摘要
根据光波在湍流大气中传播的理论分析了弱起伏条件下决定光波传播效应的折射率结构常数Ｃ２ｎ的各种路径积分参量之间的关系，导出了由光波的强度起伏所确定的等效折射率结构常数对计算大气相干长度与光波的到达角起伏、光束的扩展及漂移的相对偏差的表达式。针对折射率结构常数Ｃ２ｎ具有周期性、递减、递增和随机分布的典型湍流路径，详细分析了各相对偏差的特征。对周期性湍流路径，各相对偏差的绝对值随Ｃ２ｎ路径起伏振幅的增大而增大；随Ｃ２ｎ路径变化频率的增大作阻尼振荡并迅速趋于零。对应于递减和递增路径，存在着相当大的相对偏差。对应于随机路径，各相对偏差的时间序列呈现出强烈的随机特征，它们的时间序列统计均方根值随路径上独立变化的湍流区间数的增大而迅速减小。
The relationship between the light propagation effects in the turbulent atmosphere and the path integral parameters of the refractive index structure constant C 2 n is analyzed with the theory of light propagation in the turbulent atmosphere. The path integral parameters of C 2 n corresponding to the coherent length, the fluctuation of the arriving angle, the spreading and wandering of light beam are obtained with the equivalent refractive index structure constant derived from the measurement of the light intensity fluctuation, and the relative differences of these parameters with true values are evaluated. For periodic, decreasing, increasing, and random turbulent paths the relative differences are calculated as functions of various path parameters. The relative differences for the periodic turbulent path increase with the amplitude parameter and behave as damped oscillations with the frequency parameter. The relative differences for the decreasing and the increasing turbulent path are quite high. For a random turbulent path, the relative differences fluctuate with time series number and their statistical average values decrease with the number of the independent turbulent intervals. Suggestions for the accurate evaluation of the optical turbulence effects are given according to the results.
出处
《光学学报》
EI
CAS
CSCD
北大核心
1997年第1期79-85,共7页
Acta Optica Sinica
关键词
光传播
大气湍流
随机介质
大气光学
light propagation, atmospheric turbulence, random media.
