The Study Of Phase Retrieval Algorithm For Wavefront Curvature Sensor With A Diffraction Grating

Wave-Front sensor(WFS) is one of the most important constitutions of adaptive optics (AO) system and can be applied in astronomy, measurement, laser, optical component testing etc. Wave-Front Curvature-sensor (WFCS) is a novel and powerful WFS, which settles the difficulty of wave-front reconstruction for Shack–Hartmann(H-S) sensor. But the implementation of traditional WFCS in an optical system is difficulty, So the applications is limited. In 2000, a novel WFCS comprising a distorted diffraction grating(DGWFS), simple optics and a single camera has been described by Blanchard. It localize high and low intensity in the images in the +1 and the -1 orders, respectively. DGWFS has a novel optical configuration and is smart and straightforward for wavefront sensing, but the algorithms for wavefront reconstruction is immature. Therefore, the study of phase retrieval of DGWFS is important.In this paper, the difference of WFS and WFCS is discussed. The design of DGWFS and the quadratically distorted diffraction gratings is introduced firstly in Chapter 1. Secondly, based on the prevenient algorithms, the phase retrieval for the novel DGWCS is discussed by comparison, also more analysis is made by examples in Chapter 2. Thirdly, phase retrieval by use of Gerchberg-Saxton(GS) algorithm based algorithm and phase retrieval by use of a Green's function under Neumann boundary conditions is applied to DGWFS. The phase retrieval of combinations of Zernike is simulated in computer. The comparison of wavefront reconstruction performance of two algorithms applied to DGWFS was evaluated. Performance of two algorithms in gauss-beam conditions was investigated in detail during this work. Numerical simulations were conducted to validate the analysis presented here and to explore the possibility of the two algorithms. The study of simulations is the basis of practice and experiment.