Design of a Laser Beam Expander for Laser Tracking and Aiming System

In the laser's long-distance tracking and aiming system,collimated laser beam is demanded.To meet this requirement,a laser expander with the ratio of 18 was designed.In this paper,the design method of the laser expander is introduced systematically.Based on the theory of transformation of Gaussian beam through thin lens,the perfect distance of defocusing is calculated out,and the effect of defocusing on the location of exit beam waist and the radius of beam waist are analyzed.The analysis shows that the efficiency of beam expanding is very sensitive to defocusing.The main issues that should be paid attention in precision focusing are predicted.