High damage-resistant Mo mirror for high-power TEA CO2 laser systems

A high-purity molybdenum (Mo) mirror was developed by an electron-beam melting method (EBM Mo mirror). For the high-power TEA CO2 laser, the EBM Mo mirror has two to four times higher surface damage threshold than that of an Au-coated glass mirror, and three times longer lifetime than that of a powder metallurgy Mo mirror (PM Mo mirror) when laser energy density lower than 60 J/sq cm was irradiated with a 0.5-pps repetition rate. It was found that the difference between the EBM Mo mirror and the PM Mo mirror at the laser-damage threshold was due to the fine surface without voids and the small amount of impurities.