Photoluminescent conversion of laser light for black and white and multicolor displays. 2: systems

Recent technological developments permit the modulation and scanning of laser beams at rates comparable with those of electron beams in television receivers. This accounts for much of the current interest in laser illuminated display systems which are not constrained in size, as is the cathode ray tube, by the necessity of a vacuum enclosure. The purpose of the present work is to show how photoluminescent materials can be used in conjunction with recently developed acoustooptic deflectors and modulators to achieve high quality laser display systems. The principal function of the photoluminescent materials is that of color conversion when coated onto a viewing screen. This allows an additional degree of freedom in laser display engineering by removing the spectral constraints imposed by the limited number of practical laser emissions. Various schemes for both black and white and multicolor displays are explored. Some of the concepts which evolved have been experimentally verified by the operation of a system which projected the video signal from a PICTUREPHONE set. The source was an argon ion laser which emitted a monochromatic blue (4880-A) beam. After acoustooptic modulation and deflection, the blue beam was directed to a phosphor screen where it was converted into a brighter and speckle-free black and white display.