Fresnel reflection based fiber optic refractive index sensor for liquid concentration dedection

Measurement of refractive index which is one of the distinctive properties of materials is commonly used in many fields such as quality control of food industry, biomedical applications, biochemical analysis and measurement of environmental pollution. From the refractive index measurement methods, the one based on fiber optic stands out with their provided advantages. In this study, firstly, a simple, reliable and highly sensitive Fresnel reflection based fiber optic refractometer was setup, then the refractive indexes of various liquids were measured using this setup at different times. When the measurement results are compared with material science data sheet (MSDS) values, the percent error was found to be less than %1. Moreover, the long term stability of ethanol´s refractive index was examined and the refractive index variation of salt-water was obtained as a function of the salt concentration.