Patent ID: 7207678

Claim:
A high contrast prism assembly for use with single-chip spatial light modulator projection systems, comprising: a SLM device mounted in a package having an optical window seal, said seal window being attached directly to a first side of a first prism; a longest second side of said first prism being bonded to a first side of a second prism, the interface between said first and second prisms providing a first TIR surface having a specified critical angle for reflecting unwanted light being reflected off the surface of said SLM; a longest second side of said second prism being bonded to a first side of a third prism, providing an equal optical working distance on both sides of the projection cone, the interface between said second and third prisms providing a second TIR surface having a specified critical angle; incoming illumination entering through a third surface of said second prism at an angle greater than that of said critical angle of said second TIR surface, said light being reflected off said second TIR surface, through said second and first prisms, respectively, on to the reflective surface of said SLM; light projected off the ON pixels of said SLM at an angle less than the critical angle of said second TIR surface, passing through said second and third prism interface, and through said third prism along said projection path; the unwanted light being reflected from the OFF pixels of said SLM passing through said first prism, said light striking said first TIR surface at an angle greater than the critical angle of said TIR surface, said light being immediately reflected off said first TIR surface away from said projection path, into an optical heat sink, thereby separating said unwanted light from said projected light, increasing the contrast of the projection system; and unwanted light reflected from off-pixels, flat surfaces and edges, in, around, and under said pixels of said SLM passing through said first prism, said light striking said first TIR surface at an angle greater than the critical angle of said TIR surface, said light being immediately reflected off said first TIR surface away from said projection path, into an optical heat sink, thereby separating said unwanted light from said projected light, increasing the contrast of the projection system.