DETECTION OF SHEAR-WAVE IN ULTRASONIC RANGE BY USING A LASER-DOPPLER VIBROMETER

A laser Doppler vibrometer is used to measure shear waves propagating through solids in the ultrasonic frequency range. The laser Doppler vi brometer detects translational motion of small spherical lenses mounte d on a solid surface. Slacking of wave-form signals increases the sign al-to-noise ratio. Wave motion on a solid surface can be obtained from the surface vibrations measured at different incident angles of a las er beam. The observed longitudinal and shear wave amplitudes from a th ickness-dilation-mode transducer agreed fairly well with the calculate d amplitudes modeled by a piston force source. (C) 1998 American Insti tute of Physics. [S0034-6748(98)05706-2]