U.S. Philips Corporation

Pieter Kramer

Jan Roos

Klaas Compaan

Gijsbertus Bouwhuis

Robert Franz Forsthuber

Robert F Forsthuber

A record carrier for information, for example video and/or audio information, in the form of a disk-shaped carrier substrate provided with an optical structure in accordance with the information is described. By making the optical structure radiation-reflecting and the substrate radiation-transmitting, while the surface of the substrate more remote from the optical structure forms both the entrance face and the exit face for the read radiation, and by coating a surface of the optical structure more remote from the substrate with an additional layer, a simple record carrier is obtained which is well protected against dust particles and damage.

Reflective optical record carrier

An apparatus for recording information on a disk-shaped record carrier body by a beam of radiation. The carrier body comprises a diffractive follow-on track which is capable of being scanned with an opto-electronic system so as to produce an electrical signal for controlling the position of the beam during recording of the information.

Record carrier with a follow-on track and apparatus for recording

A disk-shaped record carrier body for storing information which is recorded thereon by a beam of radiation. The carrier body comprises a follow-on track which is capable of being scanned with an opto-electronic system so as to produce an electrical signal for controlling the position of the beam during recording of the information.

Record carrier body with a follow-on track and apparatus for recording

A record carrier is described on which information is stored in an optically readable structure of trackwise arranged areas and intermediate areas. By giving the information tracks periodic excursions towards and away from adjacent tracks, in a direction transverse to the direction of reading, the period of the excursions being substantially greater than the average period of the areas and the amplitude of the excursions being smaller than the width of the tracks, a control signal for centering the read beam of radiation on an information track can be obtained without the use of additional optical means. The excursions of the tracks have such relative phase that the tracks are in nested concentric relation and one component of the stored information represents the phase of the undulations.

Videodisc with undulating nested tracks

Apparatus for reading a record carrier provided with a spiral structure in which sound and/or image information is stored in the form of frequency modulated or phase modulated signals is disclosed. The carrier structure is composed of coplanar regions of variable length separated by coplanar areas of variable length. Where the regions and areas are all in the same plane the regions and areas have different coefficients of reflection or transmission. Where the regions and areas are not coplanar they are spaced by a distance sufficient to produce in response to impinging radiation a one-half wave length difference in the radiation exiting the regions and areas. The apparatus provides a light beam with a frequency that facilitates diffraction of the beam by the areas and regions, and also provides a radiation sensitive detection system for converting the light beam modulations caused by the record carrier into a corresponding electrical signal.

Apparatus for optically reading a phase-modulated optical record carrier

A carrier is provided with a spiral structure in which sound and/or image information is stored in the form of frequency modulated or phase modulated signals. The carrier structure is composed of coplanar regions of variable length separated by coplanar areas of variable length. Where the regions and areas are all in the same plane the regions and areas have different coefficients of reflection or transmission. Where the regions and areas are not coplanar they are spaced by a distance sufficient to produce in response to impinging radiation a one-half wave length difference in the radiation exiting the regions and areas. Apparatus for imaging the radiation exiting the carrier structure is also disclosed.

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Eindhoven, Netherlands

Pieter Kramer