为了实现激光投影仪器或系统的自动聚焦, 研究搭建了激光动态聚焦系统。该系统可依据背向反射光强信号的变化调节聚焦系统的镜组间距, 使激光扫描投影系统能够在不同距离的投影面上聚焦出最小光斑, 从而提高系统的定位精度。根据激光动态自聚焦系统的原理, 设计了光学杠杆型和反远距型2种动态自聚焦方案, 并推导出相应的数学模型; 利用ZEMAX光学设计软件进行仿真实验, 通过比较得出响应更加灵敏、结构更加合理的自聚焦系统; 搭建新型自聚焦激光扫描投影系统对动态自聚焦性能进行了验证。实验结果表明: 反远距型动态自聚焦系统更加合理, 在4.5 m处的投影面上, 汇聚光斑直径最优可达0.2 mm, 可使激光扫描投影仪在进行辅助装配时的定位准确度提高至0.1 mm, 能够达到先进制造装配工程中零部件的精准定位要求。

In order to realize the automatic focus of laser projection system, a laser dynamic focusing system was constructed. The system can adjust the mirror group spacing of the focusing system according to the change of the back-reflected light intensity signal, so that the laser scanning projection system can focus the minimum spot on the projection surface at different distances, thereby improving the positioning accuracy of the system. Firstly, according to the principle of laser dynamic self-focusing system, two kinds of dynamic self-focusing schemes, optical lever type and inverted telephoto type, were designed and the corresponding mathematical models were derived; then, through the simulation of ZEMAX, two dynamic focusing systems were compared, and the self-focusing system with faster response speed and more reasonable structure was chosen; finally, a new self-focusing laser scanning projection system was set up ,and the performance of dynamic focusing was verified. The experimental results show that the inverted telephoto type self-focusing system is more reasonable, at a projection surface of 4.5 m, the converging spot diameter is optimally up to 0.2 mm, which can improve the positioning accuracy of the laser scanning projector during auxiliary assembly to 0.1 mm. It can meet the precise positioning requirements of components in advanced manufacturing and assembly engineering.