Synthetic quartz glass and process for producing it
AssigneeAsahi Glass Company, Limited
InventorsYoshiaki Ikuta, Shinya Kikugawa, Noriaki Shimodaira, Akio Masui, Shuhei Yoshizawa
Life of this patent
Estimating the term…
Abstract
A synthetic quartz glass for optical use, to be used by irradiation with light within a range of from the ultraviolet region to the vacuum ultraviolet region, which contains fluorine, which has a ratio of the scattering peak intensity of 2250 cm−1 (I2250) to the scattering peak intensity of 800 cm−1 (I800), i.e. I2250/I800, of at most 1×10−4 in the laser Raman spectrum, and which has an absorption coefficient of light of 245 nm of at most 2×10−3 cm−1.
Claims18
A synthetic quartz glass for optical use, to be used by irradiation with light within a range of from the ultraviolet region to the vacuum ultraviolet region, which contains fluorine, which has a ratio of the scattering peak intensity of 2,250 cm−1 (I2250) to the scattering peak intensity of 800 cm−1 (I800), i.e. I2250/I800, of at most 1×10−4 in the laser Raman spectrum, and which has an absorption coefficient of light of 245 nm of at most 2×10−3 cm−1.
A synthetic quartz glass for optical use, to be used is by irradiation with light within a range of from the ultraviolet region to the vacuum ultraviolet region, which comprises a synthetic quartz glass containing OH groups and fluorine and having a chlorine concentration of at most 25 ppm, wherein the variation range of the OH group concentration is at most 15 ppm and the variation range of the fluorine concentration is at most 15 ppm, at the light transmitting region.
A synthetic quartz glass for optical use, to be used by irradiation with light within a range of from the ultraviolet region to the vacuum ultraviolet region, which comprises a synthetic quartz glass containing OH groups and fluorine and having a chlorine concentration of at most 25 ppm, wherein at the light transmitting region, the OH groups and the fluorine are distributed so that they offset the concentration distribution of the other, and the variation range of the OH group concentration is at most 25 ppm and the variation range of the fluorine concentration is at most 25 ppm.
A process for producing a synthetic quartz glass to be used by irradiation with light within a range of from the ultraviolet region to the vacuum ultraviolet region, which comprises
- (a) a step of depositing and growing fine quartz glass particles obtained by subjecting a quartz glass forming material to flame hydrolysis, on a substrate, to form a porous quartz glass body;
- (b) a step of holding the porous quartz glass body in a fluorine-containing atmosphere to obtain a porous quartz glass body containing fluorine;
- and
- (c) a step of raising the temperature of the porous quartz glass body containing fluorine to the transparent vitrification, temperature for transparent vitrification, to obtain a transparent quartz glass body.
Dependencies are inferred from the claim text.