Numerical Analysis of Narrow Band Ultrasonic Wave Generation with High Repetition Pulse Laser and Laser Scanning

3rd International Symposium on Laser Ultrasonics and Advanced Sensing

Hayashi, T.^1 ; Yamaguchi, K.^1 ; Biwa, S.^1

Graduate School of Engineering, Kyoto University, 615-8540 Kyoto, Japan^1

关键词: Calculation results;    Elastodynamic finite integration techniques;    Higher harmonics;    Large displacements;    Laser repetition rate;    Narrow-band ultrasonic;    Thermoelastic effects;    Ultrasonic energy;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/520/1/012024/pdf
DOI  :  10.1088/1742-6596/520/1/012024

来源: IOP

【 摘 要 】

Although the easiest way to enhance ultrasonic energy generated with pulse laser is to increase laser output, excessive laser output causes damage of the surface. This study introduced an alternative way to generate burst signals without any damages at the surface using a newly developed high repetition pulse laser controlled by galvano mirrors. The calculation results using two-dimensional elastodynamic finite integration technique coupled with thermoelastic effect proved that burst wave of 1 MHz and its higher harmonics were generated while supressing excessive temperature rise using this technique. Moreover, significantly large displacements at the frequency range sufficiently lower than laser repetition rate were observed of the same order of displacements generated with one single shot with the same input energy.