In-situ measurement of small diffusion fields using a phase-shifting interferometer

Measurement systems for investigation of transient diffusion fields using an accurate interferometer have been developed. This system was composed of a real-time phase-shifting interferometer. Diffusion coefficients of aqueous solutions were measured using a shear cell and a counterflow-type cell. Rapid measurement was attained using the small test cell and the phase-shifting interferometer. The present shear cell system requires a few microlitters of test liquid. In order to shorten the measurement time, a counterflow-type test cell was developed. Mass diffusivity of the solution was derived. Measurement of double diffusive convection was carried out utilizing an active heat-transfer-control test cell. It is found that the double diffusion plume is observed within a very short measurement time less than 20 s and around the seed crystal of 0.5-mm height. Double diffusion fields and the crystal growth rates are investigated under transient double diffusive convection. The relation between the supersaturation on the crystal surfaces and crystal growth rate are investigated from the transient experiments.