Fourier optical signal processors

Progress in Fourier optical processing techniques is reviewed. Particular emphasis is placed on real-time pattern recognition, which recently has received increased interest as the result of new filter formulations that can be implemented with existing spatial light modulators. Architectures for coherent optical correlation are reviewed, as are the recently reported phase-only filters. Smart filters that attack the inherent distortion sensitivity of correlation, including those suitable for implementation with phase-only modulation, are reviewed. Correlation experiments implementing real-time variation of both input and reference patterns are also reviewed. The potential for successful near-term application of these techniques is examined