Improved self-correction of nonlinearity error in 3-step phase-shifting profilometry

The generic self-correction method for nonlinearity-induced phase error (GSCN) can effectively suppress nonlinear error. However, GSCN directly ignores the periodic error of the 2N multiplication frequency in the error analysis stage, which still leads to errors in the suppressed results. In this paper, we propose a new method named improved generic self-correction method for nonlinearity-induced phase error in three-step phase-shifting profilometry. We retain the periodic error of the 2N multiplication frequency in the error analysis stage. In addition, based on the error model, we directly use the original fringes to compute the wrapped phases with -π/6, π/6, and π/3 phase shifts, respectively. Then, we use the original wrapped phase as the target phase and shifted the other three groups of wrapped phases to the target phase. Finally, we unwrap and fuse the four sets of wrapped phases to obtain the final corrected phase. Based on experimental results, the proposed method yields excellent reconstruction results and effectively suppresses nonlinear errors, making it highly efficient and precise.