Abstract
The usual type of ultrasonic transducers can not only radiate ultrasonic waves with a narrow frequency bandwidth, but it is possible to obtain a broad bandwidth by using a wedge-shaped transducer. Plano-convex transducers, which are modified wedged transducers, are made of piezoelectric ceramics having the thickness extensional vibration. The typical features of this transducer are to radiate continuous and pulsed ultrasonic waves over a broad frequency range, to transmit and receive a short ultrasonic pulse, and to radiate focused ultrasonic waves. Those features and another characteristics with this transducer is more clarified through the measurements of free impedance, radiation pattern and ringing for an impulse. As applications using the plano-convex transducer with excellent features and low noise for the pulse-echo technique, it is attempted to detect a small hole in steel(non-destractive testing), and to measure the sound velocity of the longitudinal and transverse waves in materials.
