Abstract: An optical tape including an optical recording layer for permitting information to be optically recorded thereon and a light-reflective magnetic layer. The light-reflective magnetic layer which reflects light projected onto the recording layer, also permits magnetic recording or magneto-optical recording to be performed thereon, thereby increasing a storage capacity of the optical tape remarkably. Further, the optical tape is provided with a layer to form guiding grooves for tracking control. The layer to form guiding grooves is made up of ultraviolet-hardening resin, photo-resist, or a photochromic material. For example, in the case of using ultraviolet-hardening resin, after a guiding groove pattern has been exposed by projecting an ultraviolet ray on a layer made up of ultraviolet-hardening resin, the exposed areas harden to form areas corresponding to guiding grooves between those exposed areas.

Abstract: A magnetic recording medium in accordance with the present invention is constituted by a first magnetic film having a magnetic anisotropy in a first direction parallel to the film surface and a second magnetic film that is formed on the first magnetic film and that is made of an amorphous alloy film of a rare-earth metal and a transition metal having a magnetic anisotropy in a second direction that is parallel to the film surface, and different from the first direction. In the above-mentioned magnetic recording medium, the first and second magnetic films have magnetic anisotropies having directions parallel to their surfaces and different from each other. When a magnetic latent image is formed on the magnetic recording medium of this type, it is possible to reduce the height of serration in the serrate magnetization transition structure appearing in the border of magnetization inversion in the magnetic latent image.

Abstract: In an optical memory medium comprising prepits on which a light spot is impinged to obtain information and, if required, guide grooves: each of those among the prepits which are longer than the diameter of the light spot consists of a series of pit portions and unpitted portions; each of the prepits is sandwiched between two of the discontinuous portions of guide grooves adjacent to each other; the guide grooves have one or more narrow portions, and each of the prepits is sandwiched between two of the narrow portions of guide grooves adjacent to each other; or the guide grooves have one or more long portions, one or more short portions, and narrow portions formed between the long and short portions, and each of the prepits is sandwiched between two of the short portions of guide grooves adjacent to each other.

Abstract: A thermomagnetic printer of the in-plane magnetization system includes a magnetic recording layer made of Dy.sub.x Co.sub.(1-x) or Dy.sub.y Co.sub.(1-y) and a base layer made of Ti or Ta. Since the described arrangement enables the magnetic recording layer to be formed by the sputtering method or the electron beam evaporation method, and the like, the magnetic recording layer having a uniform thickness and properties in a large area can be formed without difficulties. In addition, by adopting the Ti layer or the Ta layer as the base layer, a reduction in a residual magnetization can be prevented even when the magnetic recording layer is made thicker, thereby increasing a magnetic attraction force.

Abstract: An optical tape including an optical recording layer for permitting information to be optically recorded thereon and a light-reflective magnetic layer; the light-reflective magnetic layer which reflects light projected onto the recording layer, also permits magnetic recording or magneto-optical recording to be performed thereon, thereby increasing a storage capacity of the optical tape remarkably; further, the optical tape is provided with a layer to form guiding grooves for tracking control, which layer to form guiding grooves is made up of ultraviolet-hardening resin, photo-resist, or a photochromic material.

Abstract: An optical memory disc medium contains a plurality of guide groove tracks. The guide groove tracks are arranged parallel to each other and they are used for controlling a position of a light beam. There is a land region between the guide groove tracks which is wider than the width of the guide groove tracks as measured in the disc-radial direction. Prepits for providing address information for the guide groove tracks are provided. The prepits are formed on the land regions and interposed between the lateral edges in the disc-radial direction of adjacent parallel guide groove tracks. Each prepit has a width which width is a narrower dimension than the width of each guide groove track as measured in the disc-radial direction.

Abstract: An optical memory medium having a transparent substrate, a recording layer and a reflective layer, the recording layer and the reflective layer being formed in this order on the transparent substrate. The recording layer is a diarylethene derivative dispersed in a non-polar polymeric binder. The optical memory medium with such a recording layer fully utilizes advantageous properties of the diarylethene derivative, such as good thermal stability of recorded state, excellent durability against repeated color changes between colored and colorless states, and photosensitive property to semiconductor laser light with a wavelength of 780 nm. The optical memory medium enables high-density recording and non-destructive readout.

Abstract: An optical disk for use in an optical memory device having guide grooves and pits on one surface thereof, wherein the depth of the guide grooves is different from that of the pits and the distance from the bottom face of each of the guide grooves to the other surface of the optical disk opposite to the one surface of the optical disk on which the guide grooves and pits are disposed is the same as the distance from the bottom face of each of the pits to the other surface of the optical disk opposite to the one surface of the optical disk on which the guide grooves and pits are disposed, and a method for the production of optical memory master plates that are used for the production of the above-mentioned optical disk.

Abstract: An optical recording element comprising a recording medium which includes an information recording area formed at every unit in a non-continuous condition, the recording medium further including sample pits disposed at intervals of a fixed distance for providing basic information about the locations of the recording units in same track. Each sample pit comprises a plurality of pits disposed next to the sequence of the recording units so that the spacing between the pits differs from the spacing between the recording units. At least one of the plurality of pits is a long-sized inclined pit which is inclined at an angle in the range of 6.degree. to 80.degree. to a recording track.

Abstract: A photo-mask and a method of manufacturing a photo-mask, which includes the steps of applying a resist film onto a substrate of quartz, glass and the like, subjecting the resist film to light exposure and development to form a fine resist pattern, etching the mask substrate covered by the fine resist pattern, causing a non-light transmitting thin film of Cr, Ta, etc. to adhere thereon by vapor deposition, sputtering and the like, and removing the thin film on the resist pattern together with the resist film, thereby to form the photo-mask.

Abstract: A method for recording and reproducing information using an optical memory device being constituted by a transparent substrate, a recording film formed on the substrate and made of a resin containing a photochromic material dispersed therein, the photochromic material being capable of reversibly changing its state from achromatic to chromatic and absorbing light of at least 780 nm wavelength in the chromatic state, and a reflecting film formed on the recording film for reflecting light, the method including the steps of: applying a visible light beam of a long wavelength onto the optical memory device to turn said recording film into the achromatic state for initialization, applying thereafter a visible light beam of a short wavelength onto the optical memory device to turn the recording film into the chromatic state in accordance with binary-coded data of information for recording the information, and applying another visible light beam of a long wavelength having a light intensity lower than that of the vis

Abstract: A photo-mask comprises a light-permeable substrate, a plurality of light-shielding films that are disposed on the substrate, the light-shielding films forming a mask pattern, and a light-permeable protective film that is disposed over the surface of the substrate including the light-shielding films so as to protect the light-shielding films.

Abstract: An optical disk for use in an optical memory device having guide grooves and pits on one surface thereof, wherein the depth of the guide grooves is different from that of the pits and the distance from the bottom face of each of the guide grooves to the other surface of the optical disk opposite to the one surface of the optical disk on which the guide grooves and pits are disposed is the same as the distance from the bottom face of each of the pits to the other surface of the optical disk opposite to the one surface of the optical disk on which the guide grooves and pits are disposed, and a method for the production of optical memory master plates that are used for the production of the above-mentioned optical disk.

Abstract: An optical memory device comprising at least one transparent substrate and a light reflection layer or an optical memory layer laminated on one surface of the substrate, in which the light reflection layer or the optical memory layer is constituted with a UV-ray or electron-ray cured resin dispersingly containing a light reflective metal powder or an optical recording material.

Abstract: An optical recording element comprising a recording medium which includes an information recording area formed at every unit in a non-continuous condition, the recording medium further including sample pits disposed at intervals of a fixed distance for providing basic information about the locations of the recording units in same track. Each sample pit comprises a plurality of pits disposed next to the sequence of the recording units so that the spacing between the pits differs from the spacing between the recording units. At least one of the plurality of pits is a long-sized inclined pit which is inclined at an angle in the range of 6.degree. to 80.degree. to a recording track.

Abstract: A magneto-optic memory device, such as a magneto-optic disk or magneto-optic card having a pair of opposed substrates at least one of which is transparent. Between the substrates is a magneto-optic memory layer made of a stack of dielectric film, a rear earth-transition metal alloy thin film, a dielectric film and a light reflecting film built on the surface of the transparent substrate opposed to the other substrate. An adhesive layer covers the memory layer and bonds the transparent substrate to the other substrate. Lastly, a metal nitride film interposed between the light reflecting film of the memory layer and the adhesive layer.

Abstract: A photo-mask comprises a light-permeable substrate, a plurality of light-shielding films that are disposed on the substrate, the light-shielding films forming a mask pattern, and a light-permeable protective film that is disposed over the surface of the substrate including the light-shielding films so as to protect the light-shielding films.

Abstract: An optical recording element according to the present invention comprising: (i) a transparent substrate through which light passes; (ii) a transparent low-resistance layer having a specific resistance so as to prevent the adhesion of dust to the surface of the element caused by a static charge, the layer being formed on the surface, on which a light beam is incident, of the transparent substrate; and (iii) an optical thin film composed of at least one layer, formed on the other surface of the transparent substrate so as to transmit light beams used for recording, erasing and playback, and reflect lights which have wavelengths different from the wavelength of the above light beams and are within a specified visible region of the spectrum. With this arrangement, lights within a specified visible region of the spectrum are reflected so that the element appears to be colored according to the wavelengths of the reflected lights.

Abstract: An improved optical memory device comprising a substrate and a plurality of optical memory layers made of a photochromic material and formed over the substrate, the plurality of optical memory layers being laminated to each other through a heat conductive transparent film, which is adaptable for high density and/or high capacity recording of information.

Abstract: A magneto-optical memory element has a multi-layer construction in the order from a side first receiving light from a light-source which includes a first transparent dielectric film, a rare earth transition metal alloy film, a second transparent dielectric film and a reflective film. The magneto-optical device uses circular dichroism effect of a magnetic mater for reading information. The rare earth transition metal alloy film has a refractive index represented by n.+-..DELTA.n wherein n=3.2-3.55i and .DELTA.n=0.05-0.03i. The thickness of film is about 18 to 46 nm. The second transparent dielectric film has a refractive index of 2.0.+-.0.2 and a film thickness of 80 to 108 nm.