In order to solve the two disadvantages, serious divergence and limited scanning angle, of the traditional optical angle expansion in MEMS-based scanning system, a new method is proposed, i.e. an f-theta lens group and a wide-angle lens group are added into the traditional one. Principle of the optical angle expansion is discussed, while the relationship between emergent angle and incident angles has been given. Employing the optical design software ZEMAX, a folding scanning optical system based on MEMS mirror is designed thereafter. The folding scanning optical system we designed can not only scan in a large angle field, which is greater than $60°$, but also obtain small spot size at distance of about 160 m, where the spot size is less than 10 cm. This folding scanning optical system has a significant application value in 3D imaging lidar system.

为了解决基于MEMS的扫描系统中传统的光学角扩展的严重缺点，即散度大和扫描角受限，提出了一种新的方法，即增加了f-theta透镜组和广角透镜组。变成传统的。讨论了光学角扩展的原理，同时给出了出射角与入射角之间的关系。此后，使用光学设计软件ZEMAX，设计了基于MEMS反射镜的折叠式扫描光学系统。我们设计的折叠式扫描光学系统不仅可以在大角度场中进行扫描，还可以$60°$，但在光点尺寸小于10 cm的情况下，在约160 m的距离处也可以获得较小的光点尺寸。该折叠式扫描光学系统在3D成像激光雷达系统中具有重要的应用价值。