| 摘要 |
PURPOSE:To ensure a stable refractive index and stable transmissivity to high output laser light in a short wavelength region over a long time and to reduce fluorescence by making the structure of high purity quartz glass practically free from oxygen defects. CONSTITUTION:High purity quartz glass having >=300ppm OH group content, <=0.1ppm alkali metal content, <=0.1ppm alkaline earth metal content, <=0.01ppm transition metal content and <=0.1ppm Al content is formed by a soot process or a plasma process with gaseous SiCl4, oxygen and hydrogen. The quartz glass is heat treated in an oxidizing and/or reducing atmosphere to make the structure of the glass practically free from oxygen defects. |
