Massoli P, Beretta F, D'Alessio A
Appl Opt. 1989 Mar 15;28(6):1200-5. doi: 10.1364/AO.28.001200.
A method is described for obtaining size, velocity, and optical properties of transparent spherical droplets employing the polarization characteristics of scattered light. A preliminary analysis of the Lorenz-Mie solution, in comparison with geometrical optics, points out the importance of surface waves in the side scattering region between theta = 85 degrees and theta = 120 degrees . Here the horizontal component of scattered light due to surface waves prevails over that due to external reflection for droplets smaller than 100 microm and the polarization ratiogamma = C(HH)/C(VV) can be employed for determining the particle size. A dual-beam system is made of two equal intensity circularly counterotating polarized laser beams which generate a polarized fringe pattern in the interference volume. The polarization ratio of scattered light, at a fixed scattering angle theta, and velocity is obtained by analysis of the bursts produced by individual droplets. The method was tested by determining the size and velocity distribution functions of droplet arrays produced by a Berglund-Liu atomizer operated either in monodisperse or in bidisperse regimes. The angular pattern of the polarization ratio was determined on calibrated streams of transparent droplets with different refractive indices, and the influence of this parameter on the role of surface waves in different angular scattering regions is discussed.
描述了一种利用散射光的偏振特性来获取透明球形液滴的尺寸、速度和光学特性的方法。与几何光学相比，对洛伦兹 - 米氏解的初步分析指出了表面波在θ = 85度至θ = 120度之间的侧向散射区域中的重要性。对于小于100微米的液滴，在此处由表面波引起的散射光水平分量比由外部反射引起的水平分量更占优势，并且偏振比γ = C(HH)/C(VV)可用于确定颗粒尺寸。双光束系统由两个强度相等、圆偏振且反向旋转的激光束组成，它们在干涉体积中产生偏振条纹图案。通过分析单个液滴产生的脉冲来获得在固定散射角θ处散射光的偏振比和速度。通过确定由处于单分散或双分散状态的伯格伦德 - 刘雾化器产生的液滴阵列的尺寸和速度分布函数来测试该方法。在具有不同折射率的校准透明液滴流上确定了偏振比的角度模式，并讨论了该参数对不同角度散射区域中表面波作用的影响。
