Polarization-Modulation Scattering Measurements Of Well-Characterized Marine Plankton

Characterization of the polarization properties of light scattered from biologically-derived marine particles can be used to understand the effect of light propagated through seawater. To interpret scattering measurements from oceanic samples, it is important to investigate well-characterized marine organisms under controlled conditions. In this study, light scattering from very small, nearly spherical marine plankton, Chlorella, were investigated using a polarization-modulation technique originally developed by Hunt. This technique permits the determination of the elements of the scattering matrix that completely describe the intensity and polarization effects induced by the scattering system. The total scattered intensity and the value of the normalized matrix elements were measured as a function of angle at wavelengths of 442 and 633 nm. The scattering intensity profile was interpreted with the help of a Rayleigh-Debye theory using a spherical shell model. It was found that the Chlorella exhibited scattering behavior approximating that predicted by the Rayleigh-Debye theory. However, consistent deviations from the factored Rayleigh matrix were observed. These results and their implications for light scattering studies of marine waters are discussed.