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Proceedings Paper

Full Color Liquid Crystal Light Valve Projector
Author(s): Ronald S. Gold; Arno G. Ledebuhr
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Paper Abstract

A full-color projection display system, incorporating CRT driven liquid crystal light valves, has been designed for use in land-based command and control centers. A novel three-channel, two-projection lens approach has been utilized with this system. A polarizing beamsplitting prism partially pre-polarizes the incoming illumination and directs the light along two parallel paths. Red and green primaries of opposite polarization are directed along one illumination path where they are further separated by a main beamsplitting prism and directed to the red and green channel light valves. The blue primary illumination is directed along the other path where another beamsplitting prism directs the light to the blue channel light valve. The main prisms function as both polarizers and analyzers and direct the output light to the projection lenses. Because the light valves operate in linearly polarized light, it is necessary to remove undue stress birefringence, which, if present, would cause contrast degradation and non-uniformity in the projected image. For that reason, index-matching fluid-filled prisms are used instead of glass. The illumination system includes a 2500-watt air-cooled xenon arc lamp which produces an output of over 1500 lumens in additive white. A novel feature of the projection optics is that while one projection lens handles the red and green primaries the other projection lens (blue channel) can be laterally translated to provide for coarse mechanical registration of the images. Remaining image registration requirements are achieved by both dynamic digital-correction circuitry and by image sensors at the screen that provide feedback to the projector's analog deflection drivers. The projector has a resolution of 1400 TV lines and a contrast ratio of greater than 10:1 in white.

Paper Details

Date Published: 13 May 1985
PDF: 8 pages
Proc. SPIE 0526, Advances in Display Technology V, (13 May 1985); doi: 10.1117/12.946376
Show Author Affiliations
Ronald S. Gold, Hughes Aircraft Company (United States)
Arno G. Ledebuhr, Hughes Aircraft Company (United States)

Published in SPIE Proceedings Vol. 0526:
Advances in Display Technology V
Elliott Schlam, Editor(s)

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