Abstract: An optical disk has a recording substrate and a support base. The substrate has a first light incident plane and a first bonding surface on both sides thereof, data being to be recorded in the substrate via the first plane. The base is constituted by at least one component and has a second light incident plane and a second bonding surface on both sides thereof, the substrate and the base being bonded to each other via the bonding surfaces.

Abstract: When an LPP (land pre-pit) is formed between shallow grooves or shallow pits, the LPP is formed on a land existing between the shallow grooves or the shallow pits. Further, the LPP is formed in a position displaced from a centerline of the land in the radial direction by a predetermined amount. Furthermore, a laser beam power utilized for forming a shallow groove or a shallow pit adjacent to the LPP is reduced so as to be lower than a regular laser beam power.

Abstract: When an LPP (land pre-pit) is formed between shallow grooves or shallow pits, the LPP is formed on a land existing between the shallow grooves or the shallow pits. Further, the LPP is formed in a position displaced from a centerline of the land in the radial direction by a predetermined amount. Furthermore, a laser beam power utilized for forming a shallow groove or a shallow pit adjacent to the LPP is reduced so as to be lower than a regular laser beam power.

Abstract: A disclosed magnetic recording medium is provided with a single magnetic layer coated on one surface of a non-magnetic substrate. The magnetic layer has a thickness of not less than 2 .mu.m, protrusions on a plane of a height of 10 nm from a center plane in measurement of surface roughness of the magnetic layer with a density of 5000 to 9000 protrusions/mm.sup.2 and protrusions on a plane of a height of 30 nm from the center plane with a density of 500 to 2000 protrusions/mm.sup.2.

Abstract: A magnetic recording medium has a substrate and a magnetic layer formed on the substrate. The magnetic layer includes magnetic powder and a binder for binding the magnetic powder on the substrate. The binder includes at least a resin component containing at least an aminoquinone structure selected from an aminoquinone structure group shown with formulas (1-1a), (1-1b), (1-3a) and (1-3b) as a constitutional unit and at least a polar group selected from a group shown with a formula (1-2) in a composition of the resin component. Thus, the magnetic recording medium has excellent corrosion resistance of the magnetic powder and excellent conservation and running durability.

Abstract: The present invention provides a magnetic recording medium such as a magnetic tape suitable for long play with the thickness of the magnetic tape bring less than or equal to 12.5 without degrading the electro-magnetic conversion characteristic of the head-tape contact characteristic of the magnetic tape. The magnetic tape comprises a non-magnetic film base of thickness dA and a magnetic layer on the non-magnetic film base of thickness dM with the ratio of dA/dM.ltoreq.3.6 and a cupping rate defined as a ratio (A/B.times.100%) of a height A of a curled tape to a width B of curled tape in the traversing direction of .ltoreq.10%. The non-magnetic film vase has a first Young's modulus Y(MD) is a longitudinal direction of the magnetic recording medium and a second Young's modulus Y(TD) in a traversing direction thereof, wherein the first and second Young's modulusli y(MD) and Y(TD) respectively satisfy inequalities (1), (2) defined as follows:Y(TD).gtoreq.Y(MD)/3+1000 (Kg/mm.sup.2) . . . (1)Y(TD).gtoreq.

Abstract: A magnetic recording medium comprising a non-magnetic substrate, a magnetic layer formed at one surface of the substrate, and a back coat layer formed at the other surface of the substrate wherein the back coat layer contains a thermosetting resin and a photosetting resin and its light transmittance is at least 1%. A process for producing a magnetic recording medium which comprises the steps of applying a back coat layer containing a thermosetting resin and a photosetting resin and having a light transmittance of at least 1% to one surface of a non-magnetic substrate; irradiating the back coat layer with a light from both surfaces to carry out photosetting; applying a magnetic layer to the other surface of the non-magnetic substrate; winding the double-coated substrate in the form of a roll; and thermosetting the back coat layer. The magnetic recording media having excellent characteristics can be easily obtained without requiring any complicated apparatus.