斜程大气传输部分相干平顶光束的空间相干度

Spatial coherence of partially coherent fiat-topped beam in the slant atmosphere path

为了研究不同天顶角、传输距离、光源相干性以及湍流外尺度对接收面光束空间相干度的影响,采用广义惠更斯-菲涅耳原理和相位结构函数的平方近似,并运用张量积分的方法,得到了部分相干平顶光束通过斜程湍流大气传输后接收面光束空间相干度的解析表达式。结果表明,传输距离较短时,该光束空间相干度随两点距离的增加出现振荡现象,而传输距离较长时振荡现象消失;当传输距离给定时,天顶角越大,光束空间相干度的有效宽度相对较短。初始相干长度较短的该类光束其空间相干度的宽度不随传输距离的增加而减小;长距离传输后,光束空间相干性与光束初始相干长度不再有关。

In order to study the effect of different zenith angles,propagation distances,coherence of source and outer scale of turbulence on the spatial coherenee on the receiver, based on the extended Huygens-Fresnel principle and the quadratic approximation of phase structure function, the expression of the spatial coherence for partially coherent flat-topped beam propagating through slant turbulent atmosphere was derived with the help of tensor integral. Results show that the spatial coherence of the beam oscillates with the increase of distance between two observed points for shorter propagation distances in slant atmosphere path and the oscillating phenomenon disappears for longer propagation distances. When the propagation distance is fixed, the width of spatial coherence is shorter at larger zenith angles. In the slant atmosphere path, for the beam with shorter initial coherent lengths, the width of spatial coherence doesn＇t become shorter with the increase of propagation distance. The spatial coherence of the beam is not relevant to its initial coherence for longer propagation distances.