UST953002I4 - Optical videodisc playback system with plural photodetectors - Google Patents

Optical videodisc playback system with plural photodetectors Download PDF

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Publication number
UST953002I4
UST953002I4 US05/618,246 US61824675A UST953002I4 US T953002 I4 UST953002 I4 US T953002I4 US 61824675 A US61824675 A US 61824675A US T953002 I4 UST953002 I4 US T953002I4
Authority
US
United States
Prior art keywords
light
track
diffraction order
zero diffraction
order cone
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
US05/618,246
Inventor
Arthur Herbert Firester
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RCA Corp
Original Assignee
RCA Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
Priority to US05/618,246 priority Critical patent/UST953002I4/en
Application granted granted Critical
Publication of UST953002I4 publication Critical patent/UST953002I4/en
Expired legal-status Critical Current

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0901—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following only

Abstract

an optical playback system is provided for a record having an information track comprising a succession of depressed areas alternating along the length of the information track with relatively non-depressed areas. Light is diffracted by the track to form a zero diffraction order cone of light, and a pair of differently deviated first diffraction order cones of light, each of the latter having a respective region of overlap with the zero diffraction order cone. A light detector, having four independent photosensitive elements disposed symmetrically about the center of a light accepting region of a common housing, is disposed in the path of the diffracted light so that the light accepting region intercepts the zero diffraction order cone. Two photosensitive elements detect two separate regions of overlap representing the recorded data. The remaining elements provide radial tracking signals. In one embodiment, the light beam is focused on the track as a circular light spot having a spot diameter greater than the track width, while in a second embodiment, the light beam is focused on the track as a substantially elliptical light spot having its major axis transverse to the track and its major axis dimension less than the track width.
US05/618,246 1975-09-30 1975-09-30 Optical videodisc playback system with plural photodetectors Expired UST953002I4 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US05/618,246 UST953002I4 (en) 1975-09-30 1975-09-30 Optical videodisc playback system with plural photodetectors

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US05/618,246 UST953002I4 (en) 1975-09-30 1975-09-30 Optical videodisc playback system with plural photodetectors

Publications (1)

Publication Number Publication Date
UST953002I4 true UST953002I4 (en) 1976-12-07

Family

ID=24476920

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/618,246 Expired UST953002I4 (en) 1975-09-30 1975-09-30 Optical videodisc playback system with plural photodetectors

Country Status (1)

Country Link
US (1) UST953002I4 (en)

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