Taking advantage of small aberrations, high efficiency, and compactness, we developed a new, to our knowledge, design procedure for a binary zone-plate array (BZPA) and applied it to a parallel joint transform correlator for the recognition of the human face. Pairs of reference and unknown images of faces are displayed on a liquid-crystal spatial light modulator (SLM), Fourier transformed by the BZPA, intensity recorded on an optically addressable SLM, and inversely Fourier transformed to obtain correlation signals. Consideration of the bandwidth allows the relations among the channel number, the numerical aperture of the zone plates, and the pattern size to be determined. Experimentally a five-channel parallel correlator was implemented and tested successfully with a 100-person database. The design and the fabrication of a 20-channel BZPA for phonetic character recognition are also included.
© 1999 Optical Society of America
(050.1380) Diffraction and gratings : Binary optics
(070.0070) Fourier optics and signal processing : Fourier optics and signal processing
(070.5010) Fourier optics and signal processing : Pattern recognition
(200.3050) Optics in computing : Information processing
(200.4740) Optics in computing : Optical processing
Kashiko Kodate, Asako Hashimoto, and Roshan Thapliya, "Binary Zone-Plate Array for a Parallel Joint Transform Correlator Applied to Face Recognition," Appl. Opt. 38, 3060-3067 (1999)