海洋微生物偏振光散射的双组分模型

A two-component polarized-light scattering model for marine microorganisms

光学散射方法被广泛用于获取海洋微生物的形态和浓度信息。通过测量散射光的空间分布可以测量海洋微生物的形态和浓度;而最近发现,散射光的偏振特征却对细胞内部亚微米级散射颗粒更加敏感。把海洋微生物等效为粒径远大于入射波长的"米氏"粒子和远小于入射波长的"瑞利"粒子的混合体,以两种不同粒径的实心球作为微生物偏振光散射模型。利用蒙特卡洛模拟方法证明:散射光强的空间分布和偏振特征分别由米氏和瑞利散射成分决定。因此,测量散射光强分布只能获得微生物自身和其细胞核等"大"散射颗粒的粒径和浓度,而散射光偏振特征主要受到微生物内部亚微米细胞器等"小"散射颗粒的影响。

Optical scattering methods have been widely used in the studies of marine microorganisms.It has been known that one can measure the size and abundance of the micron sized microorganisms from the spatial distributions of the scattered light.However,resent studies show that polarization dependent measurements of the scattered light are sensitive only to the submicron structure within the microorganisms.In this article,we approximate the microorganisms as a mixture of microspheres whose sizes are either much bigger（Mie scatterers） or much smaller（Rayleigh scatterers） than the wavelength of the scattered light.Using polarization sensitive Monte Carlo simulations,we prove： the intensity spatial distribution and polarization properties of the scattered light are determined by the scatterings of Mie and Rayleigh particles respectively.Therefore,the scatterings of unpolarized light provide information on ＂bigger particles＂ such as the microorganisms themselves and their nuclei,but polarization features of the scattered photons reveal information on the ＂small scatterers＂ such as organelles within the cells.