Abstract: In measurement of the form error of complicated precise surface of machine parts by laser interferometry, it is necessary for the optical system of interferometer to design and analysis of error with simulation method. In this report, based on the optical system used in our research, the general ray tracing method in a homogeneous medium between two arbitrary surfaces considering the setting error of the optical elements, and between an arbitrary 3D surface and a common surface, such as plane, spherical, and cylindrical surfaces, and the ray tracing method in optical system composed of some homogeneous medium segments is proposed and the calculation method for the image of measured surfaces is discussed. The simulation and the measurement experiment are carried out respectively by taking planar test piece and gear flank as objects, and the two results match well, so the validity of proposed methods is proved and the usefulness of the method is verified.

Key words: Optical path difference, Image simulation, Interference fringe, Laser interferometry, Phase difference, Ray tracing