In-Process Particle Sizing by Refractive Index Measurement

提出了一种激进的新技术，可在线测量尺寸为0.1微米到10微米、体积浓度高达50%的颗粒，而不会对过程产生干扰。该方法包括从几个波长的临界角测量来计算悬浮液的光学折射率。这项技术不需要光通过悬浮液，所以它的混浊度不会限制方法。实际上，混浊悬浮液的临界角并不是很明显，但在临界角附近有很大的反射率变化。与其他广泛使用的非侵入性粒子分析方法如光谱消光和激光衍射相比，测量悬浮液的折射率具有显著的优势：-对于体积浓度高达50%的体积浓度，折射率与体积分数之间的关系是线性的。-Mie散射理论可以用来计算球体浓缩悬浮液的折射率。-悬浮液的折射率对颗粒大小和粒度分布敏感。

A radical new technique is proposed for in-line process particle measurement at sizes from 0.1micron to 10micron and concentrations up to 50% by volume without interfering in the process. The method involves calculation of optical refractive index of the suspension from critical angle measurements at several wavelengths. This technique requires no light passage through the suspension so its turbidity does not restrict the method. In practice, the critical angle is not clearly marked for turbid suspensions but there is a substantial variation of reflectance in the vicinity of the critical angle.Measuring the suspension refractive index has significant advantages over other widely used non-invasive methods of particle analysis such as spectral extinction and laser diffraction: - The relationship between refractive index and volume fraction is linear for volumetric concentrations up to 50%.- Mie scattering theory can be used to calculate the refractive index of concentrated suspensions of spheres. - Suspension refractive index is sensitive to particle size and size distribution.