卡塞格林光学遥感系统相当于一个望远系统和环形光阑的组合，无穷远物的夫琅禾费衍射谱是圆孔衍射和圆屏衍射共同作用的结果。由于系统次镜中心遮拦的影响，损失了一部分衍射谱，造成了系统调制传递函数（MTF）在中频段的下降，影响了成像质量。设计了一个2 m焦距的改进型卡塞格林光学系统。为了弥补系统成像质量的损失，运用调制传递函数补偿（MTFC）技术，通过倾斜刃边法提取卡塞格林系统所拍摄图像的点扩展函数（PSF），对退化图像进行复原，并利用多种客观图像质量评价函数对复原效果进行了评价。实验结果表明，该方法对于卡塞格林系统成像质量的提高具有良好效果。

Cassegrain optical remote sensing system is a combination of telescope system and annular aperture. Its Fraunhofer diffraction of infinite objects is the joint result of circular hole diffraction and circular screen diffraction. Because of the loss of diffraction due to central obscuration of circular screen, modulation transfer function (MTF) of the system degrades greatly in middle frequency, and this directly affects the imaging quality. A Cassegrain optical remote sensing system is designed whose focal length is 2 m. In order to make up for the loss of the image quality, a modulation transfer function compensation (MTFC) technology is used, in which the point spread function (PSF) of image is obtained by slanted-edge method, to recovery image. Some assessment functions are used to evaluate the recovery results. The experimental results indicate that the image quality is improved obviously.