光学学报, 2014, 34 (2): 0228006, 网络出版: 2014-01-23
含扫描反射镜的星载相机异速像移分析
Analysis on Different Rates Image Motion of Space Camera with a Scanning Mirror
遥感 异速像移 像移计算 偏流角 扫描反射镜 像移补偿 remote sensing different rates image motion calculation of image motion drift angle scanning mirror image motion compensation
摘要
在星载相机中,扫描反射镜通常会带来异速像移,导致时间延迟积分(TDI)CCD上像移分布不均,不同摆角下,这种分布情况均不同,给像移补偿造成困难,难以获得清晰的成像效果。为此进行分析,建立了含扫描反射镜的像移模型。针对某一低轨卫星参数进行仿真,得到了在不同摆角下,不同视场对应的像面像移量和偏流角。若以像面中心像移量和偏流角作为补偿标准,补偿后,CCD各点的偏流角残差较小,当像移量残差小于1/3 pixel时,即可认为补偿有效。不同摆角下,这种补偿效果是不同的。通过分析,当摆角在(-20°,-0.12°)和(0.17°,20°)内时,异速像移明显,成像效果不佳;在(20°,35°)、(-35°,-20°)和(-0.12°,0.17°)范围内时,补偿效果好,利于成像;摆角为0,即对星下点拍照时,成像效果较好,此时摆角的控制精度应在(-0.12°,0.17°)范围内。以上研究可为稳像机构设计提供一定参考。
Abstract
In the remote sensing camera of a satellite, its scanning mirror always bring the different rates image motion, which will make distribution of each point′s image motion on time delayed integration (TDI) CCD non-uniform. The distribution changes with angles of mirror, and it makes compensation for image motion difficult and effect of photograph un-satisfactory. For analyzing this situation, model of camera′s image motion vector with a scanning mirror is built. By concreting parameters, values of image motion and drift angles of each point on CCD with different angles of mirror are gained. When central point of CCD′s image motion is chosen as the standard of compensation, after compensation, if image motion value around all parts of CCD is below 1/3 pixel, the compensation is effective. With different angles of mirror, this effect of compensation is different. By analysis, when the angle of mirror is within the scope of (-20°,-0.12°) and (0.17°,20°), photos′ effect would be dim. This effect is satisfactory when angles of mirror are within the scope of (20°,35°) (-35°,-20°) and (-0.12°,0.17°). When angle of mirror is 0, this effect is satisfactory, and control precision of mirror′s angle should be within the scope of (-0.12°,0.17°). All of this study above can offer some reference for design of image stabilization mechanism.
张树青, 李韬. 含扫描反射镜的星载相机异速像移分析[J]. 光学学报, 2014, 34(2): 0228006. Zhang Shuqing, Li Tao. Analysis on Different Rates Image Motion of Space Camera with a Scanning Mirror[J]. Acta Optica Sinica, 2014, 34(2): 0228006.