Alignment of vectorial shearing interferometer using a simple recognition algorithm

Abstract

The vectorial shearing interferometer includes a pair of wedge prisms as a shearing system. Perfect alignment of the shearing system is crucial for the optimal detection and analysis of asymmetrical wave fronts. This paper describes a recognition algorithm for optical misalignment detection and prisms orientation based in the intensity pattern obtained in the calibration process. The key of the present algorithm is the comparison of a reference intensity pattern, against a sheared interferogram that depends on the wedge prism position. First, an optimum phase only filter is obtained from a set of reference images with the objective to discriminate between different phase changes. Then, the optimal filter is used in a digital correlator, which results in a simple and robust calibration system.