High-sensitivity absorption coefficients measurements using thermal lens spectrometry

Abstract
We report on measurements of absorption coefficients (A_e) with high-sensitivity (as small as 10^-8 cm^-1) in liquid and solid samples, using a simple pump-probe thermal lens experiment. Thermo-optical properties required for Ae determination, such as thermal conductivity K, thermal diffusivity D, and temperature coefficients of refractive index dn/dT and optical path length ds/dT, were also obtained. We measure an absorption coefficient at 457 nm of (5.3 ± 0.4)x10^-3 cm^-1 and at 514 nm of (2.50 ± 0.05)x10^-4 cm^-1 for undoped silica glass and Ethylene Glycol, respectively.