A high-accuracy nonlinear phase error compensation method

In the phase measuring profilometry, the phase measuring accuracy could be heavily affected by the nonlinearity effects of the projecting and imaging devices. Therefore, it is very important to reduce the nonlinear errors fast and efficiently. An analytic model of nonlinear errors is introduced. Then we propose a phase compensation method which is based on the accurate mathematical model of the phase error. The proportion of each harmonic component is collected by using a large-step phase-shifting algorithm to measure a reference plane. Then the phase errors of the measured object could be compensated by an iterative algorithm. The experimental results show that the proposed method can realize nonlinear error compensation effectively and improve the precision of phase measurement. Meanwhile, since all the harmonic components are pre-calibrated, there is no extra fringe needed, which can meet the requirements of fast and real-time measurement.