POINT-CONTACT ULTRASONIC TRANSDUCER OF WAVE-GUIDING STRUCTURE FOR HIGH-FREQUENCY OPERATION

This letter presents a new type of Hertzian-contact transducer of wave guiding structure operating in the MKz range. The transducer is compos ed of a fused quartz tube and a radially-polarized annular piezoelectr ic element bonded to one of its ends. The edge-bonded shear-wave trans ducer effectively excites a surface wave on the interior surface of th e tube. A small bullet pin made of quartz is inserted and fixed on the other end of the tube to make a point contact and transmit the wave e nergy to a specimen to be inspected. Using a pair of these transducers , we have succeeded in exciting and detecting surface acoustic waves a s well as Lamb waves in the 3 MHz frequency range. (C) 1996 American I nstitute of Physics.