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Proceedings Paper

Species-resolved laser-probing investigations of the hydrodynamics of KrF excimer and copper vapor laser ablation processing of materials
Author(s): Peter L. G. Ventzek; Ronald M. Gilgenbach; Chi Hong Ching; R. A. Lindley
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Paper Abstract

Hydrodynamic phenomena from KrF excimer laser ablation (10-3-20 J/cm2) of polyimide, polyethyleneterephthalate, and aluminum are diagnosed by laser beam deflection, schlieren photography, shadowgraphy, laser-induced-fluorescence and dye-laser- resonance absorption photography (DLRAP). Experiments were performed in vacuum and gaseous environments (10-5 to 760 Torr). In vacuum, the DLRAP diagnostic shows species-resolved plume expansion which is consistent with that of a reflected rarefaction wave. Increasing the background gas pressure reveals the formation of sound/shock compared to CN in the laser-ablated polyimide (Vespel) plume/shock in inert (e.g. argon) and reactive (e.g. air) gases. At low pressures (less than 10 Torr) Al and CN species are in close contact with the shock front. As the pressure increases, the species front tends to recede, until at high pressures (over 200 Torr) the species are restrained to only a few mm above the target surface. After sufficient expansion, Al and CN are no longer detectable; only the shadowgraph of the hot gas plume remains. Since CN is observable in both inert and reactive environments, it can be concluded that CN is not a reaction product between the background gas and the ablated species. By way of comparison to excimer laser ablation processing of materials, copper vapor laser machined polyimide and polymethylmethacrylate (transparent to green and yellow copper vapor laser light) are also investigated. The two polymers are observed to have markedly different machined surfaces. Hydrodynamic effects for the copper vapor laser machined materials are investigated using HeNe laser beam deflection.

Paper Details

Date Published: 24 June 1993
PDF: 10 pages
Proc. SPIE 1856, Laser Radiation Photophysics, (24 June 1993); doi: 10.1117/12.147604
Show Author Affiliations
Peter L. G. Ventzek, Univ. of Michigan (United States)
Ronald M. Gilgenbach, Univ. of Michigan (United States)
Chi Hong Ching, Univ. of Michigan (United States)
R. A. Lindley, Univ. of Michigan (United States)

Published in SPIE Proceedings Vol. 1856:
Laser Radiation Photophysics
Bodil Braren; Mikhail N. Libenson, Editor(s)

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