Wavefront reconstruction for double-grating Ronchi lateral shearing interferometry with nonlinear optimization

Abstract

Traditional phase retrieval methods for Ronchi lateral shearing interferometry eliminate the impact of high diffraction orders by increasing the number of phase-shifting interferograms, however, this introduces additional error in the phase-shifting process. We propose an optimization method combining a 2-frame phase-shifting algorithm to achieve accurate wavefront reconstruction. A numerical model matching the physical model is constructed and the cross-iterative gradient descent method is used to optimize the initial results obtained by the two-step phase-shifting method. The accuracy and robustness of the method are verified by simulations and experiments. The proposed method has the advantages of achieving high-precision wavefront reconstruction and correcting the phase-shifting errors, and it significantly simplifies the process of phase shift.