Interferometric thickness measurement of glass plate by phase-shifting analysis using wavelength scanning with elimination of bias phase error

Abstract

Phase-shifting fringe analysis using wavelength scanning has been broadly applied to the interferometric profiling of the thickness variation of glass plates. However, the nonlinear phase shifting can cause bias error during wavelength scanning. In this study, the bias error in the calculated phase was formulated by Taylor series expansion. Using the formulation, a novel 15-sample algorithm of a partially negative window was derived to enable compensation for the bias phase error. The new 15-sample algorithm was visualized by the algorithm polynomial on the complex plane and Fourier description in the frequency domain. The bias error suppression capability of the developed algorithm was examined by using the numerical simulation. Finally, the proposed algorithm was used in conjunction with a large-aperture Fizeau interferometer to examine the thickness variation of a glass parallel plate.