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大气湍流的存在将会直接影响激光雷达测距数据的离散分布特性。为此，本文在进行深入调研的基础上，改进和优化了以相位屏传播理论为基础的激光大气湍流传播算法，在 Matlab7.13 软件环境下编写了仿真程序。该程序能够分析大气湍流强度、传播距离以及大气湍流尺度等对激光雷达回波信号起伏特性的影响。通过大量的数值计算，分析了大气湍流强度对激光雷达回波信号起伏特性的影响，结果表明，随着大气湍流强度增强，光斑分布相比于真空传播将出现畸变甚至破碎的现象，表明其受到的湍流的影响较大；信号幅度的统计分布随着湍流强度的减弱，或相干长度的增加，越来越接近正态分布的形式。 本文所做的研究对于激光雷达系统的优化设计和性能评估有一定的参考价值。7498
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关键词 大气湍流 激光雷达回波信号 相位屏 强度起伏
Title Affect of turbulence near-ground on amplitude fluctuation of laser radar echo-signal
Abstract
At the presence of atmospheric turbulence, the characteristics of discrete
distribution of laser radar ranging data will be directly affected. To this
end, on the basis of in-depth research on literature, this paper improved
and optimized the algorithm of phase-screen theory based laser propagation
in turbulence, a simulation program has been written in Matlab7.13 software
environment. This program can analyze the intensity of atmospheric
turbulence, the propagation distance and atmospheric turbulence scales on
the characteristics of intensity fluctuation. Through a large number of
numerical calculation, the characteristics of intensity fluctuation of
laser radar echo signal has been analyzed. From image of echo-signal we
can see that with the turbulence intensity increasing, Spot distribution
appears to be distorted or broken compared with spreading in a vacuum; with
the turbulence intensity decreasing or the coherent length increasing,
statistical distribution of echo-signal amplitude closer to normal
distribution.
This article made some reference value for the optimization of the laser radar system design and performance evaluation.
Keywords atmospheric turbulence, laser radar echo-signal, phase screen,
intensity fluctuation 目 次
1 绪论 1
1.1 研究背景. 1
1.2 国内外研究进展. 1
1.2.1 湍流介质中光传播 2
1.2.2 光强闪烁研究进展 3
1.2.3 数值模拟发展状况 5
1.3 本文的主要工作. 6
2 大气湍流理论 7
2.1 折射率结构函数 7
2.2 大气能量密度谱. 9
2.3 大气湍流对激光传输的影响. 10
3 相位屏算法 12
3.1 湍流中的光场. 12
3.2 分步光束传播方法理论分析. 13
3.3 吸收边界理论分析. 14
3.4 相位屏模型的建立. 16
4 数值模拟及计算结果 19
4.1 相位屏的生成. 19
4.2 大气传输回波的数值模拟. 21
4.3 反射光强分析. 22
4.3.1 激光雷达回波强度空间分布. 26
4.3.2 激光雷达回波强度统计分布. 28
结 论 30
致 谢 31
参 考 文 献 32
1
1 绪论
1.1 研究背景
由于激光所特有的高强度、高单色性、高相干性、高方向性等诸多特性，因