Improved projection optics for reflective silicon CMOS light valves

The optical sub-systems for reflective mode silicon based CMOS-LCD projection display are discussed in this paper. Various methods to improve the optical efficiency of the projection system are proposed. First, new optical modes for the reflective light valve are discussed. The emphasis is on improving the reflectance. Second, a new high throughput projection system employing a 2-step process is proposed. It employs a conventional LCLV projection system capable of very high luminous output. Finally, the color separation and recombination schemes for a full color projector are discussed. A new trichroic prism assembly design is described which has the advantages of low s and p polarization splitting in the reflectance spectrum. Hence it can be used for both color separation and recombination. Thus a compact optical system for reflective projectors is possible with good light efficiency.