Optical design of a new folding scanning system in MEMS-based lidar

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 degrees, 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.