Abstract: A process for producing a synthetic silica glass optical component which contains at least 1×1017 molecules/cm3 and has an OH concentration of at most 200 ppm and substantially no reduction type defects, by treating a synthetic silica glass having a hydrogen molecule content of less than 1×1017 molecules/cm3 at a temperature of from 300 to 600° C. in a hydrogen gas-containing atmosphere at a pressure of from 2 to 30 atms.

Abstract: To provide a glass for an information recording media substrate, which is excellent in weather resistance. A glass for an information recording media substrate, which comprises, as represented by mol % based on oxide, from 61 to 66% of SiO2, from 11.5 to 17% of Al2O3, from 8 to 16% of Li2O, from 2 to 8% of Na2O, from 2.5 to 8% of K2O, from 0 to 6% of MgO, from 0 to 4% of TiO2 and from 0 to 3% of ZrO2, provided that Al2O3+MgO+TiO2 is at least 12%, and Li2O+Na2O+K2O is from 16 to 23%, wherein in a case of where B2O3 is contained, its content is less than 1%. The above glass for an information recording media substrate, wherein when the glass is left under steam atmosphere at 120° C. at 0.2 MPa for 20 hours, and the amount of Li, the amount of Na and the amount of K, which precipitate on a surface of the glass are represented as CLi, CNa and CK respectively, CNa is at most 0.7 nmol/cm2, and CLi+CNa+CK is at most 3.5 nmol/cm2.

Abstract: The present invention provides a method for lapping a glass substrate, including lapping a glass substrate having excellent maximum thickness deviation, and a method for manufacturing a glass substrate for a magnetic recording medium, including a step using the above-mentioned lapping method.

Abstract: Spots generated on a glass substrate after a polishing step are reduced. The present invention relates to a method for polishing a glass substrate including injecting a silica abrasive and a high-boiling solvent in a final glass substrate polishing step. The high-boiling solvent is preferably a solvent having a molecular weight of 300 or lower and a boiling point of 150° C. or higher. As Examples of the high-boiling solvent having a molecular weight of 300 or lower and a boiling point of 150° C. or higher includes ethylene glycol, propylene glycol and glycerine.

Abstract: To provide a glass for an information recording media substrate, which is excellent in weather resistance. A glass for an information recording media substrate, which comprises, as represented by mol % based on oxide, from 61 to 66% of SiO2, from 11.5 to 17% of Al2O3, from 8 to 16% of Li2O, from 2 to 8% of Na2O, from 2.5 to 8% of K2O, from 0 to 6% of MgO, from 0 to 4% of TiO2 and from 0 to 3% of ZrO2, provided that Al2O3+MgO+TiO2 is at least 12%, and Li2O+Na2O+K2O is from 16 to 23%, wherein in a case of where B2O3 is contained, its content is less than 1%. The above glass for an information recording media substrate, wherein when the glass is left under steam atmosphere at 120° C. at 0.2 MPa for 20 hours, and the amount of Li, the amount of Na and the amount of K, which precipitate on a surface of the glass are represented as CLi, CNa and CK respectively, CNa is at most 0.7 nmol/cm2, and CLi+CNa+CK is at most 3.5 nmol/cm2.

Abstract: To provide a glass for an information recording media substrate, which is excellent in weather resistance. A glass for an information recording media substrate, which comprises, as represented by mol % based on oxide, from 61 to 66% of SiO2, from 11.5 to 17% of Al2O3, from 8 to 16% of Li2O, from 2 to 8% of Na2O, from 2.5 to 8% of K2O, from 0 to 6% of MgO, from 0 to 4% of TiO2 and from 0 to 3% of ZrO2, provided that Al2O3+MgO+TiO2 is at least 12%, and Li2O+Na2O+K2O is from 16 to 23%, wherein in a case of where B2O3 is contained, its content is less than 1%. The above glass for an information recording media substrate, wherein when the glass is left under steam atmosphere at 120° C. at 0.2 MPa for 20 hours, and the amount of Li, the amount of Na and the amount of K, which precipitate on a surface of the glass are represented as CLi, CNa and CK respectively, CNa is at most 0.7 nmol/cm2, and CLi+CNa+CK is at most 3.5 nmol/cm2.

Abstract: The present invention relates to a method of glass surface fine processing for forming a convex portion on a surface of a glass containing alkali-metal oxides, the method including: a step of coating a surface of a first region adjacent to a surface of a second region which is to be a convex portion, with a protective layer; a step of removing alkali ions from the surface of the second region; a step of removing the protective layer from the surface of the first region; and a step of polishing the surface of the second region from which the alkali ions have been removed and the surface of the first region from which the protective layer has been removed.

Abstract: Spots generated on a glass substrate after a polishing step are reduced. The present invention relates to a method for polishing a glass substrate including injecting a silica abrasive and a high-boiling solvent in a final glass substrate polishing step. The high-boiling solvent is preferably a solvent having a molecular weight of 300 or lower and a boiling point of 150° C. or higher. As Examples of the high-boiling solvent having a molecular weight of 300 or lower and a boiling point of 150° C. or higher includes ethylene glycol, propylene glycol and glycerine.

Abstract: The claimed invention relates to a process for producing an optical material for EUV lithography, wherein the optical material contains a silica glass having a TiO2 concentration of from 3 to 12 mass % and a hydrogen molecule content of less than 5×1017 molecules/cm3 in the glass. The process including coating a multilayer film on the silica glass by ion beam sputtering.

Abstract: To provide a glass for an information recording media substrate, which is excellent in weather resistance. A glass for an information recording media substrate, which comprises, as represented by mol % based on oxide, from 61 to 66% of SiO2, from 11.5 to 17% of Al2O3, from 8 to 16% of Li2O, from 2 to 8% of Na2O, from 2.5 to 8% of K2O, from 0 to 6% of MgO, from 0 to 4% of TiO2 and from 0 to 3% of ZrO2, provided that Al2O3+MgO+TiO2 is at least 12%, and Li2O+Na2O+K2O is from 16 to 23%, wherein in a case of where B2O3 is contained, its content is less than 1%. The above glass for an information recording media substrate, wherein when the glass is left under steam atmosphere at 120° C. at 0.2 MPa for 20 hours, and the amount of Li, the amount of Na and the amount of K, which precipitate on a surface of the glass are represented as CLi, CNa and CK respectively, CNa is at most 0.7 nmol/cm2, and CLi+CNa+CK is at most 3.5 nmol/cm2.

Abstract: Conventional TiO2—SiO2 glass contains hydrogen atoms substantially, and during deposition under ultrahigh vacuum condition, the hydrogen molecules will diffuse in the chamber, and H2 molecules will be taken into a film thereby formed. Hydrogen molecules will readily diffuse, and the optical characteristics of the multilayer film are likely to be thereby changed. In an optical material for EUV lithography, a multilayer film is coated by ion beam sputtering on a silica glass having a TiO2 concentration of from 3 to 12 mass % and a hydrogen molecule content of less than 5×1017 molecules/cm3 in the glass.

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.

Abstract: An optical head device having an optical element capable of transmitting without diffracting light having a wavelength emitted from a two-wavelength semiconductor laser and capable of diffracting light having another wavelength, to provide high utilization efficiency of light in a stable manner.

Abstract: An optical head device having an optical element capable of transmitting without diffracting light having a wavelength emitted from a two-wavelength semiconductor laser and capable of diffracting light having another wavelength, to provide high utilization efficiency of light in a stable manner.

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.

Abstract: An exposure apparatus, wherein at least one of optical members constituting an exposure light source system, an illuminating optical system, a photomask and a projection optical system, is made of a synthetic quartz glass for an optical member, which has an absorption coefficient of 0.70 cm−1 or less at a wavelength of 157 nm and an infrared absorption peak attributable to SiOH stretching vibration at about 3640 cm−1.

Abstract: A synthetic quartz glass to be used for light with a wavelength of from 150 to 200 nm, wherein the OH group concentration is at most 100 ppm, the hydrogen molecule concentration is at most 1×1017 molecules/cm3, reduction type defects are at most 1×1015 defects/cm3, and the relation between &Dgr;k163 and &Dgr;k190, as between before and after irradiation of ultraviolet rays, satisfies 0<&Dgr;k163<&Dgr;k190, and a process for its production.

Abstract: A process for producing a synthetic quartz glass for an optical member, which comprises a step of irradiating a synthetic quartz glass having an OH group content of 50 ppm or lower with vacuum ultraviolet light having a wavelength of 180 nm or shorter to improve the transmittance in a region of wavelengths of not longer than 165 nm.

Abstract: A process for producing a synthetic silica glass optical component which contains at least 1×1017 molecules/cm3 and has an OH concentration of at most 200 ppm and substantially no reduction type defects, by treating a synthetic silica glass having a hydrogen molecule content of less than 1×1017 molecules/cm3 at a temperature of from 300 to 600° C. in a hydrogen gas-containing atmosphere at a pressure of from 2 to 30 atms.

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.