Correction of wavelength error of white-light interference phase-shifting algorithm

Abstract

In phase-shifting interferometry, phase unwrapping is an important algorithm for obtaining actual detection data. In general, fringe contrast is approximated to reduce the difficulty of operation. However, in the actual white light interference detection, the fringe contrast will vary with the change of the optical path difference as the wavelength is more abundant. In this paper, the three-step phase-shifting algorithm is taken as an example to derive the phase expression of the white light interference fringe contrast without approximation processing. A hemisphere with a radius of 10μm and an irregular object with a size of less than 6μm are applied to topography reconstruction. Compared with the topography reconstruction error of the three-step phase-shifting algorithm before and after the correction, it has proved that the three-step phase-shifting algorithm after the correction can increase the reconstruction accuracy by about two times, which provides a theoretical method to improve the reconstruction accuracy of the phase-shifting algorithm.