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Article Dans Une Revue Journal of the Acoustical Society of America Année : 1998

Temporal deconvolution of laser-generated longitudinal acoustic waves for optical characterization and precise longitudinal acoustic velocity evaluation

Résumé

The laser thermoelastic generation of ultrasound is a promising technique with many potential applications, but it is also a complicated process with many physical phenomena involved. Contrary to a conventional piezoelectric transducer generation, which is a surface phenomenon, a laser generation can activate acoustic sources within the material by optical penetration of the excitation wavelength, resulting in asynchronous wave arrivals at a given point. More generally, in the ideal case of a nondispersive isotropic material, the laser-ultrasonics displacement signals result from temporal convolutions between optical penetration, laser pulse duration, and laser spot extension effects. In this paper, a deconvolution technique is presented that extracts the laser pulse duration contribution from the experimental displacement signals. This deconvolution scheme applied to one-dimensional experiments, in which the laser excitation is spread over a sufficiently large area on the front side of the sample, allows the measurement of the optical absorption coefficient of the material at the excitation wavelength and also a precise evaluation of its longitudinal acoustic velocity.
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Dates et versions

hal-01287450 , version 1 (14-03-2016)

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Franck Enguehard, Lionel Bertrand. Temporal deconvolution of laser-generated longitudinal acoustic waves for optical characterization and precise longitudinal acoustic velocity evaluation. Journal of the Acoustical Society of America, 1998, 103, ⟨10.1121/1.421241⟩. ⟨hal-01287450⟩
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