Applying the phase difference property of polarization angle for measuring the concentration of solutions

This paper proposes a simple method for measuring the concentration of solutions based on the phase difference of internal reflection polarization angle and circularly polarized heterodyne interferometry. For a circularly polarized heterodyne light beam incident on the boundary surface between a hemispherical prism and a test solution, the reflected light passes through a properly oriented analyzer for interference. The phase difference between s- and p-polarized light is sensitive to the solution concentration when the incident angle equals the internal reflection polarization angle. Based on these effects, the resulting phase difference makes it possible to analyze the concentration of solution through heterodyne interferometry. The experiments in this study confirm the feasibility of this method, which provides the advantages of simple installation, ease of operation, and high accuracy.

► We proposed a measurement technique for measuring the concentration of solutions.
► The technique uses the phase difference of internal reflection polarization angle.
► Phase difference is sensitive to the solution concentration.
► Phase difference can be accurately detected by heterodyne interferometry.
► Feasibility of this method was demonstrated with a resolution about 0.263 mg/ml.