Imaging flaws close to surface using focused surface acoustic waves

Date
1986-11
Advisor
Instructor
Source Title
IEEE 1986 Ultrasonics Symposium
Print ISSN
Electronic ISSN
Publisher
IEEE
Volume
Issue
Pages
755 - 758
Language
English
Type
Conference Paper
Journal Title
Journal ISSN
Volume Title
Abstract

The resolving power and detection ability of the focused surface acoustic wave (SAW) imaging modality is investigated in this paper. In this mode of imaging, conical bulk acoustic waves are used to generate and focus leaky surface acoustic waves on smooth surfaces of materials. Imaging systems built using this technique has diffraction limited focusing property. An imaging system using this focusing principle has been built, operating at 1.5 and 20 MHz. A slow mechanical scanning system controlled by a personal computer scans the surface of the object, and the data is acquired by the computer to generate a color or a black and white image on its graphic screen. The results of the initial experiments show that the inaging system is very sensitive to the grain structure and possible residual stresses on the surface of the object. It can resolve subsurface gratings of spacing less than a SAW wavelength very close to surface. The imaging system is inherently zero background, providing a high sensitivity not found in similar systems.

Course
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Book Title
Keywords
Surface acoustic waves, Acoustic imaging, Focusing, Acoustic waves, Mirrors, Acoustic signal detection, Residual stresses, Surface waves, Reflection, Frequency
Citation
Published Version (Please cite this version)