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Proceedings Paper

Presentation and comparison of damage test procedures for fused silica and KDP crystals
Author(s): L. Lamaignère; T. Donval; M. Loiseau; S. Bouillet; R. Courchinoux; J. C. Poncetta; Betrand Bertussi; H. Bercegol
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Paper Abstract

A rasterscan test procedure [L. Lamaignère et al, Rev. Sci. Instrumen. 78, 103105 (2007)] has been implemented in order to determine low laser damage density of large aperture UV fused silica optics. This procedure was improved in terms of accuracy and repeatability and is now used for the determination of bulk damage density for KDP crystals. The large area (volume) scanned during tests permits to measure very low damage density. On small samples, small area are tested using the normalized 1/1 test procedure consisting on the irradiation of few sites at several fluences. The classical damage probability plot is converted in terms of damage density. The two testing procedures are complementary: the 1/1 mode is practical to test a wide fluence range while the rasterscan mode allows exploring low damage densities with higher accuracy. Tests have been carried out on several facilities using several pulse durations and spatial distributions. We describe the equipment, test procedure and data analysis to perform this damage test with small beams (Gaussian beams, about 1mm @ 1/e, and top hat beams). Then, beam overlap and beam shape are the two key parameters which are taken into account in order to determine damage density. After data analysis and treatment, a repeatable metrology has been obtained. Moreover, the consideration of error bars on defects distributions permits to compare data between these installations. This allows us to reach reproducibility, a necessary condition in order to share results and to make reliable predictions of laser damage resistance. Other tests are realized with larger beams (centimeter sized) and with a single shot. Due to a large beam contrast, a large fluence range is then covered. Then after data treatment, we find a good correlation between tests realised with small and large beams. This allows us to make tests with different laser characteristics (spectral modulations, pulse duration, laser polarisation) and then to study their influences on laser damage.

Paper Details

Date Published: 30 December 2008
PDF: 6 pages
Proc. SPIE 7132, Laser-Induced Damage in Optical Materials: 2008, 71320X (30 December 2008); doi: 10.1117/12.804471
Show Author Affiliations
L. Lamaignère, CEA/CESTA (France)
T. Donval, CEA/CESTA (France)
M. Loiseau, CEA/CESTA (France)
S. Bouillet, CEA/CESTA (France)
R. Courchinoux, CEA/CESTA (France)
J. C. Poncetta, CEA/CESTA (France)
Betrand Bertussi, CEA/Le Ripault (France)
H. Bercegol, CEA/CESTA (France)

Published in SPIE Proceedings Vol. 7132:
Laser-Induced Damage in Optical Materials: 2008
Gregory J. Exarhos; Detlev Ristau; M. J. Soileau; Christopher J. Stolz, Editor(s)

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