We propose a method to correct the error induced by the obscurations of Ritchey-Chretien (R-C) collimators, when measuring modulation transfer function (MTF) of high-resolution space cameras by the ISO 12,233 slanted-edge method. The obscurations of an R-C collimator include the secondary mirror (SM) and its supporting bars. Mathematical models are derived to simulate possible obscurations by virtual surfaces of Zemax, with which we get the correction function (CF) of the obscuration induced error (OIE). Simulated results manifest that the proposed method can correct the OIE. Furthermore, an experiment setup is established with the same system parameters of the previous Zemax modeled system. The experiment results verify the effectiveness of the proposed method again. Our method can guarantee the precision of the ISO 12,233 slanted-edge method when an R-C collimator is chosen.

当通过ISO 12,233斜边方法测量高分辨率空间相机的调制传递函数（MTF）时，我们提出了一种校正由Ritchey-Chretien（RC）准直器的遮蔽引起的误差的方法。RC准直仪的遮盖物包括辅助镜（SM）及其支撑杆。推导了数学模型，以模拟Zemax虚拟表面可能产生的遮挡，从而获得遮挡引起的误差（OIE）的校正函数（CF）。仿真结果表明，该方法可以校正OIE。此外，使用与以前的Zemax建模系统相同的系统参数建立了实验设置。实验结果再次验证了该方法的有效性。我们的方法可以保证ISO 12的精度