An optical disc is formed by bonding a first information recording medium to a second information recording medium. The first information recording medium includes a first substrate having opposed first and second surfaces, at least one dielectric film, at least one recording film, and a cover layer. The second information recording medium includes a second substrate having opposed third and fourth surfaces, at least one dielectric film, at least one recording film, and a cover layer. The second surface of the first substrate is bonded to the fourth surface of the second substrate. At least one of the second surface or the fourth surface includes a depression and a projection. The depression is formed in a thickness direction of the optical disc. The projection is provided inside the depression at a predetermined distance or longer from an outer circumferential edge of the depression in a radial direction of the optical disc.

An information recording medium according to the present disclosure is an information recording medium of a write-once-read-many type and records or reproduces information when irradiated with laser light. The information recording medium includes: a substrate; a plurality of information layers at least one information layer of which includes a recording film that is a WO-based recording film comprising at least tungsten (W) and oxygen (O); and a dielectric film A in contact with the WO-based recording film, the dielectric film A comprising at least 30 mol % tin oxide.

Provided is a sputtering device for a multilayer optical recording medium capable of suppressing the occurrence of defects in a recording region. A sputtering device for a multilayer optical recording medium includes an outer mask, wherein the outer mask is configured to be capable of covering an outer periphery of a film-forming surface of an intermediate layer without coming into contact with the film-forming surface.

An optical recording medium includes a light-receiving surface that receives incident light and at least three information signal layers on which information signals are to be optically recorded. Among the at least three information signal layers, the information signal layer closest to the light-receiving surface has a reflectance in a range of 4% to 11%.

A recording medium production device includes a substrate positioning pin vertically movable that performs positioning to a center-hole of a substrate; a substrate holding portion that performs positioning of substrate using the substrate positioning pin to hold the substrate; a cleaner having a gas ejection portion that ejects gas toward the surface of the substrate held by the substrate holding portion, and a gas suction portion that suctions gas; and a substrate positioning pin fixing portion that can press the substrate positioning pin downward. The fixing portion is configured so as not to contact an inner circumferential side surface of the center-hole of substrate. The substrate positioning pin fixing portion descends inside the center-hole of substrate held by the substrate, and presses and fixes the substrate positioning pin. Then the cleaner performs ejection and suction of gas.

An optical recording medium includes a plurality of information signal layers on which information signals are to be optically recorded. Among the plurality of information signal layers, the information signal layer closest to the light-receiving surface has a reflectance of more than 4%.

An optical disc recording medium includes: a substrate; at least one recording layer formed on at least one side of the substrate; and a cover layer formed on the substrate and the recording layer. The cover layer having a first thickness with reference to a surface of the substrate, in an inside of a circle having a first radius from a center of the substrate. The cover layer having a second thickness larger than the first thickness with reference to the surface of the substrate, on a circumference having a second radius longer than the first radius from the center of the substrate. The cover layer having a third thickness smaller than the first thickness with reference to the surface of the substrate, on a circumference having a third radius longer than the first radius and shorter than the second radius from the center of the substrate.

A coating apparatus includes: a nozzle having a nozzle front end configured to spray a coating solution and a head configured to store the coating solution; a movement axis configured to cause the nozzle to move back and forth in a straight line; a rotating connection member configured to connect the movement axis with the nozzle and allow the nozzle to rotate; a stage disposed under the movement axis; and a cleaning means disposed at an end of the movement axis, and having a nozzle front end insertion unit in a concave shape of the nozzle front end and a base fixing the insertion unit, wherein the nozzle is fixed in a normal direction of a surface of the stage by the movement axis, moves back and forth in an extension direction of the movement axis, and rotates with respect to the movement axis.

An optical recording medium includes a plurality of information signal layers on which information signals are to be optically recorded. Among the plurality of information signal layers, the information signal layer closest to the light-receiving surface has a reflectance of more than 4%.

Method for manufacturing an optical information recording medium includes: preparing a substrate material where a first guide groove has been formed on a first side of the substrate material; forming a second guide groove by applying an energy-curable resin material between a second side of the substrate material opposite to the first side and a stamper and subsequently curing the energy-curable resin material to form a substrate; providing at least one recording layer and a cover layer on a first side of the substrate where the first guide groove has been formed, while holding the substrate with the stamper left unremoved from the substrate to protect the second guide groove; and exposing the second guide groove by removing the stamper and providing at least one recording layer and a cover layer on a second side of the substrate where the second guide groove has been formed.