Optical block for high brightness full color video projection system

摘要

An improved optical block for use in a high brightness, full color image projection system of the type wherein high intensity (acrhomatic) projection light is modulated by a full color image composed of a plurality of monochromatic images applied to a plurality of polarization modulating light valves. A polarizer accepts the achromatic, unpolarized output of a high intensity source. Light of a preferred polarization orientation emergent therefrom is directed by the polarizer to a two level array of polarization-sensitive dichroic filters and wavelength-tuned biprisms. Input level dichroic filters separate the incoming unmodulated light into a plurality of component wavelength bands and direct each to a wavelength-tuned biprism. Each biprism directs the selected bandwidth of polarized light to the reflective surface of a light valve. Light reflected therefrom is altered in polarization in the presence of the chromatic component of the full color image and passes to the second or output level of the optical block. Polarization selective dichroic filters in the output level combine the polarization-modulated chromatic components into a high brightness, full color modulated image and direct the image to projection optics.