EP0046298A1
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EP
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Apparatus for measuring a magnetic field
Assignee: Hitachi Ltd
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Filing: 1981-08-17
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Granted: —
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Expires: 2001-08-17
Abstract
Abstract A magnetic field measuring apparatus is effective for measuring magnetic fields in places, where electrical means cannot be adopted for the measurement. The detecting portion (C) ist constructed of a small magnetic material having the Faraday rotation and is disposed at the end part or intermediate part of an optical fiber (1). Light is guided to the detecting portion (C) by the optical fiber (1). Transmitted or reflected light subjected to the Faraday rotation proportional to the intensity of the magnetic field in the detecting portion (C) is guided to a measuring portion (A) by the optical fiber (1).
Inventors
- 👤 Hiroyoshi Matsumura
- 👤 Toshio Katsuyama
- 👤 Tsuneo Suganuma
- 👤 Keikichi Ando
- 👤 Norio Ohta
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-22 18:45
CPC Classifications
G; G01; G01R; G01R15/00; G01R15/14; G01R15/24; G01R15/245; G01R15/246; G01R33/00; G01R33/02; G01R33/032; G01R33/0322; G02; G02F; G02F1/00; G02F1/0009; G02F1/0036
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
61 words
Apparatus for measuring a magnetic field, charac- terized in that there are provided a light source (9), a magnetic field detecting portion (C) including a medium (3) having the Faraday rotation, a measuring portion (A) measuring light from the detecting portion (C), and an optical fiber (1) connecting the light source (9), the detecting portion (C) and the measuring portion (A).
Claim 2
Dependent Claim
61 words
Apparatus for measuring a magnetic field, charac- terized in that there are provided a light source (9), a magnetic field detecting portion (C) including a medium (3) having the Faraday rotation, a measuring portion (A) measuring light from the detecting portion (C), and an optical fiber (1) connecting the light source (9), the detecting portion (C) and the measuring portion (A).
Claim 3
Dependent Claim
61 words
Apparatus according to claim 1, characterized in that within the detecting portion (C), there is provided a magnetic garnet film, which is installed at an intermediate part or end part of the optical fiber (1) and which is placed in such a way in the magnetic field to be measured, that it is magnetized in the direction of the transmitting light.
Claim 4
Dependent Claim
61 words
Apparatus according to claim 2, characterized in that the magnetic garnet film (7) is a medium represented by the formula: where R and M denotes at least one element selected from the following groups R = {Y, Ce, Pr, Nd, Bi, Pb, La, Sm, Eu, Gd, Er, Tm, Yb, Lu, Ca} and M = {Ga, Ge, Al, Si, Sc, In, Cr).
Claim 5
Dependent Claim
67 words
Apparatus according to claim 2 or 3, characte- rized in that the magnetic garnet film (17) is formed on at least one end face of a paramagnetic substrate (11) of gadolinium gallium garnet Gd3Ga5012, ne ody- mium gallium garnet Nd 3 Ga 5 O 12 or samarium gallium garnet Sm 3 Ga 5 O 2 , whereby the direction of magnetization is perpendicular to the end face.
Claim 6
Dependent Claim
41 words
Apparatus according to one of the claims 2 to 4, characterized in that the thickness of the magnetic garnet film (17) in the light transmitting direction is chosen in such a way so as to maximize the figure of the merit.
Claim 7
Dependent Claim
82 words
Apparatus according to one of the previous claims, characterized in that the magnetic field detecting portion (C) is arranged between an optical fiber (1) leading to the light source (9) and an optical fiber (1) leading to the measuring portion (A) and that within the detecting portion (C) there are arranged a lens (15), a polarizer (2), a first magnetic garnet film (17), a paramagnetic substrate (11), a second magnetic garnet film (17), an analyzer (4) and a lens (16) in succession.
Claim 8
Dependent Claim
21 words
Apparatus according to claim 6, characterized in that the polarizer (2) and the analyzer (4) define an angle of 45 .
Claim 9
Dependent Claim
54 words
Apparatus according to one of the claims 1 to 5, characterized in that ic field detecting portion (C) is arranged at the end of said optical fiber (1) and there is formed a lens (15), a polarizer (2), a magnetic garnet film (17), a paramagnetic substrate (11) and a reflective film (18) in succession.
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