Full-frame projection displays using a liquid-crystal-on-silicon spatial light modulator for beam shaping and speckle suppression

Abstract

This paper presents a full-frame laser projection display system in which a spatial light modulator (SLM) is used for beam shaping and speckle suppression. Phase-only computer-generated holograms (CGHs) are used to transform a cross section of the incident laser beam into a square nearly the same size as that of the display device. Under different initial conditions, the diffraction patterns generated by the CGHs possess identical intensity distributions but differ with regard to random phase distribution. Image speckles can be suppressed via the temporal addition of diffraction patterns from the CGHs when displayed by the SLM. The addition of 16 speckled images resulted in speckle suppression ratios of 0.290 in simulations and 0.345 under experimental conditions. Not only were the speckles suppressed, but the quality of the overall image was also improved considerably. The proposed approach presents a simple design with low power consumption and stable display architecture for application in pico-projectors.