Optical data processing system with reflective liquid crystal light valve

摘要

There is disclosed a high performance coherent optical data processing system using a reflective mode liquid crystal light valve which is particularly suited for application to real-time coherent optical data processing. A preferred example of the system uses a reflective light valve comprising a CdS photoconductor, a CdTe light absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The non-coherent light image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the AC voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state (voltage off the liquid crystal) and the optical birefringence effect to create the bright on-state. The liquid crystal thus modulates the polarization of the coherent read-out or projection light responsively to the non-coherent image. An analyzer is used to create an intensity modulated output beam which is projected through a Fourier transform lens onto a screen or other detector means.