WIDE-BAND DETECTION OF ULTRASONIC WAVE PULSE USING OPTICAL EVANESCENTWAVES

A wide-bandwidth ultrasonic transducer was constructed using optical e vanescent fields. Due to the nonresonant nature of this evanescent wav es transducer, a sharp pulse was observed in a glass sample as compare d to that obtained by a piezoceramic transducer. The signal correspond s to the ultrasonic displacement on the glass surface, and an absolute value of the displacement was obtained. The sound fields at the glass surface were traced with the resolution of the laser beam diameter, w hich qualitatively agreed with the calculated profile for pulsed field s.