衍射层析理论揭示了物体的散射场分布与物体的散射势之间存在傅里叶变换关系。基于衍射层析理论,提出一种反演未知折射率的浮游植物及其它弱散射颗粒粒径的方法。利用单波长、大角度范围内的散射光分布信息,通过傅里叶变换得到颗粒散射势的二次投影函数,进而获得颗粒粒径。进行数值仿真实验,并针对不同的测量角度范围、测量角度分辨率进行比较分析,结果表明:本文所开发的粒径反演算法可以通过测量大角度散射光分布,在适度噪声存在的情况下,准确反演与入射光波长相比拟的单个弱散射球形颗粒粒径。这一方法可用于测量未知折射率的浮游植物及其它微小颗粒粒径。

According to optical diffraction tomography theory,there is a Fourier relationship between the scattering amplitude in the far zone and the scattering potential of the scatterer.Based on optical diffraction tomography,a sizing approach for phytoplankton and other weakly-scattering spherical particles is proposed.The doubly projection of the scattering potential is retrieved from monochromatic scattered field over a large angular ranger via Fourier transformation.The particle size is estimated from the doubly projection of the scattering potential.Mie theory is used to compute the simulated scattered field.Numerical simulations for measurements of different angular ranges and resolutions are presented and discussed.The results demonstrate that the size of the weakly-scattering particle of wavelength order can be estimated accurately from angular optical scattering distributions in the presence of moderate noise.This method can be used to retrieve the size of phytoplankton and other weakly-scattering particles without prior knowledge of accurate refractive index.