近地大气湍流对激光传输信号幅度起伏特性的影响

【作者】 黄宏坤；

【导师】 来建成；

【作者基本信息】 南京理工大学 ， 光学工程， 2012， 硕士

【摘要】 大气湍流的存在将引起激光传输信号的幅度起伏,从而会影响激光测量和探测设备的性能。为了分析和评估湍流场对激光传输信号的影响,本文通过数值计算和实验两种途径研究了近地大气湍流对激光传输信号幅度起伏特性的影响。在理论上,以角谱传播理论为基础,结合FFT功率谱反演生成相位屏,建立了激光在大气湍流中传播的数值计算模型,并在Matlab7.8软件环境下,编写计算程序。通过大量的数值计算,分析了高斯光束在不同强度湍流场中传播不同距离后的光斑分布及特定面积上光信号的幅度统计特性、大气湍流对单向激光传输系统中接收光信号幅度起伏特性的影响和大气湍流对激光测距回波信号幅度起伏特性的影响等问题。在实验上,基于大气湍流的温湿度模型,搭建室内模拟大气湍流场的实验装置,研究了大气湍流对激光测距回波信号幅度起伏特性和测距数据离散性的影响。结果表明：随着湍流强度的增强和传播距离的减小以及敏感元面积的增大,接收光信号幅度统计分布越来越偏离正态分布且对称性越差；随着湍流强度和传播距离的增大以及敏感元面积的减小,光信号幅度平均值逐渐减小、幅度统计离散分布范围更宽。此外,激光雷达回波信号随着湍流强度的增大,幅度统计分布更趋于分散,幅度平均值逐渐减小,进而导致激光雷达测距统计分布呈现相应的离散分布。更多还原

【Abstract】 The presence of atmospheric turbulence will cause the laser transmission signal amplitude fluctuations, which will affect the laser measurement and the performance of detection equipment. In order to analyze and evaluate the influence of turbulence on the laser transmission signals, numerical simulations and experiments are used to study the impact of atmospheric turbulence on laser transmission characteristics of the signal amplitude fluctuations in this paper. In theory, based on the theory of angular spectrum propagation, and combined with inverse FFT power spectrum to generate the phase screen, a numerical model of laser propagating in atmospheric turbulence is established. The computer program is written in Matlab7.8 software environment. By a mass of numerical calculations, we studied the spot distribution of Gaussian beam propagation in the turbulent atmosphere of different intensity at different distances, the statistical properties of optical signal amplitude on specific area, the effect of atmospheric turbulence on the property of received optical laser signal amplitude fluctuation in one-way laser transmission system, and the effect of atmospheric turbulence on the property of laser ranging echo signal amplitude fluctuation. In the experiment, based on temperature and humidity models of atmospheric turbulence, we build an indoor experimental device to simulate atmospheric turbulence field to study the influence of atmospheric turbulence on the property of laser ranging echo signal amplitude fluctuation and the dispersion of ranging data. The results show as follows:As the turbulence intensity increases, or the transmission distance decreases or the area of sensitive element increases, the statistical distribution of signal amplitude is diverge from normal distribution gradually and the symmetrical characteristic is bad more and more. As the turbulence intensity increases, or the transmission distance increases or the area of sensitive element decreases, the average amplitude of optical signal gradually decreases, and the disperse range of the amplitude statistics is broader. Bisides, with the turbulence intensity increases, the amplitude statistical distribution of lidar’s signal is more disperse, and the average amplitude gradually decreases, and then result in the statistical distribution of lidar ranging presents discrete properties.更多还原