Robust sensor for turbidity measurement from light scattering and absorbing liquids

Area of Science:

• Optical Physics
• Analytical Chemistry
• Sensor Technology

Background:

• Standard turbidity measurements face challenges with simultaneous light scattering and absorption.
• Accurate quantification of solid particles in liquids is crucial for various industrial and medical applications.
• Existing methods struggle with complex liquid matrices, including those with absorbing properties.

Purpose of the Study:

• To develop and present a novel method and sensor for determining turbidity in the presence of light absorption.
• To overcome limitations of standardized turbidity measurements in complex liquid samples.
• To enable reliable turbidity assessment for ill-behaved and small-volume liquids.

Main Methods:

• Utilized a sensor based on total internal reflection of a laser beam at a liquid-prism interface.
• Employed laser speckle pattern analysis to assess turbidity.
• Applied average filtering to separate dynamic speckle (particle scattering) from static speckle (stray light).

Main Results:

• Successfully separated dynamic speckle patterns from static speckle using average filtering.
• Observed a good correlation between the standard deviation of dynamic speckle and turbidity values.
• Demonstrated the sensor's effectiveness for both non-absorbing and absorbing liquids.

Conclusions:

• The developed sensor and method provide a reliable way to measure turbidity in liquids with light absorption.
• The technique is suitable for analyzing challenging samples, including ill-behaved and small-volume turbid liquids.
• Potential applications include medicine and the process industry where accurate turbidity measurement is critical.