Phase joint transform sequential correlator for nonlinear binary correlations

Abstract

We study the performance of nonlinear optical correlations using a joint transform correlator that operates in phase-only spatial light modulation at input joint transform plane. Amplitude input nonlinear optical time sequential correlations have shown better discrimination and noise robustness than conventional linear correlations. Those nonlinear correlations are based on decomposing the reference and the target into binary slices and to add the contribution of all linear correlations between them. Those correlations can be easily implemented using a conventional joint transform correlator. However, the system has poor efficiency and low cross-correlation peak intensity, mainly because of the spatial light modulators working in amplitude mode. We use a phase-transformed input joint transform correlator in order to increase the efficiency and the discrimination. The phase morphological correlation and the phase sliced orthogonal nonlinear generalized correlation are implemented optically. We applied the method to images degraded with high degrees of substitutive noise and nonoverlapping background noise. Results show that those nonlinear phase input-encoded correlations detect the target with high discrimination capability in cases where other well-known methods fall.