Estimation Method Based on Extended Kalman Filter for Uncertain Phase Shifts in Phase-Measuring Profilometry

Phase-measuring profilometry (PMP) is increasingly applied in high-accuracy three-dimensional shape measurement. However, various factors may result in the uncertainty of phase shift values in the PMP system, and phase errors induced by actual phase shift often bring about the reconstruction failure of a measured object. A quadratic phase estimation method using the extended Kalman filter is proposed to remove the phase error introduced by uncertain phase shift. After eliminating the background and fringe modulation, the state estimation is employed to evaluate the quadratic phase coefficients in a selected mask window, and the phase shifts of adjacent fringe patterns can be estimated to compute the unwrapping phase. This paper presents a novel method for improving the accuracy of the PMP system influenced by phase shift errors, and the proposed region-wise method significantly enhances the reconstruction quality and efficiency. Experimental results show that the proposed algorithm effectively evaluates the actual phase shift and directly compensates the phase error, and has the advantages of high speed, high accuracy, and robustness.