Dynamic transverse particle velocity measurements using interferometric techniques

An optical technique is described which uses velocity interferometry to determine the particle velocity changes associated with plane shear wave propagation. In this technique, two velocity interferometers are used to monitor different diffracted laser beams from a surface which undergoes both longitudinal and shear motion. Fringes produced in the interferometer are proportional to a linear combination of both the longitudinal and shear components of the free surface velocity. By obtaining two independent recordings of the motion, the two velocity components can be determined. Selected examples of shear wave interferometry applications are reported.