准直光束在折迭路径上的孔径平滑效应

本文根据反射光路上对数振幅在弱起伏区的相关特性讨论了接收光强闪烁的孔径平滑效应.计算结果表明准直光束在反射路径上的相关长度略小于直接光路上的值,但在量级上均与第一菲涅尔带半径相当.与此相适应,直接光路上的孔径平滑因子要大于反射光路上的值.这个事实意味着使用反射镜可以降低湍流对光强起伏的影响.实验结果是完全支持上述结论的.

Aperture-averaging effects for collimated beam in a folded path

The correlation function of log amplitude fluctuations of a wave reflected from a plane target in turbulent atmosphere is derived for a weak fluctuation region and is used to evaluate the aperture-averaging effect. The results show that the correlation length of the collimated beam propagating in a folded path is smaller than that of the wave propagating the same total lengnth in the forward direction, they both agree in order of magnitude with the radius of the first Fresnel zone. From this, the aperture averaging factor in a straight path is greater than that in a folded path,which means that the turbulence induced ingtensity fluctuation can be reduced by means of a reflector.The agreement of our experimental results with our theoretical prediction is excellent.