OBSERVATION OF LEAKY SURFACE-SKIMMING COMPRESSIONAL WAVE EXCITED ON POLYMERS USING ULTRASONIC MICROSPECTROMETER

A new method for material characterization using an ultrasonic micro-s pectrometer system is described. This system with spherical-planar-pai r lenses can be used to directly estimate the reflection coefficient R (f, theta) for infinite plane waves at a local surface area on the sol id. In this paper, the characterization is carried out by comparing th e magnitude of the measured reflection coefficient \R(f, theta)\ and t hat of the calculated coefficient \R(f, theta)\ around the critical an gle of the specimen's longitudinal wave. This method is very useful fo r materials such as polymers, with a low Rayleigh velocity, because th e leaky Rayleigh wave is not excited; on the contrary, the leaky surfa ce-skimming wave is sufficiently excited to be measured. Velocity and attenuation of the longitudinal wave and the transverse wave are also estimated by means of computer fitting.