The Optical Measurement of Ultrasonic Stoneley Waves.

A numerical solution of the determinantal Stoneley wave velocity equation indicates the theoretical existence of Stoneley waves on the boundaries between transparent and opaque materials. Using differential interferometry and calibrated synchronous detection, Stoneley waves which induced 0.11 A particle motions near the boundary between isotropic nickel and borosilicate glass samples were detected. The waves were generated by surface wave conversion at the corners of obstacles and by internal longitudinal wave phase matching. Modifications of this technique were used to measure the attenuation of Rayleigh waves on fused quartz as a function of depth below the surface. Schoch effect measurements within the water cell utilized to generate Rayleigh waves partially confirmed the theory of leaky wave generation and allowed experimental optimization of longitudinal-to-surface wave conversion.