An optoacoustic transfer function for laser-ultrasonics: definition and its characterization for various lasers in the ablation regime

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ConferenceReview of Progress in Quantitative Nondestructive Evaluation, July 29 to August 3, 2001, Brunswick ME
AbstractTo maximize the signal-to-noise ratio of a laser-ultrasound system, one may choose to reduce the noise by using a better interferometer(and associated laser, optics, etc.), or to increase the signal by selecting a better generation laser. Given that interferometers have reached the detection limit of photon statistics, we focus our attention on ultrasound generation. To do so, we define an optoacoustic transfer function that describes the ultrasound generation efficiency of a pulsed laser on a specific material in a predetermined frequency bandwidth. On this basis, we compare the generation efficiency of various lasers on metals in the ablation regime. It is found that, at constant fluence, shorter pulses (ps) and shorter radiation wavelengths (UV) generate ultrasound more efficiently than longer pulses (ns) and longer radiation wavelengths (IR). It is also found that the generation efficiency is inversely proportional to frequency, as it should be if the generated ultrasonic pulse is a step function.
Publication date
AffiliationNRC Industrial Materials Institute; National Research Council Canada
Peer reviewedNo
NPARC number21273465
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Record identifiere248efed-d8df-423c-ae81-cbe74ce65f0d
Record created2015-01-09
Record modified2016-05-09
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