Abstract: A lens and combination lens able to suppress deviation of an optical axis of a lens occurring at the time of combination and able to be adjusted at a high precision, a method of producing the combination lens, and an optical pickup device and an optical disk drive mounting the combination lens thereon are provided. A first lens L1 comprising a lens body 1 where one surface on an incident side or an emitting side of light is a flat surface and the other surface parallel to the surface formed as the flat surface is a structural element and a second lens L2 comprising a lens body 2 where one surface on an incident side or an emitting side of light is a flat surface and the other surface parallel to the surface formed as the flat surface is a structural element are adhered together. The combination lens is used as the object lens for an optical pickup device and an optical disk drive.

Abstract: An optical element 100 has a shape as a rectangular parallelopiped or approximately rectangular parallelopiped formed on one surface 100U with a convex portion 103D. The optical element 100 has a substrate (base) 101 and a lens 102. The substrate 101 and the lens 102 of the optical element 100 have refractive indexes different from each other and can refract light at the boundary of the substrate 101 and the lens 102. Also, the light can be refracted at the surface of the convex portion 103D. The substrate 101 has an axially symmetric or approximately axially symmetric concave portion 101B in a bottom surface 100B of the substrate 101. A radius of curvature of the surface of this concave portion 101B is constant or approximately constant. The concave portion 101B is filled with an optical material having a refractive index different from the substrate 101, while the lens 102 is formed by the concave portion 101B filled with the optical material.

Abstract: An optical recording/reproducing apparatus accessing a recording layer of an optical rotating recording medium using an accessing means positioned a predetermined gap away from a surface of said optical rotating recording medium and mounted with an object lens, wherein a thickness of a protective transparent layer of said optical rotating recording medium, a ratio of a defect area with respect to a beam spot area, and the above predetermined gap are values determined by the conditions defined in the following inequalities: G 1 ≤ t · k ⁢   ⁢ π × tan ⁢ { sin - 1 ⁡ ( NA n )

Abstract: An optical recording medium is provided which has a substrate and a signal recording layer provided on the substrate and in which an information signal is recorded in the form of microscopic pits. A light beam is focused on the signal recording layer and some change of the light beam carried by a return light from the signal recording layer is detected to read the information signal recorded on the signal recording layer. The optical recording medium has a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. The ratio in area between the information signal recording area and non-signal recording area is 3.4 or more. The storage capacity of this medium is 2 gigabytes or more. The optical recording medium has formed at the center thereof a center hole around which an annular table-abutment convexing to one side of the medium is formed.

Abstract: An optical recording medium is provided which has a substrate and a signal recording layer provided on the substrate and in which an information signal is recorded in the form of microscopic pits. A light beam is focused on the signal recording layer and some change of the light beam carried by a return light from the signal recording layer is detected to read the information signal recorded on the signal recording layer. The optical recording medium has a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. The ratio in area between the information signal recording area and non-signal recording area is 3.4 or more. The storage capacity of this medium is 2 gigabytes or more. The optical recording medium has formed at the center thereof a center hole around which an annular table-abutment convexing to one side of the medium is formed.

Abstract: An optical recording medium is provided which has a substrate and a signal recording layer provided on the substrate and in which an information signal is recorded in the form of microscopic pits. A light beam is focused on the signal recording layer and some change of the light beam carried by a return light from the signal recording layer is detected to read the information signal recorded on the signal recording layer. The optical recording medium has a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. The ratio in area between the information signal recording area and non-signal recording area is 3.4 or more. The storage capacity of this medium is 2 gigabytes or more. The optical recording medium has formed at the center thereof a center hole around which an annular table-abutment convexing to one side of the medium is formed.

Abstract: An optical recording medium is provided which has a substrate and a signal recording layer provided on the substrate and in which an information signal is recorded in the form of microscopic pits. A light beam is focused on the signal recording layer and some change of the light beam carried by a return light from the signal recording layer is detected to read the information signal recorded on the signal recording layer. The optical recording medium has a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. The ratio in area between the information signal recording area and non-signal recording area is 3.4 or more. The storage capacity of this medium is 2 gigabytes or more. The optical recording medium has formed at the center thereof a center hole around which an annular table-abutment convexing to one side of the medium is formed.

Abstract: A first optical device according to the present invention comprises a base made of a first optical material and a second optical material having a refractive index different from that of the first optical material, and the base has a concavity, and the second optical material is filled in this concavity. A second optical device according to the present invention comprises a base made of a first optical material and a second optical material having a refractive index different from the first optical material, and the base comprises first and second faces facing each other, a first concavity is formed in the first face and a second concavity is formed in the second face, and the second optical material is filled in the first and second concavities.

Abstract: An optical recording/reproducing apparatus accessing a recording layer of an optical rotating recording medium using an accessing means positioned a predetermined gap away from a surface of said optical rotating recording medium and mounted with an object lens, wherein a thickness of a protective transparent layer of said optical rotating recording medium, a ratio of a defect area with respect to a beam spot area, and the above predetermined gap are values determined by the conditions defined in the following inequalities: 1 G 1 ≤ t · k ⁢   ⁢ π × tan ⁢   ⁢ { sin - 1 ⁡ ( NA n ) } or t ≥ G k ⁢   ⁢ π · tan ⁢   ⁢ { sin - 1 ⁡ ( NA n ) )

Abstract: An optical disc system uses an optical disc with a light-transmitting cover and an objective lens for bundling or focusing a light beam on a recording layer of the optical disc in order to perform recording and/or reproducing of information. The thickness of the light-transmitting cover falls within the range of 0.05 mm to 0.6 mm, the numerical aperture (NA) of the objective lens is set to fall within the range of 0.55 to 1.10, and the wavelength of the light beam is selected to be between 100 nm to 780 nm.

Abstract: Disclosed is a magneto-optical disc system comprising a magneto-optical disc 40 with a light-transmitting cover 41, an objective lens 2 for bundling or focusing a laser beam on a magnetic recording layer 43 of the magneto-optical disc 40 in order to perform recording and/or reproduction, and a magnetic field generating unit 9 obtained by forming a coil pattern 7 in an optical glass 8. In the above system, the thickness t2 of the light-transmitting cover 41 is set to fall within the range of 0.6 to 0.1 mm, and the numerical aperture (NA) of the objective lens 2 is set to fall within the range of 0.55 to 0.70, so as to obtain high-density recording and/or reproduction.

Abstract: A magneto-optical information recording/reproducing apparatus in which a magneto-optical information recording medium at least including a first magnetic film having perpendicular magnetic anisotropy, and a second magnetic film to which information recorded on the first magnetic film is transferred by irradiation of a laser beam, is used so that a readout laser beam is irradiated onto the second magnetic film to thereby readout the information transferred to the second magnetic film. The apparatus includes a 2-split detection circuit for receiving the readout laser beam reflected from the second magnetic film of the recording medium, and a subtraction circuit in which output signals of the two detection elements of the 2-split detection circuit are subtracted from each other to generate a differential signal.

Abstract: An optical pickup is provided with a main beam for performing recording or playback on a disc and an advance beam in a position ahead of this main beam to detect the surface state of the disc; the surface state of the disc is detected on the basis of the light reception information (an MO signal or an RF signal) of this advance beam; and control is so effected that, at the timing of the main beam passing the position where adhesion of dust or the like to the disc is detected, the laser output power of the main beam reach a level at which satisfactory operation can be executed even if there is dust adhesion or the like so as to make possible execution of accurate recording and playback operations, even if the thickness of a disc-shaped recording medium is thinned, without being affected by dust or the like stuck to the surface of the disc-shaped recording medium.

Abstract: A head unit is provided which is able to satisfactorily record/reproduce an information signal to and from a disk even if the disk can considerably be inclined (deflected) by a load applied by the head. The load applied from the magnetic head to the disk is set to be not larger than an upper limit which is calculated in accordance with a permissible range for incident angles of laser beams emitted from the optical head to the disc-shape recording medium, the thickness of the disc-shape recording medium and the radius of the disc-shape recording medium. As an alternative to this, the load is set to be not larger than an upper limit calculated in accordance with a permissible range of the amount of deviation between the point to which laser beams emitted from the optical head to the disc-shape recording medium and a point to which laser beams are converged, the thickness of the disc-shape recording medium and the radius of the disc-shape recording medium.

Abstract: An magneto-optical disc system includes an magneto-optical disc with a light-transmitting cover and an objective lens for bundling or focusing a laser beam on a recording layer of the magneto-optical disc in order to perform recording and/or reproduction. The thickness t.sub.2 of the light-transmitting cover is set to fall within the range of 0.6 to 0.1 mm, the numerical aperture (NA) of the objective lens is set to fall within the range of 0.55 to 0.70 and the wavelength of the light beam is selected to be between 635 and 680 nanometers.

Abstract: An optical disc system uses a rewritable optical disc with a light-transmitting cover and an objective lens for bundling or focusing a light beam on a recording layer of the optical disc in order to perform recording and/or reproducing of information. The recording layer is formed of a phase-change material. The thickness of the light-transmitting cover falls within the range of 0.05 mm to 0.6 mm, the numerical aperture (NA) of the objective lens is set to fall within the range of 0.55 to 1.10, and the wavelength of the light beam is selected to be between 100 nm to 780 nm.

Abstract: An optical disc system uses an optical disc with a light-transmitting cover and an objective lens for bundling or focusing a light beam on a recording layer of the optical disc in order to perform recording and/or reproducing of information. The thickness of the light-transmitting cover falls within the range of 0.05 mm to 0.6 mm, the numerical aperture (NA) of the objective lens is set to fall within the range of 0.55 to 1.10, and the wavelength of the light beam is selected to be between 100 nm to 780 nm.

Abstract: A magneto-optical disc system includes a magneto-optical disc 40 with a light-transmitting layer 41, an objective lens 2 for bundling or focusing a laser beam onto a magnetic recording layer 43 of the magneto-optical disc 40 for recording information thereon and/or reproducing information therefrom, and a magnetic field generating unit 9 having a coil pattern 7 arranged on an optical glass element 8. The thickness t.sub.2 of the light-transmitting layer 41 falls within the range of 0.6 to 0.1 mm, and the numerical aperture (NA) of the objective lens 2 falls within the range of 0.55 to 0.70.

Abstract: A magneto-optical recording and/or reproducing apparatus having a magnetic head and first and second optical systems for recording on and/or reproducing from first and second magneto-optical media. The first optical system has a first objective lens, and the second optical system has a second objective lens whose numerical aperture differs from that of the first objective lens. The magnetic head is arranged near the second objective lens. The first and second optical systems are arranged such that the respective one of the first and second magneto-optical media which is currently being subject to recording or reproducing is positioned between the first and second optical systems.

Abstract: A magneto-optical disc system includes a magneto-optical disc with a light transmitting protective layer, an objective lens for bundling or focusing a laser beam onto a magnetic recording layer of the magneto-optical disc in order to perform recording and/or reproduction, and a magnetic field generating unit formed as a coil pattern on a transparent optical glass layer. In the magneto-optical disc system, the thickness t2 of the light-transmitting protective layer is set to fall within the range of 0.6 to 1.0 0.1 mm and the numerical aperture of the objective lens is set to fall within the range of 0.55 to 0.70, so as to obtain high density recording and/or reproduction by permitting the lens to be quite close to the actual recording layer.