Time- and frequency-resolved investigation of thin film laser damage

Experimental results on the damage of dielectric coatings are considered in the light of an extended mathematical treatment of the thermoelastic material response after nanosecond up to femtosecond UV laser irradiations. The deviation from the r^0.5-law even for the thermal loss mechanisms can be understood, taking into consideration both damage measurements in a vacuum environment and the related laser intensity profile. On the other hand, the calculation and high-resolution measurement of the thermoelastic sample surface response for thermally thin as well as thick optical coatings in the frequency domain demonstrates the potentiality of the photothermal displacement technique with respect to the nondestructive, laterally and depth-resolved characterization of the laser damage resistivity within the films.