LEI Jing-fa,CHEN Zhi-qiang,ZHANG Miao,et al.Improvement of phase unwrapping method for dual-frequency projection fringe[J].Optics and Precision Engineering,2021,29(06):1337-1345.
LEI Jing-fa,CHEN Zhi-qiang,ZHANG Miao,et al.Improvement of phase unwrapping method for dual-frequency projection fringe[J].Optics and Precision Engineering,2021,29(06):1337-1345. DOI: 10.37188/OPE.20212906.1337.
Improvement of phase unwrapping method for dual-frequency projection fringe
To address the problem of abrupt changes during the phase unwrapping of fringes using the dual-frequency heterodyne method, we proposed an improved method in this study. First, the fractional part of the fringe order at a frequency was calculated based on the heterodyne principle, and the actual value of the current decimal part was calculated based on the phase principal value of the grating fringe corresponding to the frequency of the fringe order. Second, the difference between the decimal parts of the above two values was determined using a set threshold based on the inherent error of the phase principal value. Finally, the absolute phase was corrected by adding or subtracting the cycle number of the intermediate parameter based on the determination results. By adding Gaussian noise with different mean values and variances to the phase shift diagram of the simulated dual-frequency fringe pattern, and comparing the phase diagrams before and after correction, the correction rate of the improved method for phase jump errors was analyzed. In addition, the practical effect of the method was verified through actual measurement experiments of samples. The experimental results indicate that the improved method yields a correction rate of over 90% for absolute phase jump errors, with a high practicability and immunity to noise.
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