<title>In-situ measuring and monitoring of the laser conditioning of optical coatings</title>

By now laser conditioning has been proved to be a useful method to improve the optical coatings and raise the laser induced damage threshold of the thin film coatings. However, whatever happens during the laser conditioning process and which ever factor influences the laser conditioning effect are still not very clear. We produce a series samples with different roughness levels of the substrates, multilayer design, thin film material and the vacuum environment of the chamber. We make laser conditioning test to these samples by 1.06 micrometers laser. Photothermal deflection technology is employed to observe the conditioning process in-situ. A series of experimental data are obtained. We give our explanation. The mechanism of laser conditioning is also discussed.