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Proceedings Paper

Noncontact ultrasound studies of composite materials: new developments
Author(s): Christopher Edwards; Theodosia Stratoudaki; Stephen Dixon; Stuart B. Palmer
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Paper Abstract

Techniques are being developed worldwide for non-contact ultrasonic inspection of composite materials. These include laser generation and optical detection of ultrasound; both with interferometers and simpler beam deflection techniques, air coupled transducers are also used as generators and/or detectors of ultrasound. This paper compares the generation efficiency and damage thresholds of a range of different laser types: A fundamental Nd:YAG laser (1.06 micrometer), a TEA CO2 laser (10.6 micrometer normally preferred for carbon- fiber reinforced composites) and a Nd:YAG laser with an Optical Parametric Oscillator (OPO) tunable up to 4 micrometer. The laser energy is absorbed with the optical absorption depth, the temperature rise is affected by the wavelength and laser pulse duration. It is essential to remain in the thermoelastic regime in order not to damage the material. A modified Michelson interferometer is used to detect the absolute displacement of the ultrasound. Optical beam deflection techniques and air-coupled transducers are also evaluated as detectors.

Paper Details

Date Published: 13 May 2000
PDF: 8 pages
Proc. SPIE 3993, Nondestructive Evaluation of Aging Materials and Composites IV, (13 May 2000); doi: 10.1117/12.385498
Show Author Affiliations
Christopher Edwards, Univ. of Warwick (United Kingdom)
Theodosia Stratoudaki, Univ. of Warwick (United Kingdom)
Stephen Dixon, Univ. of Warwick (United Kingdom)
Stuart B. Palmer, Univ. of Warwick (United Kingdom)

Published in SPIE Proceedings Vol. 3993:
Nondestructive Evaluation of Aging Materials and Composites IV
George Y. Baaklini; Carol A. Nove; Eric S. Boltz, Editor(s)

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