Chen Wei-kang, Fang Hui
Guang Pu Xue Yu Guang Pu Fen Xi. 2016 Mar;36(3):770-4.
The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products.
基于偏振微分弹性光散射光谱技术的基本原理是，在线偏振光入射下，可根据偏振特性的差异分离来自浅表生物组织的单次散射光和来自深部组织的漫散射光。本文的新颖之处在于将该方法应用于颗粒悬浮液的检测，并在其自然状态下实现对其粒径和数密度的同时测量。我们设计并搭建了一个同轴笼式光学系统，并在特定角度测量聚苯乙烯微球悬浮液的后向散射信号。通过用线性偏振器控制入射光的偏振方向，并用另一个线性偏振器调整收集光的偏振方向，我们获得了平行偏振弹性光散射光谱和交叉偏振弹性光散射光谱。两者之差即为仅包含颗粒单次散射信息的微分偏振弹性光散射光谱。我们将该光谱与米氏散射计算结果进行比较并提取粒径。然后，我们还应用已提取的粒径对交叉偏振弹性光散射光谱进行分析。该分析基于考虑光扩散的近似表达式，由此我们能够获得颗粒悬浮液的数密度。我们将实验结果与制造商提供的值进行比较，并进一步分析粒径标准偏差对数量密度提取的影响，最终验证了该实验方法。该方法的潜在应用包括颗粒制造过程中的在线颗粒质量监测以及乳制品的脂肪和蛋白质密度检测。
