Generalized Phase Shift Deviation Estimation Method for Accurate 3-D Shape Measurement in Phase-Shifting Profilometry

Phase-shifting profilometry (PSP) has been widely used with its noncontact and high-precision characteristics in 3-D shape measurement. Motion of the measured object or assembly deviation of the mechanical projection device will, however, introduce phase-shift deviations in sequential phase shift images, which leads to phase errors and reduces 3-D measurement accuracy. This article proposes a generalized phase shift deviation estimation method for accurate 3-D shape measurement in phase-shifting profilometry. The N-step phase-shifting image sequences are grouped sequentially based on the image reusage strategy to efficiently calculate phases. The phase shift deviations are extracted from the difference information between adjacent phases without additional projection fringe, thus accurately calculating phase value. Experimental results demonstrate that the proposed method is generally applicable to the N-step PSP, which can effectively eliminate the phase error caused by the object motion and/or mechanical projector assembly errors and significantly improve the accuracy and efficiency of 3-D shape measurement.