Characterization of optical coatings by photothermal deflection.

An overview of photothermal deflection principles and applications is given. The modeling of temperature distribution and the calculation of deflection that is due to both the refractive-index gradient and the thermal deformation of the sample are presented. Three configurations usually employed are compared, and their respective advantages are discussed in relation to their application. The calibration for absolute measurement of absorption is detailed, showing that calibration limits the accuracy of measurement. Some examples of specific information obtained by photothermal mapping of absorption are given.