加工表面几何误差对光学性能的影响

发布时间：2018-01-06 11:19

本文关键词：加工表面几何误差对光学性能的影响　出处：《吉林大学》2012年硕士论文　论文类型：学位论文

【摘要】：自由曲面是指没有任何回转对称性的光学曲面，是非球面发展的高阶形式，应用自由曲面的光学系统结构简化、重量轻、有更加优异的光学性能。随着光电子仪器要求的提高，光学系统已由球面和非球面光学向自由曲面光学方向发展，自由曲面加工技术快速发展。然而由于加工过程中各种因素的影响，光学加工表面几何误差不可避免，进而影响光学零件、光学系统的光学性能，因此开展加工表面几何误差对光学性能影响的研究就十分必要。本文研究光学零件加工表面的面形误差与表面粗糙度对光学性能的影响，其数据是从恒径向进给仿真加工所得到的表面形貌数据中、应用小波分析方法分离出来的。以加工表面只有面形误差的光学零件为模型，用波像差、调制传递函数和点扩散函数为评价指标，研究面形误差对光学性能的影响；以只有粗糙度的加工表面为模型，用基于Harvey-Shack散射理论的散射表面传递函数和点扩散函数为评价指标，研究表面粗糙度对光学性能的影响。在分析面形误差对光学性能影响的过程中，为与波像差的经典定义区分，将经过已加工光学零件后的实际波面与经过设计的光学零件后的理想波面之间的偏离定义为波像差增量。利用光线追迹的方法求解含有不同面形误差光学零件的波像差及其增量，分析面形误差对波像差的影响；用Zernike多项式拟合波像差，利用Zernike多项式拟合系数与Seidel像差的对应关系，分析面形误差对Seidel像差的影响。用两次傅里叶变换法计算含有不同面形误差光学零件的光学传递函数，在此过程中点扩散函数也已求出，分析面形误差对点扩散函数与调制传递函数的影响。面形误差越大，波像差及其增量均变大，不同波像差拟合系数对应的Seidel像差变化规律不同；面形误差使像面能量分布发生变化，使成像质量降低。表面粗糙度使光透过光学零件时发生散射，本文基于Harvey-Shack散射理论，假设粗糙表面随机、且高度服从高斯分布，在此基础上分析表面粗糙度对光学性能的影响。粗糙表面数据由不同进给量仿真加工的表面形貌数据分离得到，计算其相应的方差及在X轴方向、Y轴方向的相关长度，用粗糙表面高度分布方差与相关长度描述加工表面的粗糙程度。计算不同进给量所得到加工表面的散射表面传递函数及点扩散函数，分析粗糙度对散射表面传递函数、点扩散函数的影响。分析表明，粗糙度越大，，像面能量越分散，光学零件的成像质量越低。
[Abstract]:Free-form surface is an optical surface without any rotational symmetry. It is a high-order form of aspherical development. The optical system with free-form surface is simplified and light in weight. With the improvement of optoelectronic instruments, optical system has been developed from spherical and aspherical optics to free-form surface optics. The free-form surface machining technology is developing rapidly. However, due to the influence of various factors in the process of machining, the geometric error of optical machining surface is inevitable, which further affects the optical properties of optical parts and optical systems. Therefore, it is necessary to study the effect of geometric errors on optical properties of machined surfaces. The effect of surface shape error and surface roughness of optical parts on optical properties is studied in this paper. The data are obtained from constant radial feed simulation machining. The optical parts with only surface error are used as the model, the wavefront aberration, the modulation transfer function and the point diffusion function are used as the evaluation indexes. The influence of surface shape error on optical performance is studied. Taking the machined surface with only roughness as the model, the scattering surface transfer function and the point diffusion function based on the Harvey-Shack scattering theory are used as the evaluation indexes. The effect of surface roughness on optical properties is studied. In the process of analyzing the effect of surface shape error on optical performance, it is distinguished from the classical definition of wave aberration. The deviation between the actual wavefront of the processed optical part and the ideal wave surface of the designed optical part is defined as the wave aberration increment. The method of ray tracing is used to solve the optical parts with different shape errors. Wave aberration and its increment. The influence of surface shape error on wave aberration is analyzed. The wavefront aberration is fitted with Zernike polynomial and the corresponding relation between Seidel aberration and Zernike polynomial fitting coefficient is used. The influence of surface shape error on Seidel aberration is analyzed. The optical transfer function of optical parts with different surface errors is calculated by using the twice Fourier transform method, and the point diffusion function has also been obtained in the process. The effect of plane shape error on point diffusion function and modulation transfer function is analyzed. The larger the plane shape error is, the larger the wavefront aberration and its increment are, and the variation law of Seidel aberration is different according to the fitting coefficient of different wave aberration. The shape error changes the energy distribution of the image plane and reduces the imaging quality. Surface roughness causes light scattering when it passes through optical parts. Based on Harvey-Shack scattering theory, the rough surface is assumed to be random and the height is distributed from Gao Si. On this basis, the influence of surface roughness on optical properties is analyzed. The rough surface data are separated from the surface morphology data of different feed simulation machining, and the corresponding variance and X axis direction are calculated. The correlation length of Y axis is used to describe the roughness of the machined surface with the variance of the height distribution of rough surface and the correlation length. The scattering surface transfer function and point diffusion function of the machined surface are obtained by calculating the different feed rates. The effect of roughness on the scattering surface transfer function and point diffusion function is analyzed. It is shown that the higher the roughness is, the more dispersed the image energy is, and the lower the imaging quality of the optical parts is.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH161

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