Object recognition in non-coherent optical correlator based on DMD-modulator

Abstract

There are many implementations of optical correlators based on LCD-SLM of different types currently available. Another kind of SLM, DMD-SLM, also is of great interest for use in optical correlators. The main advantage of this type of SLM relative to LCD-SLM is its very high operation speed. We developed and implemented the setup of optical correlator in which an input object is illuminated by spatially incoherent light and the filter-memory is dynamically displayed on the DMD-SLM. Experiments to estimate the impact of DMD manufacture errors on the formation of the correlation signal were performed. In these experiments it was found that to obtain a good result it is necessary to determine the size and position of the most flat area of DMD matrix, and to output the holograms on this area only. This limitation is caused by the fact that the surface of the matrix cannot be considered as perfectly flat, and using of its entire area for filter displaying will cause deterioration of the system resolution. The experiments on recognition of test objects in quasi-monochromatic spatially incoherent light on the implemented setup were performed. In these experiments, when the coincidence of the input and reference objects took place, localized correlation peak was observed. This fact demonstrates the successful objects recognition in such correlator.