Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2007-04-03
2007-04-03
Hindi, Nabil (Department: 2627)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S053190, C369S112010, C369S112100
Reexamination Certificate
active
10298909
ABSTRACT:
In an optical head apparatus for an optical recording medium, including a light source for emitting a light beam, an objective lens for focusing the light beam at the optical recording medium and receiving a reflected light beam from the optical recording medium, and a photodetector for receiving the reflected light beam from the objective lens, a unit is provided between the light source and the objective lens to generate a main beam and a sub beam from the light beam. The intensity distributions of the main beam and the sub beam are different from each other, and the sub beam is divided into a plurality of portions having different phase distributions from each other. The photodetector includes photodetecting portions for each of the main beam and the sub beam, thus obtaining a push-pull signal from each of the main beam and the sub beam.
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Hindi Nabil
NEC Corporation
Sughrue & Mion, PLLC
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