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Proceedings Paper

Laser-induced gas plasma etching of fused silica under ambient conditions
Author(s): Selim Elhadj; Gabe Guss; Manyalibo J. Matthews; Isaac Bass
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Paper Abstract

Laser machining of optics to mitigate surface defects has greatly enhanced the ability to process large optics such as those found in fusion-class lasers. Recently, the use of assist reactive gases has shown promise in enhancing manifold etching rates relative to ambient conditions for CW-laser exposures. However, these methods still require significant heating of the substrate that induce residual stress, redeposit coverage, material flow, and compromise the final surface finish and damage threshold. While very reactive fluorinated gases are capable to reduce treatment temperatures even further, they are also inherently toxic and not readily transferable to large processing facilities. In this report, we look at whether a short-lived gas plasma could provide the safe and effective etchant sought, while still reducing the thermal load on the surface. We test this approach using a YAG laserinduced gas plasma to act as a source of the etchant for fused silica, a common optical material. The configuration and orientation of the beam and optical apparatus with respect to the surface was critical in preventing surface damage while etching the surface. Results with N2 and air gas plasmas are shown, along with a description of the various experimental implementations attempted.

Paper Details

Date Published: 4 December 2012
PDF: 12 pages
Proc. SPIE 8530, Laser-Induced Damage in Optical Materials: 2012, 853022 (4 December 2012); doi: 10.1117/12.979814
Show Author Affiliations
Selim Elhadj, Lawrence Livermore National Lab. (United States)
Gabe Guss, Lawrence Livermore National Lab. (United States)
Manyalibo J. Matthews, Lawrence Livermore National Lab. (United States)
Isaac Bass, Lawrence Livermore National Lab. (United States)

Published in SPIE Proceedings Vol. 8530:
Laser-Induced Damage in Optical Materials: 2012
Gregory J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; M J Soileau, Editor(s)

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