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Proceedings Paper

Influence of thermal substrate properties on the damage threshold of UV coatings
Author(s): Holger Blaschke; Sven Martin; Andreas Morak; Ch. Koenigsdoerffer; M. Roth; Bincheng Li; Eberhard Welsch; Roland Thielsch; Norbert Kaiser
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Paper Abstract

The thermal decay of surface temperature has been calculated and measured on Al2O3/SiO2 coatings by using photothermal technique near damage threshold fluence. It could be shown that under certain conditions the decay times (tau) has been found to be in the order of some microseconds. This fact gives no explanation of the measured decrease of threshold fluence in some cases for higher repetition rates and shot numbers on Al2O3/SiO2 and HfO2/SiO2 multilayers for (lambda) equals 248nm. Furthermore, it could not be found any influence of the substrate materials. Thus, other than thermal accumulation is responsible for the lowered damage threshold by increasing repetition rate. Additionally, performed calculations of the thermal decay using 20ns, 248nm laser excitation confirm the experimental results. Even in the case of Al2O3/SiO2 coatings on copper no effect of the substrate as a heat sink could be measured. For HfO2/SiO2 coatings the behavior is in accordance with the fact that the thermal conductivity of HfO2 films is markedly lowered compared to the bulk value.

Paper Details

Date Published: 7 April 1999
PDF: 10 pages
Proc. SPIE 3578, Laser-Induced Damage in Optical Materials: 1998, (7 April 1999); doi: 10.1117/12.344387
Show Author Affiliations
Holger Blaschke, Fraunhofer-Institut fuer Angewandte Optik und Feinmechanik (Germany)
Sven Martin, Friedrich-Schiller-Univ. Jena (Germany)
Andreas Morak, Friedrich-Schiller-Univ. Jena (Germany)
Ch. Koenigsdoerffer, Friedrich-Schiller-Univ. Jena (Germany)
M. Roth, Friedrich-Schiller-Univ. Jena (Germany)
Bincheng Li, Friedrich-Schiller-Univ. Jena (Germany)
Eberhard Welsch, Friedrich-Schiller-Univ. Jena (Germany)
Roland Thielsch, Fraunhofer-Institut fuer Angewandte Optik und Feinmechanik (Germany)
Norbert Kaiser, Fraunhofer-Institut fuer Angewandte Optik und Feinmechanik (Germany)


Published in SPIE Proceedings Vol. 3578:
Laser-Induced Damage in Optical Materials: 1998
Gregory J. Exarhos; Arthur H. Guenther; Mark R. Kozlowski; Keith L. Lewis; M. J. Soileau, Editor(s)

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