| With the development of space technology, related optical systems is increasingly complex. Alignment and machining precision are required to improved. In the situation that the traditional means cannot meet the requirements, the Computer aided alignment came into being. This paper introduces the present situation of development at home and abroad about space remote sensing optical systems and computer aided alignment. Common numerical models about relations between misalignments and aberrations are summarized. Off-axis three-mirror and four-mirror optical systems are simulated aligned by using optical design software.A Wetherell TMA and a Cook TMA are designed. A axis-off four-mirror anastigmat optical system is designed by inserting fold mirror based on Cook TMA to make the optical system more compact. The systems are analyzed and compared from the imaging quality and structure.The aberration information of optical system is measured by autocollimation interference. The aberration is given in the form of Zernike coefficient. In the optical design software,merit function is also constituted by Zernike coefficients. According to the system is rotationally symmetric, the Zernike polynomials in round pupil are derived.As a result of the linear approximation, the sensitivity matrix method is only effective when the misalignments are tiny. Reverse optimization is achieved by merit function consisted of the Zernike coefficients of designed and misaligned systems. The misalignments are calculated accurately by common optimization and hammer optimization.The simulation alignments of focal 1500 mm Wetherell off-axis TMA and Cook off-axis FMA are carried out by reverse optimization. In the absence of error case, it can calculate accurately by once optimization. When there are 1%、5% and 10% error, it need several optimization. Considering there is measurement error but no surface accuracy, the wavefront RMS of center field of off-axis FMA is better than 0.04λ. |
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