Skip to Main Content
Ten precision Cu laser mirrors prepared by eight different methods were evaluated at 10.6 μm for resistance to spatially selective laser-induced damage (pitting). Surfaces essentially free of pitting and with melt thresholds close to that of intrinsic Cu were produced by electron-beam melting bulk Cu, followed by diamond turning; by diamond turning with a 20° negative top rake angle; by chemical vapor deposition of pure Cu on a diamond-turned Cu substrate; and by polishing bulk Cu on a hard lap with high pressure. The electron-beam melted surface was the most damage resistant, but residual stresses left by the melting process degraded the optical surface figure. A special cleaning method was developed to remove optically absorbing contaminants trapped by surface defects.