Research On The Difference Of Transmission Characteristics Between Circularly Polarized And Linearly Polarized Light In Underwater Environment

Light transmission under water will be affected by the water itself and the water medium to light absorption and scattering.The influence of water and its medium on the polarization of light is far less than the effect of light intensity,applying polarized light to underwater optical research can improve the quality of underwater imaging and underwater communication.Polarized light has different polarization states and can represent different polarization properties.Circularly polarized light is different from linearly polarized light,at the same time their interaction with the media after the same change of polarization is different.At present,most of the studies on polarized light are focused on atmospheric transmission,while the research on underwater polarization transmission is less.Therefore,this paper researches on the difference of transmission characteristics between circularly polarized and linearly polarized light in underwater environment.This paper mainly studies from two aspects: experiment and simulation.This paper simulates the underwater transmission of circularly polarized and linearly polarized light,using random sampling fitting function of Monte Carlo simulation method.The improved simulation method normalizes the frequency of the scattering angle obtained by multiple sampling to obtain the sampling of the scattering phase function corresponding to the distribution law of the phase function of the multi-dispersed system,to simulate the transmission of polarized light through an underwater medium containing a variety of particle sizes and make the simulation more in line with the real water situation.Simulation based on Mie scattering theory of the multiple scattering of photons in the water,tracks and statistics a large number of photons scattering paths to obtain the transmission parameters of polarized light in the underwater medium,to simulate the transmission of polarized light with different wavelengths and polarization states in different water bodies.At the same time,the transmission of circularly polarized light and linearly polarized light under water is designed experimentally,using lasers,polarization state measuring instrument,optical power meter,optical glass water tank and some optical devices to build an experimental platform for the transmission of polarized light in the water and test it.Using six types of polarized light at three wavelengths as variables,experiment studies on the degree of polarization of circularly polarized and linearly polarized light in four kinds of water body environment changing with the optical transmittance.Finally,I processed the data from both methods and verified the consistency of the simulation and experimental results by measuring parameters such as Euclidean distance,cosine similarity and correlation coefficient.The results show the depolarization of polarized light becomes more obvious with the increase of the particle size of the water medium.But in the same water under the condition of the same distance,circularly polarized light information loss less than linear polarized.At the same time,three wavelengths of visible light range of polarized light transmission characteristics also exist certain differences.