Real-time measurement of concentration and temperature of solution by two different wavelengths Mach-Zehnder interferometry during crystal growth

Real-time measurement of the variation of the concentration and temperature of the solution in liquid-phase by the use of contactless Mach-Zehnder interferometry was presented in this paper. The relationships between the temperature, concentration and refractive index of solution were investigated. The feasibility of the measurement of the temperature and concentration variation separately when they altered simultaneously was discussed. Consider the practical application, Koster prisms were chosen to built the Mach-Zehnder interferometer instead of common mirrors and beamsplitters. The use of Koester prisms made the optical system compact and increased the system stability. Utilizing two wavelength interference measurement we can work out the variation of temperature and concentration from the variation of the refractive index data using fitted second order polynomial was drew. The experiment of measuring the solution concentration and temperature by use of the undersaturation aqueous solution of KDP was done.