Local Phase Correction Method Based on Multi-Frequency Phase Heterodyne

The multi-frequency phase heterodyne method is the most common method applied in the unwrap phase, but it failed to reduce the noise error in the image and the sinusoidal error from the projector. In order to address these issues, this study proposes a local phase correction method. This study starts to determine whether a phase map needs to be corrected by calculating the deviation between the predicted and actual phase according to the slope of the projected standard fringe pattern. Then the phase is corrected by different intensities at different sections. Finally, the method compensates the phase error of the detail part with the minimum error phase correction. Experimental results showed that the local phase correction method is the optimal phase correction method, which reduced the phase error by 86.5%. Finally, the phase map of the metal workpiece surface was calculated by the various methods. And the phase map with the highest quality was obtained by using the local phase correction method.