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EP0318912A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

An optical head

Assignee: NEC Corp
•
Filing: 1988-11-29
•
Granted: —
•
Expires: 2008-11-29
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Abstract

Abstract An optical head includes a reflection type grating lens for dividing specified polarized lights into a reflected light and a diffracted light, a device for detecting a RF signal from the reflected light of the grating lens, and a device for detecting focusing and tracking error signals from the diffracted light of the grating lens. The grating lens (23) consists of a plurality of domains having different optical properties respectively, so that the reflected and diffracted lights are obtained. The optical head further includes a total reflection prism (6) to compensate a phase difference between polarized lights orthogonal to a grating groove of the grating lens and parallel thereto, and a polarizing prism (24) for dividing the reflected light into two polarized lights orthogonal to each other in polarization thereof. Thus, a simple, miniaturized, and inexpensive optical head is obtained.

Inventors

  • 👤 Akitomo C/O Nec Corporation Ohba
  • 👤 Yasuo C/O Nec Corporation Kimura
  • 👤 Yuzo C/O Nec Corporation Ono

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-27 05:23
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1381; G11B7/08; G11B7/09; G11B7/0901; G11B7/0903; G11B7/0908; G11B7/0912; G11B7/0916; G11B7/1353; G11B7/1372; G11B7/1378

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 123 words
An optical head comprising, means for radiating light beam, a beam splitter for transmitting said light beam therethrough and reflecting light beam reflected from a disk, a focusing lens for focusing said light beam on said disk and transmitting light beam reflected from said disk therethrough, a reflection type grating lens including a plurality of different optical properties for dividing specified polarized lights included in said light beam from said beam splitter into reflected and diffracted lights, means for detecting a signal stored in said disk in accordance with said reflected light of said reflection type grating lens, and means for detecting a focusing error signal and a tracking error signal in accordance with said diffracted light of said reflection type grating lens.
Claim 2
Dependent Claim 123 words
An optical head comprising, means for radiating light beam, a beam splitter for transmitting said light beam therethrough and reflecting light beam reflected from a disk, a focusing lens for focusing said light beam on said disk and transmitting light beam reflected from said disk therethrough, a reflection type grating lens including a plurality of different optical properties for dividing specified polarized lights included in said light beam from said beam splitter into reflected and diffracted lights, means for detecting a signal stored in said disk in accordance with said reflected light of said reflection type grating lens, and means for detecting a focusing error signal and a tracking error signal in accordance with said diffracted light of said reflection type grating lens.
Claim 3
Dependent Claim 36 words
An optical head according to claim 1 further comprising, a polarizing prism for dividing the zero-order diffraction light supplied from said reflection type grating lens into two polarized lights orthogonal to each other in polarizations thereof.
Claim 4
Dependent Claim 57 words
An optical head according to claim 2 further comprising, a total reflection prism for compensating a phase difference between polarized lights orthogonal to a grating groove of said reflection type grating lens and parallel thereto, said total reflection prism being provided at a specific position on a light path between said focusing lens and said polarizing prism.
Claim 5
Dependent Claim 23 words
An optical head according to any one of claims 1 to 3, wherein said means for detecting a signal comprises a two-divided photodetector.
Claim 6
Dependent Claim 30 words
An optical head according to any one of claims 1 to 4, wherein said means for detecting a focusing error signal and a tracking error signal comprises a six-divided photodetector.

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