JPH0228574A - Optical magnetic field sensor - Google Patents
Optical magnetic field sensorInfo
- Publication number
- JPH0228574A JPH0228574A JP18003788A JP18003788A JPH0228574A JP H0228574 A JPH0228574 A JP H0228574A JP 18003788 A JP18003788 A JP 18003788A JP 18003788 A JP18003788 A JP 18003788A JP H0228574 A JPH0228574 A JP H0228574A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- effect element
- faraday effect
- light
- polarizer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 23
- 230000000694 effects Effects 0.000 claims abstract description 33
- 230000010287 polarization Effects 0.000 claims abstract description 24
- 239000013307 optical fiber Substances 0.000 abstract description 19
- BGPVFRJUHWVFKM-UHFFFAOYSA-N N1=C2C=CC=CC2=[N+]([O-])C1(CC1)CCC21N=C1C=CC=CC1=[N+]2[O-] Chemical compound N1=C2C=CC=CC2=[N+]([O-])C1(CC1)CCC21N=C1C=CC=CC1=[N+]2[O-] BGPVFRJUHWVFKM-UHFFFAOYSA-N 0.000 abstract description 12
- 238000005259 measurement Methods 0.000 abstract description 3
- 230000008054 signal transmission Effects 0.000 abstract description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 1
Landscapes
- Measuring Magnetic Variables (AREA)
Abstract
Description
【発明の詳細な説明】
[産業上の利用分野]
本発明は、ファラデー効果素子を用いた光磁界センサに
関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical magnetic field sensor using a Faraday effect element.
[従来技術]
色層偏光の光が磁界を受けている物質中を進むとき、偏
光面が回転するが、これは磁界の強さに比例する。[Prior Art] When color-polarized light travels through a substance that is subject to a magnetic field, the plane of polarization rotates, and this rotation is proportional to the strength of the magnetic field.
このようなファラデー効果を顕著に生じる素子、例えば
BSO単結晶やZn5e多結晶等の素子を用いる磁界セ
ンサが開発されている。Magnetic field sensors using elements that significantly produce such a Faraday effect, such as elements such as BSO single crystal and Zn5e polycrystal, have been developed.
第4図は上記のようなファラデー効果素子を用いた光磁
界センサの構成を示す。図において2目ま偏光子、22
はファラデー効果素子、23は検光子である。直線上に
、例えば垂直方向に偏光するように偏光子21が配置さ
れ、これにファラデー効果素子22が配置され、このフ
ァラデー効果素子22をはさみ、偏光子21と反対側に
検光子23が、その偏光方向を前記偏光子21に対して
45″回転させて配置される。FIG. 4 shows the configuration of an optical magnetic field sensor using the Faraday effect element as described above. In the figure, there are two polarizers, 22
is a Faraday effect element, and 23 is an analyzer. A polarizer 21 is arranged on a straight line so as to polarize light, for example in the vertical direction, a Faraday effect element 22 is arranged on this, and an analyzer 23 is placed on the opposite side of the polarizer 21 with the Faraday effect element 22 in between. The polarization direction is rotated by 45'' with respect to the polarizer 21.
ファラデー効果素子22において光の透過する結晶の長
さをQとして、光の通過する方向で、前記素子22に及
ぶ磁界強度をH1偏光の偏光面の回転角をθ、Veをベ
ルデ定数とすると、偏光面の回転角は次式で表わされる
。In the Faraday effect element 22, the length of the crystal through which light passes is Q, the magnetic field strength that reaches the element 22 in the direction in which the light passes is H1, the rotation angle of the polarization plane of polarized light is θ, and Ve is the Verdet constant. The rotation angle of the plane of polarization is expressed by the following equation.
θ=Ve−H−ρ ・・・・0)
光源よりの光は偏光子21で直線偏光を受け、磁界Hに
よりファラデー効果素子22で偏光面の・回転を受け、
偏光子21に対し、45@の検光子角をもつ検光子23
を通過する。θ=Ve-H-ρ...0) The light from the light source receives linear polarization at the polarizer 21, and undergoes rotation of the plane of polarization at the Faraday effect element 22 due to the magnetic field H.
Analyzer 23 with an analyzer angle of 45@ with respect to polarizer 21
pass through.
Poを被測定磁界が零のとき検光子23を通過する通過
光の強さ、Pを被測定磁界があるとき検光子23を通過
する通過光の強さとすると、Pは次式%式%
なお、回転角θは45″″より充分小さいものとする。If Po is the intensity of the light passing through the analyzer 23 when the magnetic field to be measured is zero, and P is the intensity of the light passing through the analyzer 23 when there is a magnetic field to be measured, then P is the following formula % formula % , the rotation angle θ is sufficiently smaller than 45″″.
(2)式に(1)式を代入すると、
P = Po (1+ 5in2Ve −H−Q )
・・−・(3)となる。Substituting equation (1) into equation (2), P = Po (1+ 5in2Ve -H-Q)
...-(3).
ここで、偏光子21と検光子23との間に45°の検光
子角を与えているので、上記(3)式で表わされ、この
形であれば、磁界が零のとき、検光子23を通過する通
過光が求まるから、容易に5in2θ、すなわち、被α
1定磁界の大きさによって変化する出力分を取り出すこ
とができる。Here, since an analyzer angle of 45° is given between the polarizer 21 and the analyzer 23, it is expressed by the above equation (3), and in this form, when the magnetic field is zero, the analyzer angle is Since the transmitted light passing through 23 is found, it is easy to calculate 5in2θ, that is, α
It is possible to extract an output that changes depending on the magnitude of one constant magnetic field.
このように5in2θを取り出すには、上記のような構
成にかえ、第5図に示すように旋光子24を用いる構成
をとることもできる。直線上に偏光子21.45°旋光
子24.ファラデー効果素子22.検光子23が順に配
置される。旋光子24は偏光子21によって直線偏光さ
れた光の偏光面を45°回転させるものであり、例えば
BSOの単結晶を用いたものである。45°回転させら
れた偏光は、ファラデー効果素子22を通過中、磁界に
より偏光面が回転され、検光子23を透過する。この構
成では偏光子21と検光子23の偏光方向は互に平行と
なる配置をとる。In order to take out 5 in 2θ in this way, instead of the above configuration, a configuration using an optical rotator 24 as shown in FIG. 5 may be adopted. Polarizer 21. 45° rotator 24. Faraday effect element 22. Analyzers 23 are arranged in order. The optical rotator 24 rotates the plane of polarization of the light linearly polarized by the polarizer 21 by 45 degrees, and is made of, for example, a single crystal of BSO. While the polarized light rotated by 45 degrees passes through the Faraday effect element 22 , the plane of polarization is rotated by the magnetic field, and the polarized light is transmitted through the analyzer 23 . In this configuration, the polarizer 21 and analyzer 23 are arranged so that their polarization directions are parallel to each other.
この構成で磁界が零のとき、検光子23を透過する光の
強さをPoとすると、磁界が加わり、偏光面がθ回転し
たとき、検光子23を透過する光の強さPは次式で表わ
される。In this configuration, when the magnetic field is zero, the intensity of light passing through the analyzer 23 is Po, and when the magnetic field is added and the polarization plane is rotated by θ, the intensity P of the light passing through the analyzer 23 is calculated by the following formula. It is expressed as
P=Po(1+5in2θ)
= Po (1+ 5in2Ve −H−Q )
−(4)このように、偏光子、検光子を互に45°の角
度をなすようにするが、施米が45’になるようなもの
を使用すれば、被測定磁界による偏光面の回転角を容易
に求めることができ、この回転角より磁界Hの大きさを
知ることができ、もしこの磁界が線路電流によって生じ
ている場合は、線路電流値を測定できることになる。P=Po(1+5in2θ)=Po(1+5in2Ve-H-Q)
-(4) In this way, the polarizer and analyzer are set at an angle of 45° to each other, but if you use one with a 45° angle, the rotation of the plane of polarization due to the magnetic field to be measured The angle can be easily determined, and the magnitude of the magnetic field H can be determined from this rotation angle. If this magnetic field is caused by a line current, the line current value can be measured.
[解決しようとする課題]
以上説明のように、従来の構成によれば、光の通路とし
て、■図示していないが大光用光ファイバ、■偏光子、
■ファラデー効果素子、■偏光子と45″の検光子角を
もつ検光子あるいは、偏光子と45°旋光子、■出光用
の光ファイバの順、またはこの逆の順に1回ずつ通過す
る通路を有し、人出光用の光ファイバを共用化できず、
必ず2本の光ファイバを必要とする。[Problems to be Solved] As explained above, according to the conventional configuration, as a light path, ■ a high-light optical fiber (not shown), ■ a polarizer,
■A path that passes through a Faraday effect element, ■a polarizer and an analyzer with an analyzer angle of 45'', or a polarizer and a 45° optical rotator, and ■an optical fiber for light output, or in the reverse order. However, it is not possible to share optical fibers for people to use the lights.
Two optical fibers are always required.
このため、この種センサの大きさを小型化するには限界
があり、また光ファイバは2心である必要があり、信号
伝送部の細径化の妨げとなっていた。For this reason, there is a limit to reducing the size of this type of sensor, and the optical fiber must have two cores, which has been an obstacle to reducing the diameter of the signal transmission section.
[課題を解決するための手段]
本発明は上記課題を解決するため、入光、出光併せて単
心の光ファイバにより磁界センサとの間を連絡し、磁界
センサにあっては、前記単心の光ファイバにより、一つ
のゲートで光の入光、出光を行うため、偏光の折り返し
位置に反射ミラーを配置し、偏光が磁界センサ中を往復
する間に、測定上必要な偏光面の45°の回転のバイア
スを与え、これに加えて外部被測定磁界による偏光面の
回転を与えて出光するように構成するものである。[Means for Solving the Problems] In order to solve the above problems, the present invention connects a magnetic field sensor with a single-core optical fiber for both light input and output. In order to input and output light using a single gate using an optical fiber, a reflective mirror is placed at the position where the polarized light turns back, and while the polarized light travels back and forth within the magnetic field sensor, the polarization plane is adjusted to 45 degrees, which is necessary for measurement. In addition to this, the polarization plane is rotated by an external magnetic field to be measured to emit light.
ンサ」に示される磁石を用いるものが適用される。Those using magnets shown in ``Sensor'' are applicable.
[発明の構成] 以下図面により本発明を説明する。[Structure of the invention] The present invention will be explained below with reference to the drawings.
第1図は本発明の原理図である。単心の光ファイバ6の
端末と結合されたレンズ5の光軸と同一直線上に、偏光
子3.ファラデー効果素子19反射ミラー2の順で配置
される。反射ミラーは反射膜であってもよい。FIG. 1 is a diagram showing the principle of the present invention. A polarizer 3. The Faraday effect element 19 and the reflecting mirror 2 are arranged in this order. The reflective mirror may be a reflective film.
前記ファラデー効果素子1.偏光子3を囲んで環状の永
久磁石4が配置される。この磁界印加部として用いられ
る永久磁石4はその環状中心部に、光路方向と同一方向
の磁界を形成するものであって、外部被測定磁界がない
状態で、後述のように偏光がファラデー効果素子1を往
復するとき丁度偏光面に45″の角度回転のバイアスを
生じる磁界強度を発生できるものである。Said Faraday effect element 1. An annular permanent magnet 4 is arranged surrounding the polarizer 3. The permanent magnet 4 used as the magnetic field applying section forms a magnetic field in the same direction as the optical path at its annular center, and when there is no external magnetic field to be measured, the polarized light is generated by the Faraday effect element as described below. When reciprocating from 1 to 1, it is possible to generate a magnetic field strength that causes a bias of 45'' angle rotation in the plane of polarization.
光ファイバ6を出た光は、レンズ5により平行光となり
、偏光子3を通過することにより直線偏光となる。さら
に、ファラデー効果素子1を通ることにより、前記永久
磁石4が存在しなければ、外部被測定磁界によって及ぶ
磁界により、偏光面を回転させて反射ミラー2にて反射
し、再びファラデー効果素子1で偏光面を回転させ、レ
ンズ5に入るのであるが、この偏光は、ファラデー効果
素子1の中の一往復中において、永久磁石4により丁度
45@の角度のバイアスが掛けられるので、前記外部被
測定磁界強度による偏光面の回転角に、永久磁石4の磁
界強度による45°の角度のバイアスを加えた偏光面を
もって検光子3を通過し、レンズ5を通過して光ファイ
バ6に入射する。The light exiting the optical fiber 6 becomes parallel light by the lens 5, and becomes linearly polarized light by passing through the polarizer 3. Furthermore, by passing through the Faraday effect element 1, if the permanent magnet 4 were not present, the polarization plane is rotated by the magnetic field exerted by the external magnetic field to be measured and reflected by the reflection mirror 2, and the polarization is reflected by the Faraday effect element 1 again. The polarized light is rotated and enters the lens 5, but during one round trip inside the Faraday effect element 1, this polarized light is biased by an angle of exactly 45@ by the permanent magnet 4, so that the polarized light is biased by an angle of exactly 45@ It passes through the analyzer 3 with a polarization plane that is the rotation angle of the polarization plane due to the magnetic field strength plus a 45° bias due to the magnetic field strength of the permanent magnet 4, passes through the analyzer 3, passes through the lens 5, and enters the optical fiber 6.
つまり、光は本磁界センサによれば、単心の光ファイバ
より入射して、反射ミラーで反射して光ファイバに出射
する往復の間において、外部被測定磁界強度測定データ
が得られるのである。In other words, according to the present magnetic field sensor, external measured magnetic field strength measurement data can be obtained during the round trip in which light enters from a single optical fiber, is reflected by a reflection mirror, and is emitted to the optical fiber.
前記磁界センサを用いて、磁界を測定するには、第3図
のような光信号検出装置を用いて行う。To measure the magnetic field using the magnetic field sensor, an optical signal detection device as shown in FIG. 3 is used.
図示のように、発光素子8に対し、光分岐器9が結合さ
れ、光分岐器9に光ファイバ6が結合され、この光ファ
イバ6の端末に第1図の磁界センサ11が結合され、前
記光分岐器8に対し、受光素子10が配置される。As shown in the figure, an optical splitter 9 is coupled to the light emitting element 8, an optical fiber 6 is coupled to the optical splitter 9, and the magnetic field sensor 11 shown in FIG. 1 is coupled to the terminal of the optical fiber 6. A light receiving element 10 is arranged with respect to the optical splitter 8 .
さきの実施例から理解されるように、発光素子8よりの
光は光分岐器9を通り、光ファイバ6を通り、磁界セン
サ■を往復して光分岐器9に到達した光は2方向に分岐
され、その一方が受光素子IOに入力し、電気信号に変
換され、計C1ff1となる。As understood from the previous embodiment, the light from the light emitting element 8 passes through the optical splitter 9, passes through the optical fiber 6, travels back and forth to the magnetic field sensor (2), and the light that reaches the optical splitter 9 is split in two directions. The signals are branched, one of which is input to the light receiving element IO and converted into an electrical signal, resulting in a total of C1ff1.
第2図(イ)、(ロ)、(ハ)は本発明の実施例を示す
。第1図実施例と同一部分は同一符号で示す。FIGS. 2(A), 2(B), and 2(C) show embodiments of the present invention. Components that are the same as those in the embodiment of FIG. 1 are designated by the same reference numerals.
(イ)図の光磁界センサにおいては、ファラデー効果素
子1を間にして、偏光子3を囲んで、上下面をS、Hに
着磁した環状の永久磁石4を配置し、ファラデー効果素
子1の他端の反射ミラー2を設けた外側に、rrlI記
環状の永久磁石4の磁極極性と対向する極性を反射とし
て永久磁石4′を配置する。(a) In the optical magnetic field sensor shown in the figure, an annular permanent magnet 4 whose upper and lower surfaces are magnetized to S and H is arranged surrounding a polarizer 3 with a Faraday effect element 1 in between. A permanent magnet 4' is arranged outside the reflection mirror 2 at the other end, with the polarity opposite to the magnetic polarity of the annular permanent magnet 4 as a reflection.
この磁石構成により、ファラデー効果素子1内の偏光通
路に沿って正確に所要偏光角45°のバイアスをかける
ことができる。This magnet configuration allows biasing precisely along the polarization path within the Faraday effect element 1 to the required polarization angle of 45°.
(ロ)図に示すものは、第1図のものにおいて、使用さ
れる永久磁石4の磁極構成を示したものである。(b) The figure shows the magnetic pole configuration of the permanent magnet 4 used in the one shown in FIG.
(ハ)図に示すものは、永久磁石使用にかえ、電磁石又
は空心コイル口を用いたものである。電磁石、又は空心
コイルを用いるときは、ファラデー効果素子、往復で偏
光面の回転角45″のバイアスを生じしめる磁界の調整
がコイルに対する通電制御によって容易となる。このよ
うに磁界印加部とじては単に永久磁石ばかりでなく、電
磁石、空心コイルを用いることができる。(c) The one shown in the figure uses an electromagnet or an air-core coil port instead of using a permanent magnet. When an electromagnet or an air-core coil is used, the adjustment of the magnetic field that generates a bias of 45'' rotation angle of the plane of polarization by reciprocating the Faraday effect element is facilitated by controlling the energization of the coil. Not only permanent magnets but also electromagnets and air-core coils can be used.
[発明の効果コ
本発明によれば、検光子は一つの偏光子で兼用され、光
ファイバも1本ですみ、光磁界センサの小型化、信号伝
送部の細径化を計ることができる。[Effects of the Invention] According to the present invention, one polarizer can be used as an analyzer, and only one optical fiber is required, making it possible to miniaturize the optical magnetic field sensor and reduce the diameter of the signal transmission section.
第1図は、本発明の原理図を示し、第2図(イ)。
(ロ)、(ハ)は実施例を示す。
第3図は、光信号検出装置を示す。
第4図、第5図は従来の磁界センサを示す。
1・・・ファラデー効果素子、2・・・反射ミラー又は
、反射膜、3・・・偏光子、4.4’・・・永久磁石、
5・・・レンズ、6・・・光ファイバ、7・・・旋光子
、8・・・発光素子、9・・・光分岐器、1G・・・受
光素子、菫■・・・磁界センサ、!2・・・電磁石、又
は空心コイル。
算
図
懐
図
答4回
22()75デー効深濠))
%5
図FIG. 1 shows a diagram of the principle of the present invention, and FIG. 2 (A). (b) and (c) show examples. FIG. 3 shows an optical signal detection device. 4 and 5 show conventional magnetic field sensors. DESCRIPTION OF SYMBOLS 1... Faraday effect element, 2... Reflection mirror or reflective film, 3... Polarizer, 4.4'... Permanent magnet,
5... Lens, 6... Optical fiber, 7... Optical polarizer, 8... Light emitting element, 9... Optical splitter, 1G... Light receiving element, Sumire ■... Magnetic field sensor, ! 2...Electromagnet or air-core coil. Santu Kaizu Answer 4 22 () 75 Day Effect Deep Moat)) %5 Figure
Claims (3)
デー効果素子に及ぶ被測定磁界強度を前記偏光の偏光面
の回転角に基づいて測定するための光磁界センサであっ
て、前記磁界センサは入光側より偏光子、ファラデー効
果素子、反射ミラーを順に備えるとともに、前記偏光子
よりの偏光が前記ファラデー効果素子を通過し、前記ミ
ラーで反射して再度前記ファラデー効果素子を逆に通過
して前記偏光子に至る間に、被測定磁界が零の状態で、
前記ファラデー効果素子を通過する偏光に45゜の回転
角のバイアスを与える磁界印加部を備えることを特徴と
する光磁界センサ。(1) An optical magnetic field sensor for passing polarized light through a Faraday effect element and measuring the intensity of a magnetic field to be measured across the Faraday effect element based on a rotation angle of a plane of polarization of the polarized light, wherein the magnetic field sensor is A polarizer, a Faraday effect element, and a reflecting mirror are provided in this order from the light side, and the polarized light from the polarizer passes through the Faraday effect element, is reflected by the mirror, and passes back through the Faraday effect element again to produce the While reaching the polarizer, the magnetic field to be measured is zero,
An optical magnetic field sensor comprising a magnetic field applying section that applies a bias of a rotation angle of 45 degrees to the polarized light passing through the Faraday effect element.
界センサ。(2) The optical magnetic field sensor according to claim (1), wherein the magnetic field applying section is a permanent magnet.
項(1)の光磁界センサ。(3) The optical magnetic field sensor according to claim (1), wherein the magnetic field applying section is an electromagnet or an air-core coil.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18003788A JPH0228574A (en) | 1988-07-19 | 1988-07-19 | Optical magnetic field sensor |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18003788A JPH0228574A (en) | 1988-07-19 | 1988-07-19 | Optical magnetic field sensor |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH0228574A true JPH0228574A (en) | 1990-01-30 |
Family
ID=16076376
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP18003788A Pending JPH0228574A (en) | 1988-07-19 | 1988-07-19 | Optical magnetic field sensor |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0228574A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007225340A (en) * | 2006-02-21 | 2007-09-06 | National Institute Of Information & Communication Technology | High-frequency magnetic field measuring device |
JP2008523401A (en) * | 2004-12-13 | 2008-07-03 | シュランベルジェ、ホールディング、リミテッド | Magneto-optic sensor |
JP2011141172A (en) * | 2010-01-06 | 2011-07-21 | Mitsutoyo Corp | Optical fiber type magnetic field sensor |
US8153955B2 (en) | 2005-06-30 | 2012-04-10 | Nec Corporation | Electric field sensor and method for fabricating the same |
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JPH0437714A (en) * | 1990-06-01 | 1992-02-07 | Seiko Epson Corp | Liquid crystal display device |
JPH05232459A (en) * | 1992-02-19 | 1993-09-10 | Catalysts & Chem Ind Co Ltd | Liquid crystal display cell and its production |
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Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH0437714A (en) * | 1990-06-01 | 1992-02-07 | Seiko Epson Corp | Liquid crystal display device |
JPH05232459A (en) * | 1992-02-19 | 1993-09-10 | Catalysts & Chem Ind Co Ltd | Liquid crystal display cell and its production |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008523401A (en) * | 2004-12-13 | 2008-07-03 | シュランベルジェ、ホールディング、リミテッド | Magneto-optic sensor |
US8153955B2 (en) | 2005-06-30 | 2012-04-10 | Nec Corporation | Electric field sensor and method for fabricating the same |
US8519323B2 (en) | 2005-06-30 | 2013-08-27 | Nec Corporation | Electric field/magnetic field sensors and methods of fabricating the same |
JP2007225340A (en) * | 2006-02-21 | 2007-09-06 | National Institute Of Information & Communication Technology | High-frequency magnetic field measuring device |
JP2011141172A (en) * | 2010-01-06 | 2011-07-21 | Mitsutoyo Corp | Optical fiber type magnetic field sensor |
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