Liquid Refractive Index Measurement Based on Inverse Raytracing Using an Optical Angle Sensor

The refractive index of a solution correlates closely with its concentration. Estimating the concentration of a solution from its refractive index is an extremely important technique in a wide variety of fields ranging from medicine to food and industry. In this study, we propose a non-contact measuring method for obtaining the refractive index of a solution using an optical angle sensor. Our approach is based on an inverse ray tracing technique. We formulate inverse ray tracing expressions for simultaneous measurement of the refractive index of a solution and its level. We construct a prototype, and examine the validity of the proposed method.