Fast correction method for the fringe order error in multi-frequency phase unwrapping algorithm

Multi-frequency phase unwrapping algorithms (MFPUAs) are among the most robust and efficient phase unwrapping methods, and hence widely adopted in various optical measurement techniques, such as fringe projection profilometry, interferometry, and so on. However, if they are not well designed, or the measurement condition is poor, fringe order error (FOE) will be triggered during the phase unwrapping, which will result in phase unwrapping error. This paper is for coping with FOE without consuming additional fringe patterns for phase unwrapping. Firstly, a parameter called fringe order inaccuracy (FOI) which is applicable to the representative MFPUAs is defined. Secondly, FOI is employed to help quantify the possibility of the occurrence of FOE. Lastly, a fast FOE correction method is proposed with aid of FOI. Experiments validate that the proposed method contributes to suppressing FOE while keeps the efficiency of MFPUA.