Hard protective waterproof coating for high-power laser optical elements

We developed a new method for making a waterproof coating by photooxidation of silicone oil. The silicone oil was spin coated onto the surfaces of optical elements, i.e., a plastic lens, a laser mirror, and a nonlinear optical crystal, and then irradiated with a xenon excimer lamp in air, which transformed the organic silicone oil into an amorphous glass film. This technique has enabled an optical thin film to transmit ultraviolet rays of wavelengths below 200 nm and to exhibit the characteristics of homogeneity, high density, and resistance to environmental effects and to corrosion by water, and a Mobs scale value of 5. (c) 2005 Optical Society of America.