Research On Polarization Characteristics In Sea Fog Environment Based On Vector Radiation Transmission

In addition to amplitude,frequency,and phase information,polarization is another basic physical characteristic of light,and it can also be used as the basic carrier for information transmission.Sea fog is a common catastrophic weather phenomenon.Exploring the polarization transmission characteristics of polarized light in the sea fog environment is of great significance for applications in military detection,optical communication remote sensing and atmospheric environment monitoring.At present,there are few researches in this direction in China,and most of them are limited to simulation.Therefore,aiming at the vector radiation transmission problem in the sea fog environment,this paper explored the polarization characteristics of polarized light under the influence of different parameters through Monte Carlo simulation and indoor sea fog polarization transmission experiments.The main research contents are as follows:This paper simulates the vector radiation transmission process of polarized light in sea fog environment.The traditional Monte Carlo method is improved,which can only use the average particle size value instead of the actual radius value,and combining with the physical characteristics of sea fog,the "selection sampling" method is used to sample the particle radius.The method makes all photons randomly collide with a particle in the medium during scattering processes,which is more consistent with the real situation of light transmission in sea fog.Based on the improved Monte Carlo method,the sea fog polarization transmission process is simulated.Considering the multiple scattering between the photons and the sea fog particles,the scattering process of all photons is tracked and counted.The Mie scattering theory is used to calculate the scattering characteristics of a single particle,Stokes vector is selected to characterize the polarization state of photons,degree of polarization(DOP)is selected to describe the polarization characteristics of scattered light,and the effects of parameters such as laser wavelength,laser polarization state,sea fog concentration and sea fog relative humidity on the polarization characteristics are explored.This paper designs and tests polarization characteristic experiment in sea fog environment.The indoor sea fog environment simulation system is designed and built,and sea fog particles are prepared by ultrasonic atomization method,and proposed using optical thickness to characterize the concentration of particles that are not easy to monitor,and calculated the light transmittance and optical thickness under different fog-filling times.Based on the influence of environmental factors such as sea fog concentration and relative humidity on the polarization transmission characteristics of light in the theoretical analysis and simulation,the polarization transmission experiments of incident light with three wavelengths and six polarization states were carried out under the conditions of eight optical thicknesses and five relative humidity sea fog environments.The comparison and analysis of simulation and measured data show that the coincidence degree is better than 80%,which further verifies the consistency of the simulation and experimental results.The results show that with the increase of sea fog concentration and relative humidity,the polarized light of different wavelengths and different states has depolarized.Compared with linearly polarized light,circularly polarized light has better polarized-maintaining ability under the same condition.In the visible light band,the longer the wavelength is,the better the relative retention of the polarization characteristics and the stronger the penetration ability.