Abstract: A magneto-optical recording medium comprising a light-transmitting substrate 1 on which a dielectric layer 2, a memory layer 3 having perpendicular magnetic anisotropy, an intermediate layer 4 having in-plane magnetic anisotropy or slight perpendicular magnetic anisotropy, a recording layer 5 having perpendicular magnetic anisotropy, a dielectric layer 6, a metal layer 7, and a protective layer 8 are formed in a stacked form, the recording medium adapted to be magnetized for recording by a process comprising the step of modulating a first thermal condition and a second thermal condition according to a recording signal, wherein a stacked film 9 composed of the memory layer 3, the intermediate layer 4 and the recording layer 5 has a total thickness of from 1000 to 1500 .ANG., the dielectric layer 6 has a thickness of from 500 to 1500 .ANG., and the metal layer 7 has a thickness of from 250 to 1500 k.

Abstract: A recording/reproducing apparatus for use with a photomagnetic recording medium. The apparatus comprises a magnetic coil and an optical system having a numerical aperture (NA) greater than 0.8 and arranged such that an optical axis thereof traverses the center of the magnetic coil. The photomagnetic recording medium has a magneto-optic recording film and a transparent protective layer having a thickness HCO formed sequentially on a substrate. The magnetic coil and the optical system are arranged on the transparent protective layer side of the photomagnetic recording medium when the photomagnetic recording medium is used with the apparatus and such that a combined distance equal to the thickness HCO and a distance d between a surface of the magnetic coil and an adjacent surface of the photomagnetic recording medium has a value of 0 .mu.m.ltoreq.d.ltoreq.145 .mu.m. The thickness HCO of the transparent protective layer may have a value of 0 .mu.m.ltoreq.HCO.ltoreq.100 .mu.

Abstract: An optical recording medium according to the present invention includes a base layer having an information signal portion formed on a surface on the side on which laser light is incident, and a light transmissive layer formed on the base layer. A thickness t of the light transmissive layer is within the range of t=3 to 177 .mu.m at least in an area of the information signal portion. If unevenness of the light transmissive layer is .DELTA.t, N.A. of an optical system for reproduction or recording and reproduction and a wavelength .lambda. satisfies .DELTA.t.ltoreq..+-.5.26 (.lambda./N.A..sup.4) (.mu.m). A track pitch is P and a skew is .THETA., then P.ltoreq.0.64 .mu.m and .THETA..ltoreq..+-.84.115.degree. (.lambda./N.A..sup.3 /t) are satisfied. The optical recording medium is recorded or reproduced by a recording and reproducing system satisfying .lambda..ltoreq.0.68 .mu.m and N.A./.lambda..gtoreq.1.20. The optical recording medium permits a recording capacity of 8 GB.

Abstract: A multilayer optical disk having an information storage layer which can as well as be reproduced by a general purpose reproducing apparatus, for example, a compact disk player, and from which information can be read from other information storage layers by using an exclusive reproducing apparatus. The multilayer disk has a first substrate on which is formed a first information storage layer which is relatively highly reflective with respect to a light beam having a wavelength of 770-830 nm; and a second substrate on which is formed a second information layer which is relatively transparent with respect to a light beam having a first substrate on which is formed a wavelength of 770 mn to 830 nm but which is sufficiently reflective with respect to a light beam having a wavelength of 615-655 nm.

Abstract: A recording/reproducing apparatus for use with a photomagnetic recording medium. The apparatus comprises a magnetic coil and an optical system having a numerical aperture (NA) greater than 0.8 and arranged such that an optical axis thereof traverses the center of the magnetic coil. The photomagnetic recording medium has a magneto-optic recording film and a transparent protective layer having a thickness HCO formed sequentially on a substrate. The magnetic coil and the optical system are arranged on the transparent protective layer side of the photomagnetic recording medium when the photomagnetic recording medium is used with the apparatus and such that a combined distance equal to the thickness HCO and a distance d between a surface of the magnetic coil and an adjacent surface of the photomagnetic recording medium has a value of 0 .mu.m.ltoreq.d.ltoreq.145 .mu.m. The thickness HCO of the transparent protective layer may have a values of 0 .mu.m.ltoreq.HCO.ltoreq.100 .mu.

Abstract: A multilayer optical disk having an information storage layer which can as well as be reproduced by a general-purpose reproducing apparatus, for example, a compact disk player, and from which information can be read from other information storage layers by using an exclusive reproducing apparatus. The multilayer optical disk having a plurality of information storage layers according to the present invention includes a plurality of information storage layers, wherein one of the plural information storage layers has a reflection factor of 70% or higher with respect to a wavelength of 770 nm to 830 nm which is a first wavelength of reproducing light, and other information storage layers are reproduced with reproducing light having a second wavelength which is different from the first wavelength of reproducing light. Each of the other information storage layers has a reflection factor of 20% or higher with respect to the second wavelength of reproducing light.

Abstract: The present invention provides a multi-layer optical disk, in which even if a wave length of read light is changed at a time of reproducing, both of reproduction signals from a first information memory layer and a second information memory layer have sufficient levels.In a multi-layer optical disk, in which a first information memory layer and a second information memory layer are sequentially film-formed on a substrate and information recorded on the first information memory layer and the second information memory layer are reproduced by irradiating read light from a substrate side,the first information memory layer and the second information memory layer can be reproduced by a first read light and a second read light which is shorter in wave length than this first read light, andthe first information memory layer is made of material in which a refractive index n and an extinction coefficient k in a wave length area of the first read light comply with the following conditions:0.ltoreq.k.ltoreq.0.25n=.alpha.

Abstract: A novel multi-layer optical disc according to the present invention can treat a large volume of information without deterioration in level of reproduction signals from the respective information storage layers thereof. The multi-layer optical disc comprises a substrate having a light-transmission property, a read-only-memory type information storage portion formed on the substrate, a semi-transmission layer disposed on the read-only-memory type information storage portion, a spacer layer disposed on the semi-transmission layer and having a light-transmission property, and a rewritable information storage layer disposed on said spacer layer.

Abstract: A magneto-optical recording apparatus records information on a magneto-optical recording medium composed of a memory layer and a recording layer which are disposed on a substrate, each comprising a magnetic thin film of amorphous-rare-earth transition-metal alloy. The memory and recording layers are magnetically coupled directly, or through an intermediate layer therebetween, to each other under an exchange force. A recording magnetic field generator such as a permanent magnet or an electromagnet applies a recording magnetic field to the magneto-optical recording medium, and an initializing magnetic field generator such as a permanent magnet or an electromagnet applies an initializing magnetic force to the magneto-optical recording medium. The initializing magnetic field generator has a magnetic pole confronting a surface of the magneto-optical recording medium. The initializing magnetic force comprises a magnetic field H.sub.

Abstract: A thermomagnetic recording method is disclosed using a thermomagnetic recording medium where first, second and third magnetic thin films each formed of rare-earth and transition metals are sequentially superposed to form layers in a magnetically coupled manner. The recording is carried out by heating the thermomagnetic recording medium under a predetermined magnetic field perpendicular to the film plane thereof while selectively modulating, in accordance with data to be recorded, a first heating state at a first temperature T1 substantially above the Curie point Tc1 of the first magnetic thin film and adequate to hold the sublattice magnetization of the transition metal of the second magnetic thin film in a predetermined direction, and a second heating state at a second temperature T2 substantially above the Curie point Tc1 and adequate to invert the sublattice magnetization of the transition metal of the second magnetic thin film to the reverse of the predetermined direction.