Complex data mapping on a binary ferroelectric liquid crystal electrically addressed spatial light modulator for target recognition

For displaying a complex valued function onto a binary amplitude-only or phase-only spatial light modulator, an encoding technique is required. In this paper, we implement an encoding scheme proposed by Davis et al. [ Appl Opt , 42 (2003) 2003] for optical processing the complex product function in the hybrid digital-optical correlator. The output of this correlator consists of two autocorrelation peaks along with a strong dc . Out of these three terms, our interest is in capturing only one of the correlation peaks, while discarding the other correlation peak and strong dc . For capturing only one of the correlation peaks, we multiplied a chirp function with the rotation-invariant maximum average correlation height filter. The product function, that is basically a multiplied product of the input scene’s Fourier spectrum and the chirp-encoded filter, is inverse Fourier transformed to obtain the correlation peaks. Due to chirp encoding, the correlation signals are focused in three different planes. Thus, placing our peak capturing CCD camera at a particular plane we can capture only one autocorrelation peak. Results with almost similar tank images having different energy values have also been shown.