Research On Backscatter Echo And Polarization Characteristics Of Ultraviolet Light In Haze

Haze,also known as dust-haze,in recent years,the haze weather has become serious increasingly.The haze not only damages human health,but also affects optical properties of the atmosphere in local region.Therefore,it is very necessary to detect the haze for environmental monitoring and researching on optical communication in atmospheric.In this paper,"solar-blind" ultraviolet light with strong anti-interference ability and high privacy is used as the detection light source to improve the accuracy and real-time of haze detection.The backscatter echo and polarization characteristics of haze with different physical properties are studied according to the model of detecting haze by "solar-blind" UV backscattering and the UV polarization model of haze particles,the focuses of research are as follows:(1)The model of detecting haze by "solar-blind" ultraviolet light backscattering is constructed,based on the Monte Carlo method to simulate the process of photon motion.Mie scattering theory and T-matrix method are used to simulate the backscattering echo characteristics of spherical and non-spherical haze particles under different concentrations.The simulation results show that when the haze concentration is less than 500 ?g/m3,the peak power of backscatter echo of UV pulse increases with the increase of haze concentration,and there is a linear relationship between the peak power of pulse echo under different concentrations of haze,the full width at half maximum of pulse echo decreases with the increase of haze concentration.For ellipsoidal and cylindrical haze particles,under the same concentration,the smaller the shape variable of particles is,the larger the peak power and the full width at half maximum of pulse echo are.For chebyshev haze particles,under the same concentration,the larger the deformation parameters and ripple parameters are,the larger the peak power and the full width at half maximum of pulse echo are.(2)Mie scattering theory and T-matrix method were used to simulate the changes of the degree of linear polarization for spherical and non-spherical haze particles under different physical parameters,and the differences of the degree of linear polarization between spherical and non-spherical haze particles with different parameters were compared,based on the ultraviolet light scattering polarization model of haze particles.The simulation results show that the degree of linear polarization of haze particles varies greatly in the backscatter angle.When the effective radius of particles is smaller and the real part of complex refractive index is smaller,the maximum value of the degree of linear polarization is larger.When the imaginary part of complex refractive index is larger,the maximum value of the degree of linear polarization is larger.For ellipsoidal and cylindrical haze particles,the maximum value of the degree of linear polarization is larger when the particle shape variable is smaller.For chebyshev haze particles,the maximum value of the degree of linear polarization is larger when the deformation parameters and ripple parameters are smaller.In most backscattering angles,the degree of linear polarization of spherical haze particles is greater than that of non-spherical haze particles.In conclusion,we can detect haze particles with different physical properties by combining changes of the backscattering echo of ultraviolet pulse and the degree of linear polarization in the backscatter angle...