No abstract

Phase retrieval is crucial in phase-shifting interferometry and other phase measurement techniques. However, in noisy wrapped phase maps with high steepness, discontinuities arise and cause phase unwrapping errors. To solve this problem, this Letter presents a phase retrieval method based on a simulated wrapped phase. By establishing the correspondence between the simulated and measured interferograms, the difference in wrapped phases between them can be obtained. The difference in wrapped phase map, which has sparse and wide interference fringes, has a higher reliability of phase unwrapping. The proposed method not only possesses high phase retrieval accuracy but it also simplifies the processing of interferograms. Furthermore, the layout of all interferometric systems, the parameters of optical components, and the model of the measured object are known, so the proposed method can be used as a reference for phase retrieval.

When laser interferometry is applied to measure the form deviation of a helical tooth flank, dense interference fringes are almost inevitable because of the distorted shape of the helical tooth flank. The high-density fringe leads to poor processing accuracy of interferograms and is an important indicator of the interferogram quality. An optical path optimization method based on position errors analysis is proposed to modulate the fringe density. First, some factors that may affect fringe density in the optical system are modeled. Consequently, the incident angle of the measured light is proved to be the main factor affecting the fringe density and is the primary parameter that modulates the interference fringe density. Subsequently, an analytical model is established, and a fringe density modulation method based on the optimized incident angle is proposed for designing the optical path. Finally, simulated and actual experimental results are provided to verify the correctness of the analysis of the main factor affecting the fringe density and feasibility of the modulation method.