Phase shifting method for non-sinusoidal interference fringes with phase shift error

Abstract

When applying phase shifting interferometry to practical phase measurement, the wave may become non-sinusoidal, and could include some phase shift errors. Prior phase shift algorithms are primarily used for sinusoidal cases, and can cause system errors when used for these non-sinusoidal interference. We propose two phase recovery methods for non-sinusoidal interference fringes: specifically, a least-squares-based fitting algorithm that eliminates system errors using a sufficient number of measured images, and a Fourier transform-based method that effectively suppresses system errors using a lower (or insufficient) number of images. Simulation and experimental results verify the efficacy of the proposed methods.

Signal Retrieval from Non-Sinusoidal Intensity Modulations in X-ray and Neutron Interferometry Using Piecewise-Defined Polynomial Function

“…Non-sinusoidal modulations have been approached by fitting higher orders of a Fourier series [31], which is a computationally inexpensive method for phase retrieval. However, it remains unclear how this approach can handle such a variety of modulations such as, e.g., given in Figure 1.…”