分析了温度梯度和均匀温度对潜望式激光通信终端反射镜形变的影响, 利用椭圆域上的Zernike多项式对椭圆反射镜的波前进行拟合, 计算由于热形变导致的波前畸变误差, 给出了星间激光通信终端反射镜均方根值、发射光束瞄准误差、接收端光强随温度梯度和均匀温度的变化关系。结果表明:温度梯度对反射镜的影响只是引起峰值光强的漂移和少许下降, 当温度梯度为14 ℃/m时瞄准误差达2.1 μrad。均匀温度会引起接收端的光强分布变化, 从而导致很大的瞄准误差和光强衰减, 当均匀温度与参考温度的差值小于0.6 ℃时, 由波前畸变误差引起的瞄准误差小于1 μrad, 当差值大于0.6 ℃时, 瞄准误差突然增大到几μrad, 接收端光强分布发生变化, 此时反射镜热形变引起的像散项对光强分布起重要作用。

Effects of temperature gradient and uniform temperature on reflectors in periscopic laser communication terminals were studied. Zernike polynomials on elliptical aperture were used to fit wave-front aberration of the elliptical reflectors due to temperature distribution. RMS value, pointing error and peak intensity degradation at the receiver caused by thermal deformation were studied in inter-satellite laser communication system. The results show that the effect of temperature gradient cause drift of peak intensity and a little degradation. The pointing error reaches 2.1 μrad when temperature gradient is 14 ℃/m. The uniform temperature will cause variation of intensity distribution at the receiver and result in larger pointing error and degradation of intensity. The pointing error is less than 1 μrad when the difference between uniform temperature and reference temperature is less than 0.6 ℃. But the pointing error rises rapidly and the intensity distribution changes when the difference is larger than 0.6 ℃. The astigmatism caused by thermal distortion is very important.