US 2021/0327466 A1 · OPTICAL DISK, METHOD OF MANUFACTURING SAME, OPTICAL INFORMATION DEVICE, AND INFORMATION PROCESSING METHOD

Abstract

Provided is a method of manufacturing an optical disk having at least a cover layer, a first information recording surface, a first intermediate layer, a second information recording surface, a second intermediate layer, and a third information recording surface in order from a surface irradiated with a light beam on at least one side, wherein a numerical aperture of an objective lens that converges the light beam on any of the recording surface of the optical disk when information recording or information reproduction of the optical disk is performed is 0.91, standard value dk of each thickness from the surface to the first to third information recording surfaces is set on the premise of standard refractive index no, where k is 1, 2, 3, and a target value of each actual thickness from the surface to the first to third information recording surfaces is determined by a product of conversion coefficient g(n) depending on refractive index n from the first to third information recording surfaces, and standard value dk.

Claims8

Dependent claims

A method of manufacturing an optical disk having at least a cover layer, a first information recording surface, a first intermediate layer, a second information recording surface, a second intermediate layer, and a third information recording surface in order from a surface irradiated with a light beam on at least one side of the optical disk, the method comprising:

setting a numerical aperture of an objective lens to 0.91 when information recording or information reproduction of the optical disk is performed, the objective lens converging the light beam on the first to third information recording surfaces of the optical disk;
setting a standard value dk of a thickness from the surface to each of the first to third information recording surfaces on a premise of standard refractive index no, where k is 1, 2, 3;
and
determining a target value of an actual thickness from the surface to each of the first to third information recording surfaces by a product of a conversion coefficient g(n) depending on a refractive index n from the first to third information recording surfaces, and the standard value dk, and establishing g(n)=−0.859218n3+4.55298n2−7.70815n+5.19674.

1 more element

setting a numerical aperture of an objective lens to 0.91 when information recording or information reproduction of the optical disk is performed, the objective lens converging the light beam on the first to third information recording surfaces of the optical disk;
when an actual thickness of each of the cover layer, the first intermediate layer, and the second intermediate layer is trk, where k is 1, 2, 3, calculating an effective thickness tk on a premise of a standard refractive index no by a product of the actual thickness trk and a conversion coefficient f(n) depending on a refractive index n of a material forming a thickness;
establishing f(n)=−1.37834n3+7.62795n2−14.7462n+10.7120;
causing values of tk to be different from one another by a certain value or more;
and
causing all of the values of tk to be larger than a certain value.

3 more elements

Dependencies are inferred from the claim text.

Optical disk, method of manufacturing same, optical information device, and information processing method

Life of this patent

Optical disk, method of manufacturing same, optical information device, and information processing method

Life of this patent

Abstract

Claims8