| 题名 | 基于CGH的非球面混合补偿检测及离轴光学系统装调的关键技术研究 |
| 作者 | 李明 |
| 学位类别 | 博士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院大学 |
| 导师 | 张学军 |
| 关键词 | 非球面 光学检测 计算全息图 混合补偿检测 光学系统装调 |
| 其他题名 | Research on key technology of hybrid null testing of aspheric mirrorand off-axis optical system alignment based on CGH |
| 学位专业 | 光学工程 |
| 中文摘要 | 随着空间技术发展，空间相机对地遥感观测要求分辨率越来越高，视场角越来越大，光学系统的口径越来越大，相应的对非球面的应用需求也不断提高，所需非球面元件口径也越来越大。传统两镜反射望远光学系统视场过小，逐渐无法满足空间相机视场角需求，三反射镜消像散(three-mirror anastigmat，TMA)形式的光学系统可解决了两镜反射望远光学系统视场过小的缺点，并实现平像场和高成像质量，其中离轴TMA（简称离轴三反）还具有中频调制传递函数(MTF)高、结构紧凑和杂光特性好等优势，在空间相机中应用越来越广泛。然而非球面口径增大，离轴三反系统的广泛使用，在使系统成像效果更卓越的同时，也给光学制造过程带来了新的困难，其中包括大口径非球面高精度检测和离轴三反光学系统装调。` 本文针对大口径非球面高精度检测和离轴三反光学系统装调难题，研究了使用计算全息图(Computer-generated hologram, CGH)与其他光学元件(或检测方法)混合补偿检测非球面的方法和基于CGH的离轴光学系统装调技术，结合实验室工程型号项目，主要开展了以下工作： 1. 提出了CGH与辅助球面混合补偿检测方法，构建了基于CGH辅助区域的对准方案，可解决大口径离轴非球面和中等口径凸非球面的零位补偿检测难题，理论分析检测精度优于1/100λ RMS。用该方法检测了某120mm直径的凸非球面，在1/50λ RMS面形误差情况下与子孔径拼接检测结果一致。并利用该方法检测了某332mm× 144mm的长条形离轴凸椭球面。并以此检测原理为基础，提出了CGH与系统主镜混合补偿检测系统次镜的检测方法。 2. 提出了基于CGH的子孔径拼接检测方法，可检测偏离量较大不能直接子孔径拼接检测的凸非球面，可与上述CGH与辅助球面混合补偿检测方法相互校验，提高检测可靠性。构建了基于CGH辅助区域的对准方案，可实现基于子孔径拼接仪的自动拼接检测。利用该方法同样检测某332mm× 144mm的长条形离轴凸椭球面，同CGH与辅助球面混合补偿检测结果一致。 3. 对离轴三反光学系统装调进行了分析，分别提出针对Cook型离轴三反系统和Rug型离轴三反系统的CGH辅助装调方法： 在CGH的指导下完成系统主镜与三镜(或主镜与次镜)的相对位置调整，再调整次镜(或三镜)完成光学系统装调。理论分析表明，该方法在调整次镜(或三镜)时仅需要选择某个视场进行装调，便可确保全视场均获得良好像质，且该装调解即为光学系统的设计解。使用该CGH辅助装调方法只需调整次镜(或三镜)，且无需在迭代过程中反复测量多个视场的波象差，因此装调效率大大提高。使用该方法对某离轴三反光学系统进行了装调，实验结果表明该方法可在获得全视场衍射受限良好像质的同时大幅度提高装调效率。 工程实践表明，充分利用CGH设计的灵活性，将CGH与其他光学元件或检测方法混合，不仅能完成大口径非球面的高精度零位补偿检测，还可实现离轴三反光学系统的高精度高效率装调，在光学系统的制造过程中具有良好的应用前景。 |
| 英文摘要 | With the development of space technology, we need higher resolution, wider field of view, larger aperture optical system in the field of remote sensing. At the same time, the demand for aspherical mirrors becomes higher, and aperture of aspherical mirrors becomes larger. The field of view of one-mirror and two-mirror telescope is so small that it can’t meet the demands of space telescope. Theree-Mirror Anastigmat(TMA) optical system not only overcome the shortcoming of small field, but also provides a flat focal plane and high accuracy of image. On the other hand, off-axis TMA can obtain a long effective focal length in the limited optical package length, and higher modulation transfer function (MTF) in mid-frequency, thanks to its unobstruction, making it popular in space telescope. However, with the widely used of TMA optical system with large aperture, it brings challenge to optical manufactory, including large aspherical mirror testing and TMA optical system alignment. In the thesis, aiming at the problem of testing of aspherical mirror with large aperture in high precision and alignment of TMA optical system. We studied hybrid compensation method combining CGH technology with other optical elements or testing methods, and alignment technique based on CGH. Combining with actual project, our main research work is as follows: 1. We propose a hybrid null test method combining CGH and auxiliary spherical mirror. An alignment model is also established based on auxiliary area of CGH. It can be used to accomplish the null testing of aspheric mirror with large aperture, either concave or convex mirror. The testing accuracy can be within 1/100λ RMS. The method is also applied to the testing of a φ120mm convex aspheric mirror. The testing map is in consistent with the stitching map at 1/50λ RMS. Based on this theory, we provided hybrid null testing of secondary mirror of optical system with CGH and primary mirror. 2. We provided a hybrid null testing method combining CGH and sub-stitching method. It can be used to test aspheric mirror with large deviation, which means testing can’t be accomplished with stitching testing alone. The validity and accuracy of this method can be tested by comparing the testing map with the testing result obtained with method mentioned in the above paragraph. At the same time, we established a alignment method based on auxiliary area of CGH, which makes the automatic stitching testing of SSI (subaperture stitching interferometry) possible. The method is also applied to the testing of the 332mm× 144mm convex ellipsoid mirror. The testing result is in consistent with the testing map obtained with the method in section 1. 3. We analyzed the alignment of off-axis TMA optical system, then we provides alignment methods for both Cook TMA and Rug TMA optical system. Following the guide of CGH, we first accomplish the alignment between two mirrors. Then the other mirror is placed on the correct position, which makes the alignment of optical system accomplished. The analysis indicates that one field of view (FoV) aligned graranty all FoV is aligned. And all mirrors are identical to their relative position in design. As a result, only one mirror need to be aligned in the general computer-assistant-alignment (CAA) method, and only one FoV need to be tested in this CAA method. Some off-axis TMA optical system are aligned in CGH method, and it showed that diffraction limited results can be obtained in all FoV with efficiency improved substantially. It can be seen from actual projects that combining CGH technology with other optical components or testing methods, it not only can accomplish the high-accuracy null testing to aspheric mirror with large aperture, but also can be used to accomplish the alignment of off-axis TMA with high accuracy and efficiency. There will be a good application of CGH in the optical manufactory. |
| 公开日期 | 2015-12-24 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ciomp.ac.cn/handle/181722/48861]  |
| 专题 | 长春光学精密机械与物理研究所_中科院长春光机所知识产出 |
| 推荐引用方式 GB/T 7714 | 李明. 基于CGH的非球面混合补偿检测及离轴光学系统装调的关键技术研究[D]. 中国科学院大学. 2015. |
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