| As the space remote sensing technology progresses, higher and higher groundsampling distance (G.S.D.) is requested. If the height of a satellite is fixed and theCCD camera meets the limited resolution, G.S.D. is inversely proportional to the focallength of optical system. So enlarging the focal length of camera is good forimproving G.S.D. of system. With wider field of view, larger area of object planecould be detected. Long focal length and wide field of view would be generaldevelopmental direction.At first, this paper introduces the development of space mapping cameras athome and abroad, such as Cartosat-1for IRS P5mission and TMC for Chandrayaan-1in India, PRISM installed on the ALOS in Japan, HRS on SPOT-5and Pleiades inFrance.Two kinds of new-style reflective system were designed, based on ordinarytwo-mirror and three-mirror optical system. They are two-mirror three-reflectiveoptical system and three-mirror optical system based on Gregorian. The design ofthem was analyzed, and two examples were furnished.According to the design demands for the space mapping camera with long focallength and wide field of view, it was designed by three ways. Finally satisfied resultswere got respectively via three ways.Considering design index and the cost of manufacturing and alignment, off-axisthree-mirror optical system was adopted. The facility isn’t able to get design levelbecause of many industrial factors. Toleration limitation analysis was carried on theforegoing result by Zemax program. From the analysis data, it is easy to understandhow important the industrial factors are to degrade the camera image quality. |
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