An iterative actuator calibration method for accurate phase-shifting in N-bucket phase-shift interferometry

A new calibration method of phase-shifting actuators for N-bucket phase-shift interferometry has been developed to overcome the errors introduced by nonlinear, irregular, or unknown phase-step increments of actuators. First an evaluation measure of fringe displacement error is proposed to detect and evaluate the phase-shifting of the interference fringe induced by stepwise movements of actuator. Second an iterative calibration method is proposed, which is based on the regulation control theory. For the evaluation and verification of the proposed simple calibration method comparing with conventional complex ones, a series of simulations is performed in various conditions, and simulation results are discussed in detail.