Department of Physics and Mathematics, University of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland.
Opt Lett. 2009 Dec 1;34(23):3743-5. doi: 10.1364/OL.34.003743.
Internationally standardized turbidity measurements for probing solid particles in liquid are problematic in the case of simultaneous light scattering and absorption. A method and a sensor to determine the turbidity in the presence of light absorption are presented. The developed sensor makes use of the total internal reflection of a laser beam at the liquid-prism interface, and the turbidity is assessed using the concept of laser speckle pattern. Using average filtering in speckle data analyzing the observed dynamic speckle pattern, which is due to light scattering from particles and the static speckle due to stray light of the sensor, can be separated from each other. Good correlation between the standard deviation of dynamic speckle and turbidity value for nonabsorbing and for absorbing liquids was observed. The sensor is suggested, for instance, for the measurement of ill-behaved as well as small-volume turbid liquids in both medicine and process industry.
在同时存在光散射和吸收的情况下，用于探测液体中固体颗粒的国际标准化浊度测量存在问题。本文提出了一种在存在光吸收的情况下确定浊度的方法和传感器。所开发的传感器利用激光束在液体棱镜界面处的全内反射，并且使用激光散斑图案的概念来评估浊度。通过在散斑数据分析中使用平均滤波，可以将由于颗粒光散射引起的观察到的动态散斑图案与由于传感器杂散光引起的静态散斑图案彼此分离。对于不吸收和吸收液体，观察到动态散斑的标准偏差与浊度值之间具有良好的相关性。该传感器建议用于测量医学和过程工业中行为不良和小体积混浊液体。
