Phase Unwrapped Method of Modified Fringe Order

Abstract

Phase measurement profilometry is an optical three-dimensional measurement method, in which phase is the key factor to accurately obtain the three-dimensional coordinates of the measured object, but there will be phase jump error in phase unwrapped process. In order to eliminate the phase jump error existing in the phase unwrapped process based on the principle of multi-frequency heterodyne, a phase unwrapped method with modified fringe orders is proposed. Modifying the integer part of the fringe orders according to the relationship between the integer part of the fringe orders of adjacent pixels can effectively eliminate the jump of the fringe orders caused by the small error, and avoid the transmission and amplification of the phase jump error in the process of fringe heterodyne. Using the multi-frequency characteristic, the absolute phase of the fringe with the middle period is solved by combining the phase information of the fringe with different periods, so as to improve the accuracy of the phase details of the solution. Both simulation and experimental results show that the proposed method has obvious correction effect on the phase jump error, and the unwrapped phase is smoother. Compared with existing methods, the phase error of the proposed method is reduced by an average of 23%.