Absorption Measurement of Layers or Materials: How to Calibrate?

Abstract The knowledge of the absorption in the optical materials is important because it can generate problematic phenomena (distortion, depolarization, damage…) when high-power lasers are used. Photothermal Deflection (P.D.) makes it possible to quantify it with the measurement of the deflection of a probe beam caused by the propagation of a pump laser in the material or a thin layer. The deflection depends on the thermomechanical parameters and needs to be calibrated. The purpose of this paper is to present a method for measuring the absorption and to establish simple ratios to estimate it. This method is supported with a thermal modeling.