An optical correlator using digital micro-mirrors devices

Two optical correlators using DMDs (Digital Micromirror Devices) are presented; the 4-f correlator and the Fourier Transform Imaging correlator. Optical correlators have been used for fast detection purposes and the speed of the DMDs is of great interest. However, data have to be encoded into binary to be input into a DMD. As a consequence, a study of possible encodings has been done. This study includes an analysis of the binary encoding’s different parameters, its consequences on the correlation, and its performance for different signal characteristics, with a comparison with analog encodings. The two correlators have then been set up, and signals with various time occupancy, bandwidth occupancy, and signal to noise ratio have been correlated. The results are far from the theory but remain good. Finally some improvements and future work have been suggested.