Study On Transmission Characteristics Of Polarized Light In Multi-layer Sea Fog Environment

With the increase of human social activities in the ocean,the marine atmospheric environment is complex and changeable.When light is transmitted in the atmospheric environment,it is scattered many times with the medium,which shortens the transmission distance of light and makes it difficult to receive information.All these have a great impact on maritime transportation,signal acquisition and military activities.Previous studies only considered the influence of a single medium on polarized light transmission.Aiming at this problem,this paper establishes a simulation system in multi-layer sea fog environment,compares the simulation data with the test data,and analyzes the transmission characteristics and attenuation law of polarized light in multi-layer sea fog environment,which provides an important basis for the study of polarized light transmission characteristics in marine environment.The main research contents are as follows:Firstly,aiming at the complexity of polarized photon transmission process in multi-layer sea fog environment,vector Monte Carlo method is used to simulate the transmission process of polarized photon,so as to obtain the variation law of polarization state.The multi-layer sea fog environment includes salt fog layer,water fog layer and atmospheric molecular layer.Aiming at the problem of solving the vector radiative transfer equation,the multiple addition method is used to analyze the scattering characteristics of multi-layer sea fog dielectric particles,and then different scattering and transmission laws are obtained.Finally,the radiation properties,optimal degree of polarization and azimuth of multi-layer sea fog are obtained.Secondly,based on the simulation modeling,a semi physical indoor multi-layer sea fog environment simulation system is designed and built.The polarization transmission test is carried out by changing the parameters such as medium concentration,laser wavelength,polarization state and relative humidity.Finally,the simulation and measured data are compared and analyzed to verify the consistency of the simulation and test results.In addition,with the increase of the thickness of the sea and the relative humidity of the fog,it can be seen that the influence of the multi-layer film on the water absorption and scattering of particles will gradually increase with the increase of the thickness of the sea and the relative humidity of the fog.Due to the memory effect of circularly polarized light,the ability of circularly polarized light to maintain polarization characteristics when scattering in the environment with many scattering media is better,and it is obviously better than linearly polarized light.At the same time,because the scattering coefficient of polarized light is inversely proportional to the wavelength,the longer the wavelength,the smaller the scattering coefficient.Therefore,the polarization maintaining ability of polarized light with longer wavelength is better than that of polarized light with shorter wavelength.