A diffraction-based optical method for the detection of in-plane motion of Lamb waves

Author

Yang, Che-Hua ; Tsai, Yua-Ching

Author_Institution

Dept. of Mech. Eng., Chang Gung Univ., Taoyuan, Taiwan

Volume

52

Issue

8

fYear

2005

Firstpage

1372

Lastpage

1377

Abstract

This paper describes a laser optical technique that allows the detection of in-plane motion of Lamb waves. This interference-based laser optical technique includes a tiny square indentation with a width of about 30 /spl mu/ on the sample surface and a relatively simple optical arrangement. The current technique is applied for the detection of in-plane motions of Lamb waves propagating in a 70-/spl mu/. thick brass plate. Measurement of S/sub 0/ mode dominated by in-plane motion in the low fd (frequency times thickness) regime is successfully demonstrated with the current technique. With the indentation replaced by a microreflector in a microelectromechanical (MEMS) structure, this technique is applicable for the detection of in-plane motion in MEMS structures.

Keywords

light diffraction; light interferometry; micro-optics; micromechanical devices; remote sensing by laser beam; surface acoustic waves; ultrasonic variables measurement; Lamb waves; S/sub 0/ mode; diffraction-based optical method; in-plane motion detection; interference-based technique; laser optical technique; microelectromechanical structure; microreflector; square indentation; thick brass plate; Current measurement; Frequency measurement; Interference; Micromechanical devices; Motion detection; Motion measurement; Optical diffraction; Optical propagation; Optical surface waves; Surface emitting lasers;

fLanguage

English

Journal_Title

Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Publisher

ieee

ISSN

0885-3010

Type

jour

DOI

10.1109/TUFFC.2005.1509796

Filename

1509796