EFFICIENT ILLUMINATION SYSTEM FOR COLOR PROJECTION DISPLAYS

摘要

A method and system for providing an improved color image wherein a broad spectrum light is supplied to a phase grating which provides dispersed light having multiple diffraction orders. The dispersed light is supplied to a zero-order phase shifter which shifts the phase of the undiffracted (zero order) light relative to the diffracted light. The light from the phase shifter is thereupon concentrated so that the plane of the phase grating is imaged onto a display having a plurality of pixels assigned to transmit different spectral regions. The depths of the grating elements of each of the grating periods of the phase grating and the depth of the zero-order phase element of the phase shifter are selected to maximize the area of chromaticity space spanned by the different spectral regions at the display.