Real Time Extraction System Using Double-Layered Piezoelectric Transducer for Second-Harmonic Ultrasonic Pulse Waves

Abstract

A novel detection system for second harmonic ultrasonic pulse waves is constructed by modifying an existing system using a double-layered piezoelectric transducer (DLPT). Two unique methods are introduced into the system, namely, the switching of the electrical connection of the DLPT and the pulse inversion excitation method, in which the DLPT is excited by both inphase and out-of-phase pulses alternatively and averaged to cancel the fundamental and odd harmonic components. As a result of using these two methods, enhanced second harmonic waves are displayed on an oscilloscope in real time, and an improved sensitivity of 80 dB is obtained. Finally, drilled holes are imaged as an application of the new system and to demonstrate its usefulness.

Detection of subharmonic components generated from microbubbles in water using double-layered piezoelectric transducer with aligning polarization directions

“…When the switch is turned on, the DLPT is connected in parallel (1 MHz), and when the switch is turned off, the DLPT is connected in series (2 MHz). This switching control method coincides with the configuration of the second harmonic detection system presented by the authors [10].…”

“…A real-time detection system comprising a double-layered piezoelectric transducer (DLPT) with opposing polarization directions for detecting second harmonic components has been constructed by the authors [10]. Our system has been applied to harmonic imaging [11] and the detection of second harmonic components generated from a plastically deformed metal rod [12].…”

A Novel Double-Layered Piezoelectric Transducer for Detecting Second Harmonic Ultrasonic Pulse Waves

“…Figure 3 shows the driving voltage waveform for the PIA method [11]. The driving voltage waveform was designed as a burst of 20 cycles of the 1 MHz sinewaves (burst duration time: 20 μs), and the period T [s] to the next inverted driving signal was determined to be 0.5 ms, which was much longer than the round trip time (about 50 μs) of ultrasonic wave.…”

“…A method of generating short ultrasonic pulse waves using a double-layered piezoelectric transducer (DLPT) has been reported by the authors [1,11]. The DLPT in an electrically parallel connection has the advantage of transmitting the fundamental pulse waves with a higher sensitivity to the fundamental frequency compared with a conventional single transducer.…”

“…Furthermore, the pulse inversion averaging (PIA) method [11] for extracting the second harmonic pulse waves is applied to obtain the second harmonic pulse waves in real time. Finally, a drilled hole in an aluminum plate is imaged to demonstrate the effectiveness of this system.…”