研究了光学元件装调加工误差引起的光斑尺寸和光轴偏转对空间光混频器混频效率的影响。推导了高斯模型下的光混频效率表达式, 得到当光斑尺寸与靶面尺寸的比例为0.64时, 混频效率最高。在此基础上推导了光斑尺寸偏差、光轴偏转与光混频效率的表达式。并进行仿真分析, 得到光斑尺寸偏差、光轴偏转与光混频效率变化曲线。当混频效率大于10%时, 光斑尺寸偏差范围为-42~250 μm, 光轴偏转范围为203 μrad。通过计算光斑尺寸偏差和光轴偏转综合误差发现, 调整光斑尺寸偏差可以改善光轴偏转带来的混频效率恶化。进一步搭建空间光混频器影响因素实验平台, 进行了三种光斑尺寸偏差下光混频效率随光轴偏转变化的实验。实验所测曲线与仿真结果趋势一致, 受实验器件插入损耗的影响, 实验值略低于仿真值。所得影响规律为空间光混频器设计、装调和加工提供了一定参考。

Effect of light spot size and optical axis deflection on heterodyne efficiency of space optical hybrid was focused on in this paper. With deduction of the heterodyne efficiency expression based on Gaussian model, the result shows that when the proportion of the light spot size and target plane equals 0.64, the heterodyne efficiency reaches optimal. Then by calculating and simulating the expressions which included spot size deviation and optical axis deflection, the curve of relation between heterodyne efficiency and spot size deviation and optical axis deflection was obtained. By these works several results can be shown: Firstly, the scope of spot size deviation is between -42 μm and 250 μm and the scope of axis deflection is 203 μrad when heterodyne efficiency is 10%. Besides, by calculating the spot size deviation and comprehensive optical axis deflection error, negative influence of heterodyne caused by axis error can be improved with modulating the light spot size deviation. In order to test the theoretical result, an experimental platform of influence factor of spatial optical hybrid was built up and an experiment of deflection angle of optical axis with choosing three light spot sizes was implemented. The result is consistent with that of the simulation. The curves of actual measurement are slightly less than the theoretical value because of the influence of insertion loss caused by experiment components. These influence obtained may provide technical reference for the design, adjustment and process of spatial optical hybrid.