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Proceedings Paper

Damage to copper mirrors by high-power CO2 laser radiation
Author(s): A. Angenent; C. R. Haas; Joachim Koch; Ernst-Wolfgang Kreutz; David A. Wesner
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Paper Abstract

A focused, cw CO2 laser is used to irradiate polished Cu mirrors at power densities near 40 kW/cm2. Uncoated mirrors and mirrors having a reflection-enhancing Au coating with a protective Y2O3 layer are tested. During irradiation in-situ measurements of the temperature distribution in the surface are made and the morphology is monitored by interferometry. Chemical changes are determined by ex-situ x-ray photoemission and scanning Auger measurements. Damage to uncoated mirrors is connected with irreversible deformation, an increase in thermal gradients under irradiation (attributable to increased absorption), and oxidation of the surface layer, with formation of Cu2O and CuO. While the whole surface becomes oxidized, the effect is strongest in the laser focus, where an enhanced carbon content is also found. Similar thermal and morphological changes occur in coated mirrors under analogous irradiation conditions, but the relatively inert Y2O3 protective layer is not chemically changed. Structural changes are present in the surface and may contribute to the changed absorption.

Paper Details

Date Published: 24 June 1993
PDF: 7 pages
Proc. SPIE 1848, 24th Annual Boulder Damage Symposium Proceedings -- Laser-Induced Damage in Optical Materials: 1992, (24 June 1993); doi: 10.1117/12.147430
Show Author Affiliations
A. Angenent, Technical Univ. of Aachen (Germany)
C. R. Haas, Technical Univ. of Aachen (Germany)
Joachim Koch, Technical Univ. of Aachen (Germany)
Ernst-Wolfgang Kreutz, Technical Univ. of Aachen (Germany)
David A. Wesner, Technical Univ. of Aachen (Germany)

Published in SPIE Proceedings Vol. 1848:
24th Annual Boulder Damage Symposium Proceedings -- Laser-Induced Damage in Optical Materials: 1992
Harold E. Bennett; Lloyd L. Chase; Arthur H. Guenther; Brian Emerson Newnam; M. J. Soileau, Editor(s)

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