Rahim Ullah

By Rahim Ullah, Raja Yasir Mehmood Khan and Muhammad Faisal

Human diet is primarily comprised of optically active ingredients like glucose, sucrose, fructose, amino acids, lactic acid, cholesterol etc. Quality control is one of the most important processes in food industries to test, measure and verify the product for quality control standards. Optical techniques are mostly adopted in these industries for standardization of purity and concentration of optically active ingredients in their products. Quantitative measurements of optically active materials (OAMs) in a solution by interferometry have attracted the intention in present days due to their wide working range, high sensitivity and lower limit of detection. OAMs cause rotation of the angle of polarization when a plane-polarized light passes through them. The angle of rotation is distinct for different materials at different concentrations. For interferometric quantitative determination, the OAMs are generically placed in an arm of the interferometer and their effect on the interference fringe patterns are monitored as a function of their concentrations. Furthermore, the refractive indices of OAMs varies with their concentrations which directly affect the resultant interference pattern. Owing to the vast range of interferometric arrangements and processing techniques, this review assesses the different approaches adopted in detection of concentration of OAMs in a solution by interferometry.

Part of the book: Optical Interferometry