基于横向多剪切量的二维波前重建.docVIP

 Two-dimensional wavefront reconstruction from lateral multi-shear interferograms# 5 10 15 GUO Yunfeng, CHEN Hao, DING Jianping** (National Laboratory of Solid State Microstructures and School of physics, Nanjing University, Nanjing 210093) Abstract: We propose and demonstrate a multiple shearing interferometry for measuring two-dimensional object phase. Multi-shear interference can effectively rectify the problem of spectral leakage resulting from the single-shear interference. Our study shows that the reconstruction precision increases as the number of shear steps increases. By using Fourier expansion, the Fourier coefficients of two-dimensional wave-front are computed from multi-group phase differences which are acquired by shearing interferometer and then the desired phase is reconstructed. Numerical and optical test have confirmed the multiple shearing interferometry possess higher recovery accuracy than single-shear interferometry. Key words: Interferometry; Phase measurement; Fourier transform. 0 Introduction Lateral shearing interferometry is a useful technique for evaluating optical wave-front and is 20 25 30 35 40 a promising measurement tool in many applications [1-7]. It provides advantages over conventional interferometry in sense of self-reference, which makes it highly resistant against vibration and more suitable in absence of available reference beam. However, the measured shearing interferogram only comprise information about phase differences of the wave-front under test. The measured phase difference must be postprocessed in order to reconstruct the desired phase distribution. A variety of algorithms have been proposed to reconstruct wave-front from phase difference [8-21]. One of the evaluation methods frequently adapted is the polynomial modal expansion method that estimates the underlying wave front by a polynomial set whose unknown coefficients are determined by least squares fitting. The Fourier modal expansion was proposed by Fr