设计了一种高清成像的硬性内窥镜。通过控制特征光线在中继透镜表面上的入射高度和出射角，可保证有效视场和通光孔径内所有的光线在口径为2.7 mm的透镜组中正常传播。将入瞳直径提高到0.3 mm，使物方分辨率优于21 lp/mm，角分辨率为8.45 C/(°)。同时有效避免棒镜内壁的全反射杂光导致像质下降。系统成像质量达到了衍射极限，调制传递函数值在空间频率120 lp/mm处大于0.3；通过将系统设置为多重物距的结构实现大景深设计。加入目镜优化设计后，整体系统的调制传递函数值在空间频率3 lp/mrad处为0.1，达到了人眼的分辨极限。测试验证表明，完成研制的内窥镜系统分辨率达到设计值。

A rigid endoscope with high definition is designed. In order to ensure the effective field of view and normal transmission path in the limited lenses with diameters of 2.7 mm, the incident height and exit angle on the relay lens of feature rays are controlled during the optimization. As a result, an entrance pupil of 0.3 mm is achieved, with a resolution of higher than 21 lp/mm and an angular resolution of 8.45 C/(°) in the object space. Stray light caused by total reflection on the inner wall of the rod lens is avoided at the same time. The modulation transfer function (MTF) reaches diffraction limit and the values of all fields are higher than 0.3 at 120 lp/mm. By taking consideration of large depth of field (DOF), a system with multiple object distance configurations is set up before the optimization. After optimization with an eyepiece added, the MTF values of all fields are 0.1 at 3 lp/mrad, close to the resolution limit of human eye. Test results show that the resolution of fabricated system reaches theoretical design values.