针对以凸面镜作为反射式点光源的系统建模不够完善,限制其指向精度提高的问题,提出以太阳矢量为参照基准的系统建模方法,提高了系统指向精度。通过实验数据的线性度拟合确定拟合系数R2在0.999以上,确保了实验数据的可靠性,以最小二乘法解算模型求解系统固有安置几何误差,最后,通过反解模型求解目标值方法和太阳图像质心比对法,分别验证标校后模型的正确性。实验结果表明,目标编码器角度与实际测量角度值基本一致,俯仰角度误差标准偏差为0.0043°,方位角度误差标准差为0.00299°,误差范围保持在0.04°以内,图像质心比对法像素差值在2 pixel左右,对应的像素角分辨率误差在0.036°上下,系统综合指向精度优于0.1°,验证了此种方法建模的正确性与可行性,为实现多空间分辨率的高分辨率光学遥感卫星传感器高精度、高频次、业务化、全动态范围的在轨绝对辐射定标奠定了基础。

A system modeling method based on solar vector is proposed to improve the system modeling and pointing accuracy of convex mirrors which are used as reflective light sources. The fitting coefficient (R²) of 0.999 or higher obtained by linearity fitting of experimental data ensures the reliability of our experimental data. The model is solved by the least-squares method,and inherent geometric errors of the system are obtained. Finally, the correctness of the calibrated model is verified by using the reverse model to solve the target value and comparing the centroid of the sun image. The experimental results show that the angle of the target encoder is essentially the same as that of the actual measurement. To summarize, the standard deviation of pitch angle error is 0.0043°, standard deviation of azimuth angle error is 0.00299°, error range is kept within 0.04°, difference of image centroid pixel is approximately 2 pixel, angular resolution error of pixel is approximately 0.036°, and comprehensive pointing accuracy of the system is better than 0.1°. Therefore, the validity and feasibility of this method are verified; this lays the foundation for the on-orbit absolute radiometric calibration of multi-spatial resolution optical remote-sensing satellite sensors with high accuracy, high frequency, and operational and full dynamic range.