Rca Inc.

Robert Alfred Bartolini

Allen Bloom

Alan E Bell

William J Burke

Jacob M Hammer

Daniel Louis Ross

John P Russell

Brown F Williams

Clyde C Neil

Ling K Hung

Jonathan Isaac Gittleman

Herbert A Weakliem

Sidney S Seffren

Rabah Shahbender

A multi-layer optical record blank and information record comprises a light-reflective layer, a light-transmissive layer, a light-absorptive layer, and a heat-sensitive information layer wherein the thicknesses of the layers are chosen to achieve a low-reflection condition. Information is recorded as variations of an optical property in the information layer indirectly heated by light absorbed in the absorptive layer.

Optical record blank and information record

An optical recording medium comprises a light reflecting material which is coated with a light absorbing layer and overcoated with a 0.05-1 millimeter thick layer of an optically transparent and chemically and thermally stable material such as a silicone resin. During recording, portions of the light absorbing layer are ablated or melted by a modulated focussed light beam, thereby exposing portions of the reflecting layer while leaving the overcoat layer intact. Information is recorded in the form of a reflective-antireflective pattern. Dust particles and other surface contaminants settle on the upper surface of the overcoat layer, so far removed from the focal plane of the recording lens that their effect on the recording or playback signal is considerably reduced, and no defect is noticeable on the playback monitor.

Thick protective overcoat layer for optical video disc

An ablative optical recording medium comprises a substrate coated with a light reflecting coating of passivated aluminum which in turn is coated with a light absorbing ablative layer. During recording, portions of the light absorbing layer are ablated, or vaporized, by a modulated focussed light beam, thereby exposing portions of the reflective layer. Information is recorded in the form of a reflective-antireflective pattern.

Method of recording an ablative optical recording medium

An optical recording medium comprises a light reflecting material which is coated with a light absorbing layer and overcoated with a thin, amorphous, coherent layer of an optically transparent and chemically and thermally stable material such as silicon dioxide. During recording, portions of the light absorbing layer are ablated by a modulated focussed light beam, thereby exposing portions of the reflecting layer while leaving the overcoat layer intact. Information is recorded in the form of a reflective-antireflective pattern. Dust particles and other surface contaminants can be wiped or washed off the recording medium without damage to the light absorbing layer.

Thin protective overcoat layer for optical video disc

A flat major surface of a disc-shaped substrate (e.g., glass or plastic) is coated with a light-reflective layer (e.g., aluminum) which is coated with a dielectric material (e.g., silicon dioxide) highly transparent for light of a frequency supplied by a recording laser. The dielectric material is coated with a thin layer of a smooth continuous, low melting point, low thermal diffusion length metal (e.g., tellurium) absorptive for light of the frequencies supplied by the recording laser. The coating parameters are chosen to establish an anti-reflective 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 at least cause melting of the absorptive layer, an information track is formed as a succession of spaced pits in which, the reflective layer is effectively exposed through the layer of dielectric material. For playback, light of a constant intensity is focused on the information track as the disc is rotated. During playback, the focused light is of insufficient intensity to effect melting of the remaining absorptive layer, but is of a frequency at which the undisturbed regions of the coated disc exhibit an anti-reflective condition. A photo-detector, 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.

Sensitivity information record

An ablative recording medium comprises a substrate coated with a light reflecting layer which in turn is coated with a light absorptive layer of 6,6'-diethoxythioindigo. During recording, portions of the light absorptive layer are ablated by a modulated focussed light beam, thereby exposing portions of the reflecting layer. Video information is recorded as a reflective-antireflective pattern.

Ablatable medium for optical recording

A flat major surface of a disc-shaped substrate (e.g., of glass) is coated with a light-reflective layer (e.g., of aluminum) which is coated with a dielectric material (e.g., silicon dioxide) highly transparent for light of a frequency supplied by a recording laser and of a thickness equal to an integer multiple of the half-wavelength of the laser light output in the dielectric material. The dielectric material is coated with a layer of material moderately absorptive for light of the frequency supplied by the recording laser (e.g., an organic dye such as fluorescein). 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 reflective layer is effectively exposed through the layer of dielectric material. For playback, 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 layer, but is of a frequency at which the undisturbed 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.

Antireflective information record having an optically passive

An optical record blank structure comprises a disc-shaped substrate (e.g., glass), a layer of light-reflective material (e.g., aluminum) overlying a surface of the disc-shaped substrate, a coating of a transparent material (e.g., silicon dioxide) overlying the light-reflective layer and a coating of a moderately absorptive material (e.g., an organic dye such as fluorescein) overlying the dielectric coating. The coating parameters are chosen to establish an antireflective condition to a recording light beam incident on the disc surface. The transparent coating thickness is selected such that the transparent coating is optically passive to the recording light beam, i.e., the thickness of the transparent coating is selected to be an integer multiple of the half-wavelength of the recording light beam wavelength in the transparent material. With this structure the efficiency of energy coupling into the absorptive coating is enhanced by the antireflective condition, the reflective surface of the substrate and the thickness of the transparent coating.

Recorder and antireflective record blank having an optically passive

Playback apparatus, providing a playback beam of light, effects signal recovery, from an information record, with a high signal-to-noise ratio. An information record, suitable for use with such playback apparatus, comprises a flat major surface of a disc-shaped foundation coated with a layer of a thermally conductive material overlaid with a layer of a thermally insulating material. Information storage is effected in a layer of material (e.g., platinum-cobalt), highly absorptive for light of a frequency supplied by a recording laser, which layer overlies the insulating layer. By proper choice of thicknesses for the insulating and the conductive layers, absorptive layer sensitivity to the intensity of the playback beam of lights is effectively reduced to enable record playback at high playback beam intensity levels without damage thereto. Where the foundation is formed of a thermally conductive material, the layer of thermally conductive material may be dispensed with.

Record playback apparatus and information record therefor

A primary recording medium simultaneously receives a pair of reference beams, one of which is comprised of rays that are parallel to an axis of rotation of the primary medium. The primary medium is incrementally rotated about the axis after each of a plurality of object beams is transmitted in sequence thereto from a fixedly disposed source. Interactions between the object beams and the reference beams are recorded in the primary medium as volume holograms, whereby a primary record is recorded. Reconstructions of the object beams and corresponding reference beams emanate from the primary record in response to a primary reconstructing beam. An interaction between the reconstructions is recorded as a volume hologram in a secondary recording medium whereby a secondary record is recorded. A reconstruction of a selected one of the object beams emanates from the secondary record in response to a secondary reconstructing beam.

Duplicating a holographic record by using two reference beams

An optical recording medium comprises a light reflecting material coated with a light absorbing material which is coated with a transparent barrier layer and overcoated with a relatively thick transparent protective layer. During recording, portions of the light absorbing layer are ablated by a modulated focussed light beam, thereby exposing portions of the reflecting layer while leaving the barrier and overcoat layers intact. Information is recorded in the form of a reflective-antireflective pattern. The overcoat layer suspends dust particles far above the focal plane of the recording lens, thereby reducing their effect on the recording or playback signal. The barrier layer insulates the light absorbing layer and the overcoat layer from chemical and thermal interactions which might result in a decreased signal-to-noise ratio.

Overcoat structure for optical video disc

The optical efficiency, with which a coupling portion of a fiber-optic can be coupled by evanescent fields to a planar optical waveguide through a phase-matching diffraction grating on the surface of the planar optical waveguide, is increased by deforming the coupling portion so that it is a negative replica of the undulating surface of the diffraction grating.

Optical coupler having improved efficiency

Organic holographic recording media comprise organic photosensitive compounds such as .alpha.-diketones, quinones and nitro compounds in sucrose benzoate as host.

Organic volume phase holographic recording media using sucrose benzoate

Permanent thin-phase holograms are recorded wherein the recording medium contains a recording layer comprised of an olefinically unsaturated negative photoresist polymer containing an .alpha.-diketone.

Organic medium for thin-phase holography

Holographic recording media which form permanent holograms with excellent recording sensitivity are prepared from .alpha.-diketones which are capable of intermolecular hydrogen atom abstraction dissolved in a transparent, cured vinyl benzene polyester polymerhost.

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Trenton, NJ, United States of America

Robert Alfred Bartolini