中文摘要：

红外探测器的尺寸是制约光学系统大幅宽成像的重要因素，选择合适的光学系统结构和成像方式，则可以规避探测器的限制。文中提出了一种像方摆扫成像模式，基于成熟的常规尺寸红外面阵探测器，采用多帧图像拼接的方式，满足了光学系统的大幅宽成像要求。鉴于像方摆扫需要在平行光路中进行，在两反无焦系统的基础上，研究了三反无焦系统的设计方法，给出了初始结构的计算公式。光学系统总体上分为前置的无焦压缩系统、扫描摆镜、成像组。其中，扫描摆镜位于平行光路中的出瞳位置，采用视场分光的方式分别实现中波红外和长波红外成像，通过仿真分析，光学系统的冷反射得到有效抑制，MTF接近衍射极限。

英文摘要：

The design of optical systems with wide ground coverage are restricted by the size of infrared detector. This problem can be solved by choosing the appropriate imaging mode. A kind of image space scanning method was given in the paper. It could satisfy the optical systems with general area infrared detectors. The picture was built by image mosaics technology. Because the image space scanning method needs to be done in the parallel light path, the design method of three-mirror afocal system was studied based on two-mirror afocal system and the formulas to compute the initial structure was given. The optical system consists of afocal system, scanning mirror and imaging part. The scanning mirror was placed at the exit pupil of the afoacl system. The MWIR and LWIR were separated by the field-bias method and imaged respectively. The simulation analysis shows that the Narcissus is under control and the MTF of the optical system is very close to the diffraction limit.