Olivares Ignacio E, Carrazana P
Departamento de Física, Universidad de Santiago de Chile, Avenida Ecuador 3493, Estación Central 9170124, Santiago, Chile.
Physics Department, California State University, 25800 Carlos Bee Boulevard, Hayward, California 94542, USA.
Rev Sci Instrum. 2020 Aug 1;91(8):083112. doi: 10.1063/5.0015050.
Two experiments to measure the size of microscopic dielectric spherical particles immersed in purified water with spheres of a nominal diameter 5.2 ± 0.15 μm have been carried out in order to revisit Mie scattering techniques. The first experiment uses a 1 mW helium-neon (He-Ne) laser with a wavelength of 632.8 nm, while the second one is carried out using a diode laser of 780.0 nm wavelength and a nominal power of 80 mW. The distribution of the scattered light intensity is recorded experimentally, and since the theoretical background has been known for several decades (see references), only a modest amount of theory is included. We considered the Mie scattering by a set of spheres of different diameters in our case with a distribution of sphere diameters with mean diameter 5.2 μm and standard deviation 0.15 μm. Our measured Mie scattering angular distribution accounts for the effect of the diameter distribution, which we assume to be a Gaussian distribution. Our results indicate that there is very good agreement between experiment and theoretical predictions. The technique we offer here is found to be useful to familiarize technicians who work in the areas of applied optics, such as chemistry, electronics, water contamination, and optical instruments with Mie scattering techniques, and who may not have a formal introduction to the electromagnetic theory. One specific area in which these techniques might be useful is the study of aerosols that may arise when naturally produced droplets from humans, such as those produced by coughing, sneezing, talking, and breathing, are present, as it happens in response to the Severe Acute Respiratory Syndrome Coronavirus 2, also known as SARS-CoV-2.
为了重新审视米氏散射技术，已经进行了两项实验来测量浸没在纯水中的标称直径为5.2±0.15μm的微观介电球形颗粒的大小。第一个实验使用波长为632.8nm的1mW氦氖（He-Ne）激光器，而第二个实验则使用波长为780.0nm、标称功率为80mW的二极管激光器。实验记录了散射光强度的分布，由于理论背景已经为人所知数十年（见参考文献），因此只包含了少量理论内容。在我们的案例中，我们考虑了一组不同直径的球体的米氏散射，球体直径分布的平均直径为5.2μm，标准差为0.15μm。我们测量的米氏散射角分布考虑了直径分布的影响，我们假设其为高斯分布。我们的结果表明实验与理论预测之间有非常好的一致性。我们在此提供的技术被发现对于让在应用光学领域工作的技术人员熟悉米氏散射技术很有用，这些技术人员例如来自化学、电子、水污染和光学仪器领域，并且可能没有正式学习过电磁理论。这些技术可能有用的一个特定领域是研究当存在人类自然产生的飞沫时可能出现的气溶胶，比如咳嗽、打喷嚏、说话和呼吸产生的飞沫，就像在应对严重急性呼吸综合征冠状病毒2（也称为SARS-CoV-2）时所发生的情况。
