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Proceedings Paper

Bulk absorption measurements of highly transparent DUV/VUV optical materials
Author(s): Christian Muhlig; Siegfried Kufert; Wolfgang Triebel; Frank Coriand; Lutz Parthier; Andreas Voitsch
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Paper Abstract

The laser induced deflection technique (LID) is introduced for measuring small absorption coefficients of highly transparent DUV/VUV optical materials with high sensitivity and accuracy. The measuring principle, the calibration and the developed experimental realization are explained. At 193 nm in situ absorption and fluorescence measurements of fused silica give evidence that a commonly observed absorption decrease at the onset of laser irradiation is a bulk effect and due to a diminution of oxygen deficient centers ODC II. This decline is caused by a single photon absorption process and terminates after a dose of 4-5 kJ/cm2. Fluence dependent bulk absorption measurements of fused silica are presented which indicate the presence of a nonlinear dependence between the absorption coefficient α and the fluence H. For calcium fluoride a very good agreement between direct absorption and conventional transmission measurements is obtained. At 157 nm, a modified compact experimental setup is introduced which exhibits a significantly higher sensitivity than that applied for 193 nm experiments. First measurements of high quality calcium fluoride show that the obtained absorption is independent on the laser repetition rate. The investigation of equivalent CaF2 samples of different thickness (10 mm and 20 mm) indicates that the measured absorption coefficient is virtually free of contributions from the irradiated surfaces. Finally, a very good agreement is obtained by comparing LID data with transmission measurements of 100 mm long samples.

Paper Details

Date Published: 10 September 2004
PDF: 12 pages
Proc. SPIE 5457, Optical Metrology in Production Engineering, (10 September 2004); doi: 10.1117/12.545601
Show Author Affiliations
Christian Muhlig, Institut fur Physikalische Hochtechnologie e.V. (Germany)
Siegfried Kufert, Institut fur Physikalische Hochtechnologie e.V. (Germany)
Wolfgang Triebel, Institut fur Physikalische Hochtechnologie e.V. (Germany)
Frank Coriand, Schott Lithotec AG (Germany)
Lutz Parthier, Schott Lithotec AG (Germany)
Andreas Voitsch, Schott Lithotec AG (Germany)

Published in SPIE Proceedings Vol. 5457:
Optical Metrology in Production Engineering
Wolfgang Osten; Mitsuo Takeda, Editor(s)

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