中文摘要：

为了用同一台仪器获得不同口径的激光准直光束,设计了一个连续变倍激光扩束系统,系统扩束比可在55-155之间连续变化,可以得到比传统扩束系统更大的激光光斑,满足对大口径激光束应用的要求。该系统由两级扩束子系统构成,一级折射式无焦变倍扩束系统实现激光光束口径连续变化,变焦系统选用仅有4片透镜的三组元结构,并采用＂正-负-正＂的形式,有利于减小系统整体结构尺寸。考虑到可能产生的热形变,对入射光斑较小的变倍移动组的材料进行了分析选择。二级折反射系统实现激光束的高倍率扩束,由球面反射镜取代离轴抛物面镜,用一片弯月透镜补偿像差。由于单透镜折射元件对系统性能影响很大,对其结构形式和材料进行了分析,确定了透镜的厚度与材料。应用光学设计软件CODEV给出了系统的优化设计,设计结果显示该系统像差得到了很好地校正,成像质量达到衍射极限。最后用Lighttools软件进行三维建模分析,系统准直度与理论设计值相符。

英文摘要：

In order to obtain different diameters of laser beam by using one optical system, a catadiopric beam expander zoom optical system was designed. The beam expanding ratio was changed from 55 to 155 continuously, which was greater than before, and could expand the application areas. The system was composed of two main parts： one afocal zoom system was located in the front could achieve continuous laser beam expanding. Only four sphere lenses were used to design the zoom system. In order to reduce the size of total system, a ＂Positive-Negative-Positive＂ form was introduced. The material of variable part of zoom system was analyzed because the beam diameter was so small that the distortion was appeared for the temperature changing by the laser irradiation. The other secondary catadioptric system was used to achieve high ratio beam expanding. A sphere mirror was used to replace an off-axial parabolic mirror, and a meniscus lens was introduced to compensate aberrations. The lens in the secondary system was so important to the performance that it was analyzed, and then the thickness and material of the lens were chosen. The model was built up in CODEV. By optimizing aberrations, the performance of the system reaches diffraction limitation after adding perfect lens. Finally, the software light tools were used to analyze the collimation and the result matches the theoretical design.