Polarized scattering characteristics of typical suspended particles near 180° via Scheimpflug lidar and polarized VSF...

The polarized scattering properties of particles constitute one of the fundamental issues in marine scientific research and serve as a cornerstone for active and passive optical remote sensing. Complex particle types influence the optical properties of water, thereby affecting the interpretation of remote sensing data. To gain a deeper understanding of the polarized scattering characteristics of different particles, we developed a Scheimpflug lidar and a backward small-angle Mueller matrix measurement system, and conducted measurement experiments on various standard particles and marine algal species. The Mueller matrix measurement system, designed with an off-axis parabolic mirror and a bilateral telecentric optical path, enables high-resolution measurement of the polarized volume scattering function at near-180° backward scattering angles. Based on rigorous calibration, the independent measurement results of the volume scattering function for the same sample by the two systems show good consistency, with a correlation coefficient of approximately 0.77 and a mean relative error of about 0.24. Within the effective detection range, Mie scattering simulations can effectively reproduce the measured results of the standard particle volume scattering functions. Three parameters were used for particle classification exploration: color ratio, depolarization ratio, and volume scattering function. Different types of particles exhibit different characteristics in this three-parameter classification, verifying the potential of multi-wavelength polarized oceanic lidar for the retrieval of particle groups, concentrations, and other parameters.