The principle and experimental design of a real-time multichannel multiplexed optical pattern recognition system via use of a 25-focus dichromated gelatin holographic lens (hololens) are described. Each of the 25 foci of the hololens may have a storage and matched filtering capability approaching that of a single-lens correlator. If the space-bandwidth product of an input image is limited, as is true in most practical cases, the 25-focus hololens system has 25 times the capability of a single lens. Experimental results have shown that the interfilter noise is not serious. The system has already demonstrated the storage and recognition of over 70 matched filters—which is a larger capacity than any optical pattern recognition system reported to date.
Don A. Gregory and H. K. Liu, "Large-memory real-time multichannel multiplexed pattern recognition," Appl. Opt. 23, 4560-4570 (1984)