title: Simultaneous phase-shifting interferometry: immune to azimuth error of fast-axes in retarder array.
abstract: Simultaneous phase-shifting interferometry based on a 2×2 retarder array with random fast-axes (RARF-SPSI) is proposed for real-time wavefront measurements. The retarder array is used as the phase-shift component, where the phase retardances are π/2, π, 3π/2, and 2π and the four fast-axes of the four retarders can be somewhat random. In this paper, the mathematical model of RARF-SPSI is built by using a Stokes vector and a Mueller matrix, the phase demodulation method through solving equations is derived, and the coefficient matrix of the equations that is associated with the azimuth of the fast-axes is calculated by Fourier analysis. Then the corresponding simulation analysis is executed. In the experiment, four simultaneous phase-shifting interferograms are captured and the phase distribution under test is demodulated through the proposed method. Compared with the four-bucket phase-shifting algorithm adopted in traditional simultaneous phase-shifting interferometry, the ripple error is suppressed well. The advantage of the proposed RARF-SPSI is that there is no need to calibrate the fast-axes of the phase-shift component before measuring; in other words, the phase demodulation error caused by the azimuth error of fast-axes is eliminated.
authors.forename: Donghui
authors.initials: D
authors.lastname: Zheng
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Jinpeng
authors.initials: J
authors.lastname: Li
authors.forename: Chenfeng
authors.initials: C
authors.lastname: Gu
authors.forename: Wenhua
authors.initials: W
authors.lastname: Zhu
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Han