Indoor and outdoor measurements and validation of laser polarization transmission characteristics under sea fog conditions

The transmission of polarized light in sea fog is severely affected by multiple scattering and depolarization phenomena, which limit the performance of polarization-based optical systems. This study systematically verified the transmission of polarized laser light in sea fog by combining outdoor field experiments, indoor hardware-in-the-loop simulations, and numerical simulations. Outdoor measurements were conducted under real sea fog conditions, and the measured visibility was converted into extinction coefficients and optical thickness to establish an equivalent indoor experiment. Four laser wavelengths (450, 532, 671, and 808 nm) were investigated for both linearly and circularly polarized states under visibility conditions ranging from 5 to 11 kilometers. Results indicate that laser polarization exhibits a pronounced attenuation trend with decreasing visibility (increasing optical thickness), and this depolarization process is strongly wavelength-dependent. At identical visibility conditions, longer wavelengths demonstrate superior polarization retention compared to shorter wavelengths. Circularly polarized light generally outperforms linearly polarized light under identical scattering conditions, exhibiting higher resistance to depolarization. Outdoor experiments, indoor hardware-in-the-loop simulations, and numerical simulations achieved good consistency, with consistency levels of approximately 78% and 85%, respectively, and root mean square errors below 0.20. This fully demonstrates the high consistency of laser polarization transmission patterns in sea fog environments.