Dual wavelength interferometric technique for simultaneous temperature and concentration measurements in liquids

This paper evaluates the application of a dual frequency interferometric technique for simultaneous temperature and concentration measurements in liquids. All of the measurements were made using the classical Mach-Zehnder interferometer with a tunable laser light source. Measurements were made in a stably stratified aqueous salt water column heated from below. Interferograms were acquired at two laser light source wavelengths: lambda(1) = 476.5 nm and lambda(2) = 514.5 nm. It has been demonstrated that dual wavelength interferometric techniques have limited applications in liquids. The technique was found to yield satisfactory results for test conditions corresponding to a combination of low temperature and high concentration gradients. For other test conditions, the measured errors were large due to inadequate separation in the light source wavelengths.