The determination of the zero-order interferometric region and its central fringe in white-light interferometry

In a white-light interferometer the ambiguities of the determination of the zero-order interferometric region and its central fringe decrease the resolution of the system. In this paper, we report an efficient method to make the amplitude difference between the zero- and first-order interferometric regions, and that between the central fringe and its side fringes dominant. By the use of our signal-processing scheme, it is found theoretically and experimentally that the minimum signal-to-noise ratio required for the determination of the zero-order interferometric region and its central fringe is greatly reduced.