光栅剪切干涉波前测量技术研究
文献类型：学位论文
| 作者 | 李杰 |
| 学位类别 | 博士 |
| 答辩日期 | 2016 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 王向朝 |
| 关键词 | 波前测量 横向剪切干涉 波前重建 光栅元件 系统误差 |
| 其他题名 | Research on wavefront measurement techniques based on grating shearing interferometry |
| 中文摘要 | 干涉测量技术是目前精度最高的波前测量技术，在天文、军事、工业、医疗等领域发挥着越来越重要的作用。相比传统的干涉法波前测量技术，横向剪切干涉技术具有不需要参考波前、测量范围大等优点，在现代光学精密制造、极大规模集成电路制造、惯性约束核聚变、眼科医学等领域得到了广泛的应用。光栅剪切干涉技术是一种使用光栅作为分光元件的横向剪切干涉技术，主要应用于高精度波像差检测和波前传感等领域。光栅剪切干涉技术测量的是待测波前在剪切方向上的斜率（差分波前），需要使用波前重建技术从差分波前中恢复待测波前。由于光栅的多级衍射光干涉，在特定位置测量或者使用光窗滤波才能得到高对比度的干涉条纹，限制了光栅剪切干涉技术的应用范围及测量精度。此外，使用光栅剪切干涉技术测量会聚或发散光束时，几何光程误差、探测器倾斜误差、光栅衍射误差等系统误差将影响波前测量精度。 本文针对光栅剪切干涉技术在高精度波像差检测和波前传感等领域存在的问题开展理论和实验研究，主要包括以下几项工作： 1. 针对任意光瞳形状的待测波前，提出基于差分Zernike多项式拟合法的扩展模式法与区域法的高精度波前重建技术及其评价方法，提高波前重建精度。在模式法中，将基于Zernike多项式的差分多项式拟合法推广到一般基函数，并使用测得的差分数据与重建波前的差分数据之间的误差（差分波前误差）评价模式法波前重建算法的精度。在区域法中，使用Zernike多项式拟合重建结果得到连续的拟合波前，计算重建波前与拟合波前在各区域内的直流量差值得到各区域之间的伪直流误差。使用伪直流误差评价孤立区域波前的重建精度，并根据评价结果使用迭代算法提高重建精度。通过数值计算和实验研究高精度波前重建技术及其评价方法的有效性，结果表明所提出的两种重建技术及其评价方法可实现任意光瞳形状待测波前的高精度重建。 2. 提出一种基于差分波前离散采样的快速模式法波前重建技术，提高波前重建效率，在此基础上设计一种高端光刻机原位像质检测系统。通过数值计算和实验研究差分波前的采样点数与用于描述待测波前的基函数项数之间的关系。结果表明噪声水平和剪切率合理且差分波前的采样点数大于四倍差分Zernike多项式的径向阶数时，采样数据重建精度可以满足测量要求，同时提高波前重建的计算效率。根据快速模式法波前重建技术设计的高端光刻机原位像质检测系统使用小孔阵列对干涉图进行采样，提高波像差检测的空间分辨率，同时增加像质检测并行通道数，提高畸变、场曲的检测精度。 3. 对随机编码混合光栅（REHG）与改进型哈特曼掩模（MHM）开展比较研究，通过优化REHG的透过率分布，降低光栅加工难度。通过理论分析和数值计算比较REHG与MHM的衍射频谱、工作带宽、测量误差以及加工方式。结果表明基于REHG的光栅剪切干涉仪性能优于MHM，将其用于波前传感技术领域可以实现理想的四光束剪切干涉。另外，通过数值计算研究基于不同量化参数的REHG透过率分布并得到最优量化参数，在不影响测量精度的前提下降低小周期光栅的加工难度。 4. 分析光栅剪切干涉仪结构设计方案及其系统误差，得到此类干涉仪的适用范围，并使用三种系统误差消除方法提高波前测量精度。通过理论分析和数值计算研究光栅剪切干涉仪的系统设计方案，分析其适用范围，并根据其结构使用光线追迹法分析主要系统误差：光栅衍射误差和探测器倾斜误差，为光栅剪切干涉仪设计和系统误差消除提供理论依据。根据系统参数与误差之间的关系使用三种方法消除系统误差，通过准确测得的系统参数和多次测量结果消除光栅衍射误差和探测器倾斜误差，并通过数值计算验证上述系统误差消除方法的有效性。 |
| 英文摘要 | Interferometry is the most accurate wavefront measurement technology at present and plays an increasingly important role in the field of astronomy, military, industry, medicine and so on. Compared with conventional interferometry, lateral shearing interferometry does not need the reference wavefront and has large measurement range. Owing to these advantages, lateral shearing interferometry has been applied extensively in many fields, such as modern optical ultra-precision manufacturing, ultra-large scale integrated circuit manufacturing, inertial confinement fusion, and ophthalmology. Grating shearing interferometry, using grating elements as the beam splitter to create the sheared copies, is a kind of lateral shearing interferometry and has been applied in the field of high accuracy aberration measurement and wavefront sensing. The grating shearing interferometry measures the wavefront slope (difference front) in the shear direction rather than the test wavefront itself. Therefore, wavefront reconstruction technology is indispensable for the grating lateral shearing interferometry to retrieve the test wavefront from the difference fronts. Due to the interference of multiple diffraction beams, the interferogram with a good contrast can only be obtained measuring at specific locations or using a window-window filter. The measurement accuracy of the grating shearing interferometry is limited in the practical application. In addition, systematic errors, such as geometrical aberration, detector misalignment error, and diffraction aberration, have a negative effect on the measurement accuracy for convergence or divergence beams. In order to solve the problems mentioned above, both theoretical analysis and experiment research are performed in this dissertation. The main contents are as follows. 1. Based on the extended modal method and zonal method, high accuracy wavefront reconstruction techniques and the corresponding evaluation methods are proposed to retrieve the test wavefront with an arbitrary pupil. In modal reconstruction, difference Zernike polynomial fitting method is extended by using general basis functions, and the deviations between the measured difference fronts and the difference fronts calculated from the reconstruction result (the difference front error) are used to evaluate the reconstruction accuracy. In zonal reconstruction, Zernike polynomial fitting of the reconstruction result is used to obtain a continuous wavefront. The piston differences between the fitting result and the reconstruction result are calculated to obtain the pseudo piston errors. According to the pseudo piston errors, an iterative algorithm is used to improve the reconstruction accuracy of the segmented wavefront. Simulation and experiment results show that the test wavefront with an arbitrary pupil can be reconstructed accurately using the proposed techniques. 2. A modal method based on difference-front sampling is proposed to improve the wavefront reconstruction efficiency. According to the proposed method, an in-situ measurement equipment of wavefront aberration for advanced lithography is designed. Simulation and experiment results show that the reconstruction accuracy meets the requirement of measurement accuracy only if the grid number of the sampled difference fronts is more than 4 times of the radial order of difference Zernike polynomials within reasonable noise level and shear ratio. The computation efficiency of wavefront reconstruction is also improved by the sampling technique. Using a pinhole array to sample the interferogram in the measurement setup, the spatial resolution of wavefront aberration measurement is improved. In addition, the number of parallel measuring fieldpoint is increased and the measurement accuracy of distortion and curvature is improved. 3. Comparative study of randomly encoded hybrid grating (REHG) and modified Hartmann mask (MHM) is performed. The difficulty of the grating manufacture is reduced by optimizing the transmittance distribution of the REHG. The diffraction orders, contrast of carrier fringes, available spectral bandwidth, measurement accuracy, and manufacture approach of REHG and MHM are analyzed. The results show that the performance of lateral shearing interferometry based on the REHG is superior to that based on the MHM. Quadriwave interference can be achieved by the lateral shearing interferometry based on the REHG in the field of wavefront sensing. In addition, the transmittance distribution of the REHG with different quantization parameters is simulated and the optimal quantization parameter is obtained to reduce the difficulty of manufacturing small period gratings within reasonable measurement accuracy. 4. Based on the analysis of configuration parameters and systematic errors of the grating shearing interferometer, the application range is obtained and three calibration methods are used to improve the measurement accuracy. Theoretical analysis and numerical simulation of the configuration design are performed to analyze the application range of the grating shearing interferometer. Two of the most significant systematic errors, diffraction aberration and detector misalignment error, are simulated by the ray tracing technique with respect to the configuration parameters. According to the simulation results, three methods based on either the accurately measured configuration parameters or multiple measured results are used to calibrate the systematic errors. Simulation results show that the measurement accuracy can be improved using the calibration methods. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15965]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 李杰. 光栅剪切干涉波前测量技术研究[D]. 中国科学院上海光学精密机械研究所. 2016. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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