Research On Characteristic Of Laser Propagation Near Earth In Atmosphere

The laser propagation in atmosphere near earth is studied in this paper. Based on Generalized Lorenz-Mie Theory, the scattering theory of single sphere particle to Gauss beam is introduced. The formulations of scattering cross and asymmetry factor are presented. For the narrow laser beam the key of Gauss beam propagating in atmosphere is to compute laser beam shape coefficients. Using Localized interpretation the scattering cross and asymmetry factor is calculated systematically with Gauss beam input. On this base the method and simulation process of Monte Carlo are introduced as Gauss beam propagation in atmosphere. Using Monte Carlo method, scattering characteristic of Gauss beam propagating in discrete random medium is simulated. The transmissivity and attenuation of laser beam propagation in discrete random medium are affected by beam waist radius and wavelength. The wider beam waist radius is, the less transmissivity is, that is, the more attenuation is. Hence, scattering of particle for beam increases with beam waist and wavelength increasing.The two-frequency mutual-coherence function and pulse shape for a beam wave propagation in turbulence atmosphere are investigated. The relations between beam size pulse shape and two-frequency mutual-coherence function is analyzed. The results shown that the main turbulent atmospheric factor affected on two-frequency mutual coherence function is atmospheric structure constant. Under moderate intensity condition, the effect of inner-scale is also considered. The pulse shape is changed due to the variation of beam size.Visible software is designed to show the propagation characteristic of laser in atmosphere. The dynamic visible software can display the calculated result about laser propagating in cloud, fog, aerosol, turbulence atmosphere. The software presentes a tool for about the research.