EP0309689A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Optical pickup and hologram therefor
Assignee: NEC Corp
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Filing: 1988-08-04
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Granted: —
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Expires: 2008-08-04
Abstract
Abstract An optical pickup for picking up signals from an optical disk (6) comprises a hologram (15) to split a laser beam emitted from a laser light source (1) into one 0th diffraction light beam and two lst diffraction light beams, and also to diffract return light beams reflected from the optical disk (1) with two grating areas (15a,15b) formed on one surface thereof. The diffracted light beams from the hologram (15) are detected by a 6-piece-divided photodetector (11). The optical pickup needs only a small number of parts.
Inventors
- 👤 Shuichi Nec Home Electronics Ltd. Onayama
- 👤 Kazuhiko Nec Home Electronics Ltd. Nosaka
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 08:32
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0908; G11B7/0916; G02; G02B; G02B5/00; G02B5/32; G11B7/12; G11B7/135; G11B7/1353; G11B7/1381; G11B7/0901; G11B7/0903
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
128 words
An optical pickup for picking up signals from a signal surface of an optical disk (6), comprising: a laser light source (1) for emitting a laser beam; splitting means (2;15B) for splitting said laser beam emitted from said laser light source (1) into three light beams; an object lens (5) disposed in front of said optical disk (1), for focusing said three light beams coming from said splitting means (2) on said signal surface of said optical disk (1); diffraction means (10A;15A) disposed between said splitting means (2) and said object lens (5), for diffracting return light beams reflected from said signal surface (1); and photodetector means (11) disposed in a direction of diffracted return light beams from said diffraction means, for detecting said diffracted return light beams.
Claim 2
Dependent Claim
128 words
An optical pickup for picking up signals from a signal surface of an optical disk (6), comprising: a laser light source (1) for emitting a laser beam; splitting means (2;15B) for splitting said laser beam emitted from said laser light source (1) into three light beams; an object lens (5) disposed in front of said optical disk (1), for focusing said three light beams coming from said splitting means (2) on said signal surface of said optical disk (1); diffraction means (10A;15A) disposed between said splitting means (2) and said object lens (5), for diffracting return light beams reflected from said signal surface (1); and photodetector means (11) disposed in a direction of diffracted return light beams from said diffraction means, for detecting said diffracted return light beams.
Claim 3
Dependent Claim
21 words
An optical pickup as claimed in Claim 1, wherein said diffraction means is a first surface (10A;15A) of a hologram (10;15).
Claim 4
Dependent Claim
21 words
An optical pickup as claimed in Claim 1 or 2, wherein said splitting means (2;15B) is a diffraction grating (Fig. 2).
Claim 5
Dependent Claim
23 words
An optical pickup as claimed in Claim 3, wherein said diffraction grating (15B) is formed on a second surface of said hologram (15).
Claim 6
Dependent Claim
63 words
An optical pickup as claimed in one of Claims 2 to 4, wherein and said first surface (10A;15A) of said hologram (10;15) comprises two diffraction grating areas (10a,10b;15a,15b) with different grating pitches in such a manner that each of said diffracted return light beams from said first surface (10A;15A) of said hologram is focused on two different points on said photodetector means (11).
Claim 7
Dependent Claim
21 words
An optical pickup as claimed in one of the preceding Claims, in which the photodetector means is a 6-piece-divided photodetector (11).
Claim 8
Dependent Claim
37 words
An optical pickup as claimed in Claim 6, wherein said 6-piece-divided photodetector comprises a 4-piece-divided (A,B,C,D) photosensor and 2-piece-divided (E,F) photosensor, two photosensors (E,F) of said 2-piece-divided photosensor being disposed at respective outsides of said 4-piece-divided photosensor.
Claim 9
Dependent Claim
68 words
An optical pickup as claimed in Claim 6, wherein one of said diffracted return light beams from said diffraction means originates from a 0th diffraction light beam from said splitting means (2;15B) and irradiates said 4-piece-divided photosensor, and two of said diffraction light beams from said diffraction means originate from lst diffraction light beams from said splitting means (2;15B), and irradiate said respective photosensors of said 2-piece-divided photosensor.
Claim 10
Dependent Claim
57 words
A hologram (15), comprising: a first surface (15A) as a hologram surface which comprises two areas (15a,15b) in such a manner that each of diffraction light beams from said hologram surface is focused on two different points; and a second surface (15B) which comprises a diffraction grating for splitting an incident light beam into three light beams.
Claim 11
Dependent Claim
57 words
A hologram (15), comprising: a first surface (15A) as a hologram surface which comprises two areas (15a,15b) in such a manner that each of diffraction light beams from said hologram surface is focused on two different points; and a second surface (15B) which comprises a diffraction grating for splitting an incident light beam into three light beams.
Claim 12
Dependent Claim
24 words
A hologram as claimed in Claim 9, wherein said two areas (15a,15b) are two diffraction grating areas with different grating pitches from each other.
Claim 13
Dependent Claim
17 words
A hologram as claimed in Claim 10, wherein said diffraction light beams are lst diffraction light beams.
Claim 14
Dependent Claim
29 words
A hologram as claimed in one of Claims 9 to 11, wherein said split three light beams are one 0th diffraction light beam and two lst diffraction light beams.
References Cited (Backward Citations)
No citation records indexed.
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