Minolta Company, Ltd.

Hoya Corporation

Konica Minolta Opto, Inc.

Toshiharu Mori

Hideki Kawai

Hideki Nagata

Kazuhiko Ishimaru

Hiroshi Yuki

Akira Sugimoto

Takuji Hatano

Hiroshi Kajita

Hazuki Nakae

Akio Oogaki

Shinji Fukumoto

Yousuke Yamaguchi

Shinji Sakai

Shiro Nishimoto

Mitsugu Tokunaga

For an information storage medium a glass substrate is produced in a method including the steps of: polishing a glass substrate with a polishing agent applied thereon; and subsequently, chemically strengthening a major surface of the glass substrate. The polishing agent contains cerium oxide at a purity equal to or larger than 99% by mass for CeO/TREO, and has an alkaline earth metal content having a total mass equal to or smaller than 10 ppm by mass. The step of polishing is performed with a soft polishing pad to polish the glass substrate.

Method for producing glass substrate for information storage medium, and information storage medium

The present invention relates to the glass substrate for an information recording medium comprising the following glass components: SiO: 52 to 67; AlO: 8 to 20; BO: 0 to 6, with these three oxides FMO: 70 to 85; LiO: 0.5 to 4; NaO: 1 to 8; KO: 0 to 5; and with these three oxides R2O: 5 to 15; MgO: 2 to 9; CaO: 0.1 to 5; BaO: 0 to 3; SrO: 0 to 3; ZnO: 0 to 5; and with these five oxides: 5 to 15; YO: 0 to 4; LaO: 0 to 4; GdO: 0 to 4; CeO: 0 to 4; TiO: 1 to 7; HfO: 0 to 2; ZrO: 0 to 5; NbO: 0.2 to 5; and TaO: 0 to 5, and satisfies LiO/R2O: 0.05 to 0.35; LiO/FMO: 0.005 to 0.035; LiO/(MgO+ZnO): less than 2 and NbO/SiO: 0.01 to 0.075.

Glass substrate for information recording medium

The present invention relates to a glass substrate of which the outer periphery portion is unprocessed. The present invention also relates to a manufacturing method for a glass substrate of which the outer periphery portion is unprocessed, characterized in that a first lapping process, a second lapping process, a polishing process and a washing process are carried out after a press molding process is carried out so as to compress glass between an upper mold and a lower mold without regulating the edge surface of the outer periphery portion of the glass and, then, a crystallization process or an annealing process is carried out.

Press molding method for manufacturing of glass substrate

The optical glass of the invention comprising: SiO: 10 to 30%, BO: 15 to 35%, LiO: 0 (inclusive) to 10%, NaO: 0 (inclusive) to 5%, and KO: 0 (inclusive) to 5% provided that LiO+NaO+KO: 0 to 15%; MgO: 0 (inclusive) to 25%, CaO: 0 (inclusive) to 25%, BaO: 0 (inclusive) to 25%, SrO: 0 (inclusive) to 25%, and ZnO: 18 to 55% provided that MgO+CaO+BaO+SrO+ZnO: 18 to 55%; and LaO: 5 to 20%. This optical glass does not substantially contain poisonous materials such as lead and arsenic. This optical glass has given optical constants, has a low Tg, a low TL and a good devitrification resistance, and is suitable for press molding.

Optical glass and optical element

A glass substrate for use as the substrate of an information recording medium such as a magnetic disk, magneto-optical disk, DVD, or MD or of an optical communication device, and a glass composition for making such a glass substrate, contains the following glass ingredients: 45 to 75% by weight of SiO; 1 to 20% by weight of AlO; 0 to 15% by weight, zero inclusive, of BO; SiO+AlO+BOaccounting for 65 to 90% by weight; a total of 7 to 20% by weight of RO compounds, where R=Li, Na, and K; and a total of 0 to 12% by weight, zero inclusive, of R'O compounds, where R&#x2032;=Mg, Ca, Sr, Ba, and Zn. Moreover, the following conditions are fulfilled: BO=0% by weight, or AlO/BO&#x2267;1.0; and (SiO+AlO+BO)/(the total of RO compounds+the total of RO compounds)&#x2267;3.

Glass composition and glass substrate

Molten glass is press-molded by a metallic die in which a cylindrical body is provided in a vertically standing manner at a central part of a bottom surface of a bottomed hole and a molding surface corresponding to a chamfering shape of an outer peripheral edge surface of a glass substrate is consecutively formed in an inner peripheral wall, and a glass substrate precursor provided with the chamfering shape axially consecutive on an outer peripheral surface thereof and a through hole formed at a central part thereof is thereby formed. The glass substrate precursor is cut perpendicular to an axial direction to be separated into respective glass substrates. Next, the respective glass substrates are subjected to a lapping process and a polishing process, if necessary, to produce a glass substrate as a final product. According to the manufacturing method, a glass substrate for information recording medium whose inner and outer peripheral edge surfaces are chamfered can be manufactured with an improved efficiency. Further, a glass substrate having a small diameter can be manufactured with a high efficiency.

Method of manufacturing glass substrate for information recording medium

A glass substrate for use as the substrate of an information recording medium such as a magnetic disk, magneto-optical disk, DVD, or MD or of an optical communication device, and a glass composition for making such a glass substrate, contains the following glass ingredients: 45 to 75% by weight of SiO; 1 to 20% by weight of AlO; 0 to 8% by weight, zero inclusive, of BO; SiO+AlO+BOaccounting for 60 to 90% by weight; a total of 0 to 20% by weight, zero inclusive, of RO compounds, where R=Li, Na, and K; and a total of 0 to 15% by weight, zero inclusive, of TiO+ZrO+LnO, where LnOrepresents at least one compound selected from the group consisting of lanthanoid metal oxides, YO, NbO, and TaO.

The optical waveguide includes an optical waveguide layer, and a filter element including an ultraviolet curing liquid crystal layer disposed in a position which divides the optical waveguide layer in a waveguide direction. The ultraviolet curing liquid crystal layer having a twisted structure in which a helical pitch after curing reflects light of a predetermined wavelength.

Optical filter device and method of making same

A polished glass disk medium substrate suitable for use as a substrate for a hard disk, a hard disk containing the substrate and methods for making the substrate. The substrate containing glass forming raw materials may be formed so as to have a Young's modulus of 110 or higher.

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Settsu, Japan

Toshiharu Mori