Open AccessAbsolute measurement of surface and bulk absorption in DUV optics from temperature induced wavefront deformation
Author(s) -
Bernd Schäfer,
Matthias Schöneck,
Armin Bayer,
Klaus Mann
Publication year - 2010
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.18.021534
Subject(s) - optics , wavefront , collimated light , materials science , wavefront sensor , laser , refractive index , absorption (acoustics) , distortion (music) , physics , optoelectronics , amplifier , cmos
A measurement system for quantitative determination of both surface and bulk contributions to the photo-thermal absorption in DUV optics was developed. It is based upon a Hartmann-Shack wavefront sensor with a sensitivity of ~λ/10000 rms, accomplishing precise on-line monitoring of wavefront deformations of a collimated test laser beam transmitted perpendicular through the excimer laser-irradiated site of a cuboid sample. Caused by the temperature dependence of the refractive index as well as thermal expansion, the initially plane wavefront of the test laser is distorted into a cylindrical shape, with bending ends towards the surface. Sign and magnitude depend on index change and expansion. By comparison with thermal theory, this transient wavefront distortion yields a quantitative absolute measure of bulk and surface absorption losses in the sample. First rresults for fused silica are presented.