采用ZEMAX对单点激光测振仪中的扩束聚焦镜进行了分析设计。首先对高斯氦氖激光光源进行了模拟，然后计算了系统的初始结构。分析了前透镜移动距离与激光聚焦距离的关系，获得了不同聚焦距离下的光斑尺寸。最后设计了可调扩束聚焦系统的机械结构。该结构具有调节平滑，前透镜不旋转的特点，减小了由旋转透镜带来的误差。

A beam expanding focusing lens of single scanning laser vibrometer is analyzed and designed by ZEMAX. Firstly, the Gauss He-Ne laser source is simulated, and then the initial structure of the system is calculated. The relationship between the moving distance of the front lens and the laser focusing distance is analyzed, and the spot sizes at different focusing distances are obtained. Finally, the mechanical structure of the adjustable focusing system is designed. The adjustment of the structure is smooth, and the front lens can not rotate. Thereby the errors caused by rotating lens are reduced.