星相机的指向精度是评价星相机性能的最重要的指标。提出了针对亚角秒级星相机的实验室精度测定方法。基于静态多星靶标和平行光管完成了瞬态误差(Temporal Error, TE)的测量, 并考虑了星相机实际使用时的信号水平; 采用Stewart平台进行微距调整, 通过帧间差分处理获取同名星点间的坐标差, 经统计分析可以得到高频误差HSFE, 优点是避免了规划特殊路径; 通过使用不同谱段的滤光片, 等效计算得到色差导致的低频误差LSFE; 此外, 还给出了星相机畸变标定导致的低频误差和星点靶标标记误差导致的低频误差。试验结果与设计值一致, 验证了上述方法的有效性。

Pointing accuracy is the most important parameter to evaluate the performance of the star camera. Laboratory accuracy determination methods for sub-arcsec star camera were presented. Temporal error (TE) was tested with static multiple stars target and collimator considering real signal level of the star camera. Stewart platform was used to adjust the camera with micro-steps, inter-frame difference method was applied to obtain relative distance of tie-points, then high spatial frequency error (HSFE) was calculated with statistics method with the benefit of avoiding planning special paths. Low spatial frequency error (LSFE) introduced by chromatic aberration was measured equivalently with different kind of optical filters; moreover, LSFE in distortion calibration and target measurement was calculated. Test is taken and the result is in line with design value, the validity of the above methods is verified.