Introduction to rheometry for researchers of ultrasonics

In this paper, some recent topics on the methodology of viscoelasticity are introduced for researching ultrasonics. First, the role of viscoelasticity in ultrasonic relaxation phenomena is briefly summarized from the viewpoint of rheology. Then, the relaxation of two-dimensional viscoelasticity studied by surface light scattering experiments, which is analogous to the Brillouin scattering to detect thermal phonons, is discussed. Progress in the general method of rheometry using a rotational viscometer is also shown, in which the remote sensing of the viscosity by an electromagnetic spinning (EMS) method is described. Also examined is the possible accuracy of magneto levitated EMS, which can lead to the quantum standard of viscosity. Finally, ultrafast measurement of liquid properties, including surface tension and viscoelasticity, in which the technologies of micro liquid manipulation are employed, is introduced.