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EP0260114A2
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EP
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Opto-magnetic signal reproducing apparatus for reading, by differential detection using a magneto-optical effect, information magnetically recorded on a record medium
Assignee: Canon Inc
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Filing: 1987-09-08
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Granted: —
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Expires: 2007-09-08
Abstract
Abstract There is disclosed an opto-magnetic signal reproducing apparatus comprising a light source unit (1 to 4) for applying a linearly polarized light beam to a record medium (5) having magnetically recorded information, a splitter (3, 6, 7, 9) for splitting the light beam modulated responding to the recorded information by a magneto-optic effect, into two light beams having different polarization directions from each other, and a reproduce device (8, 10) for differentially detecting the split light beams to reproduce the recorded information and wherein the splitter imparts a phase difference equal to an integer multiple of π to each of the split light beams.
Inventors
- 👤 Osamu Koyama
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 07:11
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10532; G11B11/10541; G11B11/10543; G11B11/10502; G11B11/10515
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
86 words
An opto-magnetic signal reproducing apparatus comprising: means for applying a linearly polarized light beam to a record medium having information magnetically recorded thereon; split means for splitting the light beam modulated in accordance with said information by a magneto-optic effect into two light beams having different polarization directions from each other, said split means imparting a phase difference equal to an integer multiple of π to each of the split light beams; and reproduce means for differentially detecting the split light beams to reproduce said information.
Claim 2
Dependent Claim
86 words
An opto-magnetic signal reproducing apparatus comprising: means for applying a linearly polarized light beam to a record medium having information magnetically recorded thereon; split means for splitting the light beam modulated in accordance with said information by a magneto-optic effect into two light beams having different polarization directions from each other, said split means imparting a phase difference equal to an integer multiple of π to each of the split light beams; and reproduce means for differentially detecting the split light beams to reproduce said information.
Claim 3
Dependent Claim
36 words
An opto-magnetic signal reproducing apparatus according to Claim 1 wherein said irradiation means includes a light source, and an optical system for focusing a light emitted from said light source into a spot on said medium.
Claim 4
Dependent Claim
36 words
An opto-magnetic signal reproducing apparatus according to Claim 1 wherein said split means includes a half-mirror and two analyzers arranged in light paths of the light beams split by said half-mirror and having orthogonal transmission axes.
Claim 5
Dependent Claim
18 words
An opto-magnetic signal reproducing apparatus according to Claim 1 wherein said split means includes a polarization beam splitter.
Claim 6
Dependent Claim
33 words
An opto-magnetic signal reproducing apparatus according to Claim 1 wherein said reproduce means includes two photo-detectors for detecting the split light beams and a differential amplifier for differentiating the outputs of said photo-detectors.
Claim 7
Dependent Claim
28 words
An opto-magnetic signal reproducing apparatus according to Claim 1 wherein a phase difference 8 between the split light beams meets a relation of where n is an integer.
Claim 8
Dependent Claim
46 words
An opto-magnetic signal reproducing apparatus according to Claim 1 further comprising a beam splitter for separating the light beam reflected by said medium and modulated with said information from the light beam irradiated to said medium and directing the separated light beam to said split means.
Claim 9
Dependent Claim
69 words
An opto-magnetic signal reproducing apparatus in which a light beam transmitted from an opto-magnetic record medium is split and detected by at least two detectors which are arranged to detect light having mutually different polarisation directions, each light beam having a relative phase difference introduced into the components thereof; characterised in that the total relative phase difference in each beam corresponds within limits to an integral number of half-wavelengths.
Claim 10
Dependent Claim
69 words
An opto-magnetic signal reproducing apparatus in which a light beam transmitted from an opto-magnetic record medium is split and detected by at least two detectors which are arranged to detect light having mutually different polarisation directions, each light beam having a relative phase difference introduced into the components thereof; characterised in that the total relative phase difference in each beam corresponds within limits to an integral number of half-wavelengths.
References Cited (Backward Citations)
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