US4907847A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical pickup and hologram therefor
Assignee: NEC Corp
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Filing: 1988-08-02
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Granted: 1990-03-13
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Expires: 2008-08-02
Abstract
Abstract An optical pickup for picking up signals from an optical disk comprises a hologram to split a laser beam emitted from a laser light source into one 0th order diffraction light beam and two 1st order diffraction light beams, and also to diffract return light beams reflected from the optical disk with two grating areas formed on one surface thereof. The diffracted light beams from the hologram are detected by a 6-piece-divided photodetector. The number of parts included in the system has been greatly reduced.
Inventors
- 👤 Shuichi Onayama
- 👤 Kazuhiko Nosaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:14
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: 6
Claim 1
Independent Claim
49 words
A hologram having a beam splitter and focusing error detection, comprising: a first diffractive surface, comprising two areas for respectively forming light beams which are focused on two different points; and a second surface which comprises a diffraction grating for splitting an incident light beam into three light beams.
Claim 2
Dependent Claim
49 words
A hologram having a beam splitter and focusing error detection, comprising: a first diffractive surface, comprising two areas for respectively forming light beams which are focused on two different points; and a second surface which comprises a diffraction grating for splitting an incident light beam into three light beams.
Claim 3
Dependent Claim
27 words
A hologram as claimed in claim 1, wherein said split three light beams are one 0th order diffraction light beam and two 1st order diffraction light beams.
Claim 4
Dependent Claim
57 words
A hologram comprising: a first diffractive surface, comprising two areas for respectively forming light beams which are focused on two different points; and a second surface which comprises a diffraction grating for splitting an incident light beam into three light beams, wherein said two areas are two diffraction grating areas with different grating pitches from each other.
Claim 5
Dependent Claim
57 words
A hologram comprising: a first diffractive surface, comprising two areas for respectively forming light beams which are focused on two different points; and a second surface which comprises a diffraction grating for splitting an incident light beam into three light beams, wherein said two areas are two diffraction grating areas with different grating pitches from each other.
Claim 6
Dependent Claim
18 words
A hologram as claimed in claim 3, wherein said diffraction light beams are 1st order diffraction light beams.
References Cited (Backward Citations)
US3767310A
Cited
US4779943A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-12 | 1993-09-11 | 1994-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-12 | 1997-09-11 | 1998-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-12 | 2001-09-11 | 2002-03-13 | $7700.00 | Window Closed / Lapsed |