HIGH-EFFICIENCY LIGHT VALVE PROJECTORS AND HIGH-EFFICIENCY LASER-LIGHT SOURCES

The optical efficiency of an active matrix liquid crystal display (AML CD) light valve projector is determined by the optical design, the met hod of modulation, and the efficiency of the light source. This paper describes a new projector with an efficient modulation technique, whic h can employ unpolarized light by using a unique diffraction grating f ormed in a liquid crystal panel. The technique uses a Schlieren optica l system and has been tested with xenon arcs, metal halide arcs, and e fficient solid-state laser light sources. The optical system reduces l aser speckle significantly when highly coherent baser sources are used All source combinations exceeded 3 lm/W for white light projection pe rformance, and the experimental results of the combinations are discus sed. This modulation technique obtains a high contrast ratio with smal ler panels than can be achieved with rotation-of-polarization light va lve projectors.