Design of a Phase-shifting Algorithm for Interferometric Measurement of Optical Thickness Variation

摘要

The optical thickness is an important property of transparent plates when fabricating critical components. Spatiallynonuniform errors, which are major factors in the measurement of the absolute optical thickness, can be brought about byphase errors related to the nonlinear error term. In this study, equations and a new sampling window for suppressingspatially uniform errors were constructed. Using these equations and new sampling amplitudes, we designed a newphase-shifting algorithm with 17 samples. Herein, the characteristics and advantages to the measurement of highlyreflective surfaces when applying this new 17-sample algorithm are presented based on a Fourier representation. Inaddition, the superiority of the new algorithm in terms of its error control is demonstrated by comparing the errorsoccurring from a varying object phase, as well as root mean square errors, with those from different conventionalalgorithms.