针对大视场空间相机的像移补偿, 建立了基于坐标变换和姿态动力学的离轴三反大视场空间相机通用像移速度场模型。建模过程中考虑了离轴三反光学系统的离轴角对像移模型的影响, 推导了离轴三反大视场空间相机的像速场解析式。以某大视场空间相机为例, 分析了3种典型成像姿态下焦面像移速度和偏流角的分布特点, 研究了卫星姿态稳定度对相机成像质量的影响。分析表明, 卫星三轴姿态稳定度的降低会导致相机焦面动态传递函数(MTF)下降, 其中俯仰姿态稳定度对焦面动态MTF的影响最大; 并且随着积分级数增加, 下降会愈发明显。相机侧摆姿态成像时, 对卫星姿态稳定度的要求更高。以传递函数下降5%为限, 积分级数为96级的大视场空间相机, 要求卫星姿态稳定度控制在0.001(°)/s以内。实验结果验证了文中对卫星姿态稳定度的分析, 证明了像移速度场模型的准确性, 为大视场空间相机像移补偿提供了可靠依据。

To compensate the image motion of a space camera with large field, a general image motion velocity field model was established by combination of coordinate transformation and attitude dynamics for an off-axis three mirror anastigmat camera. In modelling, the effect of off-axis angles of three-mirror system on the image motion was taken into account, and the formulas of image motion velocity field in the off-axis three-mirror system were derived. By taking a space camera with large field for an example, the distribution characteristics of imaging motion velocity field under three typical imaging attitudes were analyzed. The influence of three axis attitude stability on imaging quality of the satellite was studied. The results indicate that the decline of satellite attitude stability, especially the pitching attitude stability, will lead to the decrease of dynamic Modulation Transfer Function (MTF)of focal plane. And the decrease is more obvious when the integration stages are increased. Moreover, the satellite attitude should be more stable when the camera is imaged in a side rolling with a large angle. For the space camera with 96 integration stages and the reduction of MTF no more than 5%, the satellite three-axis attitude stability should be controlled under 0.001(°)/s. the experiment results confirm the above analysis of satellite stability, verify the accuracy of the proposed image motion velocity field model and provide a reliable basis for the image motion compensation of space cameras with large fields.