Abstract: The laser beam divergence angle is one of the important parameters to evaluate the quality of the laser beam. It can not only accurately indicate the nature of the beam divergence when the laser beam is transmitted over a long distance, but also objectively evaluate the performance of the laser system. At present, lidar has received a lot of attention as a core component of environment awareness technology. Micro-electromechanical system (MEMS) micromirror has become the first choice for three-dimensional imaging lidar because of its small size and fast scanning speed. However, due to the small size of the MEMS micromirror, the lidar scanning system has a small field of view (FOV). In order to achieve a wide range of scanning imaging, collimating optical system and wide-angle optical system are generally added to the system. However, due to the inherent properties of the optical lens, it is impossible to perfect the imaging, so the effects of collimating and expanding the beam will be different at different angles. This article aims to propose a measurement system that dynamically measures the divergence angles of MEMS scanning lidar beams in different fields of view to objectively evaluate the performances of scanning lidar systems.

Key words: laser divergence angle, lidar, CCD, different fields of view (FOV)