Rca Inc.

Fred W Spong

Thomas L Credelle

William J Hannan

Alan E Bell

William E Barnette

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

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. The focused light is of insufficient intensity to effect ablation of the remaining absorptive material, 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.

Multilayer record blank for use in optical recording

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.

Optical record playback apparatus employing light frequency at which

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. The focused light is of insufficient intensity to effect ablation of the remaining absorptive material, 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.

Recording methods for a multilayer optical record

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.

Capacitance distance sensor apparatus for video disc player/recorder

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.

Recording a synthetic focused-image hologram on a thermally deformable

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.

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Lawrenceville, NJ, United States of America

Fred W Spong