Optical engines for tricolor projectors having co-planar like optical

Abstract

The invented optical engines are characterized as including generally parallel planar glass plate-mounted or coated dichroic and turning mirror and light valve elements. An important topological feature of the invented optical engines is the fact that like optical elements are positioned and oriented to be coplanar, i.e. the light-splitting dichroic mirror elements are coplanar with one another, the split beam-turning mirror elements are coplanar and the light valves are coplanar. This important feature of the invention renders compact optical engines that are simply and inexpensively manufactured and maintained because the critical optical elements are in part self-aligning when like optical elements are placed in an aligning mounting structure or more preferably on a common substrate that renders them self-positioning and self-aligning relative to one another. A common white light entry region and modulated tricolor beam exit region of the invented optical engines, coupled with equal optical path lengths through the engine, permit the use of a single input pupil astigmatism correction plate near the entry region and a single output image astigmatism correction plate assembly near the exit region of the engines. The optical engines may be used along with conventional other optical elements including, for example, a white light source and an optical output stack, to render a pixel-modulated tricolor projector.