| 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. ThereeMirror 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 midfrequency, 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 φ 120 mm 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× 144 mm 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(Fo V) aligned graranty all Fo V 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 Fo V 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 Fo V 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. |
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