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Proceedings Paper

Development of a laser damage growth mitigation process, based on CO2 laser micro processing, for the Laser MegaJoule fused silica optics
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Paper Abstract

In the context of high power laser systems, the laser damage resistance of fused silica surfaces at 351 nm in the nanosecond regime is a major concern. Under successive nanosecond laser irradiations, an initiated damage can grow which can make the component unsuitable. The localized CO2 laser processing has demonstrated its ability to mitigate (stopping) laser damage growth. In order to mitigate large damage sites (millimetric), a method based on fast microablation of silica has been proposed by Bass et al. [Bass et al., Proc. SPIE 7842, 784220 (2010)]. This is accomplished by scanning of the CO2 laser spot with a fast galvanometer beam scanner to form a crater with a typical conical shape. The objective of the present work is to develop a similar fast micro-ablation process for application to the Laser MegaJoule optical components. We present in this paper the developed experimental system and process. We describe also the characterization tools used in this study for shape measurements which are critical for the application. Experimental and numerical studies of the downstream intensifications, resulting of cone formation on the fused silica surface, are presented. The experimental results are compared to numerical simulations for different crater shape in order to find optimal process conditions to minimize the intensifications in the LMJ configuration. We show the laser damage test experimental conditions and procedures to evaluate the laser damage resistance of the mitigated sites and discuss the efficiency of the process for our application.

Paper Details

Date Published: 6 December 2016
PDF: 10 pages
Proc. SPIE 10014, Laser-Induced Damage in Optical Materials 2016, 1001407 (6 December 2016); doi: 10.1117/12.2245148
Show Author Affiliations
Thomas Doualle, Aix-Marseille Univ., Ctr. Marseille, Institut Fresnel, CNRS (France)
Laurent Gallais, Aix-Marseille Univ., Ctr. Marseille, Institut Fresnel, CNRS (France)
Serge Monneret, Aix-Marseille Univ., Ctr. Marseille, Institut Fresnel, CNRS (France)
Stephane Bouillet, Commissariat à l'Énergie Atomique (France)
Antoine Bourgeade, Commissariat à l'Énergie Atomique (France)
Christel Ameil, Commissariat à l'Énergie Atomique (France)
Laurent Lamaignère, Commissariat à l'Énergie Atomique (France)
Philippe Cormont, Commissariat à l'Énergie Atomique (France)

Published in SPIE Proceedings Vol. 10014:
Laser-Induced Damage in Optical Materials 2016
Greg J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; MJ Soileau, Editor(s)

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