SYNTHETIC QUARTZ GLASS FOR OPTICAL PART, ITS PRODUCTION AND USE THREOF

摘要

PROBLEM TO BE SOLVED: To efficiently and easily impart high transmittance to a synthetic quartz glass by irradiating a synthetic quartz glass having a specific OH group content with a vacuum ultraviolet light having specific wavelength, thereby improving the transmittance of light of a specific wavelength range. SOLUTION: A synthetic quartz glass having an OH group content of <=50 ppm is irradiated with vacuum ultraviolet light having a wavelength of <=180 nm to improve the transmittance of light having a wavelength ofη165 nm. The light source for the vacuum ultraviolet light is e.g. a xenon excimer lamp using xenon as a medium (main wavelength: 172 nm) and a fluorine laser using fluorine as a medium (main wavelength: 157 nm). The xenon excimer lamp is preferable in the case necessitating the improvement of the transmittance at wavelength of <=165 nm over a wide range and the fluorine laser is preferable from the viewpoint of productivity. The transmittance of synthetic quartz glass can be improved at a small dose of ultraviolet irradiation when the glass has a hydrogen molecule content of >=3×1016 molecules/cm3. The glass preferably has a fluorine content of about 100-2,000 ppm and is essentially free from reduced-type defects.