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Ultrasound generated by a femtosecond and a picosecond laser pulse near the ablation threshold.
- Source :
-
Journal of Applied Physics . 8/1/2005, Vol. 98 Issue 3, p033104. 7p. 2 Diagrams, 3 Graphs. - Publication Year :
- 2005
-
Abstract
- We have investigated high-frequency ultrasound generated by single laser pulses in thin (50 μm) aluminum foils as a function of the laser fluence. Laser-pulse durations of 80 fs and 270 ps were used to compare the ultrasound generated in two very different regimes: thermoelastic and ablation. The measured rear-surface displacement induced by the ultrasound pulse is similar after 50-μm propagation through the foils for the two laser-pulse durations in the fluence range of 0.1–0.7 J/cm2. For fluences greater than the ablation threshold (0.25 and 0.63 J/cm2 for the 80-fs and 270-ps pulses, respectively), the ultrasound amplitude generated by the 270-ps laser pulse is increased significantly due to absorption of laser energy by the ablating plasma. This is not observed for the 80-fs laser pulse since ablation is produced well after the laser-pulse irradiation of the target. The measured surface displacement as a function of laser fluence is compared to the calculations of a one-dimensional fluid code for both laser-pulse durations. The model calculations agree in many ways with the experimental results, but some discrepancies are observed. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00218979
- Volume :
- 98
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Journal of Applied Physics
- Publication Type :
- Academic Journal
- Accession number :
- 17961189
- Full Text :
- https://doi.org/10.1063/1.1999827