Abstract

Motivated by the introduction of fast binary spatial light modulators such as the magnetooptic devices by Semetex and Litton, research in binary phase-only filters (BPOFs) has been active. Many techniques have been suggested for selecting a particular real binary representation of a desired complex filter function.^1,2 All the resulting BPOFs represent real functions, which implies certain limitations. Among these limitations is a Hermitian impulse response, which means that correlation filters represented as BPOFs cannot discriminate between a target function and its mirror image. This presentation introduces the quad-phase-only filter (QPOF), which consists of the binarized real and imaginary parts of the desired filter function G(f): The SNR performance of the QPOF is considered, and it is shown that, for certain classes of target image, the QPOF performance is superior to the BPOF. A detour phase implementation is presented, which has some advantages over a two-beam interferometric implementation. Among these are a simpler single-beam optical system and tolerance of device phase errors. Both simulated and optically implemented results are presented.

© 1988 Optical Society of America