Investigation of the breakdown mechanism on the surfaces of IR-optics materials under the effect of pulsed CO2-laser radiation

A technique for measuring breakdown thresholds on the surfaces of IR-optics materials is described. It is shown that the appearance of breakdown under the effect of pulsed CO2-laser radiation is mainly conditioned by the presence of water adsorbed in the surface layer. The successive stages in the development of breakdown are investigated, and the features characterizing the breakdown are examined in relation to the parameters of the laser radiation, the state of the surface, and the external conditions. Consideration is given to the possibility of raising the breakdown thresholds on the surfaces of IR-optics materials by improving the surface-finishing technology or by modifying the modes of laser operation.