激光传输湍流大气的折射率起伏双尺度模型

运用Kolmogorov 1941串级湍流模型理论和近似①湍流大气中传输激光束的强度起伏可抽象为大尺度湍涡导致对小尺度湍涡产生强度起伏倍乘性再调制的双尺度过程;②分别由大尺度湍涡和小尺度湍涡产生的光闪烁相互统计独立;③在双尺度模型下,即使在湍流起伏饱和区,用于处理光闪烁的Rytov方法仍然适用.导出了包含湍流内外尺度因子的简化折射率起伏双尺度模型和湍流大气中传输平面波的闪烁孔径平滑因子.结果表明,有限湍流内、外尺度在0.5＜d＜3.5孔径区域增加了闪烁的孔径平滑作用.

Two-scales Model of the Refractive-index Fluctuations for Laser Propagation in an Atmospheric Turbulence

Using the cascade turbulent model of the Kolmogorov 1941 theory and the approximation:①the irradiance fluctuations of an laser beam propagation in a turbulent atmosphere can be modeled as a two-scales modulation process in which the fluctuations caused by small-scale eddies are multiplicatively modulated by the fluctuations which are caused by large-scale eddies;②The scintillations caused by small-and large-scale eddy,respectively,are statistically independent;③The Rytov method for optical scintillation is valid even into the saturation regime with the two scales model,we develop a relatively simple two-scale model of the refractive-index fluctuations which include the outer-and inner-scale of turbulence and the aperture-averaging factor of optical scintillations for plane wave propagating in the turbulent atmosphere.The results show that the finite outer-and inner-scale increase the affection of the aperture averaging for optical scintillations in the regime of 0.5＜d＜3.5.