A projection optical apparatus has a light source for emitting light, an illumination optical system for emitting as illumination light the light radiated from the light source, a Digital Micromirror Device, having a plurality of micromirrors, for separating the illumination light into signal light and...http://www.google.com/patents/US6382799?utm_source=gb-gplus-sharePatent US6382799 - Projection optical apparatus
