Researches On Transmission Characteristics Of Infrared Polarization Information In Complex Cloudy And Foggy Scattering Systems

Polarization is one of the basic physical properties of light.It can also be used as a carrier of information.Polarization with multi-dimensional parameters,which not only includes accurate information of the detected target,but also reflects the internal distribution characteristics of the transmission medium.This paper mainly uses the Monte Carlo algorithm to simulate the transmission characteristics of light waves in different complex scattering systems,including mono-dispersion and mixed double-dispersion system and Poly-disperse system with certain distribution.Based on polarization and scattering theory,calculate the scattering and absorption parameters of polarized light in the medium,and use the Monte Carlo method to track the changes of its position and polarization state.This article focuses on the analysis of the Mueller matrix of the scattering medium to calculate the polarization purity index(IPPs)of the scattering system to analyze the transmission characteristics of different dispersion systems.The paper simulates a typical cloud and fog environment,here we construct a basic cloud and fog scattering model and a parameter database,study the influence of incident wavelength,particle concentration and particle size distribution on the transmission characteristics of light waves.The simulation results show that,use the polarization purity index(IPPs)of the scattering medium is superior to the traditional description method based on the degree of polarization.The main content of this paper is as follows:(1)First,the basic theory of light polarization and several special polarization states are introduced;then several common methods for describing polarization states are summarized,such as Jones vector method,Stokes vector method,and Bonga sphere method,etc;At the same time,the polarization purity index method that characterizes the depolarization ability of the scattering system is derived from the Mueller matrix;then the Rayleigh scattering theory and the Mie scattering theory are analyzed,and use the Monte Carlo algorithm to track the transmission of light waves in different scattering systems.Finally,the main implementation steps of Monte Carlo algorithm are briefly introduced.(2)Based on the Monte Carlo simulation algorithm,for typical Nanjing fog dispersion system,build mono-disperse system and mix-double-disperse system and poly-disperse system with certain distribution.And in the infrared band,incident four kinds of polarized light to calculate the Mueller matrix of the scattering medium,using polarization purity indicators(IPPs),circular polarization and linear polarization to analysis the polarization information transmission in the scattering system.Simulate the transmission characteristics of the mono-disperse systems and poly-disperse systems with certain distribution.The simulation results show that the polarization purity index(IPPs)can better describe the transmission characteristics of different scattering systems than circular polarization and linear polarization.(3)For the water cloud dispersion system,based on the Monte Carlo simulation algorithm,a single mono-disperse systems,mixed two-particle dispersion system and poly-disperse system with a certain distribution are constructed.Use infrared light incident to obtain the Mueller matrix of different dispersion media,use polarization purity indexes(IPPs),circular polarization degree and linear polarization degree to analyze the polarization information transmission in the scattering system.Simulate the transmission characteristics of the mono-disperse systems and poly-disperse systems with certain distribution.The simulation results show that in the water cloud scattering environment,the linear polarization degree and circular polarization degree and polarization purity index show less volatility,and the polarization purity index can better describe the changing characteristics of different scattering systems.