JPS60138480A - Optical magnetic field sensor - Google Patents
Optical magnetic field sensorInfo
- Publication number
- JPS60138480A JPS60138480A JP24814483A JP24814483A JPS60138480A JP S60138480 A JPS60138480 A JP S60138480A JP 24814483 A JP24814483 A JP 24814483A JP 24814483 A JP24814483 A JP 24814483A JP S60138480 A JPS60138480 A JP S60138480A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- polarizer
- light
- half mirror
- optical fiber
- 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
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/032—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
- G01R33/0322—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect using the Faraday or Voigt effect
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Measuring Magnetic Variables (AREA)
Abstract
Description
【発明の詳細な説明】
［発明の背景及び目的］
本発明は磁界センサ特にファラデー素子を利用した光学
式磁界センサに関するものである。DETAILED DESCRIPTION OF THE INVENTION [Background and Objects of the Invention] The present invention relates to a magnetic field sensor, particularly an optical magnetic field sensor using a Faraday element.
従来、磁界測定は種々の方法で行なわれている。Conventionally, magnetic field measurements have been performed in various ways.
それらの大部分は、磁性材料やコイルの磁気現象を利用
したものであるが、応答速度、検出感度、測定範囲、精
度、温度特性、形状など、実用的な観点から問題のある
場合が多い、また、ホール効果を有する素子も有力な検
出器として使用されている。この場合、小型、軽量で、
測定範囲も広く、高周波でも使用できるという利点があ
るが、ホール係数の温度依存性が大きいこと、および非
絶縁性のため高電圧下での使用が難かしいという問題が
ある。Most of them utilize the magnetic phenomena of magnetic materials or coils, but they often have problems from a practical standpoint, such as response speed, detection sensitivity, measurement range, accuracy, temperature characteristics, and shape. Elements having the Hall effect are also used as effective detectors. In this case, it is small, lightweight,
It has the advantage of having a wide measurement range and can be used at high frequencies, but it has problems such as the large temperature dependence of the Hall coefficient and the fact that it is difficult to use under high voltage because it is non-insulating.
これらに対し、光と磁界の相互作用を有するものとして
よく知られているものにファラデー素子がある。ファラ
デー素子は磁界によってその通過する光の偏光面が回転
するという性質を有するものであり、近年光ファイバと
の組合せで多くの注目を集めている。On the other hand, a Faraday element is well known as one that has an interaction between light and a magnetic field. Faraday elements have the property that the polarization plane of light passing through them is rotated by a magnetic field, and have recently attracted much attention in combination with optical fibers.
しかし、実用化を妨げるいくつかの問題がある。However, there are several problems that hinder practical application.
その一つは、ファラデー素子の持つファラデー効果をい
かにして精度良くしかも簡単で実用的な方法で検出する
かという点にある。従来採られている検出方法にはいく
つかあるが、その一つは、偏光面を直交さけた２つの偏
光子、検光子の間にファラデー素子を挿入し、両側に設
置した光ファイバにより光を通過伝搬させ、その透過光
量により磁界の強さを知る方法である。この場合、構造
が簡単ではあるが、光フアイバ光路の伝送損失が直接測
定精度に影響すること、および磁界の方向が逆であって
し同一の出力として検出されるために交番磁界の波形検
出はできないという問題点があった。光路の伝送損失の
影響を除去し、磁界波形をも検出可能な方法として、偏
光面を互いに４５度傾けて設置した２つの偏光子、検光
子の間にファラデー素子を挿入する方法がある。この場
合、検出される透過光は４５度成分として１／Ｊ７を零
位として正負両極性を得ることが可能であるが、伝送損
失の影響を除去するためには、直流分く磁界零の出力）
を基準として交流会の比率をめる必要があり、直流磁界
及び直流分を有する交流磁界には使用できない。これら
を改善した検出方法として、前記の４５度傾けた検光子
として偏光ビームスプリッタを使用し、該検光子の偏光
の直交成分をも検知し、これらの直交２成分の和と差の
比率から検出する方法も考えられているが、３本の光フ
ァイバーを必要とし、実使用上簡便な構造のものとはな
らない難点があった。One of these is how to detect the Faraday effect of a Faraday element with high accuracy and in a simple and practical manner. There are several conventional detection methods, one of which is to insert a Faraday element between two polarizers and an analyzer whose polarization planes are perpendicular to each other, and to emit light through optical fibers installed on both sides. In this method, the strength of the magnetic field can be determined by the amount of transmitted light. In this case, although the structure is simple, the transmission loss of the optical fiber optical path directly affects the measurement accuracy, and the waveform detection of the alternating magnetic field is difficult because the direction of the magnetic field is reversed and it is detected as the same output. The problem was that it couldn't be done. As a method that can remove the influence of transmission loss in the optical path and also detect the magnetic field waveform, there is a method of inserting a Faraday element between two polarizers and an analyzer whose planes of polarization are tilted at 45 degrees to each other. In this case, the detected transmitted light can have both positive and negative polarity as a 45 degree component with 1/J7 as the zero level, but in order to eliminate the influence of transmission loss, it is necessary to )
It is necessary to determine the ratio of exchange meetings based on , and it cannot be used for DC magnetic fields and AC magnetic fields with a DC component. As a detection method that improves these, a polarizing beam splitter is used as the analyzer tilted at 45 degrees, and the orthogonal components of the polarization of the analyzer are also detected, and detection is performed from the ratio of the sum and difference of these two orthogonal components. A method to do so has been considered, but it requires three optical fibers and has a drawback that it is not a simple structure for practical use.
本発明の目的は、前記した従来技術の欠点を解消し、精
度が高く構造が簡便であり、しかも直流磁界及び直流分
を含む交流磁界をも精度良く検出可能な新規の光学式磁
界はンザを提供することにある。An object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a new optical magnetic field that is highly accurate, simple in structure, and capable of detecting DC magnetic fields and AC magnetic fields including DC components with high accuracy. It is about providing.
［発明の概要コ
すなわち、本発明の要旨は、ファラデー素子の両側に互
に偏光面を４５°傾ｔ）だ偏光子を設置し、これらの両
件面に設置した２本の光ファイバにより光路を形成し、
該光路に進向方向が各々逆方向の光を通過さゼ該光路を
双方向路として使用したことにある。[Summary of the Invention] In other words, the gist of the present invention is to install polarizers on both sides of a Faraday element with their planes of polarization tilted at 45 degrees, and to create an optical path using two optical fibers installed on both sides. form,
This is because the optical path is used as a bidirectional path, since the optical path is used as a bidirectional path, since the light beams traveling in opposite directions are passed through the optical path.
［実施例コ
以下、本発明の光学式磁界センサの構成を実施例を用い
て図面により説明する。[Example 7] Hereinafter, the configuration of the optical magnetic field sensor of the present invention will be explained with reference to the drawings using an example.
第１図は本発明の一実施例の構成を示す説明図であり、
第２図は光の偏光状態を示すベクトル図である。FIG. 1 is an explanatory diagram showing the configuration of an embodiment of the present invention,
FIG. 2 is a vector diagram showing the polarization state of light.
第１図において、ＬＥＤ光源１の発光はハーフミラ−２
１にＪ：り直進方向及び直角方向に２等分される。直進
方向にハーフミラ−２１を透過した光は更にハーフミラ
−２２を透過直進し光ファイバ３１に入光する。この光
の進行方向は図示した磁界１１の向きと同方向であるの
で以下順方向と呼ぶ。この順方向の光は偏光子５１によ
り第２図の１４の偏光面に直線偏光され、ファラデー素
子６を通過してベクトル１６に示ず様に角度ψたけ偏光
面が回転する。これが偏光子５１に対し偏光面４５度傾
りた偏光子５２を通過するとベクトル１７の成分となり
、光ファイバ３２を通過後ハーフミラ−２３で直角方向
に反射し受光素子７２に到達する。一方、ハーフミラ−
２１により直角方向に反射した逆方向の光はハーフミラ
−２３を透過後光ファイバ３２に入光する。偏光子５２
を通過すると偏光面１５に直線偏光され、ファラデー素
子６を通過してベクトル１８に示す様に角度ψだけ回転
する。偏光子５１を通過するとベクトル１９の成分とな
り、光ファイバ３１を通過後ハーフミラ−２２で直角方
向に反射し、受光素子７１に入光する。In FIG. 1, the light emitted from the LED light source 1 is emitted from the half mirror 2.
J: is divided into two equal parts in the straight direction and the right angle direction. The light that has passed through the half mirror 21 in the straight direction further passes through the half mirror 22 and enters the optical fiber 31. The direction in which this light travels is the same as the direction of the illustrated magnetic field 11, so it will be hereinafter referred to as the forward direction. This forward light is linearly polarized by the polarizer 51 to the plane of polarization 14 in FIG. When this light passes through the polarizer 52 whose polarization plane is tilted by 45 degrees with respect to the polarizer 51, it becomes a component of the vector 17, and after passing through the optical fiber 32, it is reflected in the right angle direction by the half mirror 23 and reaches the light receiving element 72. On the other hand, half mirror
The light in the opposite direction reflected by the mirror 21 in the right angle direction enters the optical fiber 32 after passing through the half mirror 23. Polarizer 52
When it passes through, it is linearly polarized into a polarization plane 15, passes through a Faraday element 6, and is rotated by an angle ψ as shown by a vector 18. When the light passes through the polarizer 51, it becomes a component of the vector 19, passes through the optical fiber 31, is reflected in the right angle direction by the half mirror 22, and enters the light receiving element 71.
受光素子７２及び７１で検出される光の強度は各々、
（受光素子７２の検出光強度）−Ｋ・（１−ｓｉｎ ２
ψ）−−−−−（＋）
（受光素子７１の検出光強度）＝Ｋ・（１＋５ｉｎ２ψ
＞ −−−−−（２）
となる。ただし、ＫはＬＥＤ光ａｉ１の発光強度及び光
路の損失を含む定数である。これらの検出光強度は各々
光電変換増幅器８１．８２により電気信号に変換され、
減算増幅器９により前記（＋）、（２）式の差、加算増
幅器１０により和が出力される。The intensity of the light detected by the light receiving elements 72 and 71 is respectively (detected light intensity of the light receiving element 72) -K・(1-sin 2
ψ) −−−−−(+) (Detected light intensity of light receiving element 71) = K・(1+5in2ψ
> −−−−−(2). However, K is a constant including the emission intensity of the LED light ai1 and the optical path loss. These detected light intensities are each converted into electrical signals by photoelectric conversion amplifiers 81 and 82,
The subtracting amplifier 9 outputs the difference between the equations (+) and (2), and the summing amplifier 10 outputs the sum.
すなわち、各々の出力は増幅度を１とすると、（減算増
幅器９の出力）−２に一５ｉｎ２ψ−−−−−（３）
（加算増幅者１０の出力）−２に
−−−−−（４）
となる。その後、割算器１１により９の出力を１０の出
力で割綽すると、
（割算器１１の出力）＝ｓｉｎ２ψ
−−−−−（５）
となり、ψが十分小さい領域では、
ｓｉｎ ２ψ′：２ψ −−−−−ｆ５） ”となって
磁界Ｈに比例した出力が得られ、換評器１２により出力
を磁界の強さに換算後出力端子１３に出力される。That is, assuming the amplification degree of each output is 1, (output of subtracting amplifier 9) -2 to -5in2ψ -------(3) (output of summing amplifier 10) -2 to -------( 4) It becomes. After that, when the output of 9 is divided by the output of 10 by the divider 11, (output of the divider 11) = sin2ψ −−−−−(5), and in the region where ψ is sufficiently small, sin 2ψ′: 2ψ −−−−−f5)”, an output proportional to the magnetic field H is obtained, and the converter 12 converts the output into the strength of the magnetic field and outputs it to the output terminal 13.
第１図の実施例にＪ３いては、単一のＬＥＤ光源１の発
光をハーフミラ−２１により２等分して使用したが、ハ
ーフミラ−２１を省略し、２つのＬＥＤ光源を使用する
ことももちろん可能である。In the embodiment shown in FIG. 1, in J3, the light emitted from a single LED light source 1 is divided into two by a half mirror 21, but it is also possible to omit the half mirror 21 and use two LED light sources. It is possible.
また光源はＬＥＤに限定されるものではなく、レーザー
等別種の光源の使用も可能である。Furthermore, the light source is not limited to LEDs, and other types of light sources such as lasers can also be used.
本発明の磁界センサに使用する光ファイバは、光路を形
成し得る限り、多モードファイバ、単一モードファイバ
等の種類及び形状、構造等に制限条件はなく、光源の種
類、受光素子の感度、光路の伝送損失等を考慮して自由
に選択し得るものである。The optical fiber used in the magnetic field sensor of the present invention is not limited to the type, shape, structure, etc. of multimode fiber or single mode fiber as long as it can form an optical path, and there are no restrictions on the type of light source, the sensitivity of the light receiving element, etc. It can be freely selected in consideration of the transmission loss of the optical path and the like.
［発明の効果］
以上説明したように、本発明の光学式磁界センサによれ
ば、２本の光ファイバにより実質的には３本の光ファイ
バを用いた検出方式と同等の効果を有し、構造が簡単で
取扱性が良好かつ高精度の磁界検出が可能となる顕著な
効果を奏することができる。[Effects of the Invention] As explained above, according to the optical magnetic field sensor of the present invention, two optical fibers have substantially the same effect as a detection method using three optical fibers, The structure is simple, the handling is good, and the remarkable effect of enabling highly accurate magnetic field detection can be achieved.
第１図は本発明の光学式磁界センサの一実施例の構成を
示す読ＦｉＡ図であり、第２図は第１図における各部の
光の偏光状態を示すベクトル図である。
１：光源、２１〜３３：ハーフミラ−，３１゜３２：光
ファイバー、４１，４４：光フアイバー結合部、５１．
５２：偏光子、６：ファラデー素子、７１．７２：受光
素子、８１．８２：光電変換増幅器、９：減算増幅器、
１ｏ：加算増幅器、１１：割算器、１２：換算器、１３
：出力端子、１４：偏光子５１の偏光面、１５：偏光子
５２の偏光面、１６：フッラブ−回転後の順方向（磁界
Ｈ方向）光幅光面、１７：偏光子５１を通過する１６の
成分、１８：ファラデー回転後の逆方向光偏光面、１９
：偏光子５２を通過する１８の成分。FIG. 1 is a reading FiA diagram showing the configuration of an embodiment of the optical magnetic field sensor of the present invention, and FIG. 2 is a vector diagram showing the polarization state of light at each part in FIG. 1. 1: light source, 21-33: half mirror, 31° 32: optical fiber, 41, 44: optical fiber coupling part, 51.
52: polarizer, 6: Faraday element, 71.72: light receiving element, 81.82: photoelectric conversion amplifier, 9: subtraction amplifier,
1o: summing amplifier, 11: divider, 12: converter, 13
: Output terminal, 14: Polarization plane of polarizer 51, 15: Polarization plane of polarizer 52, 16: Forward direction (magnetic field H direction) light width light plane after full-lab rotation, 17: 16 passing through polarizer 51 component, 18: Reverse light polarization plane after Faraday rotation, 19
: 18 components passing through the polarizer 52.
Claims (1)
サにおいて、ファラデー素子６の両側に偏光面が相互に
４５°傾くように偏光子５１゜５２が設けられており、
該偏光子５１、ファラデー素子６及び偏光子５２を挾ん
で光ファイバ３１゜３２が対向配置されており、該光フ
ァイバ３１゜３２の双方に光を大剣するための光源１と
、ファラデー素子６及び偏光子５１．５２を透過して光
ファイバ３１．３２の双方から出射した光をそれぞれ受
光するための受光素子７１．７２と、受光信号を減算及
び加算し、その比をめるための演算回路とが設けられて
いることを特徴とする光学式磁界センサ。In an optical magnetic field sensor using an optical fiber and a Faraday element, polarizers 51 and 52 are provided on both sides of the Faraday element 6 so that the planes of polarization are mutually inclined by 45 degrees,
Optical fibers 31 and 32 are arranged opposite to each other with the polarizer 51, Faraday element 6, and polarizer 52 in between, and a light source 1 and a Faraday element 6 are arranged to direct light to both of the optical fibers 31 and 32. and a light receiving element 71.72 for receiving the light transmitted through the polarizer 51.52 and emitted from both the optical fibers 31.32, and an operation for subtracting and adding the received light signals and calculating the ratio thereof. An optical magnetic field sensor characterized by being provided with a circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24814483A JPS60138480A (en) | 1983-12-27 | 1983-12-27 | Optical magnetic field sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24814483A JPS60138480A (en) | 1983-12-27 | 1983-12-27 | Optical magnetic field sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS60138480A true JPS60138480A (en) | 1985-07-23 |
Family
ID=17173875
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24814483A Pending JPS60138480A (en) | 1983-12-27 | 1983-12-27 | Optical magnetic field sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60138480A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02222847A (en) * | 1990-01-11 | 1990-09-05 | Univ Osaka | Magnetic field sensor |
| US5382901A (en) * | 1991-08-29 | 1995-01-17 | Ngk Insulators, Ltd. | Optical magnetic field sensor capable of precise measurement without temperature induced errors |
| WO1996020411A1 (en) * | 1994-12-23 | 1996-07-04 | Siemens Aktiengesellschaft | Process and arrangement for measuring a magnetic field using the faraday effect with compensation of variations in intensity and temperature effects |
| WO1996026452A1 (en) * | 1995-02-22 | 1996-08-29 | Siemens Aktiengesellschaft | Process and device for measuring a magnetic field by faraday effect while compensating for intensity variations |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5637565A (en) * | 1979-09-04 | 1981-04-11 | Tokyo Electric Power Co Inc:The | Electric current measuring apparatus |
| JPS5827071A (en) * | 1981-08-12 | 1983-02-17 | Hitachi Ltd | Photomagnetic field detector |
-
1983
- 1983-12-27 JP JP24814483A patent/JPS60138480A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5637565A (en) * | 1979-09-04 | 1981-04-11 | Tokyo Electric Power Co Inc:The | Electric current measuring apparatus |
| JPS5827071A (en) * | 1981-08-12 | 1983-02-17 | Hitachi Ltd | Photomagnetic field detector |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02222847A (en) * | 1990-01-11 | 1990-09-05 | Univ Osaka | Magnetic field sensor |
| US5382901A (en) * | 1991-08-29 | 1995-01-17 | Ngk Insulators, Ltd. | Optical magnetic field sensor capable of precise measurement without temperature induced errors |
| WO1996020411A1 (en) * | 1994-12-23 | 1996-07-04 | Siemens Aktiengesellschaft | Process and arrangement for measuring a magnetic field using the faraday effect with compensation of variations in intensity and temperature effects |
| US5933000A (en) * | 1994-12-23 | 1999-08-03 | Siemens Aktiengesellschaft | Process and arrangement for measuring a magnetic field using the faraday effect with compensation for variations in intensity and temperature effects |
| WO1996026452A1 (en) * | 1995-02-22 | 1996-08-29 | Siemens Aktiengesellschaft | Process and device for measuring a magnetic field by faraday effect while compensating for intensity variations |
| US6034523A (en) * | 1995-02-22 | 2000-03-07 | Siemens Aktiengesellschaft | Method and arrangement for measuring a magnetic field using the Faraday effect, with compensation for intensity changes |
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