Variations of the phase-only filter

Summary form only given, as follows. An alternative to the classical method filter, namely the phase-only filter, is shown to be useful for pattern recognition and image correlation. It exhibits extremely narrow correlation peaks with very small sidelobes, better discrimination between similar objects, and 100% throughput when implemented optically. Several alternatives derived from the phase-only filter and implementable optically on both phase- or amplitude-modulating real-time devices are shown and discussed. Performance is tested through computer simulation and optical bench experimentation. Results are shown for signal-to-noise ratio and discrimination ability