Theoretical proposal of high dynamic range surface profile measurement by amplitude modulated wave interference

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.