Standard DUV mirror systems with conventional quarterwave design were deposited from oxide materials by ion beam sputtering deposition (IBS) and from fluoride materials by conventional thermal evaporation for the wavelength 193 nm. In addition, a protected fluoride mirror system was manufactured consisting of a conventional fluoride stack with a dense SiO₂ protection layer. In a comparative study, these mirror systems were characterised in respect to their optical properties and absorption in the VUV spectral range. Subsequently, the value of the laser-induced damage threshold (LIDT) of the mirrors was determined in an S-on-1 procedure. All DUV measurements were conducted under the conditions of nitrogen purging. It was observed that all mirror system exhibit a similar optical performance and loss levels at 193 nm. However, it was found for the LIDT value, that for IBS oxide system the damage mechanism is defect induced at a comparable low level, whereas the LIDT value of evaporated fluoride mirror is absorption induced, with 1-on-1 values of up to 6 J/cm². The protected fluoride mirror exhibits value in the intermediate range.

Date Published: 15 January 2007
PDF: 8 pages
Proc. SPIE 6403, Laser-Induced Damage in Optical Materials: 2006, 640318 (15 January 2007); doi: 10.1117/12.696241

Published in SPIE Proceedings Vol. 6403:
Laser-Induced Damage in Optical Materials: 2006
Gregory J. Exarhos; Arthur H. Guenther; Keith L. Lewis; Detlev Ristau; M. J. Soileau; Christopher J. Stolz, Editor(s)