[1] Zhang Z, Xin Y, Yang B. The application of self-adaptation optics on space optical sensors. Spacecraft Recovery of Remote Sensing, 2000, 10(3): 23-29

[2] Duchmann O, Planche G. How to meet intersatellite links mission requirements by an adequate optical terminal design. Proceedings of the Society for Photo-Instrumentation Engineers, 1991, 1417: 30-41

[3] Xing Z, Guang J. Design of extra wide short wave infrared spectral imager’s fore-optics. Acta Optica Sinica, 2012, 32(10): 1022004

[4] Rodgers J M. Unobscured mirror designs. Proceedings of the Society for Photo-Instrumentation Engineers, 2002, 4832: 33-60

[5] Rodgers J M. Aberrations of unobscured reflective optical systems. Dissertation for the Doctoral Degree. Tucson: University of Arizona, 1983

[6] Hui L, Li X, Pei Y, Ming P. Design of off-axis three-mirror optical system. Laser & Optoelectronics Progress, 2008, 10(12): 59-63

[7] Guo Y, Li Y, Liang T, Chen Q. Optical design of the uncoaxial three-mirror system with wide field of view. Acta Optica Sinica, 2010, 30(9): 2680-2683

[8] Wu H, Wang P. Designs of reflective off-axis system. Opto- Electronic Engineering, 2006, 33(1): 34-37

[9] ang T, Zhu J, Jin G. Design of freeform imaging systems with linear field-of-view using a construction and iteration process. Optics Express, 2014, 22(3): 3362-3374

[10] Yang T, Zhu J, Wu X, Jin G. Direct design of freeform surfaces and freeform imaging systems with a point-by-point three-dimensional construction-iteration method. Optics Express, 2015, 23(8): 10233- 10246

[11] Nie Y, Thienpont H, Duerr F. Multi-fields direct design approach in 3D: calculating a two-surface freeform lens with an entrance pupil for line imaging systems. Optics Express, 2015, 23(26): 34042- 34054

[12] Shealy D L, Wang C, Jiang W, Jin L, Hoover R B. Design and analysis of a fast two-mirrorsoft-x-ray microscope. In: Proceedings of SPIE- The International Society for Optical Engineering, 1992, 1741

[13] Semin V A. Calculating aspheric surfaces by modelling an optical system by means of differential equations. Journal of Optical Technology, 1999, 66(3): 247-251

[14] Xia C Q, Xing Z, Guang J. Design of the off-axis four mirrors system by differential equations. Acta Optica Sinica, 2015, 35(9): 0922002

[15] Meng Q, Wang W, Ma H, Dong J. Easy-aligned off-axis threemirror system with wide field of view using freeform surface based on integration of primary and tertiary mirror. Applied Optics, 2014, 53(14): 3028-3034

[16] Guo J, Sun J, Shao M, Hu H. Calculation of focal length for off-axis TMA aerospace mapping camera. Optics and Precision Engineering., 2012, 20(8): 1754-1758