Optical pickup apparatus and information recording and/or...

Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system

Reexamination Certificate

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Details

C369S112020, C369S118000, C386S349000

Reexamination Certificate

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06885616

ABSTRACT:
A phase device for providing a phase difference between an inner radius portion and an outer radius portion of a light beam which is emitted from a light source is provided in an optical path between the light source of an optical pickup apparatus and an objective lens. The light beam to which the phase difference has been provided is converged by the objective lens and irradiated to an optical disc. An interference of an inner radius portion and an outer radius portion of the returning light beam caused when the light beam is diffracted by the optical disc with ±1 primary diffracted light caused by the diffraction is suppressed. Therefore, an intensity fluctuation of the returning light beam caused by the interference is suppressed. A spherical aberration error showing a thickness error of the optical disc and a focusing error having a high linearity can be detected with high precision on the basis of the returning light. A numerical aperture of the objective lens, consequently, can be increased, high density information recording and information reproduction can be performed, and further, an optical pickup apparatus and an information recording and/or reproducing apparatus each having compatibility are realized.

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patent: 2000-182254 (2000-06-01), None

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