Light-controlled light valves

Recent technical approaches to optically addressable, cyclic or erasable, light valves for high resolution projection or direct-view display are reviewed. The general concept of light-valving cathode-ray tubes is first presented for historic and technological perspective. Secondly, photoconductor-controlled devices that incorporate a variety of electrically stimulated optically responsive active elements for light modulation, including ferroelectric ceramics, liquid crystals, electrooptic crystals, and deformable media, are compared for their reported functional characteristics. From the standpoint of performance only, there exist several potentially significant technologies that offer the capabilities of high optical sensitivity and rapid response, high amplification ratios, optical storage, and resolution which are not presently available in light valves addressed by means other than optical.