Optical head including focusing error detecting system

Details Optical head including focusing error detecting system Optical head including focusing error detecting system

1992-01-03

1993-09-07

Envall, Jr., Roy N.

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

369 4412, 369 4423, 369112, 2502015, G11B 712

Patent

active

052435857

ABSTRACT:
In an optical head, a converging lens and a holographic optical element are arranged in the optical path of light reflected by the recording surface of an optical memory recording medium and passing through an objective lens. The holographic optical element has a hologram formed in at least one of two regions split by a region splitting line crossing the optical axis of the converging lens. A photodetector is arranged on the extension line of the optical axis. The photodetector has a plurality of detection surfaces which are respectively split along the region partition line of the holographic optical element to detect light beams diffracted by the hologram. The optical head also includes a detecting system for detecting a focusing error of the objective lens of the optical head by performing predetermined arithmetic operations using an incorporated processing circuit on the basis of output signals obtained by the plurality of detection surfaces of the photodetector.

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patent: 5070493 (1991-12-01), Marshall et al.
patent: 5111448 (1992-05-01), Komma et al.

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