The size effects of inclusions on laser induced film damage

The damage of thin films due to inclusions can be caused by thermal accumulation, interference of scattered light with the incident laser beam and laser induced plasma. The synergic effects of these three mechanisms determine the damage characteristics of optical thin films, each of which is related to the size of inclusions in thin films. Our research results show that the films are damaged owing to the localized interference of light and the melting of thin films when the radii of inclusion particles lie within 24 nm and 40 nm. The laser-induced plasma resulting from the evaporation and ionization of thin film material will be generated when the radii of inclusion particles are larger than 40 nm. Those smaller than 24 nm, can be regarded as safe and free from inducing damage.