利用环形子孔径哈特曼-夏克斜率数据复原全孔径波前相位算法研究

提出了一种适用于哈特曼-夏克波前传感器的环形子孔径拼接检测技术的拼接复原算法.该算法通过建立各个环形子孔径内有效的哈特曼-夏克斜率数据和全孔径波前相位的关系,避免了环形子孔径区域的波前复原过程,从而有效地解决了环形子孔径区域的哈特曼-夏克波前传感器有效采样率低的问题.算法对斜率测量噪声较不敏感,具有较好的抗噪声干扰的能...     

The high precision positioning algorithm of circular landmark center in visual measurement

For vision measurement in the center circle landmark location problem, an improved center of the ellipse based on Zernike moments sub-pixel positioning algorithm was proposed. First, using Sobel operator edge of the image pixel level positioning and then use the constructed Zernike moments to solve the model, combined with Zernike orthogonal polynomials and completeness and plural moment magnitude rotational invariance calculated edge sub-pixel position; followed by analysis of the principle deviation generated by the moments template and ideals model, a correction formula was proposed to compensate and improved edge criterion used to image sub-pixel edge positioning; finally, using the least-squares ellipse fitting algorithm fitting circle center, reverse edge point, filtered residuals larger point, and then precise positioning of the ellipse center. The experimental results show that this method has good stability and high positioning accuracy can be efficiently used in many applications.     

基于单幅干涉图的波前重构技术研究

条纹中心法是干涉测量技术中分析单幅干涉图的一种重要处理方法,该方法主要包括图像预处理、波前重构和样品表面形貌及参数的测量等三个部分。研究了条纹中心法的关键技术,特别是应用协方差矩阵法求解泽尼克多项式以进行波前重构的过程。提出了基于单幅干涉图自动波前重构的流程方法。最后应用该流程方法处理由泰曼-格林干涉系统采集的精密抛光铝制盘基片表面形成的一幅干涉图像。实验结果表明,该方法可以实现单幅干涉图的自动波前重构,干涉波前重构的拟合精度可达1．4686×10^-6nm,还可以自动获得精密抛光铝制盘基片表面的形貌及参数。     

Aspheric surface reconstruction for scanning interference

A simplified reconstructing method for the aspheric surface testing based on scanning interference technology is presented. The aspheric normal intersects the optical axis at different points with different angles, which is called normal congruence; a normal congruence can identify an aspheric surface. In this method, the test aspheric surface is shifted along the optical axis to scan the tested aspheric surface; meanwhile a series of interferograms and phase maps are obtained. The angles between the normal lines and the aspheric axis are obtained using the positions of zero-phase points, according to the image-forming principle of the camera. Here, Zernike polynomials are applied to analyze the phase maps and extract the zero-phase points. Finally, the absolute coordinates of the test surface is rebuilt through iterative integration. Because both the system deformation and amplification do not affect the reconstruction result, this method can avoid complicated stitching algorithm in the subaperture stitching interferometric method. Experimental results show that the method has high accuracy and reliability.     

激光原位角膜磨镶手术后不良症状的光学分析

测量了准分子激光原位角膜磨镶(LASIK)手术后人眼的单色像差。并根据术后症状,将所有数据分类为视物星芒状组、单眼复视组、视物雾状组和参考组。视物星芒状组和视物雾状组的三阶和四阶泽尼克(Zernike)像差的均方根(RMS)值明显大于无症状的参考组。术后有不良症状各组的人眼的调制传递函数(MTF)明显低于参考组的调制传递函数。在明视觉条件下,四阶像差特别是对称性的泽尼克球差,对调制传递函数的影响大;而在暗视觉条件下,三阶像差特别是非对称性的泽尼克彗差对调制传递函数的影响大。四阶以上的高阶像差对各有症状组的调制传递函数曲线有影响,而这些高阶像差对参考组的调制传递函数已无明显影响。像差的均方根值和调制传递函数曲线是研究术后不良症状的较有效光学手段。     

Coma measurement using a PSM and transmission image sensor

As feature size decreases, especially with the use of resolution enhancement technique, requirements for the coma aberrations in the projection lenses of the lithographic tools have become extremely severe. So, fast and accurate in situ measurement of coma is necessary. In the present paper, we present a new method for characterizing the coma aberrations in the projection lens using a phase-shifting mask and a transmission image sensor. By measuring the image positions at multiple NA and partial coherence settings, we are able to extract the coma aberration. The simulation results show that the accuracy of coma measurement increases approximately 20% compared to the previous straightforward measurement technique.     

离轴抛物面反射镜模拟空间环境镜面变形分析

在卫星红外多光谱扫描仪模拟空间环境辐射定标试验中,环境模拟器舱内的稳、瞬态温度场会给光学系统成像质量带来影响.以试验中的实测温度变化作为温度载荷,借助有限元软件,分析了定标系统中通光孔径为φ400mm的离轴抛物面主镜的温度场分布和热弹性变形.选用在单位圆内正交的Zernike多项式为拟合基函数,通过坐标变换,将抛物镜表...     

一种基于瞳面相位差的波前传感器相位恢复

根据瞳面相位差波前传感器的特点,提出把模式分解和随机并行梯度下降算法结合起来实现波前相位的恢复.以32单元变形镜的初始面形和Roddier提出的相位生成方法随机产生的一帧相屏为研究对象,分析所提出的相位恢复算法的性能.结果表明,两种情况下的畸变波前都得到了很好的恢复.当像差仅含有低阶成分时,使用模式分解法就可获得令人满...     

基于固定校正元件的椭球形窗口光学系统设计

提出了一种基于非球面固定校正元件的椭球形窗口光学系统设计方法。结合广义科丁顿公式及几何光学原理,推导出非球面校正元件的像散表达式,在此基础上,以消像散和正弦条件作为非球面校正元件像差评价参数,采用最小二乘法拟合出满足消像散及彗差的非球面面形方程。并建立以泽尼克(Zernike)多项式特殊优化函数取代传统的光学系统评价函数,克服了采用传统光学设计方法设计椭球形窗口光学系统时系统评价函数收敛缓慢的问题。成像光学系统设计时通过比对不同材料匹配实现了光学系统的无热化。给出了完整的椭球形窗口光学系统的设计,设计结果表明,系统的调制传递函数在整个扫描视场范围内接近衍射极限。     

Error compensation for mirror symmetry absolute test

A method is proposed to compensate intrinsic error in mirror symmetry absolute test. Because of the limitation of rotation times of flat A, intrinsic error of CNθ terms occurs in reconstructed wavefronts of flats A, B and C. If flat A is rotated to a new azimuthal position, and the wavefront difference between two measurements before and after rotation is calculated, the Zernike coefficients of CNθ terms can be obtained by solving coefficient equations due to rotation invariability of the form of Zernike polynomials in polar coordinates. Therefore, the intrinsic error of CNθ terms may be compensated. Because the amount of CNθ terms is infinite, the compensated terms are decided in terms of the balance between intrinsic error reduction and computational effort. Computer simulation proves the validity of the proposed method.