Study On Polarization Transmission Characteristics Of Visible Light In Sea Fog Environment

Sea fog is a weather phenomenon that reduces the visibility of the sea surface.It is mainly suspended in the oceanic atmospheric boundary layer.Polarized light has the property of penetrating sea fog and can be used to detect and identify targets in sea fog environment.However,in complex sea fog environment,the detection performance of polarization detection equipment is greatly reduced.In order to improve the detection performance and achieve the purpose of "clear recognition and far view" under sea fog environment,it is necessary to study the interaction mechanism between sea fog particles and polarized light and master the evolution law of transmission characteristics.However,the current polarization transmission research mainly focuses on uniform particles,and few studies regard sea fog particles as non-uniform state.Therefore,it is of great significance to study the polarization characteristics of visible light in the environment of non-uniform sea fog particles.This paper mainly from the theoretical simulation and laboratory experiment two parts of research.In order to study the changes of visible light polarization characteristics in the environment of heterogeneous sea fog particles,the heterogeneous sea fog particles were characterized by the double-layer ball model.Based on the Mie scattering theory and the idea of equivalent analysis,the equivalent refractive index of heterogeneous sea fog particles was solved,and the heterogeneous particle scattering model was constructed by improving the Monte Carlo method.An indoor heterogeneous sea fog test system was designed and built,including a multi-wavelength polarized light generator,a multi-layer heterogeneous sea fog simulator and a full-polarization characteristic receiver.The polarization characteristics of visible light under different optical thickness,polarization state,wavelength and humidity were studied by using heterogeneous particle scattering model and laboratory experiment system.The transmission law of partial visible light in non-uniform sea fog environment is obtained.The results of simulation experiments show that when the optical thickness increases,the polarization degree of linearly polarized light and circularly polarized light decreases.This is because when the optical thickness increases,the number of collisions between photons and sea fog particles increases,and the polarization degree decreases accordingly.The polarization of circularly polarized light is greater than that of linearly polarized light,because circularly polarized light has better polarization-preserving ability than linearly polarized light.When the wavelength increases,the polarization decreases.This is because the larger the wavelength is,the larger the equivalent refractive index of the heterogeneous sea fog particles is,and the stronger the scattering ability of the particles is.When the humidity increases,the polarization degree tends to increase,because the higher the humidity is,the smaller the equivalent refractive index of the heterogeneous sea fog particles is,and the smaller the scattering ability of the particles is.By comparing the results of simulation experiment and simulation experiment,the confidence degree of the non-uniform particle scattering model is 75.2% at the minimum and 86.6% at the maximum,which shows that the model is accurate and reliable.