Opto-electronic Bistable Devices for Image Processing

Several opto-electronic bistable devices with twisted nematic liquid crystals are designed and used for image processing. The optical bistability characteristics of liquid crystals are used for two types of light valve, those with array structure and parallel operation and those with single cell with sequential operation. Experimental studies demonstrate the application of these opto-electronic bistable devices in important operations currently used in image processors, such as intensity limiting for contrast improvement and noise elimination, contour accentuation for pattern recognition, linear and nonlinear optical filtering (in spatial and spectral domains), incoherent-to-coherent image conversion and logic operations.