Study On Light Transmission In Scattering Media Of Multi-shaped Particles Based On Monte Carlo Method

Atmospheric aerosols are closely related to weather conditions and human health.In recent years,frequent haze and dust weather have seriously affected daily life and work.The traditional Monte Carlo method is usually used to simulate the light transmission of single-shape-particlescattering medium,however,the atmosphere contains particles of various shapes.In order to make the simulation of light transmission in atmospheric environment more in line with the actual situation,this paper proposes a light propagation model of multi-shape-particlescattering medium,the particle shapes in the medium are ellipsoidal,cylindrical and Chebyshev.First,the single scattering characteristics of atmospheric aerosol particles are calculated by T matrix theory,including the effects of different shapes and sizes on the scattering phase function.In addition,the relationship between the extinction efficiency factor and the size parameters are analyzed in detail.Then,the results obtained from the T matrix theory are applied to the improved Monte Carlo method to simulate the multiple scattering process,and the transmission characteristics of polarized light after multiple scattering are studied.First,the polarization characteristics of polarized light with different wavelengths in the multi-shape-particle-medium are compared and analyzed,second,the influence of the proportion of particles with different shapes on the polarization characteristics is further analyzed.The results show that in the range of 0.3 to 1.06 μm,the polarization maintaining ability of circularly polarized light is stronger than linearly polarized light in the multi-shape-particlemedium and the traditional single-shape-particle-medium.Compared with other wavelengths,the wavelength of backscattering linearly polarized light of 1.06 μm has the largest difference on the degree of polarization in the multi-shape-particle-medium and traditional single-shape-particlemedium.When the proportion of particles with different shapes is different in the multi-shapeparticle-medium,the polarization-maintaining ability of linearly polarized light and circularly polarized light is greatly different.In addition,three light propagation model of different types of non-spherical particle size distribution(L,M,H)media are established.The variation of the degree of polarization vs.the optical thickness for three types of media is studied.The polarization maintaining ability of linearly polarized light and circularly polarized light in the range of 0.3 to 10 μm is further analyzed.The results show that the particle shape has a great influence on the transmission characteristics of polarized light.The transmission characteristics of polarized light in the three types of media are quite different.In the range of 1.06 to 1.8 μm,the helicity flipping of the backscattering circularly polarized light occurs in these three types of media.In this paper,the research methods and conclusions of the light propagation model of multishape-particle-medium provide theoretical support for laser communication,polarization imaging and other fields,which is of great significance to promote the development of related technologies.