Non-conventional joint-transform correlations for pattern recognition by use of grating filters and heterodyne scanning

The spatial light modulators (SLMs) at the Fourier planes of a conventional joint-transform correlation (JTC) are eliminated using simple grating filters such as rectangular and triangular ones. To achieve this goal, two non-conventional real-time JTC architectures are proposed: (a) the grating filter is used along with a heterodyning and one-dimensional optical scanning technique to capture the cross-correlation functions of the input images without major processing and (b) the one-dimensional optical scanning is eliminated to achieve a faster (but a little bit more complicated) processing. The proposed techniques significantly reduce the time processing needed for real-time applications by eliminating the drawbacks of the non-ideal characteristics of the SLMs.