湍流大气中准直激光束的光斑特征Ⅰ.特征半径

利用数值方法研究了不同光传播起伏条件下湍流大气中准直激光束的光斑特征 ,结果表明 ,光斑稳定半径(Rrbt)和等效半径 (Reff)具有很好的相关性 ,虽然Rrbt 可应用于更一般的光斑 ,但它们都不适合衡量光斑质量 ;而锐度半径 (Rshp)可以恰当地反映光斑质量。对于准直激光束 ,在极弱起伏条件下 ,约有一半的光斑其质量变好或变差 ,但变化幅度很小 ;随起伏条件的加强 ,越来越多的光斑质量变差 ,但仍有一部分光斑质量变好 ,且程度越来越高

Pattern Characteristics of Collimated Laser Beam in a Turbulent Atmosphere Ⅰ.Characteristic Radii

Besides the effective radius R eff , the robust radius R rbt  and the sharpness radius R shp  are introduced. The validity of three kinds of radii, two characteristic radii, for describing the pattern quality are test through numerically generated patterns of a collimated laser beam propagating through a turbulent atmosphere, and main results could be summarized as follows. R rbt  and R eff  are equivalent for Gaussian beams, but the former can be used for more general patterns. Both of them are not valid for evaluating the pattern quality; and R shp  can well used for the purpose. For laser beam patterns in the turbulence under very weak fluctuation condition, in a very limited extent, the pattern quality for half of them will be degraded, and for another half the quality will be refined. With increase of the fluctuation condition, the quality of more and more patterns will be degraded, and there still be some patterns whose quality will be refined in a deeper extent.