Detection of ultrasonic vibrations in self-supporting thin films using a laser spectrometer

Author

Moreau, A. ; Ketterson, J.B. ; Huang, J.

Author_Institution

Northwestern Univ., Evanston, IL, USA

fYear

1989

fDate

3-6 Oct 1989

Firstpage

1197

Abstract

A heterodyne laser spectrometer has been used to detect the vibrations normal to the plane of a metallic self-supporting thin film (on the order of 1-μm thick or thicker) with a sensitivity on the order of 0.01 Å. The film is excited by attaching it to an interdigital transducer. With continuous scanning of the laser probe across the surface of the film and measuring the amplitude and phase of the vibrations at a fixed frequency, the propagation vector of the modes excited can be accurately determined. This makes it possible to calculate the sound velocity of the antisymmetric Lamb mode and to deduce either the thickness of the film or its elastic flexural modulus

Keywords

elastic moduli; laser beam applications; measurement by laser beam; metallic thin films; surface acoustic waves; ultrasonic velocity measurement; 1 micron; antisymmetric Lamb mode; elastic flexural modulus; heterodyne laser spectrometer; interdigital transducer; laser probe; metallic self-supporting thin film; propagation vector; sound velocity; thickness; ultrasonic vibrations; Acoustic transducers; Frequency measurement; Joining processes; Laser excitation; Laser modes; Probes; Spectroscopy; Surface emitting lasers; Transistors; Vibration measurement;

fLanguage

English

Publisher

ieee

Conference_Titel

Ultrasonics Symposium, 1989. Proceedings., IEEE 1989

Conference_Location

Montreal, Que.

Type

conf

DOI

10.1109/ULTSYM.1989.67178

Filename

67178