Study On Key Techniques Of φ300mm Phase-shifting Interferometer

The rapid development of large-aperture optical systems brings an urgent and high demand for phase-shifting interferometer with large-aperture. The key techniques of large-aperture phase-shifting interferometer via PZT are discussed, including: on-line calibration of PZT, supporting scheme for the large-aperture reference mirror, absolute test of large-aperture flat, test of dynamic phase, of large-aperture collimated wavefront and of the interferometer's frequency response function. Theoretical simulation and experimental measurement have been done for developing larger-aperture phase-shifting interferometers. The main research work in the dissertation is as follows. An improved algorithm is adopted for on-line precise calibration of phase-shifter, which is based on the convergent iterative method for solving nonlinear and transcendental equation; In order to find an optimal supporting scheme for the large-aperture reference mirror, different supports are modeled and analyzed by means of finite element method. According to the design result, a certain allowance should be given for deformation when polishing mirror blank; Absolute liquid reference for phase-shifting interferometer with large-aperture and high-accuracy is set for measuring surface of the reference mirror under laboratory environment, with results showing that the structural design of the mirror meets technical requirements very well; For evaluating dynamic phase, a novel method for static interferogram analysis, based on virtual grating technique, phase-shifting interferometry and moire technique, is introduced and analyzed; A simple and convenient method named pentaprism scanning method is presented for measuring large beam collimation, which is founded on one-dimensional slope wavefront measuring principle. The feasibility of interferogram analysis with moire methods and the pentaprism scanning method are achieved by comparing test results respectively with ZYGO's; After the power spectral density (PSD) is introduced as an estimated parameter, the mathematic model for calibrating interferometer's frequency response function is constructed. The calibration method with a step sample is pointed out and experiment is done on ZYGO. Experimental data and curves are also given and error sources are systemically analyzed in the end.