US Patent 7518662 Contrast enhancement for liquid crystal based projection systems

Described are tilted compensators for compensating for in-plate and out-of-plane retardances of LC panels in their dark states, including a single tilted biaxial retarder or compound retarder comprising more than one biaxial film, which are effective to compensate both for nonideal polarization effects of LC panels and other optical components in optical projection systems. Also described are tilted compensators for deflecting away from a projection system optical path unwanted reflected light.