitative judgment is sufficient.
Furthermore, since the suitability of a screen must finally
be judged by the user on a subjective basis, both objective
-and subjective criteria have been taken into account. The
important parameters are listed below along with qualitative,
or subjective, specifications, where applicable. These are
followed by what we consider to be reasonable and attainable
quantitative, or objective, specifications. In some cases
the values for lenticular screens differ from those for
scattering screens. Following the listing, we discuss how
each specification was arrived at. Central to this whole
discussion is a recognition of the wisdom of separating the
photo-interpretation task into two operations, scanning the
image on a rear-view screen and examining details with a
periscope arrangement bypassing the screen.
II. Screen Specifications
Parameter Specification
Qualitative Quantitative
1. Resolution
2. Front reflection
Specular
Diffuse
Screen should
not appear to
limit resolution.
-Reflected images
should not be
distracting.
Should not unduly
restrict ambient
light level.
RD
-1
MTF z. 0.7 at 10 mm
< 0.5% at all viewing
angles.