大口径空间相机像质的微振动频率响应计算

由于大口径空间相机对空间环境变化和卫星内部振源引起的微振动十分敏感,本文研究了影响成像质量的微振动频率响应的计算方法,以改善相机的在轨动态成像质量。该方法通过实际光学模型取代线性光学模型,建立微振动光机集成模型,从而计算影响成像质量的微振动频率响应。首先,建立大口径空间相机有限元模型,进行结构频率响应计算,得到采样频率点的光学表面节点位移和相位。然后,通过蒙特卡洛分析方法,建立微振动光机集成模型,以均方根光学系统动态传递函数和视轴漂移衡量大口径空间相机动态成像性能。最后,研制了大口径空间相机力学样机,对其进行了振动试验,验证了有限元模型的正确性。试验结果表明仿真结果与试验结果接近,误差均在5%以内,满足大口径空间相机动态成像质量分析的要求。

Frequency response of imaging quality by micro-vibration for large-aperture space-borne telescope

The imaging quality of a large-aperture space-borne telescope is very sensitive to the micro-vibration induced by space environmental variation and the vibration inner of a satellite. Therefore, this paper researches the calculation method of frequency response of imaging quality effected by the micro-vibration to improve the dynamic imaging quality of the satellite in orbit. By using a real optical model to replace the linear optical model, it establishes an optical-mechanical integrated model to calculate the frequency response of the micro-vibration. Firstly, it builds Finite Element Model(FEM) for a space-borne telescope to calculate the structural frequency response and to obtain the displacement and phase of the optical surface nodes for each sampling frequency point. Then, the Monte-Carlo statistical method is used to establish the the optical-mechanical integrated model, and the root-mean-square (RMS) of system dynamic Modulation Transfer Function(MTF) and the Line of Sight(LOS) drift are analyzed to measure dynamic imaging performance of the large-aperture space-borne telescope. Finally, a structural prototype of large-aperture space-borne telescope is developed to verify the reliability of the FEM. The results show that the measured frequency is close to that of the FEM analysis and the error is under 5%, which meets the requirements of large-aperture space-borne telescopes for analysis of the dynamic imaging quality.