高精度多波段空间光通信端机远场分布测试系统研究

Study on High Precision and Multiband Far Field Distribution Measuring System of Space Laser Communication Terminals

分析了基于透镜的傅里叶变换特性实现空间光通信端机远场分布测试原理，以球差、彗差为代表模拟测试系统自身像差对焦面光强分布的影响，由结果可以看出球差主要影响最大光强，其分布仍然保持旋转对称性，而彗差不仅使得光强峰值减弱，且接收面上光强变为非旋转对称分布，当系统像差均方根（RMS）值小于0．02λ时，最大光强的变化小于0．2％，可以忽略不计。基于以上分析，设计了离轴卡塞格林长焦系统，利用Zemax-EE对系统进行了分析，分析结果表明，在整个工作波段（800～1700nm）内，中心视场RMS值为0．0001λ，全视场点列图均远优于衍射极限。对研制完成的远场分布测试系统进行了测试，得到的光斑暗环实际值与理论值的误差均在2．5％以内，满足要求。

The principle of the far field distribution measurement of space laser communication terminals based on the Fourier-transform characteristics of lens is analyzed. The influence of test system with spherical and coma aberrations on the far field distribution of the beam is described and simulated. The simulated results show that the spherical and coma aberrations both reduce the maximum power at the receiving plane and the rotational symmetry of field distribution is only influenced by coma aberrations. The maximum power changes by lower than 0.2 % with the root mean squares （RMS） developed. The measurement system is analyzed with Zemax-EE software. The analyzed results demonstrate that the RMS aberrations of the test system are below 0.02λ. The wavefront error of a long focal off-axis Cassegrain optical system is less than 0. 0001λ in the working wavelength （800 ~ 1700 nm） and good diffraction-limited quality is obtained in full field. The experimental results indicate that the maximum dusky ring dimension error is less than 2.5 % compared with the theoretical values. These results prove the feasibility of the far field distribution measurement system.