UV LASER-INDUCED DAMAGE TO GRAZING INCIDENCE METAL MIRRORS

摘要

We have performed experiments to establish the feasibility of grazing-incidence metal mirrors for laser fluences up to 5 J/cm~2 normal to the beam for extended periods of time up to 100,000 shots. Mirrors were fabricated by diamond turning or polishing of aluminum plates, by diamond turning of pure Al electroplated onto Al alloy substrates, and by deposition of thin Al films onto highly polished SiC substrates. Extended laser testing with 20-ns, 248-nm laser pulses showed marked differences in the surface response due to the strong dependence on the material microstructure. Diamond-turned surfaces exhibited the greatest damage resistance.