Boundary-aware single fringe pattern demodulation

Abstract

Optical interferometric techniques offer non-contact, high accuracy and full field measurements, which are very attractive in various research and application fields. Single fringe pattern processing is often needed when measuring fast phenomenon. However, several difficulties are encountered in phase retrieval, among which the discontinuity problem of the fringe pattern is challenging and requires attention due to the increasing complexity of manufactured pieces. In this paper, we propose a complete flowchart for discontinuous single fringe pattern processing, which uses segmentation as universal pre-processing for all discontinuous fringe pattern problems. Within the flowchart, we also propose a systematic way to introduce boundary-awareness into demodulation methods by a masking function to improve demodulation accuracy and a quality-guided scanning strategy with a novel composite quality map to improve demodulation robustness. To the best of our knowledge, this is the first time a complete solution is proposed for single and discontinuous fringe pattern processing. Three typical demodulation methods, the frequency-guided regularized phase tracker with quadratic phase matching, the windowed Fourier ridges, and the spiral phase quadrature transform, are used to demonstrate how demodulation methods can be made boundary-aware. The proposed methods are verified by successful demodulation results from both simulated and experimental fringe patterns.