The present invention pertains to a glass for a data storage medium substrate which contains a specific amount of each of SiO.sub.2, Al.sub.2O.sub.3, MgO, CaO, SrO, BaO, Li.sub.2O, Na.sub.2O, and K.sub.2O, in molar percentage based on the oxides, and does not substantially contain B.sub.2O.sub.3 or ZrO.sub.2, wherein the sum of the Li.sub.2O, Na.sub.2O, and K.sub.2O contents (R.sub.2O), the molar ratio of the SiO.sub.2 content to the Al.sub.2O.sub.3 content (SiO.sub.2/Al.sub.2O.sub.3), and the molar ratio of the sum of the SiO.sub.2 and Al.sub.2O.sub.3 contents (SiO.sub.2+Al.sub.2O.sub.3) to R.sub.2O [(SiO.sub.2+Al.sub.2O.sub.3)/R.sub.2O] fall within their specific ranges, formula (1): 90<[SiO.sub.2]+2[Al.sub.2O.sub.3]+0.8[RO]0.5[R.sub.2O] [in formula (1), RO represents the sum of the MgO, CaO, SrO, and BaO contents] is satisfied, and the glass transition point T.sub.g, the alkali resistance, and the acid resistance fall within their specific ranges.

A storage medium includes a base substrate, a first metallic layer, a first border region, and a first cover substrate. The base substrate includes a first side and a second side. The first side and the second side oppose one another. The first metallic layer defines a first pattern. The first metallic layer directly abuts the first side of the base substrate. The first border region extends about the first pattern. The first cover substrate is positioned against an exposed surface of the first metallic layer such that the first metallic layer is positioned between the first side of the base substrate and the first cover substrate. The first cover substrate is coupled to the first border region.

A storage medium includes a base substrate, a first metallic layer, a first border region, and a first cover substrate. The base substrate includes a first side and a second side. The first side and the second side oppose one another. The first metallic layer defines a first pattern. The first metallic layer directly abuts the first side of the base substrate. The first border region extends about the first pattern. The first cover substrate is positioned against an exposed surface of the first metallic layer such that the first metallic layer is positioned between the first side of the base substrate and the first cover substrate. The first cover substrate is coupled to the first border region.

Provided is an optical recording medium including: two discs, each of which includes a substrate and a plurality of recording layers; and an attachment layer which is provided between the two discs and includes ultraviolet curable resin, wherein thickness of each of the substrates in the two discs is equal to or greater than 0.3 mm and equal to or less than 0.545 mm, wherein transmittance of the two discs is equal to or less than 20%, and wherein inversion rates on both surface sides of the attachment layer are equal or substantially equal to each other, and are equal to or greater than 70%.

Provided is an optical recording medium including: two discs, each of which includes a substrate and a plurality of recording layers; and an attachment layer which is provided between the two discs and includes ultraviolet curable resin, wherein thickness of each of the substrates in the two discs is equal to or greater than 0.3 mm and equal to or less than 0.545 mm, wherein transmittance of the two discs is equal to or less than 20%, and wherein inversion rates on both surface sides of the attachment layer are equal or substantially equal to each other, and are equal to or greater than 70%.

A storage medium includes a base substrate, a first metallic layer, a first border region, and a first cover substrate. The base substrate includes a first side and a second side. The first side and the second side oppose one another. The first metallic layer defines a first pattern. The first metallic layer directly abuts the first side of the base substrate. The first border region extends about the first pattern. The first cover substrate is positioned against an exposed surface of the first metallic layer such that the first metallic layer is positioned between the first side of the base substrate and the first cover substrate. The first cover substrate is coupled to the first border region.

A storage medium includes a base substrate, a first metallic layer, a first border region, and a first cover substrate. The base substrate includes a first side and a second side. The first side and the second side oppose one another. The first metallic layer defines a first pattern. The first metallic layer directly abuts the first side of the base substrate. The first border region extends about the first pattern. The first cover substrate is positioned against an exposed surface of the first metallic layer such that the first metallic layer is positioned between the first side of the base substrate and the first cover substrate. The first cover substrate is coupled to the first border region.

A method of fabricating an optical element comprises: providing a substrate of a transparent material; applying a plurality of circularly polarised focused femtosecond laser pulses to a volume within the substrate to create substantially spherical nanopores in the volume; and applying at least one and not more than ten non-circularly polarised focused femtosecond laser pulses to the volume to transform the spherical nanopores into oblate spheroidal nanopores.

A method of fabricating an optical element comprises: providing a substrate of a transparent material; applying a plurality of circularly polarised focused femtosecond laser pulses to a volume within the substrate to create substantially spherical nanopores in the volume; and applying at least one and not more than ten non-circularly polarised focused femtosecond laser pulses to the volume to transform the spherical nanopores into oblate spheroidal nanopores.