Abstract: A magnetic magneto-optic recording structure and method in which a magneto-optic active layer is positioned within the fringing magnetic field of a magnetic recording medium, the structure preferably being disk-shaped. The magneto-optic layer is irradiated by a continuous wave laser beam, by way of a transparent substrate thereon, to locally reduce the coercivity of the magneto-optic layer, so that the magneto-optic layer becomes locally magnetized to align itself with the fringing magnetic fields created by the magnetization pattern of information previously recorded on the magnetic recording layer. The information thus recorded on the magneto-optic layer can be read out with a laser beam of lesser power, employing the Kerr effect.

Abstract: A record/playback apparatus is provided for recording/reproducing information signals in cooperation with an optical tape medium. The record apparatus comprises a laser source which is modulated in accordance with the information signals. A switching mirror, which is interposed between the laser source and the optical tape, switches the light beam emitted by the source to alternately scan helical tracks across an optical tape. In the playback mode a light detector is arranged to intercept the light reflected from the optical tape. The reflected light contains the information which was recorded on the optical tape during the recording operation.

Abstract: An information storage device in combination with a radiation recording structure comprising a substrate, a recording layer, a thin electrically conductive over-layer on the outer surface of the recording structure and a neutralizing means for maintaining said over-layer at a neutral electrical potential.

Abstract: An optical recording structure layer has an optical reflecting layer, a phase layer on the reflective layer, an active layer on the phase layer and a matrix layer on the active layer. The phase layer and matrix layer are substantially transparent to radiation. A thin metal layer on the matrix layer has a thickness from 20 to 100 Angstroms to achieve a relatively constant absorption and reflection characteristics for the structure over a broad band of radiation.

Abstract: A radiation recording structure for use in an information storage device having focused write and read radiation beams includes a substrate supported reflective layer, an active structure supported on the reflective layer. The structure also includes a dust defocusing layer as an outer surface for the structure for defocusing the image of dust on the outer surface and an aluminum adhesion layer between the dust defocusing layer and the active recording layer. The adhesion layer is transparent to the radiation beams and provides surface energy to draw the defocusing layer and the recording layer together.

Abstract: Laminated optical recording medium that provides desired optical properties in combination with pregrooved channels that define data tracks on which data may be written. Annular or spiral grooves are selectively placed on a base disc substrate. A recording layer is deposited on a transparent disc substrate. The two disc substrates are then bonded together so that the recording layer on the transparent disc substrate confronts the grooves on the base disc substrate. The covered grooves thus form chambers exposed to the recording layer. Prior to bonding the two disc substrates together, the chambers may be filled with an inert gas. A rigid support disc, such as is made from aluminum, may optionally be bonded to the underside of the grooved base disc substrate.

Abstract: A flat major surface of a disc-shaped substrate (e.g., of glass) is coated with a light-reflective layer (e.g., of aluminum). Overlying the reflective layer is a layer of material (e.g., fluorescein) which is highly absorptive for light of a frequency supplied by a recording laser. The coating parameters are chosen to establish an anit-reflection condition for the coated record blank at the recording light frequency. The light output of the laser, which is intensity modulated in accordance with a signal to be recorded, is focused upon the coated surface of the disc as the disc is rotated. With the peak intensity of the focused light sufficient to cause ablation of the absorptive layer, an information track is formed as a succession of spaced pits in which the reflecting layer is effectively exposed. For playback, light of a constant intensity is focused on the information track as the disc is rotated.

Abstract: For playback of a disc record information track, in which regions of a light reflective surface overlaid with a layer of light absorptive material alternate with regions of said light reflective surface free of said overlying absorptive material, light of a constant intensity is focused on the information track as the disc is rotated. The focused light is of insufficient intensity to effect ablation of the remaining absorptive material, but is of a frequency at which the overlaid regions of the coated disc exhibit an anti-reflection condition. A photodetector, positioned to receive light reflected from the information track as the pits pass through the path of the focused light, develops a signal representative of the recorded information.

Abstract: A flat major surface of a disc-shaped substrate (e.g., of glass) is coated with a light-reflective layer (e.g., of aluminum). Overlying the reflective layer is a layer of material (e.g., fluorescein) which is highly absorptive for light of a frequency supplied by a recording laser. The coating parameters are chosen to establish an anti-reflection condition for the coated record blank at the recording light frequency. The light output of the laser, which is intensity modulated in accordance with a signal to be recorded, is focused upon the coated surface of the disc as the disc is rotated. With the peak intensity of the focused light sufficient to cause ablation of the absorptive layer, an information track is formed as a succession of spaced pits in which the reflecting layer is effectively exposed. For playback, light of a constant intensity is focused on the information track as the disc is rotated.

Abstract: A non-contact type, capacitance distance sensing probe having one or two electrodes disposed about one end of an objective lens system in an optical video disc system is used with a focus control servo loop to maintain focus of a light beam on the surface of a reflective disc record despite undesirable axial displacements of the surface when the record is rotated. The two electrode probe is balanced to provide immunity to variations in the impedance of the external circuit which grounds the disc.

Abstract: A synthetic focused image hologram of a white light image is recorded as variations in the depths of grooves of a diffraction grating in a layer of thermoplastic material located on a layer of photoconductive material. The thermoplastic layer is manufactured with initial, uniform, shallow grooves of the diffraction grating. A voltage is applied across the layers to deposit a uniform charge, a white-light image is projected on the thermoplastic layer, the layers are recharged and the thermoplastic layer is heated, whereby the initial shallow grooves are selectively deepened in accordance with the image.

Abstract: A layer of thermally deformable plastic used, for example, in a holographic recording medium has an undulated surface whereby the layer has an uneven thickness. Because of the uneven thickness, the layer has a composite spatial frequency pass band greater than the spatial frequency pass band of a layer of uniform thickness.

Abstract: A layer of thermally deformable plastic used, for example, in a holographic recording medium has an undulated surface whereby the layer has an uneven thickness. Because of the uneven thickness, the layer has a composite spatial frequency pass band greater than the spatial frequency pass band of a layer of uniform thickness.