Optical breakdown of the surface of K8 glass modified by low-temperature ion exchange

A study was made of the optical breakdown threshold of the surface of K8 glass subjected to low-temperature ion-exchange diffusion in KNO₃ and NaNO₃ melts. It was found that the treatment of glass in KNO₃ increased and that in NaNO₃ reduced the breakdown threshold. The increase in the threshold was due to removal of absorbing inclusions in the process of diffusion treatment in the chemically active molten salt. Compressive stresses in the diffused layers reduced the size of the cracks in the surface layer of glass and stabilized the time dependence of the breakdown threshold.