title: Method for measuring small optical absorption coefficients with use of a Shack-Hartmann wave-front detector.
abstract: We present a method for measuring absorption at the 1 x 10(-5) cm(-1) level in high-quality optical materials. Using a Shack-Hartmann wave-front detector, thermal lensing in these materials may be measured. Then, the absorption coefficient may be estimated by fitting the observed deformation to a thermal lensing model based on the temperature dependences of the refractive index and the thermal expansion coefficient. For a particular sample of fused silica, the absorption coefficient was determined to be 1.8 +/- 0.4 x 10(-5) cm(-1). Obtaining this result requires a resolution in the optical path length better than +/- 0.1 nm.
authors.affiliation: Laser Interferometer Gravitational-Wave Observatory-Livingston, 19100 Ligo Lane, P.O. Box 940, Livingston, Louisiana 70754, USA. syoshida@selu.edu
authors.forename: Sanichiro
authors.initials: S
authors.lastname: Yoshida
authors.forename: David H
authors.initials: DH
authors.lastname: Reitze
authors.forename: David B
authors.initials: DB
authors.lastname: Tanner
authors.forename: Justin D
authors.initials: JD
authors.lastname: Mansell