Optical observation method for ultrasonic field using the shadowgraph introducing pulse inversion averaging

Abstract

Abstract:The pulse inversion averaging (PIA) method is introduced to the shadowgraph imaging system to visualize the second-harmonic component of the ultrasonic field. The principle of the PIA method is summarized and the method is customized for observing an second-harmonic ultrasonic field. An experiment of a shadowgraph with PIA using a 1-MHz concave focused transducer is conducted to evaluate the system. The fundamental component of 1 MHz is suppressed more than 30 dB with respect to the second-harmonic component. With this system, both a normal shadowgraph image and a second-harmonic image are visualized in real time.

Sensitive tint visualization system for Lamb waves propagation in a glass plate

“…Thereby, the time transition of ultrasonic waves propagation can be observed by varying the delay time ÁT of the delay unit. In the imaging process, the differential method [19][20][21], in which the sound-off image is subtracted from the sound-on image was used to enhance the contrast of the image. Figures 3(a)-3(d) show ultrasonic waves propagation images of 30-cycle S0-mode burst sine Lamb waves for delay times, ÁT, of 14 ms, 18 ms, 26 ms and 38 ms, respectively.…”

Use of energy trapping type piezoelectric transducer to suppress lateral vibration in the transducer

“…Fig. 4 shows Schlieren photograph of the underwater sound field [21,27] when the transducer was driven with 1 MHz, burst sine waves of 80 cycles of 100 Vp-p to evaluate the sound field in water. The photographs show that the 1 MHz ultrasonic wave radiated upward from the lower transducer.…”