US4584470A
Expired / Lapsed
US
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Single-polarization fiber optics magnetic sensor
Assignee: Hitachi Cable Ltd
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Filing: 1983-12-07
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Granted: 1986-04-22
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Expires: 2003-12-07
Abstract
Abstract In a single-polarization fiber optics magnetic sensor comprising a light source, a Faraday rotation element, a photodetector, and optical waveguide means for optically coupling them; according to a first embodiment, the optical waveguide means comprises upstream and downstream polarization-maintaining optical fibers coupled to the entrance and exit of the Faraday rotation element without a polarizer or an analyzer interposed therebetween; according to a second embodiment, in addition thereto, the axis of polarization of the downstream polarization-maintaining optical fiber is at an angle of about 45 degrees with respect to the orientation of the linearly polarized light exiting from the Faraday rotation element at a magnetic field intensity H equal to 0; and according to a third embodiment, in addition thereto, a polarization beam splitter is located in alignment with the orientation of polarization of the exit light from the downstream polarization-maintaining optical fiber, and two polarized light beams produced by said beam splitter are received by two photo-detectors for subsequent signal computation.
Inventors
- 👤 Hisao Iizuka
- 👤 Hiroshi Kajioka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:31
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/032; G01R33/0322
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
86 words
In a single-polarization fiber optics magnetic sensor comprising: a light source; a Faraday rotation element; a photo-detector; and optical waveguide means for optically coupling together said light source, Faraday rotation element and photo-detector; the improvement wherein: said optical waveguide means comprises polarization-maintaining optical fibers coupled to opposite sides of said Faraday rotation element without a polarizer and without an an analyzer interposed between said Faraday rotation element and said respective polarization-maintaining optical fibers, said optical fibers serving only as an optical waveguide for transmitting optical signals.
Claim 2
Dependent Claim
86 words
In a single-polarization fiber optics magnetic sensor comprising: a light source; a Faraday rotation element; a photo-detector; and optical waveguide means for optically coupling together said light source, Faraday rotation element and photo-detector; the improvement wherein: said optical waveguide means comprises polarization-maintaining optical fibers coupled to opposite sides of said Faraday rotation element without a polarizer and without an an analyzer interposed between said Faraday rotation element and said respective polarization-maintaining optical fibers, said optical fibers serving only as an optical waveguide for transmitting optical signals.
Claim 3
Dependent Claim
140 words
In a single-polarization fiber optics magnetic sensor comprising: a light source; a Faraday rotation element having an entrance and an exit; a photo-detector; and optical waveguide means for optically coupling together said light source, Faraday rotation element and photo-detector; the improvement wherein: said optical waveguide means comprises upstream and downstream polarization-maintaining optical fibers respectively coupled to said entrance and exit of said Faraday rotation element without a polarizer and without an analyzer interposed said Faraday rotation element and said respective polarization-maintaining optical fibers, said optical fibers serving only as an optical waveguide for transmitting optical signals; and said downstream polarization-maintaining optical fiber has an axis of polarization which is at an angle of substantially 45 degrees with respect to the orientation of linearly polarized light exiting from said Faraday rotation element at a magnetic field intensity H equal to 0.
Claim 4
Dependent Claim
140 words
In a single-polarization fiber optics magnetic sensor comprising: a light source; a Faraday rotation element having an entrance and an exit; a photo-detector; and optical waveguide means for optically coupling together said light source, Faraday rotation element and photo-detector; the improvement wherein: said optical waveguide means comprises upstream and downstream polarization-maintaining optical fibers respectively coupled to said entrance and exit of said Faraday rotation element without a polarizer and without an analyzer interposed said Faraday rotation element and said respective polarization-maintaining optical fibers, said optical fibers serving only as an optical waveguide for transmitting optical signals; and said downstream polarization-maintaining optical fiber has an axis of polarization which is at an angle of substantially 45 degrees with respect to the orientation of linearly polarized light exiting from said Faraday rotation element at a magnetic field intensity H equal to 0.
Claim 5
Dependent Claim
64 words
The single-polarization fiber optics magnetic sensor of claim 2, wherein said light source is coupled to said upstream polarization-maintaining optical fiber such that linearly polarized light may enter said upstream polarization-maintaining fiber in the same directions as the axis of polarization of said upstream polarization-maintaining fiber, whereby said linearly polarized light is transmitted to said Faraday rotation element via said upstream polarization-maintaining optical fiber.
Claim 6
Dependent Claim
65 words
The single-polarization fiber optics magnetic sensor of claim 2, further comprising a polarizer coupled between said light source and said upstream polarization-maintaining optical fiber, whereby linearly polarized light may enter said upstream polarization-maintaining fiber in the same direction as the axis of polarization of said upstream polarization-maintaining fiber, said linearly polarized light being transmitted to said Faraday rotation element via said upstream polarization-maintaining optical fiber.
Claim 7
Dependent Claim
42 words
The single-polarization fiber optics magnetic sensor of claim 2, wherein said angle of said axis of polarization of said downstream polarization-maintaining optical fiber with respect to the orientation of said linearly polarized light is in a range of 45 degrees ±2 degrees.
Claim 8
Dependent Claim
197 words
In a single-polarization fiber optics magnetic sensor comprising: a light source; a Faraday rotation element having an entrance and an exit; a photo-detector; and optical waveguide means for optically coupling together said light source, Faraday rotation element and photo-detector; the improvement wherein: said optical waveguide means comprises upstream and downstream polarization-maintaining optical fibers respectively coupled to said entrance and exit of said Faraday rotation element without a polarizer and without an analyzer interposed between said Faraday rotation element and said respective polarization-maintaining optical fibers, said optical fibers serving only as an optical waveguide for transmitting optical signals; said downstream polarization-maintaining optical fiber has an axis of polarization which is at an angle of substantially 45 degrees with respect to the orientation of linearly polarized light exiting from said Faraday rotation element at a magnetic field intensity H equals to 0; a polarization beam splitter is provided and is arranged in alignment with the orientation of polarization of light exiting from said downstream polarization-maintaining optical fiber, said polarization beam splitter producing two polarized light beams; and two photo-detectors are coupled to respectively detect said two polarized light beams and to deliver resultant detection signals to a computation means.
Claim 9
Dependent Claim
197 words
In a single-polarization fiber optics magnetic sensor comprising: a light source; a Faraday rotation element having an entrance and an exit; a photo-detector; and optical waveguide means for optically coupling together said light source, Faraday rotation element and photo-detector; the improvement wherein: said optical waveguide means comprises upstream and downstream polarization-maintaining optical fibers respectively coupled to said entrance and exit of said Faraday rotation element without a polarizer and without an analyzer interposed between said Faraday rotation element and said respective polarization-maintaining optical fibers, said optical fibers serving only as an optical waveguide for transmitting optical signals; said downstream polarization-maintaining optical fiber has an axis of polarization which is at an angle of substantially 45 degrees with respect to the orientation of linearly polarized light exiting from said Faraday rotation element at a magnetic field intensity H equals to 0; a polarization beam splitter is provided and is arranged in alignment with the orientation of polarization of light exiting from said downstream polarization-maintaining optical fiber, said polarization beam splitter producing two polarized light beams; and two photo-detectors are coupled to respectively detect said two polarized light beams and to deliver resultant detection signals to a computation means.
Claim 10
Dependent Claim
67 words
The single-polarization fiber optics magnetic sensor of claim 6, wherein said light source and a polarizer are coupled to said upstream polarization-maintaining optical fiber such that linearly polarized light may enter said upstream polarization-maintaining fiber in the same direction as the axis of polarization of said upstream polarization-maintaining fiber, whereby said linearly polarized light is transmitted to said Faraday rotation element via said upstream polarization-maintaining optical fiber.
Claim 11
Dependent Claim
66 words
The single-polarization fiber optics magnetic sensor of claim 6, further comprising a computation means coupled to said two photo-detectors for performing a predetermined computation on the output signals from said two photo-detectors to generate a signal which is independent of variations in the output of said light source and which is free of a direct current component at a magnetic field intensity H equals to 0.
Claim 12
Dependent Claim
42 words
The single-polarization fiber optics magnetic sensor of claim 6, wherein said angle of said axis of polarization of said downstream polarization-maintaining optical fiber with respect to the orientation of said linearly polarized light is in a range of 45 degrees ±2 degrees.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-04-21 | 1989-10-21 | 1990-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-21 | 1993-10-21 | 1994-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-21 | 1997-10-21 | 1998-04-22 | $7700.00 | Window Closed / Lapsed |