Photo-oxidized Coating on the Optical Materials for High Power Laser Resistance and Waterproof

ABSTRACTA photo-oxidized thin film, which transformed the organic silicone oil into inorganic glass, was coated on optical materials surface by using Xe2 excimer lamp at room temperature. This technique has enabled an optical thin coating capable of transmitting ultraviolet rays [UV] of wavelengths under 200 nm and possessing the characteristics of hardness, strain-free, resistance to high power laser, and resistance to water. UV and IR spectroscopic analysis was carried out for investigation of the oxidized silicone oil. The results revealed that the absorption peak of the CH3 group at 2900 cm-1 decreased as the irradiation time of the excimer lamp increased, and the transmittance of the light in the 172 nm wavelengths conversely became high. The UV transmittance of the silicone oil was 29.2 % before the lamp irradiation; and it improved to 90.6 % after the irradiation for 120 minutes. Moreover, in order to evaluate for resistance to laser damage [J/cm2/10 ns], the films were further irradiated with the Nd: YAG laser of ω [1.06 μm] or 2ω [0.503 μm]. The silica glass substrate had almost same laser tolerance in ω and 2ω, 112 J/cm2 and 113 J/cm2, respectively. The laser damage threshold of the photo-oxidized 100 nm thick film formed on the fused silica substrate was 72 J/cm2 in ω and 107 J/cm2 in 2ω.