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Proceedings Paper

Visualizing microair blasts using double-exposure holographic interferometry
Author(s): Gopalan Jagadeesh; Osamu Onodera; Toshihiro Ogawa; Kazuyoshi Takayama
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Paper Abstract

Micro air blasts are generated over planar and corrugated surfaces, at stand-off distances of 4 and 11 mm, by focusing a 1.38J, 18 ns Nd:Glass laser pulse in a tiny spot of 300 micrometer diameter, under ambient conditions. This triggers the breakdown of air at optical frequencies with subsequent formation of laser plasma, which generates an outward propagating spherical micro-blast wave. The velocity of this wave decreases as time elapses, since the energy deposition is finite, with reference to both space and time. The evolution, propagation and subsequent reflection of the spherical micro- blast wave, from planar and corrugated surfaces are experimentally investigated, using double exposure holographic interferometry. One planar surface and four surfaces with varying degree of surface corrugations are used in this study. Mach reflection of the blast wave is observed at a stand-off distance of 4 mm over a planar obstacle while only regular reflection is visualized at an 11 mm stand-off distance. However only regular reflection is observed at both stand-off distances, in the case of corrugated surfaces.

Paper Details

Date Published: 17 April 2001
PDF: 10 pages
Proc. SPIE 4183, 24th International Congress on High-Speed Photography and Photonics, (17 April 2001); doi: 10.1117/12.424356
Show Author Affiliations
Gopalan Jagadeesh, Tohoku Univ. (Japan)
Osamu Onodera, Tohoku Univ. (Japan)
Toshihiro Ogawa, Tohoku Univ. (Japan)
Kazuyoshi Takayama, Tohoku Univ. (Japan)

Published in SPIE Proceedings Vol. 4183:
24th International Congress on High-Speed Photography and Photonics
Kazuyoshi Takayama; Tsutomo Saito; Harald Kleine; Eugene V. Timofeev, Editor(s)

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