Abstract: An optical recording medium includes a first disk, a second disk, and an adhesive layer for bonding the first disk to the second disk. The first disk and the second disk each include a substrate having a first surface and a second surface and having a gradient on an outer peripheral portion of the second surface, two or more information signal layers disposed on the first surface, an intermediate layer disposed between adjacent information signal layers, and a cover layer covering the two or more information signal layers and the intermediate layer. The second surface of the substrate included in the first disk faces the second surface of the substrate included in the second disk with the adhesive interposed therebetween.

Abstract: An optical recording medium includes a first disk, a second disk, and an adhesive layer for bonding the first disk to the second disk. The first disk and the second disk each include a substrate having a first surface and a second surface and having a gradient on an outer peripheral portion of the second surface, two or more information signal layers disposed on the first surface, an intermediate layer disposed between adjacent information signal layers, and a cover layer covering the two or more information signal layers and the intermediate layer. The second surface of the substrate included in the first disk faces the second surface of the substrate included in the second disk with the adhesive interposed therebetween.

Abstract: 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%.

Abstract: 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%.

Abstract: A boundary lubricant film 1 is formed on a stamper 22 contact portion of a stationary mirror 21 and/or a stationary mirror 21 contact portion of the stamper 22. The boundary lubricant film 1 contains one of kinds of phosphate esters. A material is injected into a cavity 14. As a result, a disc substrate for an optical disc is molded.

Abstract: A boundary lubricant film 1 is formed on a stamper 22 contact portion of a stationary mirror 21 and/or a stationary mirror 21 contact portion of the stamper 22. The boundary lubricant film 1 contains one of kinds of phosphate esters. A material is injected into a cavity 14. As a result, a disc substrate for an optical disc is molded.

Abstract: A boundary lubricant film 1 is formed on a stamper 22 contact portion of a stationary mirror 21 and/or a stationary mirror 21 contact portion of the stamper 22. The boundary lubricant film 1 contains one of kinds of phosphate esters. A material is injected into a cavity 14. As a result, a disc substrate for an optical disc is molded.

Abstract: In an optical disc in which an information signal is recorded/reproduced by irradiating a laser beam to a disc substrate 1 in which an information signal portion 1c has been provided on one principal plane from the side where the information signal portion 1c exists, a clamp reference surface 3a is set to the information signal portion 1c side of a replica substrate 1a constructing the optical disc. The clamp reference surface 3a is set to a flat surface and a thickness of the replica substrate 1a in a clamping area 3 is set to be larger than that of the convex-shaped replica substrate 1a in an information recording area 4. The replica substrate 1a in which a periphery of a center hole 1b is thicker than the information recording area 4 is used.

Abstract: A boundary lubricant film 1 is formed on a stamper 22 contact portion of a stationary mirror 21 and/or a stationary mirror 21 contact portion of the stamper 22. The boundary lubricant film 1 contains one of kinds of phosphate esters. A material is injected into a cavity 14. As a result, a disc substrate for an optical disc is molded.

Abstract: A data area to record and/or reproduce data and an eccentricity measuring area 14 in which a groove area formed with spiral grooves and a planer mirror area are spatially alternately arranged are provided for a disc substrate. A width of groove area formed in the eccentricity measuring area, a width of mirror area, and an interval between the grooves in the groove area are selected so that a conventional mechanical characteristics measuring apparatus can track a plurality of grooves formed in the groove area as if the grooves were a single groove.

Abstract: In an optical disc in which an information signal is recorded/reproduced by irradiating a laser beam to a disc substrate 1 in which an information signal portion 1c has been provided on one principal plane from the side where the information signal portion 1c exists, a clamp reference surface 3a is set to the information signal portion 1c side of a replica substrate 1a constructing the optical disc. The clamp reference surface 3a is set to a flat surface and a thickness of the replica substrate 1a in a clamping area 3 is set to be larger than that of the convex-shaped replica substrate 1a in an information recording area 4. The replica substrate 1a in which a periphery of a center hole 1b is thicker than the information recording area 4 is used.