Key Technology For Polarization Characteristics Of Light Forward Transmission In Mie Scattering Environments

With expanding and deepening of human exploration of the world,research environments have become complicated and diversified.Some instruments constructed by traditional theories have reached their technical limit,which has brought more and more challenges to optoelectronic equipment.Some new technologies have been developed in recent years,such as polarization technology.However,the lag of related technology research gradually restrains the development of polarization technology.There is an urgent need to make progress in key technology research.The research on the key technology of light transmission in scattering environments is an important issue,which can promote the development of polarization technology.Mie scattering environments are common in scattering environments,such as clouds,fog,and turbid waters are generally Mie scattering environments in the visible light band.When light is scattered in Mie scattering environments,the intensity of scattered light is usually stronger in forward direction.Light intensity is one of the consideration indicators for practical applications.Many fields such as detection,remote sensing and communication are particular concern the forward transmission characteristic of light.Polarization characteristics are rich,sensitive and regular.When polarization is used to characterize the light forward transmission characteristic in Mie scattering environments,it is not only helpful to extract good light signals,but also can reverse attributes of environments,and even estimate environmental impact.Polarization characteristics of light forward transmission in Mie scattering environments are highly valued and have broad application prospects in communication,navigation,detection and so on.Therefore,this article focuses on key technologies for polarization characteristics of light forward transmission in Mie scattering environments.Key technical issues involve evaluation method,calculation algorithm,and production of core device.Furthermore,polystyrene suspensions and complex air environments were selected for research the polarization state characteristic of light forward transmission.The research content of this article mainly includes five parts:(1)Evaluation method for polarization state persistence of light forward transmission in Mie scattering mediaA new method was proposed to describe the retention rate of polarization state for light forward transmission.Stokes parameters are usually used to distinguish polarization state.However,Stokes parameters are related to the intensity difference between the defined six specific polarization states.It leads to Stokes parameters and its deformation present incomplete correlation of polarization state changes,which affects the reliability of Stokes parameters and its deformation to distinguish polarization state persistence.Stokes-Mueller calculation form is generally used to judge the change of polarization state.However,it generally describes the recombination state of photons,and it is difficult to judge the change of polarization state of each photon.To solve the shortcoming of current evaluation methods,a new parameter RoPS that can describe the polarization state change of forward scattered light or photon is proposed.It means the retention rate of polarization state.When transmitted in the form of light,RoPSlight avoids the error of intensity difference of orthogonal components.Compared with the Stokes parameter,RoPSlight has higher calculation accuracy.When transmitted in the form of photons.RoPSphoton is more conducive than Stokes-Mueller calculation form to reflect the polarization state change of photons.(2)Optimizing and improving the polarization meridian Monte Carlo methodTo solve the problem of discrepancy between calculated results of the polarization meridian Monte Carlo method and test results,the original polarization meridian Monte Carlo method was optimized and improved.The original algorithm collects all forward scattered light,but receiving devices generally receive part of forward scattered light.For this reason,the improved algorithm limits the receiving range of forward scattered light,and the limited receiving range for simulation is consistent with receiving range of receiving devices.The improved algorithm can better match measured results by experiments.(3)Structural design and fabrication of a near-infrared double-layer metal gratingA near-infrared double-layer metal grating was fabricated for experiments.Metallic materials and base materials of the micropolarizer were selected.Based on the finite-difference time-domain statutory analysis,the influence of duty cycle,height,and period on performance of the micro polarizer was determined.And the structural parameters were determined.The process parameters of thermal nanoimprinting and ultraviolet-thermal nanoimprinting were optimized.The micropolarizer was fabricated by nanoimprinting process and thermal evaporation process.Finally,the micropolarizer was tested,which had suitable TM light(transverse magnetic wave)transmittance and comfortable extinction ratio.It is suitable on experiments in near infrared bands.(4)Theoretical and experimental research on polarization characteristics of light forward transmission in polystyrene suspensionVariable controllable scattering environments are convenient for experimental verification of simulation.The polystyrene suspension,which was one type of controllable environments,was selected for research.The effects of particle size,wavelength,and type of polarized light on polarization state persistence of light forward transmission were analyzed.And some experiments were made to verify the reliability of simulation.(5)Theoretical and experimental research on polarization characteristics of light forward transmission in complex air environmentsHaze,fog,clouds,smoke,sand and other complex air environments are universal.Exploring polarization characteristics of light forward transmission in complex air environments has broadly application values.To investigate forward transmission characteristics of polarized light in complex air environments,haze and fog and smoke environments were selected.Three kinds of water vapor,which including wet haze and radiant fog and advection fog,were used to explore rules and mechanisms.Smoke environments were selected for experimental verification.First,the polarization state persistence of polarized light during forward transmission was explored.Two issues were emphasized:one is which wavelength of polarized light has better polarization state persistence characteristic;the other is which type of polarized light has better polarization state persistence characteristic.Then,the mechanism of simulation law was analyzed.Finally,smoke environments were selected for experimental verification.Test results verified the reliable and universal of simulation.