Real-Time Implementation of Nonlinear Processing Functions.
Final technical rept. 15 Apr 77-14 Apr 81,
HUGHES RESEARCH LABS MALIBU CA
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Optical data processing has not achieved its potential of increased capacity and speed compared wth conventional electronic techniques primarily for lack of a practical real-time image modulator and because optical techniques have been almost exclusively limited to linear operations. The research outlined in this report of a four year research program attacks these issues by studying the implementation of real-time nonlinear parallel-processing techniques. The various implementations studied all employ real-time liquid-crystal light valves. These spatial light modulators were developed and specially modified for these tasks by Hughes Research Laboratories. One approach we have investigated was to modify and characterize the standard twisted-nematic liquid-crystal devices and then to use them in a coherent optical data-processing apparatus using halftone masks custom designed at the University of Southern California. With the halftone mask technique, we have demonstrated logarithmic nonlinear transformation, allowing us to separate multiplicative images and perform homomorphic filtering. In addition, a novel analog-to-digital converter, based on a modified purebirefringence liquid-crystal light valve, was developed and demonstrated. It can perform parallel processing using incoherent light, and it promises high data throughput rates. Furthermore, a novel device that converts local light variations to local liquid-crystal phase grating period variations has been fabricated and was evaluated and improved.
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