Application of area-multiplexed CGH spatial filters to pattern recognition

Abstract

The ability of a real-time optical processor, using a computer-generated spatial frequency filter, to recognize any one of many different patterns often depends on the number of different reference patterns represented in the filter. An area multiplexing scheme has been devised that is similar to frequency-division multiplexing and is independent of amplitude or intensity superimposition. The increase in number of filter patterns at the expense of single pattern processing performance may make the scheme valuable for certain applications, especially phase-only processing. Results were compared with multiplexing schemes that distribute information about the reference patterns throughout the spatial frequency plane, but via superposition only or via entirely separate copies of the frequency distribution. Potential advantages of the area multiplexing scheme include an increased number of filter reference functions, less stringent transmittance linearity requirements for the CGH filter material, and the ability to incorporate different CGH carrier configurations. Disadvantages include reduced single-pattern processing performance, undesirable cross-modulation terms, and increased spatial resolution requirements in the filter.