Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2005-05-17
2005-05-17
Psitos, Aristotelis (Department: 2653)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S112170, C369S112150
Reexamination Certificate
active
06894958
ABSTRACT:
In an optical head apparatus, reflected light from the disk is diffracted by a hologram optical element, and received by an optical detector. A focusing error signal is detected from −1st-order diffracted light of the hologram optical element. A tracking error signal by the differential phase method, a tracking error signal by a push-pull method and the data signal recorded on the disk are detected from +1st-order diffracted light of the hologram optical element. A diffraction efficiency of the +1st-order diffracted light is higher than a diffraction efficiency of the −1st-order diffracted light.
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Nec Corporation
Psitos Aristotelis
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