Photorefractive edge-enhancement joint transform correlator

In this paper, we present a photorefractive edge-enhancement joint transform correlator. On the spectral plane of a joint transform correlator, a Cr-doped Strontium Barium Niobate (SBN:Cr) crystal is placed and a coherent pump beam is input. Taking the nonlinear energy transfer property of the photorefractive two-beam coupling between the pump beam and the signal beam bearing the joint transform spectra of the target and reference image in a crystal, we can construct an edge-enhancement joint transform correlator. Because the intensity of the high frequency component carrying the edge information of the image is much weaker than that of the low frequency, the coupling under certain conditions will result in an enhancement of the high frequency component of the joint transform spectra. Compared with the classical correlator, the photorefractive edge-enhancement joint transform correlator provides larger normalized intensity and narrower width of the ±1 level correlation peaks. Experimental results accord with the computer simulation.