Optical path difference and lateral displacement of Sagnac lateral shearing interferometer

Abstract

The basic principle of the Sagnac lateral shearing interferometer with a large optical path difference (OPD) is explained. Using the method of prism expansion, the exact expressions of the OPD and the lateral displacement as a function of different parameters are obtained. In order to analyze and discuss the influences of the incident angle, , the angle between the incident plane and the bottom plane of the Sagnac lateral shearing interferometer, along with the acute angles and on the OPD and the lateral displacement, computer simulations were carried out. To ensure a large OPD and lateral displacement, the incident angle is controlled in the range while the angle has minimal impact on the OPD and the lateral displacement. Moreover, if the relative error of the OPD is required to be less than 2%, the deviations of and relative to the ideal situation () must be in the ranges and , respectively. The result provides a theoretical and practical guidance for improving the spectral resolution of the Sagnac lateral shearing interferometer together with its engineering realization.