抄録
A novel detection system for second harmonic ultrasonic pulse waves is constructed by modifying the double-layered piezoelectric transducer (DLPT). The new DLPT composed of two PbTiO3 thickness-mode piezoceramic concave disks is employed: one is a conventional concave transducer and the other is a ring type concave transducer. Since the switch for the electrical connection used in the conventional DLPT system is not required, a simple system for detecting second harmonic ultrasonic pulse waves can be constructed. Furthermore, for real time detection of second harmonic ultrasonic pulse waves, pulse inversion averaging (PIA) is carried out. As a result, the enhanced second harmonic ultrasonic pulse waves are displayed on an oscilloscope in real time. A drilled hole in an aluminum plate is then imaged to demonstrate the effectiveness of this system.
