空间光学自由曲面应用的关键技术研究

发布时间：2018-06-08 19:28

本文选题：光学自由曲面 + 面形表征　；参考：《中国科学院长春光学精密机械与物理研究所》2017年博士论文

【摘要】：自由曲面在光学系统中的应用,在不增加光学元件数量的前提下增加系统自由度,可以有效减少光学系统设计残差和光学元件数量,同时实现成像质量的改善和光学系统结构的简化。作为一类复杂的、非旋转对称的异形曲面,自由曲面拥有更大的设计自由度,使得光学系统设计者可根据空间相机设计参数的特殊需要,突破传统光学系统的概念,运用于全新的系统设计方案中。因而,具有减少光学元件数量,提高成像质量,适应轻量化要求等优势。目前,空间遥感光学系统正朝着大口径、长焦距、小体积和轻量化方向发展。随着科技不断发展,对成像性能和质量提出了更高的要求,这对仅使用球面、非球面的传统光学系统提出了巨大挑战,而采用自由曲面光学元件,以其具有的非对称结构形式,提供灵活的空间布局、拓展优化自由度、提升轴外像差平衡能力、改善视场适应能力,逐渐成为必然趋势。自上世纪90年代,自由曲面首先在照明光学、头盔显示等系统中得到了成功应用之后,近年来,国外欧美发达国家投入大量资金和研究力量,在自由曲面光学系统相关研究技术领域取得了突破,为基于自由曲面的离轴光学系统研制奠定了坚实的技术基础。基于自由曲面的光学系统应用研究已经成为现代高性能空间光学系统发展的重要方向。对高精度自由曲面光学元件的制造需求随之而来。正如从球面到非球面、离轴非球面的变革中,曲面描述方式从曲率半径增加到二次曲面系数、高次非球面项系数、离轴量等参数一样,自由曲面的描述需以现有检测、加工手段为根本,提出一套可靠的参数指标体系,用来指导自由曲面的制造;同时,也必然要求现有的加工检测技术有所提高。因此,研究自由曲面在空间光学系统应用中的关键技术,保证自由曲面光学元件制造精度,以使光学系统符合各项设计指标,就成为自由曲面在空间光学系统应用中的重要课题。本论文基于以上问题针对空间光学自由曲面的表征、微分与频段特征分析、检测与加工技术应用进行了以下方面的研究:(1)通过研究空间光学自由曲面常用面形基底及优化项类型,分析了其微分信息和频率信息,比较了各种表征方式的特征。分析了其公差表征形式及物理意义。(2)通过对自由曲面面形微分特征的分析,使用面形斜率在研磨阶段轮廓检测中精确补偿了接触测量误差;使用面形曲率在非零位子孔径拼接检测中实现了被检镜面面形误差、标准镜面形误差与调整量的解耦,降低了拼接算法对噪声的敏感性,提高了检测精度;研究了扫描曲率检测及面形重构算法,理论分析并实验验证了该方法的参数解算精度。(3)通过自由曲面曲率分布特征的描述,建立模型分析了磨头参数对工件不吻合度及加工收敛效率的影响;针对小型磨头,通过工艺试验及参数选取,提高了抛光阶段的材料去除速率、稳定性;使用区域性加工策略,提高了收敛的时间效率。(4)建立模型描述了自由曲面由于边缘效应引起的去除量偏差,分析了应用尖刀型去除函数对边缘效应的抑制作用,得到尖刀运动参数的理论优化结果。设计并实现了利用单一主轴的复合运动机械结构,结合频段误差加权优化算法,实现了对加工过程边缘效应的有效抑制。
[Abstract]:The application of free-form surface in optical system can increase the degree of freedom of the system without increasing the number of optical elements. It can effectively reduce the design residual and the number of optical elements, improve the imaging quality and simplify the structure of optical system. As a kind of complex, non rotating symmetric surface, free form surface, free surface With more freedom of design, the optical system designer can break through the concept of the traditional optical system according to the special needs of the space camera design parameters and apply it to the new system design. Therefore, it has the advantages of reducing the number of optical elements, improving the quality of imaging, and the requirement of light quantization. At present, the space remote sensing optical system The system is developing towards large aperture, long focal distance, small volume and light weight. With the continuous development of science and technology, higher requirements for imaging performance and quality are put forward, which poses great challenges to the traditional optical systems that only use spherical and aspherical surfaces, and the use of free surface optical elements is flexible in its asymmetric structure. In the 90s of last century, free surface has been successfully applied in the lighting optics, helmet display and so on. In recent years, a large amount of funds and research forces have been put into the developed countries in Europe and the United States and Europe. A breakthrough has been made in the related research field of free surface optical system, which lays a solid technical foundation for the development of free surface based off-axis optical system. The application of optical system based on free-form surface has become an important direction for the development of modern high performance space optical systems. In the change from the spherical to aspheric surface and the aspheric aspheric surface, the description of the surface from the radius of curvature to the coefficient of two surface, the coefficient of higher aspherical terms, the off axis and other parameters, the description of the free surface should be based on the existing testing and processing means, and a set of reliable parameter index system is put forward. To guide the manufacture of free-form surface; at the same time, it must also require the improvement of the existing processing technology. Therefore, the study of the key technology of the free surface in the application of the space optical system is to ensure the precision of the manufacturing of the free surface optical element and make the optical system conform to the design reference, and become a free surface in the application of the space optical system. Based on the above problems, this paper studies the characterization of space optical free-form surface, differential and frequency feature analysis, and the application of detection and processing technology in the following aspects: (1) the differential information and frequency information are analyzed by studying the common surface base and the optimal term type of the space optical free-form surface. The characteristic form and the physical meaning are analyzed. (2) through the analysis of the differential features of the surface shape of the free surface, the contact measurement error is accurately compensated by the surface slope in the grinding stage contour detection, and the surface shape error is realized by the surface curvature in the non zero bit aperture joint detection. The decoupling of the mirror shape error and the adjustment amount reduces the sensitivity of the stitching algorithm to the noise and improves the detection precision. The algorithm of scanning curvature detection and surface reconstruction is studied. The theoretical analysis and experiments verify the accuracy of the method's parameter calculation. (3) the parameters of the grinding head are analyzed by the model of the curvature distribution of the free-form surface. The effect of the workpiece is not consistent and the efficiency of processing convergence; for the small grinding head, the material removal rate and stability of the polishing stage are improved through the process test and parameter selection. The time efficiency of convergence is improved by using the regional processing strategy. (4) a model is established to describe the removal deviation caused by the edge effect of the free surface, and the analysis is analyzed. The effect of the sharp knife removal function on the edge effect is applied, and the theoretical optimization results of the motion parameters of the sharp knife are obtained. A composite motor structure with a single spindle is designed and realized, and the effective suppression of the edge effect of the machining process is realized by combining the weighted optimization algorithm of the frequency band error.
【学位授予单位】：中国科学院长春光学精密机械与物理研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TH74

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