Correction of aberrations in an optical correlator by using it as a point diffraction interferometer

摘要

In VanderLugt type correlators, the input scene and the filter could be implemented onto twisted liquid crystal displays (LCD's). The modulator used to display the scene and the elements placed before the filter usually introduce phase aberrations. These aberrations have an important influence in the final correlation plane. We propose a new method to evaluate and correct in situ these aberrations by using the correlator as a point diffraction interferometer. In this work, the wave front phase distribution evaluation is performed by means of the phase shift interferometry (PSI) technique. We present the theory on which the method is based and the experimental results obtained by applying it in a convergent correlator.