Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Patent
1980-12-19
1983-03-08
Faber, Alan
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
369 46, 369112, 250201, 350423, G11B 712
Patent
active
043763030
ABSTRACT:
Recovery from a record of data recorded in an elongated information track, comprising depressed areas of a given width, a given depth and variable length, alternating along the length of the track with relatively non-depressed areas, is effected by an optical playback system. The playback system employs means for focusing light from a laser source on the information track as a light spot having a diameter which is diffraction limited. The focusing system includes an additional light source (e.g., laser) which impinges on the surface of the record as a circular spot which illuminates a plurality of elongated tracks. The circular spot is imaged by a lens system on a detector plane which is positioned at a plane which is conjugate to the record surface. The focus error signal which is used to adjust the position of the objective lens with respect to the record surface is representative of a measure of the diameter of the circular spot imaged on the detector plane, and, thus, is a measure of the diameter of the circular spot at the record surface. The imaging lens system includes a quasi-zoom lens arrangement that permits adjustment of the correct focus when the surface of the record is at the required position.
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U.S. Patent App. Ser. No. 218,100, Jebens; 12/9/80; Optical Focus Sensor.
Faber Alan
RCA Corporation
Roehling J. E.
Tripoli J. S.
Whitacre E. M.
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