Apparatus for optically scanning a radiation-reflecting information plane
AssigneeU.S. Philips Corporation
InventorsPeter Coops, Adrianus J. Duijvestijn
Life of this patent
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Abstract
Optical scanning apparatus which includes a diode laser producing a radiation beam which is focussed by a lens system on a reflecting information plane to be scanned thereby. The reflected radiation is diffracted by a composite diffraction grating which includes a pair of sub-gratings, forming respective radiation spots on respective pairs of radiation detectors. The detectors in each pair are separated by a separating strip, the separating strips being substantially parallel to or co-linear with the bonding line between the sub-gratings. Such arrangement achieves correction for wavelength variations of the radiation beam, as well as fairly wide tolerances in the relative positioning of the various optical elements of the apparatus.
Claims6
An apparatus for optically scanning a radiation-reflecting information plane, which apparatus comprises a diode laser supplying a scanning beam, an objective system for focusing the scanning beam to a scanning spot in the information plane and for re-imaging the scanning spot on a composite radiation-sensitive detection system, and a composite diffraction element arranged in the radiation path between the diode laser and the objective system for deflecting a part of the radiation beam reflected by the information plane towards the radiation-sensitive detection system and for splitting the deflected beam into a plurality of sub-beams which respectively form respective radiation spots re-imaged on respective detector pairs of the composite detection system, the two detectors of each pair having a separating strip there-between which is oriented so that displacements of the re-imaged radiation spot thereon resulting from wavelength variations of the scanning beam do not have any influence on the detector signals;
- characterized in that the separating strips of the detector pairs are substantially parallel to a connecting line from the centre of the radiation-emitting surface of the diode laser to the centre of the composite radiation-sensitive detection system.
Dependencies are inferred from the claim text.