A two steps phase-shifting demodulation method using the VU factorization

Abstract

In this paper, we present a two steps phase-shifting fringe pattern demodulation method using the VU factorization. Compared with other methods, our proposal is robust to non-constant background illuminations and modulating terms (non-normalized fringes). We use the two given fringe patterns, and from these, we synthetically generate another two images that approach the background illumination in order to obtain a total set of four images. Such set is used in a matrix model that can be factorized using the VU factorization method to determine the modulating phase. Our proposal is able to recover the phase without 1) known phase shift, 2) normalized fringe patterns, and 3) any special non-linear pre-processing. Tests and results with an important representative diversity of interferograms, taken from different experiments, are shown to demonstrate the feasibility of this method.