Near-earth Atmospheric Turbulence On Laser Transmission Signal Amplitude Fluctuation Characteristics

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.