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Proceedings Paper

Pulsed top-hat beam thermal lens: a simple and sensitive tool for in-situ measurement on ultraviolet dielectric components
Author(s): Bincheng Li; Sven Martin; Eberhard Welsch; Roland Thielsch; Joerg Heber; Norbert Kaiser
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Paper Abstract

A mode-mismatched surface thermal lens technique with pulsed top-hat beam excitation and near field detection scheme is developed to measure in situ the thermoelastic response of UV dielectric coatings and bulk materials under excimer laser irradiation. The thermal lens technique is demonstrated to be not only convenient for an accurate determination of the laser-induced damage threshold (LIDT), but also sensitive to measure the thermoelastic response of dielectric coatings irradiated with fluences much below the LIDT, and hence, to carry out time resolved predamage investigation. The minimum detectable surface displacement of approximately 0.002nm is achieved with a simple experimental configuration. Nonlinear absorption of UV dielectric materials and coatings are demonstrated. The surface thermal lens technique is also a convenient technique to distinguish different damage mechanisms: thermal stress induced damage or melting induced damage, depending on the thermo-elastic properties of the substrate. Hence, this technique allows to indicate qualitatively the relative contribution of linear and nonlinear absorption as possible causes for laser damage. Moreover, the nonlinear effect in laser conditioning of a LaF3/MgF2 highly reflective dielectric coating has been observed experimentally.

Paper Details

Date Published: 3 March 2000
PDF: 9 pages
Proc. SPIE 3902, Laser-Induced Damage in Optical Materials: 1999, (3 March 2000); doi: 10.1117/12.379313
Show Author Affiliations
Bincheng Li, Friedrich-Schiller-Univ. Jena (Germany)
Sven Martin, Friedrich-Schiller-Univ. Jena (Germany)
Eberhard Welsch, Friedrich-Schiller-Univ. Jena (Germany)
Roland Thielsch, Fraunhofer-Institut fuer Angewandte Optik und Feinmechanik (Germany)
Joerg Heber, Fraunhofer-Institut fuer Angewandte Optik und Feinmechanik (Germany)
Norbert Kaiser, Fraunhofer-Institut fuer Angewandte Optik und Feinmechanik (Germany)

Published in SPIE Proceedings Vol. 3902:
Laser-Induced Damage in Optical Materials: 1999
Gregory J. Exarhos; Arthur H. Guenther; Mark R. Kozlowski; Keith L. Lewis; M. J. Soileau, Editor(s)

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