Leaky-Rayleigh wave detection at air–solid interfaces by optical heterodyne interferometry

摘要

Recent developments have proven optical heterodyne interferometry to be a sensitive detector for ultrasonic amplitude and phase measurements in transparent materials. In this letter it is shown that this optical technique is sensitive enough to detect leaky-Rayleigh as well as leaky-Lamb waves in air reradiated from solids in the megaHertz region. Probing the leaky wave field at several positions parallel to the solid surface can yield the Rayleigh wave velocity of both transparent and opaque solids. This method can be used for low optical reflectivity solid surfaces: thus it can be extended for noncontact nondestructive evaluation applications.