Study Of Influences Of Atmospheric Transmission Characteristics On Laser Detection Performances

The applications of laser are increasing and omnipresent because of its high coherent, brightness, directivity, which general light sources can't compare to it. Performances of various laser engineering systems (such as laser communication, laser radar, laser detecting) are restricted seriously by the atmosphere for long span laser transmission. The transmission of laser plays an important role in the ability of laser radar when it detecting target. Therefore, atmospheric transmission must be taken into account when in the designing, development and calibration of laser radar system.In this paper, the atmospheric propagation characteristic of 1.06μm laser is theoreticly investigated, the two effects: attenuation and scintillation induced by turbulence, are discussed which influence the performance of the laser radar's detection. The influence of atmospheric attenuation upon laser radar, including the absorption and scattering induced by gas molecule and aerosol are discussed. Various factors which influence the transmission of laser are analyzed. In different weathers, such as clearness, fog, haze, rain and snow etc, the attenuation and atmospheric transmission at 1.06μm are calculated with several experiential formulas. The results show that Mie theory is more reasonable than experiential model for atmospheric hazes attenuation prediction in the troposphere. The attenuation induced by clouds and fog increase quickly with the visibility decrease. Therefore, for Vb < 15km, the haze attenuation must be considered. For lower V b, the performance of laser system is limited by the attenuation of clouds and fog.On the base of range equation of laser radar and parameters of laser radar system desired,on some visibility, the minimal receiver power and the minimal input SNR of general detection as a function of the maximal detection range are researched.In addition, the influence of weakly turbulence on laser transmission is depicted, the scintillation of the turbulence influence on the direct detect system for laser radar is studied. These researches are helpful for designing laser systems for laser radar.