Study On Scattering Polarization Characteristics Of Laser In Low Visibility Atmosphere

The main content of this paper is the scattering polarization characteristics of laser transmission in low visibility atmosphere.Laser plays an important role in optical communication,laser lidar,remote sensing,aerospace and other fields.At the same time,polarized light has attracted more and more attention because of its unique way of information recording.It has great scientific and practical value in environmental media measurement,target detection and other aspects.The effects of laser transmission in the atmosphere are varied and the consequences are different.Therefore,it is of great significance to study the polarization characteristics of laser scattering in the atmosphere.In this paper,the cause of low visibility in the atmosphere is analyzed,and the main aerosol particles in the atmosphere are introduced.The concept,classification,refractive index and the relationship between size distribution,type,visibility and water content of fog droplets are introduced.The concept,composition,refractive index and theoretical model of smoke cluster particles are also discussed.It lays a foundation for studying the scattering characteristics of laser in fog or smoke.Mie theory is used to calculate the scattering characteristics of a single spherical particle.Based on the theory of radiation transmission,the procedure of Monte Carlo method and its application in multiple scattering are introduced.Monte Carlo method is used to simulate the multiple scattering of laser in low-visibility fog,and the relationships between the forward scattering,backward scattering and attenuation of laser transmission and the wavelength,fog type,visibility and transmission distance are obtained.In order to study the polarization characteristics of laser transmission,the introduction of stokes vector and Mueller matrix,the vector radiative transfer theory and Monte Carlo simulation method,the corresponding polarized light of vector of Monte Carlo simulation steps are introduced in detail,also combined with the properties change of polarized light in the cloud and mist cloud characteristics research,and calculate the horizontal polarization and vertical polarization of the change of horizontal and vertical component and the change of the degree of polarization,convenient and practical application.In addition,an improved Monte Carlo simulation method for multiple scattering is proposed.Instead of using the average physical characteristics of the discrete random medium,random sampling is conducted on the particles scattered by each collision according to their size distribution,which is more consistent with the actual situation and verifies its accuracy.