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Proceedings Paper

Investigation of the photoacoustic signal dependence on laser power
Author(s): Jan Niemi; Torbjörn Löfqvist; Per Gren
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Paper Abstract

In this study we have focused on exploring the photoacoustic signal generated by laser induced dielectric breakdown process in pure water, under normal conditions. In this case the dielectric breakdown will lead to a formation of a shock wave. We investigated the relation between pulse energy and amplitude, group velocity and power spectrum of the shock wave. Also, the threshold for dielectric breakdown is estimated. A pulsed, high power Nd:YAG laser with λ = 532 nm and a pulse duration of 12 ns was used. The laser pulse energy ranges from 0.1 mJ to 7.4 mJ. Only photoacoustic signals generated from dielectric breakdown was considered. We found that the amplitude and the average group velocity of the shock wave correlates to the laser pulse energy. The frequency contents of the photoacoustic signal changes due to both non-linear behaviour and dissipative effects. We estimated the dielectric breakdown threshold to be 0.44 × 1011Wcm-2.

Paper Details

Date Published: 5 June 2008
PDF: 9 pages
Proc. SPIE 7022, Advanced Laser Technologies 2007, 70220C (5 June 2008); doi: 10.1117/12.803915
Show Author Affiliations
Jan Niemi, Lulea Univ. of Technology (Sweden)
Torbjörn Löfqvist, Lulea Univ. of Technology (Sweden)
Per Gren, Lulea Univ. of Technology (Sweden)


Published in SPIE Proceedings Vol. 7022:
Advanced Laser Technologies 2007

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