Abstract: A method of manufacturing an optical recording substrate, comprising the steps of: contacting the surface having pit or land/grooves of a stamper having the pit or land/grooves to an organic polymer sheet having a glass transition temperature of 120 to 190° C., a single-pass birefringence retardation of +10 nm to ?10 nm and a thickness of 0.35 mm or less under reduced pressure; and thermally pressing them. According to this method, an optical recording substrate which can transfer a stamper pattern to a thin organic polymer sheet easily and thoroughly can be manufactured.

Abstract: A method of manufacturing an optical recording substrate, comprising the steps of:

Abstract: An optical recording medium for recording and reproducing information utilizing the change of a physical property of a recording layer caused by the irradiation with light, which comprises a substrate, characterized in that the substrate comprises a hydrogenated styrene polymer having a content of nucleus-hydrogenated styrene units of 80 wt % or more, has a glass transition temperature of 110° C. or higher, has a light transmittance of 88% or more at 400 nm, and exhibits an absolute value of retardation of 30 nm or less at 0° and 30° from the normal direction of the plane thereof. The optical recording medium suitable for use in the high density optical recording capable of responding to a greater number of openings and the use of a light having a shorter wave length in an optical head.

Abstract: In a phase change optical recording medium in which writing, reading and/or erasing of information is conducted by utilizing change of phase of a recording layer by irradiation with light, the recording layer is made of a material containing oxygen in an amount of 1 to 30 atomic %; or the recording medium comprises an additional transparent dielectric layer 1 to 10 nm thick between the recording layer and the underlying transparent dielectric layer and the inserted transparent dielectric layer in contact with the recording layer comprising oxygen in a molar ratio greater than a molar ratio of oxygen in the underlying transparent dielectric layer; or the transparent dielectric layer underlying and in contact with the recording layer comprises oxygen in a molar ratio greater than a molar ratio of oxygen in the other transparent dielectric layer.

Abstract: An optical recording medium comprising, in the following order, a substrate, a reflecting layer, a lower dielectric layer, an optical recording layer, the optical recording layer recording information by means of change in a physical property of the optical recording layer which is generated by an applied light beam, the change in a physical property of the optical recording layer being conducted at an operating temperature, and an upper dielectric layer, wherein the substrate has a thermal deformation temperature lower than the operating temperature and the optical recording medium further comprises a thermally insulating layer between the substrate and the reflecting layer.

Abstract: In a phase change optical recording medium in which writing, reading and/or erasing of information is conducted by utilizing change of phase of a recording layer by irradiation with light, the recording layer is made of a material containing oxygen in an amount of 1 to 30 atomic %; or the recording medium comprises an additional transparent dielectric layer 1 to 10 nm thick between the recording layer and the underlying transparent dielectric layer and the inserted transparent dielectric layer in contact with the recording layer comprising oxygen in a molar ratio greater than a molar ratio of oxygen in the underlying transparent dielectric layer; or the transparent dielectric layer underlying and in contact with the recording layer comprises oxygen in a molar ratio greater than a molar ratio of oxygen in the other transparent dielectric layer.

Abstract: A metal reflecting layer of an aluminum or silver alloy containing gold has a lower thermal conductivity than aluminum or silver and gold while maintaining a high reflectivity, and thus an optical recording medium, particularly a magneto-optical recording medium, having a high recording sensitivity and a C/N ratio, as well as an improved durability, can be provided. The content of Au in the Al alloy is 0.5-20 at % and that in the silver alloy is 0.5-30 at %. Preferably, at least one of the group consisting of titanium, tantalum, zirconium and yittrium is added to an alloy of Al or Ag with Au, and the content of at least one of the group consisting of titanium, tantalum, zirconium and yittrium is preferably 0.3-5.0 at % in an Al-Au alloy and 0.3-12.0 at % in an Ag-Au alloy. More preferably, the total content of Au and at least one of the group consisting of titanium, tantalum, zirconium and yittrium is 1.0-15 at %.

Abstract: A thin film type magnetic recording medium having a durability close to that of the coating type magneting recording medium is provided by a metal oxide protective layer which is formed by a physical vapor deposition.

Abstract: A magnetic recording medium conventionally utilizes the in-plane magnetization mode, but recently the perpendicular magnetization mode utilizing the perpendicular anisotropy of an hcp cobalt alloy layer, in which the C axis is oriented perpendicular to the layer surface, has been proposed. The known perpendicular magnetic recording medium is produced by means of RF sputtering and comprises a Permalloy layer, as layer of a low coercive-force material, between the nonmagnetic base and the hcp cobalt alloy layer. The perpendicular anisotropy attained by the present invention in very excellent and is superior to that of a perpendicular recording medium having no Permalloy layer because a Co-Ta alloy is used as the layer of a low coercive-force material.

Abstract: A magnetic recording medium conventionally utilizes the in-plane magnetization mode, but recently the perpendicular magnetization mode utilizing the perpendicular anisotropy of an hcp cobalt alloy layer, in which the C axis is oriented perpendicular to the layer surface, has been proposed. The known perpendicular magnetic recording medium is produced by means of RF sputtering and comprises a Permalloy layer, as layer of a low coercive-force material, between the nonmagnetic base and the hcp cobalt alloy layer. The perpendicular anisotropy attained by the present invention is very excellent and is superior to that of a perpendicular recording medium having no Permalloy layer because a Co-Ta alloy is used as the layer of a low coercive-force material.

Abstract: A magnetic recording medium conventionally utilizes the in-plane magnetization mode, but recently the perpendicular magnetization mode utilizing the perpendicular anisotropy of an hcp cobalt alloy layer, in which the C axis is oriented perpendicular to the layer surface, has been proposed. The known perpendicular magnetic recording medium is produced by means of RF sputtering and comprises a Permalloy layer, as layer of a low coercive-force material, between the nonmagnetic base and the hcp cobalt alloy layer. The perpendicular anisotropy attained by the present invention in very excellent and is superior to that of a perpendicular recording medium having no Permalloy layer because a Co-Ta alloy is used as the layer of a low coercive-force material.

Abstract: Magnetic recording medium conventionally utilizes the in-plane magnetization mode, but, recently, the perpendicular magnetization mode utilizing the perpendicular anisotropy of an hcp cobalt alloy layer, in which C axis is oriented normal to the layer surface, is proposed. The known perpendicular magnetic recording medium has been produced by an RF sputtering, but such medium is of too low flexibility to use it in the form of a magnetic tape. In addition, the production rate of the perpendicular magnetic recording medium by RF sputtering is very low.The perpendicular magnetic recording medium is very flexible due to particle pattern (FIGS. 10, 12 and 13) completely distinct from the conventional columnar pattern (FIGS. 8 and 11). In addition, the production rate is high, because the base (20) is located beside a space between the targets (T.sub.1, T.sub.2) of a sputtering device and further the magnetic field is generated perpendicularly to the sputtering surfaces (T.sub.1s, T.sub.

Abstract: A magnetic recording medium composed of an oriented polyethylene terephthalate film as a support layer and a thin magnetic metallic layer formed on one surface (A) of the support layer and optionally a lubricant layer formed on the other surface (B) of the support layer; characterized in that(1) the surface A has a center-line average (CLA) of not more than 0.005 .mu.m,(2) the surface A has a peak-to-valley (PV) value of not more than 0.06 .mu.m,(3) the number of protrusions having a height of 0.27 to 0.54 .mu.m on the surface A is at most 0.2 per mm.sup.2, and(4) the surface A is substantially free from protrusions having a height larger than 0.54 .mu.m.

Abstract: Magnetic recording medium conventionally utilizes the in-plane magnetization mode, but, recently, the perpendicular magnetization mode utilizing the perpendicular anistropy of an hcp cobalt alloy layer, in which C axis is oriented normal to the layer surface, is proposed. The known perpendicular magnetic recording medium has been produced by an RF sputtering, but such medium is of too low flexibility to use it in the form of a magnetic tape. In addition, the production rate of the perpendicular magnetic recording medium by RF sputtering is very low.The perpendicular magnetic recording medium is very flexible due to particle pattern (FIGS. 10, 12 and 13) completely distinct from the conventional columnar pattern (FIGS. 8 and 11). In addition, the production rate is high, because the base (20) is located beside a space between the targets (T.sub.1, T.sub.2) of a sputtering device and further the magnetic field is generated perpendicularly to the sputtering surfaces (T.sub.1s, T.sub.