New modified phase locked loop method for fringe pattern demodulation

The modified phase locked loop (PLL) technique applied to the analysis of 2-D carrier-frequency fringe patterns is presented. It uses two images with a projected grating shifted in phase by half of its period. The proposed technique was tested for the mannequin shape determination with good results obtained with two iterations only. Due to the properties of the PLL technique there is no problem with phase unwrapping and very short calculation time is needed. (C) 1997 Society of Photo-Optical Instrumentation Engineers.