Potentiality of the photothermal surface-displacement technique for precisely performed absorption measurement of optical coatings

The absolute and comparative determination of the absorption of optical films by the Photothermal-Surface-Displacement-Technique (PTD) is only possible if the sample configuration is in agreement with the limits of the theoretical model. Carrying out simultaneous absorption measurements in the IR-region at λ=10, 6 μm by using laser calorimetry as well as the surface displacement technique, it can be demonstrated that the thermophysical properties of the film contribute to the probed surface displacement. The results of PTD measurements at a wavelength of 488 nm show, that there is a similar influence of the film properties on the PTD signal.