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Proceedings Paper

Nanosecond interferometric studies of surface deformations of dielectrics induced by laser irradiation
Author(s): Scott R. Greenfield; Joanna L. Casson; Aaron C. Koskelo
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Paper Abstract

Transient surface deformations in dielectric materials induced by laser irradiation were investigated with time-resolved interferometry. Deformation images were acquired at various delay times after exposure to single pulses (100 ps at 1.064 micrometer) on fresh sample regions. Above the ablation threshold, we observe prompt ejection of material and the formation of a single unipolar compressional surface acoustic wave propagating away from the ablation crater. For calcite, no deformation -- either transient or permanent -- is discernable at laser fluences below the threshold for material ejection. Above and below-threshold behavior was investigated using a phosphate glass sample with substantial near infrared absorption (Schott filter KG3). Below threshold, KG3 exhibits the formation of a small bulge roughly the size of the laser spot that reaches its maximum amplitude by approximately 5 ns. By tens of nanoseconds, the deformations become quite complex and very sensitive to laser fluence. The above-threshold behavior of KG3 combines the ablation-induced surface acoustic wave seen in calcite with the bulge seen below threshold in KG3. A velocity of 2.97 +/- 0.03 km/s is measured for the KG3 surface acoustic wave, very close to the Rayleigh wave velocity calculated from material elastic parameters. Details of the transient interferometry system are also given.

Paper Details

Date Published: 16 August 2000
PDF: 10 pages
Proc. SPIE 4065, High-Power Laser Ablation III, (16 August 2000); doi: 10.1117/12.407380
Show Author Affiliations
Scott R. Greenfield, Los Alamos National Lab. (United States)
Joanna L. Casson, Los Alamos National Lab. (United States)
Aaron C. Koskelo, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 4065:
High-Power Laser Ablation III
Claude R. Phipps, Editor(s)

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