Optical wavelet joint transform correlator for automatic target recognition

Novel optical wavelet joint transform correlators (WJTCs) are presented in this paper. Instead of computing the correlation between the target and the reference patterns, these optical WJTCs compute the correlation between the wavelet transform coefficients of the target and reference patterns. It incorporates the efficient feature detection and noise suppression capabilities of wavelet transformation and the inherent high speed and 2-D nature of optics. The feature extraction and target identification operations are performed in a single step. By suitably choosing the wavelet functions and their dilation factors, these wavelet correlators are capable of effectively recognizing targets in me presence of clutter and noise. Since the reference pattern can be updated conveniently, WJTCs are suitable for adaptive programmable operation. In this paper, a family of wavelet functions that can be represented very simply in the frequency domain and thus are suitable for optical implementation are described. The principle and optical architecture of optical WJTC are presented. Preliminary experimental results are provided.