Apparatus for optically reconstructing information
AssigneeHitachi, Ltd.
InventorsYasutsugu Takeda, Hisashi Nakamura, Yoshito Tsunoda, Toshihisa Tsukada, Toshimitsu Miyauchi
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Abstract
Optical information reconstructing apparatus comprising a disc having at least one surface on which groups of dots bearing information are concentrically or spirally arrayed, a mechanism for rotating the disc, a light source for projecting a light beam on the array of groups of dots, and at least one photodetector for detecting diffracted light waves from the groups of dots, characterized in that a semiconductor laser array is used as the light source and that the light emission is switched from one laser source to another in the laser array in tracking the information.
Claims12
In an apparatus for optically reconstructing information provided on a disc on which a plurality of information bearing dots are arrayed in at least one track, including means to rotate said disc, a light source capable of projecting a beam onto the plurality of dots, and a photodetector which detects diffracted light waves from the plurality of dots, the improvement beng characterized in that said light source comprises an array formed of a plurality of semiconductor light emitting elements which can be driven independently and said photodetector comprises at least one set of light detecting elements capable of detectng a deviation of said beam from the tracks of dots, and further including driving means responsive to said photodetector for individually driving selected light emitting elements in said array to effect a tracking of said array of dots by said light source.
Dependencies are inferred from the claim text.