US4569035A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magneto-optical information reading apparatus
Assignee: Canon Inc
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Filing: 1983-09-06
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Granted: 1986-02-04
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Expires: 2003-09-06
Abstract
Abstract This specification discloses a magneto-optical information reading apparatus which comprises a device for causing a light beam polarized in a predetermined direction to enter a magnetic recording medium on which information is recorded, an analyzer provided in the optical path of the light beam modulated by the magneto-optic effect in accordance with the information, and a photodetector having the current amplifying function and photoelectrically detecting the light beam transmitted through the analyzer, and in which the following equation is substantially satisfied: ##EQU1## where φ is the transmission axis azimuth of the analyzer relative to the predetermined direction of polarization and η is the extinction factor of the analyzer.
Inventors
- 👤 Yasuo Tomita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:55
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10532
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
101 words
A magneto-optical information reading apparatus comprising: means for causing a light beam polarized in a predetermined direction to enter a magnetic recording medium on which information is recorded; an analyzer provided in the optical path of said light beam modulated by the magneto-optic effect in accordance with said information; and a photodetector having the current amplifying function and photoelectrically detecting the light beam transmitted through said analyzer; wherein the following equation is substantially satisfied: ##EQU8## where φ is the transmission axis azimuth of said analyzer relative to said predetermined direction of polarization and η is the extinction factor of said analyzer.
Claim 2
Dependent Claim
101 words
A magneto-optical information reading apparatus comprising: means for causing a light beam polarized in a predetermined direction to enter a magnetic recording medium on which information is recorded; an analyzer provided in the optical path of said light beam modulated by the magneto-optic effect in accordance with said information; and a photodetector having the current amplifying function and photoelectrically detecting the light beam transmitted through said analyzer; wherein the following equation is substantially satisfied: ##EQU8## where φ is the transmission axis azimuth of said analyzer relative to said predetermined direction of polarization and η is the extinction factor of said analyzer.
Claim 3
Dependent Claim
122 words
A magneto-optical information reading apparatus comprising: means for causing a light beam polarized in a predetermined direction to enter a magnetic recording medium on which information is recorded; dividing means for dividing said light beam modulated by the magneto-optic effect in acordance with said information; two analyzers provided in the optical paths of said divided light beams; and two photodetectors each having the current amplifying function and differentially detecting the light beams transmitted through said two analyzers; the transmission axes of said two analyzers being inclined in opposite directions relative to said predetermined direction of polarization; wherein the following equation is substantially satisfied: ##EQU9## where φ is the azimuth of said transmission axes and η is the extinction factor of said analyzers.
Claim 4
Dependent Claim
122 words
A magneto-optical information reading apparatus comprising: means for causing a light beam polarized in a predetermined direction to enter a magnetic recording medium on which information is recorded; dividing means for dividing said light beam modulated by the magneto-optic effect in acordance with said information; two analyzers provided in the optical paths of said divided light beams; and two photodetectors each having the current amplifying function and differentially detecting the light beams transmitted through said two analyzers; the transmission axes of said two analyzers being inclined in opposite directions relative to said predetermined direction of polarization; wherein the following equation is substantially satisfied: ##EQU9## where φ is the azimuth of said transmission axes and η is the extinction factor of said analyzers.
Claim 5
Dependent Claim
20 words
A magneto-optical information reading apparatus according to claim 1, wherein said transmission axis azimuth exists in the range of 70°-85°.
Claim 6
Dependent Claim
16 words
A magento-optical information reading apparatus according to claim 1, wherein said photodetector is a photomultiplier tube.
Claim 7
Dependent Claim
16 words
A magneto-optical information reading apparatus according to claim 1, wherein said photodetector is an avalanche photodiode.
Claim 8
Dependent Claim
20 words
A magneto-optical information reading apparatus according to claim 2, wherein said transmission axis azimuth exists in the range of 70°-85°.
Claim 9
Dependent Claim
15 words
A magneto-optical information reading apparatus according to claim 2, wherein said photodetectors are photomultiplier tubes.
Claim 10
Dependent Claim
15 words
A magneto-optical information reading apparatus according to claim 2, wherein said photodetectors are avalanche photodiodes.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-02-03 | 1989-08-05 | 1990-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-03 | 1993-08-05 | 1994-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-03 | 1997-08-05 | 1998-02-04 | $7700.00 | Window Closed / Lapsed |