Noncontinuous fringe pattern demodulation using a digital phase-locked loop algorithm

Abstract

A digital phase locked loop (DPLL) algorithm has been applied successfully to demodulate continuous fringe patterns. An attempt was made by Ochoa et al. to extend the DPLL algorithm to demodulate non-continuous fringe patterns. Their algorithm depends on masking the invalid regions in a fringe pattern and exclude them from processing using the DPLL algorithm. Ochoa et al. have employed the standard deviation algorithm to mask the invalid regions and detect the regions with valid information. The algorithm failed in masking noisy invalid areas and detecting valid regions with low modulation indices. In this paper, a different method is used successfully in the masking of the invalid regions, detecting the valid areas and the method is applied to demodulate non-continuous fringe patterns using the DPLL algorithm.