Objective The distribution of particles in the marine atmospheric medium environment is different. When the laser is transmitting through the sea fog, these unavoidable environmental factors have an un-negligible impact on the detection of marine targets and the polarization information transmission. In recent years, it has become a research hotspot to investigate the transmission characteristics of polarized light in complex environments. At present, the disadvantages of analyzing the transmission characteristics include simulations and experiments only for a single type of particle. To further explore the polarization transmission characteristics of polarized light in the multilayer sea fog environment, this paper improves the traditional Monte Carlo model based on the stratification of the marine atmosphere, and designs and builds the multilayer sea fog environment simulation device for experiments.
Methods The marine atmosphere is divided into three regions and a multilayer Monte Carlo simulation model is established. Photons will be scattered and collide with the particle groups in different regions, namely, salt fog, water fog, and aerosol. Based on the particle formation process in the marine atmosphere environment, as shown in Fig.3, a multilayer sea fog environment simulation system device was designed and built (Fig.6). Changing the wavelength or polarization state of the laser, the relationship between the change of environmental humidity and the degree of polarization (DOP) was explored.
Results and Discussions The analysis of the simulation data in Fig.2 shows that for different incident light wavelengths of the same polarization state, the DOP of the 671 nm wavelength is generally higher than that of the 532 nm and 450 nm wavelengths. With the increase of humidity, the DOP of the three wavelengths is gradually decreasing, the longer the wavelength, the more obvious the advantage. For different polarization states in the same wavelength, the DOP of the circularly polarized light is generally higher than that of linearly polarized light. The trend of the test results and simulation results in Fig.7 is the same, which shows the high degree of conformity between the two, and the experimental device has a certain practical value.
Conclusions By preparing varieties of particles in the marine atmosphere and designing and constructing a multilayer sea fog environment simulation system device according to the characteristics of various particles, laser transmission test experiments were carried out under controlled conditions. The simulation and test results show that the system can more realistically reflect the influence of the sea fog environment on the polarized light transmission. It provides data support and theoretical support for the subsequent research on polarization transmission.
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