Rca Inc.

Alan E Bell

Robert Alfred Bartolini

Allen Bloom

Brown F Williams

David E Carlson

Fred W Spong

William J Burke

Yehuda Arie

Sidney S Seffren

Rabah Shahbender

An optical tape record/playback apparatus is provided for recording/reproducing information signals onto an optical tape. The record apparatus comprises laser sources which are modulated in accordance with the information signals. A sequence number is recorded by the laser sources to aid in the recovery of information. 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 operations. The high packing density of the information recorded in the tape may affect the proper recovery of the recorded information. During the recording operation a sequence number is recorded in a special section of the optical tape to aid in the recovery of the recorded information signals.

Signal format for optical tape record/playback system

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.

Optical video or data tape record and playback apparatus

The invention is a recording medium wherein the light absorptive layer is a granular material comprising domains of a light sensitive material embedded in a dielectric matrix. The domains comprise a material which can be reversibly switched from a first state to a second state having different optical properties by the absorption of light. The matrix is composed of a material which is effective for inhibiting the formation of an irreversible change in the optical properties of the absorptive layer. The invention further comprises this optical recording medium having an information track recorded therein as a series of regions in the absorptive layer wherein the domains have been reversibly switched to a second state having different optical properties.

Reversible recording medium and information record

The invention is an improved optical recording medium and information record where information is recorded in the form of one or more bubbles in a light absorptive layer and a reinforcement layer which preferentially adheres to a light absorptive layer during the formation of the bubble. The reinforcement layer provides a path for heat to diffuse away from the bubble, thereby desensitizing the recording process and increasing the range of incident light powers over which a bubble is formed.

Reinforced bubble recording medium and information record

An optical recording medium comprising a substrate, a light absorptive layer overlying the substrate, a buffer layer overlying the absorptive layer and a masking layer having slots therethrough overlying the buffer layer. The invention also includes an information record having information recorded in the absorptive layer as a series of regions of the absorptive layer, underlying the slots in the masking layer, whose optical properties differ from those of the remainder of the absorptive layer. The presence of the slots in this medium can provide a spatially varying recording sensitivity, track identification and a means for obtaining a radial tracking error signal.

Optical recording medium and information record with tracking aid

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, which dielectric material is coated with a thin layer of a material absorptive for light of the frequency supplied by the recording laser (e.g., titanium). 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 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. 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-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.

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 optical recording medium which comprises a light reflective layer, a light transmissive layer and a light absorptive layer where the light transmissive layer is comprised of an organic material which has a melting, sublimation or decomposition temperature at least 300.degree. C. less than that of the material comprising the absorptive layer and where the absorptive layer has a melting temperature of at least 1000.degree. C. Information is recorded as bubbles in the absorptive layer. This storage mechanism produces topographical features which are suitable for replication, thus allowing direct replication of the recorded information.

Replicable 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

An optical recording medium which comprises a light reflective layer, a light transmissive layer and a light absorptive layer, the material comprising the light transmissive layer has a melting, sublimation or decomposition temperature at least 300.degree. C. less than that of the material comprising the absorptive layer. Information is recorded as openings in both the light transmissive and absorptive layers or as bubbles in the absorptive layer. These storage mechanisms produce topographical features which are suitable for replication, thus allowing direct replication of the recorded information.

A flat major surface of a disc-shaped substrate (e.g., of glass) is coated with a first light reflective layer (e.g., Rhodium) which is coated with a layer of a dielectric material (e.g., silicon dioxide) highly transparent of light of a frequency supplied by a playback laser, which transparent layer is coated with a second light reflective layer (e.g., Rhodium). The light output of a recording 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 second reflective layer, an information track is formed as a succession of spaced pits in which the first reflective layer is effectively exposed through the layer of dielectric material. For playback, light of a constant intensity is focused on the information track and the adjacent land areas as the disc is rotated. The focused light is of insufficient intensity to effect melting of the remaining portions of the second reflective layer, but is of a frequency at which the thickness of the dielectric layer exposed through the pits introduces a phase change of approximately (2K+1) .pi. radians between reflected portions of the focused light which fall on the pits and reflected portions of the focused light which fall on the undisturbed areas of the disc, where k is zero or any integer. 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.

Playback information record using phase cancellation for reading

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

Optical anti-reflective information record

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.

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East Windsor, NJ, United States of America

Alan E Bell