【作者】 罗群；

【导师】 姜文汉； 饶长辉；

【作者基本信息】 国防科学技术大学 ， 光学工程， 2012， 博士

【摘要】 为了追求更高的观测分辨力，无论地基还是天基望远镜，一个共同的发展趋势就是不断增大望远镜的主镜口径。通光孔径的尺寸在一定程度上成为了反映天文望远镜观测能力的指标。然而，由于大气湍流的影响，大口径天文望远镜并不能发挥其应有的优势，其分辨能力与小口径望远镜相比并无明显改善。因此，需要借助自适应光学技术对大气湍流引起的波前误差进行校正，而有效地探测波前畸变则是实现有效校正的重要前提。另一方面，主镜尺寸的不断增大，给望远镜的设计、加工、制造、检测等技术带来了前所未有的挑战。拼接主镜概念的提出，虽然有效地降低了主镜的质量、成本、体积和制造周期，使得超大口径望远镜的设想能够实现，但也带来了许多问题，其中最为典型的就是各拼接子镜之间的共相误差难以测量和控制。随着大口径天文望远镜的发展，有必要开展相应的自适应光学系统波前探测技术的研究，并将其应用到大口径拼接型望远镜的共相误差检测之中。本文就是围绕以上课题背景，针对相位差波前探测器对连续像差和非连续像差的检测能力展开了全面深入的研究，并取得了一系列成果。第一，相位差波前探测器是一种基于像面光强分布复原相位信息的高精度波前测量器件，本文通过数值模拟和实验验证的手段深入分析了图像采集器件参数、图像信噪比、离焦量大小等因素对相位差波前探测器检测精度的影响，这一工作对理论研究和工程应用具有重要意义，分析结果能够为实际应用提供有利指导，并为其性能改善指明方向。第二，将相位差波前探测器用于降质图像的直接解卷积复原，并针对此应用展开了实验研究。实验结果表明：将相位差波前探测器对系统静态波前畸变的检测结果直接用于成像系统降质图像的恢复，复原图像的质量明显改善，且接近理想成像系统的成像质量。文中设计了一种基于组合棱镜的相位差波前探测器，降低了光路调整和器件加工的难度，实现了焦面和离焦面图像采集同步性和实时性的要求，解决了相位差波前探测器对动态波前畸变的检测问题。第三，设计了一种基于振幅型光栅分光原理的新型相位差波前探测器，降低了相位差波前探测器对成像探测器件信噪比和灵敏度的要求、改善了波前畸变的探测精度。这种新型的相位差波前探测器，巧妙地利用了不同衍射级次光斑的形状相同但强度不同这一特点，将0级和±1级衍射光斑图像拼接形成一个信噪比更高、光强分布信息更丰富的像面图像，从而实现提高波前检测精度的目标。数值仿真和实验验证的结果说明：振幅型光栅的引入为相位差波前探测器的高精度波前检测提供了一种可能。第四，围绕拼接型天文望远镜中主镜的共相误差检测问题，本文开展了大量研究工作验证相位差波前探测器用于非连续像差检测的可行性。数值仿真和实验验证的结果表明：相位差波前探测器可以准确测量拼接子镜之间的非连续像差，且不受子镜尺寸和形状的限制，其检测精度满足拼接型主镜共相精度的要求。本文针对连续像差和多种非连续像差所展开研究，在一定程度上将自适应光学系统波前探测和拼接镜共相误差检测统一起来。本文针对相位差波前探测器自身性能及其在大口径拼接型望远镜共相检测中的应用展开相关的仿真分析和实验研究，为相位差波前探测器的工程应用提供了有利指导，也为我国大口径拼接型望远镜所需的自适应光学系统和共相控制系统中波前畸变与共相误差的统一测量提供参考，从而简化了波前检测系统的复杂性，确保了波前检测数据一致性，同时拓展了相位差波前探测器的应用范围。更多还原

【Abstract】 For better observing resolution, the developing trend of astronomical telescope isto enlarge the aperture size, whatever on the ground or space. In some certain, theobserving ability for one telescope is always defined according its aperture size.However, better observing results may not be obtained for a larger aperture sizetelescope, and it may not better than a small one due to the influence of atmospheredisturb. So adaptive optics technology must be introduced into telescope system tocorrecte the disturbed wavefront, and the important premise is to measure accuratelythis wavefont aberration. In other hand, the design, manufacturing, machining andtesting suffer unprecedented challenge with the enlarging of telescope aperture size. Theproposal of the segmented primary mirror decrease markedly the weight, cost, periodand volum of telecope, and a super large telescope could be come ture. However, somechallenges are concomitant, and one of the most classic challenges is measuring andcontrolling of the co-phasing error of the segmented primary mirror. With developmentof the larger aperture size telescope, some new wavefront sensing technique and itsapplication in co-phasing testing must be study deeply.Based on above description, we introduce briefly the basic principle and thecorresponding wavefront reconstruction algorithm of phase diversity (PD) wavefrontsensor (WFS). A set of experimental study is also done for continuous anddiscontinuous surface wavefront aberration, and some innovative results have beenachieved as follows:Firstly, some influence factors such as the parameter of image recorder,signal-to-noise ratio (SNR) and defocus distance between the focus plane and defocusplane, which may degrade the measurement accuracy of PD WFS, are analyzed deeply.The analysis results are important for theoretical study and engineering application, andit can direct how to apply in practice and to improve performance.Secondly, we apply the PD WFS for image deconvolution, and the accordingexperimental study is also done. The experimental results show that the wavefront dataof PD WFS can be used to reconstruct the image with wavefront aberration and thereconstructing results have good quality near by the image with diffraction limit. Inaddition, a new structure for PD WFS is proposed based on combinatorial prism, and itcan be applied for the measurement of dynamic wavefront.Thirdly, a modified PD WFS based on the beam splitting principle of a diffractiongrating is proposed to improve the capability of wavefront sensing, such as higher SNR,higher sensitivity and higher measurement capability for high spatial wavefron undertest. Higher measurement accuracy could be achieved for this new PD WFS. Thenumeric and experiment results show that the measurement ability of G-PD WFS is improved obviously, especially for the wavefront aberration with larger amplitude. Thisnew PD WFS may be a better choice for higher accuracy wavefront measurement.Finally, numeric and experimental validation have been done for discontinuouswavefront measurement, such as pistion error and tip-tilt error. Numeric andexperimental results show that the co-phasing errors could be exactly measured by thePD WFS, especially for the co-phasing errors of several segmented mirrors could bemeasured exactly and simultaneously. So that the PD WFS can be used as a co-phasingsensor for the segmented primary mirror.In total, these results and innovations can guide for engineering application, and itcan be used as a unificate wavefront sensor for wavefront sensing in adaptive opticssystem and co-phasing sensing in a common segmented primary mirror telescope. If so,the wavefront sensing system in this segmented telescope can be simplified, and thedata consistency can be assured.更多还原