Abstract This study proposes theoretically an optical measurement method based on double heterodyne interferometry to measure 3D sample thicknesses from nanometers to millimeters using a single interference optical system. Our previously proposed method has the limitation that it can only measure the thickness at one point in a microscopic area irradiated with laser light. In this study, a method for measuring the surface thickness distribution of a sample in off-axis double heterodyne interferometry and theoretical measurement accuracy is clarified using theoretical analysis. Furthermore, an analytical solution for the 4-beam polarized interfering electric field in double heterodyne interference is derived based on Jones calculus.
Tanaka et al. (2025) studied this question.