Geometric distortion correction of oblique incidence laser interferometer system for helical surface topography measurement

When laser interferometry is applied to measure the topography of the helical surface, the interferogram is the only carrier of the measured morphology, and its quality is crucial for the measurement results. Due to the influence of many factors in actual measurement, the interferogram inevitably has geometric distortion, which leads to difficulty in subsequent image processing and even measurement failure. This paper proposes a comprehensive correction method for geometric distortion in the interferograms. Firstly, the sources of geometric distortion in the interferogram are analyzed, including geometric distortion from the measurement optical path and the optical component error. Secondly, a correction model is established combining the effects of component pose errors and lens distortion on the measurement results, and a six-parameter iterative algorithm is proposed to solve the optimal parameters of the model. Finally, the experiments are designed to verify that the corrected interferograms are closer to the standard images, which proves the feasibility of the proposed correction method.