Optical head apparatus including light focusing and refocusing l

Details Optical head apparatus including light focusing and refocusing l Optical head apparatus including light focusing and refocusing l

1996-05-22

1998-01-13

Huber, Paul W.

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

369112, G11B 700

Patent

active

057086486

ABSTRACT:
An optical head apparatus includes a light source, an objective lens, a beam splitter, a refocusing lens, a pinhole, and a photodetector. The objective lens and the beam splitter focus light emitted from the light source on an information recording medium. The objective lens, the beam splitter, and the refocusing lens refocus light reflected by the information recording medium and have a light-receiving numerical aperture which is larger than a light-focusing numerical aperture of the objective lens. The pinhole extracts only a central portion of light focused by the objective lens, the beam splitter, and the refocusing lens. The photodetector receives and detects light extracted by the pinhole.

REFERENCES:
patent: Re32660 (1988-05-01), Lindow et al.
patent: 5063556 (1991-11-01), Chikuma
patent: 5153873 (1992-10-01), Spruit et al.
patent: 5195081 (1993-03-01), Usui
patent: 5247510 (1993-09-01), Lee et al.

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