Investigation of surface acoustic wave propagation on a sphere using laser ultrasonics
- Laboratoire Ondes et Acoustique, Universite Paris 7 - CNRS UMR 7587 ESPCI - 10, rue Vauquelin, 75231 Paris Cedex 05 (France)
Using the noncontact laser ultrasonic technique, we investigate the propagation of surface acoustic waves on a sphere (SSAW). A finite thermoelastic line source gives rise to combined focusing and reversal effects. As for propagation on a cylinder surface, the reversal of the SSAW pulse is explained by the dispersion of the high frequency components of the laser-generated acoustic pulse. The focusing effect, due to the curvature of the surface, depends on the angular aperture of the source. From diffraction theory, optimal conditions for diffraction free propagation are derived, both in harmonic and pulse regimes. On a steel sphere of radius 25 mm, Rayleigh waves excited by a 20 ns YAG laser pulse focused onto a 3 mm line propagate with a nearly constant amplitude.
- OSTI ID:
- 20634284
- Journal Information:
- Applied Physics Letters, Vol. 85, Issue 12; Other Information: DOI: 10.1063/1.1791331; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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