Intensity-dependent absorption in Cu and Ag metal mirrors - The role of temperature and surface roughness

The intensity-dependent absorption in diamond-turned Cu and Ag metal mirrors and mechanically polished Cu mirrors was investigated at 1.06 and 0.532 μm. The absorption increased with increasing intensity. The change is explained in terms of thermal mechanisms. The absorption is independent of the surface alterations introduced by irradiation. The observed reduction in damage resistance of the altered material may be caused by the interaction of light with the sharp edges produced by mechanical deformation.