Viscosity and surface tension measurement by laser-induced capillary wave method (development of technique for solving inverse problem)

Recently, in many fields of science and industry, there is the growing need for the measurement technique applicable to the process in which the viscosity drastically changes within a short period of time. In order to meet the need, we have developed a new viscometry based on the laser-induced capillary wave, which enables very short-time (μs∼ms) and small-sample volume (μL∼mL) measurement. In the present study, we have developed an analytical technique for solving inverse problem for the determination of viscosity and surface tension by curve fitting of detected signals to rather complex theoretical formulas. We have measured several Newtonian liquid samples whose viscosity ranges from 0.304∼7 080 mPa∼s. The results agree well within about 10% from reference values in the wide range of viscosity.