JPH05273260A - Voltage sensor - Google Patents
Voltage sensorInfo
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- JPH05273260A JPH05273260A JP7194292A JP7194292A JPH05273260A JP H05273260 A JPH05273260 A JP H05273260A JP 7194292 A JP7194292 A JP 7194292A JP 7194292 A JP7194292 A JP 7194292A JP H05273260 A JPH05273260 A JP H05273260A
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- Prior art keywords
- light
- waveguide
- voltage sensor
- optical waveguide
- voltage
- Prior art date
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は光導波路を利用した電圧
センサに関する。特に、電気光学効果を示す材料により
形成された光導波路を用い、電圧による伝搬光の位相変
化を検出する電圧センサに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage sensor using an optical waveguide. In particular, the present invention relates to a voltage sensor that uses an optical waveguide formed of a material exhibiting an electro-optical effect and detects a phase change of propagating light due to a voltage.
【０００２】[0002]
【従来の技術】図４は光導波路を利用した電圧センサの
従来例構造を示す斜視図である。2. Description of the Related Art FIG. 4 is a perspective view showing a conventional structure of a voltage sensor using an optical waveguide.
【０００３】この従来例はＬｉＮｂＯ3 、ＧａＡｓなど
の電気光学効果を示す材料からなる基板３１に形成され
た光導波路３２を備え、この光導波路３２は、入射端か
ら二つに分岐し、再び一つに合流して出射端に至る形状
をもつ。さらにこの従来例は、光導波路３２の一方の分
岐路に沿って二つの電極３３を備え、この二つの電極３
３にプローブ端子３４が接続される。光導波路３２の入
射端および出射端にはそれぞれ光ファイバ３５、３６が
光学的に結合される。This conventional example is provided with an optical waveguide 32 formed on a substrate 31 made of a material exhibiting an electro-optical effect such as LiNbO 3 and GaAs. It has a shape that merges into one and reaches the exit end. Further, in this conventional example, two electrodes 33 are provided along one branch of the optical waveguide 32, and the two electrodes 3
3 is connected to the probe terminal 34. Optical fibers 35 and 36 are optically coupled to the entrance end and the exit end of the optical waveguide 32, respectively.
【０００４】光ファイバ３５からの入射光は、光導波路
３２を伝搬し、二つに分岐して再び合流し、光ファイバ
３６に伝搬する。プローブ端子３４から電極３３に電圧
が印加されると、光導波路３２の一方の分岐路で伝搬光
の位相が変化し、それを他方の分岐路の伝搬光と合波す
ると干渉が生じる。この干渉による光強度変化を測定す
れば、プローブ端子３４の電圧を検出することができ
る。The incident light from the optical fiber 35 propagates through the optical waveguide 32, is branched into two, is merged again, and is propagated to the optical fiber 36. When a voltage is applied from the probe terminal 34 to the electrode 33, the phase of the propagating light changes in one branch of the optical waveguide 32, and when it is combined with the propagating light of the other branch, interference occurs. The voltage of the probe terminal 34 can be detected by measuring the change in light intensity due to this interference.
【０００５】このような電圧センサは、（１）基板３１
の大きさが、長さ（光導波路３２の方向）７ｍｍ、幅５
ｍｍ程度と小型である、（２）入力容量が２〜４ｐＦ程
度と小さいという利点がある。Such a voltage sensor has (1) substrate 31
Has a length of 7 mm (direction of the optical waveguide 32) and a width of 5
The advantages are that it is as small as about mm and (2) the input capacitance is as small as about 2-4 pF.
【０００６】このような電圧センサについては、例え
ば、 （１）横河技報、Ｖｏｌ．２８、Ｎｏ．４、１９８４年 （２）アプライド・フィジクス・レターズ第４６巻、第
４６２頁、１９８５年（Appl.Phys.Lett., Vol.46, p.4
62, 1985） （３）光導波エレクトロニクス、日本学術振興会刊、１
９８１年 に詳しく示されている。Regarding such a voltage sensor, for example, (1) Yokogawa Technical Report, Vol. 28, No. 4, 1984 (2) Applied Physics Letters, Vol. 46, p. 462, 1985 (Appl.Phys.Lett., Vol.46, p.4)
62, 1985) (3) Optical waveguide electronics, published by Japan Society for the Promotion of Science, 1
This is detailed in 981.
【０００７】[0007]
【発明が解決しようとする課題】このような電圧センサ
の使用形態を考えると、電圧センサを一つのユニットと
してパッケージングし、光源および光検出器を含む測定
系を別のユニットとし、二つのユニットを二本の光ファ
イバで接続することが望ましい。このとき、電圧センサ
のパッケージから二本の光ファイバを二つの方向に引き
出すのではなく、同一方向に引き出すことが望ましい。
しかし、このようにすると、従来の電圧センサでは光フ
ァイバをパッケージ内で曲げなければならず、その最小
曲げ半径をパッケージ内で確保しなければならない。こ
のため従来の電圧センサは、パッケージの大きさが基板
の二倍程度となっていた。Considering the usage form of such a voltage sensor, the voltage sensor is packaged as one unit, the measurement system including the light source and the photodetector is set as another unit, and two units are provided. It is desirable to connect the two with two optical fibers. At this time, it is desirable to pull out the two optical fibers from the package of the voltage sensor in the same direction, not in two directions.
However, in this case, in the conventional voltage sensor, the optical fiber must be bent in the package, and its minimum bending radius must be ensured in the package. Therefore, in the conventional voltage sensor, the package size is about twice that of the substrate.
【０００８】また、電極の位置が基板の端から離れてい
るため、プローブ端子と電極との距離が長くなり、入力
容量も大きくなる問題があった。Further, since the position of the electrode is far from the end of the substrate, there is a problem that the distance between the probe terminal and the electrode becomes long and the input capacitance becomes large.
【０００９】本発明は、このような課題を解決し、パッ
ケージが小型で入力容量の小さな電圧センサを提供する
ことを目的とする。An object of the present invention is to solve the above problems and provide a voltage sensor having a small package and a small input capacitance.
【００１０】[0010]
【課題を解決するための手段】本発明の電圧センサは、
電気光学効果を示す材料により形成された光導波路と、
この光導波路に被測定電圧源からの電圧を印加してその
伝搬光に位相変化を与える電極とを備えた電圧センサに
おいて、光導波路の一端に反射手段が設けられ、光入射
端と光出射端とが共通の導波路であることを特徴とす
る。The voltage sensor of the present invention comprises:
An optical waveguide formed of a material exhibiting an electro-optical effect,
In a voltage sensor provided with an electrode for applying a voltage from a voltage source to be measured to this optical waveguide to change the phase of its propagating light, a reflecting means is provided at one end of the optical waveguide, and a light incident end and a light emitting end are provided. And are common waveguides.
【００１１】光導波路はＬｉＮｂＯ3 またはＧａＡｓの
基板に形成されることが望ましい。The optical waveguide is preferably formed on a substrate of LiNbO 3 or GaAs.
【００１２】[0012]
【作用】光導波路の一端に反射手段を設けることによ
り、伝搬光が折り返され、ほぼ半分の長さの光導波路で
反射手段を設けない場合と同等の位相変化が得られる。
また、光入射端と光出射端とを共通化するので、一本の
光ファイバで測定系のユニットに接続できる。By providing the reflecting means at one end of the optical waveguide, the propagating light is folded back, and a phase change equivalent to the case where the reflecting means is not provided in the optical waveguide having a length of about half is obtained.
Further, since the light incident end and the light emitting end are made common, it is possible to connect to the unit of the measurement system with one optical fiber.
【００１３】光導波路としては、一つの光入出射導波路
に対して二つの分岐導波路が設けられたＹ字型導波路を
用い、二つの分岐導波路にそれぞれ反射手段を設け、二
つの分岐導波路の少なくとも一方に沿って電極が設けた
構造、すなわち分岐干渉型構造であることがよい。この
とき、二つの分岐導波路で生じた伝搬光の位相差により
光入出射導波路で干渉が生じ、光強度変化として測定で
きる。As the optical waveguide, a Y-shaped waveguide in which two branch waveguides are provided for one light input / output waveguide is used, and a reflecting means is provided in each of the two branch waveguides to provide two branch waveguides. A structure in which electrodes are provided along at least one of the waveguides, that is, a branched interference type structure is preferable. At this time, due to the phase difference of the propagating light generated in the two branch waveguides, interference occurs in the light input / output waveguide, which can be measured as a change in light intensity.
【００１４】また、光導波路を一本の導波路とし、その
入出射端に偏光板を配置することもできる。この場合に
は、位相変化により偏波面が回転し、偏光板の透過強度
が変化する。Further, the optical waveguide may be a single waveguide, and a polarizing plate may be arranged at the input / output end thereof. In this case, the polarization plane rotates due to the phase change, and the transmission intensity of the polarizing plate changes.
【００１５】[0015]
【実施例】以下本発明の実施例を図面を参照して説明す
るが、実施例については図４の従来例に比べて拡大して
示したおり、実際の寸法には対応していない。Embodiments of the present invention will now be described with reference to the drawings, but the embodiments are shown enlarged in comparison with the conventional example of FIG. 4 and do not correspond to actual dimensions.
【００１６】図１は本発明第一実施例の電圧センサとそ
の測定系とを示す図であり、電圧センサを斜視図で示
し、測定系をブロック構成で示す。FIG. 1 is a diagram showing a voltage sensor and its measuring system according to the first embodiment of the present invention. The voltage sensor is shown in a perspective view, and the measuring system is shown in a block configuration.
【００１７】この実施例は、電気光学効果を示す基板１
に形成された光導波路２と、この光導波路２に被測定電
圧源からの電圧を印加してその伝搬光に位相変化を与え
る電極５、６とを備える。電極５、６は各々プローブ端
子９、１０に接続される。基板１としては、例えばＬｉ
ＮｂＯ3 またはＧａＡｓを用いる。This embodiment is a substrate 1 which exhibits an electro-optical effect.
And the electrodes 5 and 6 which apply a voltage from a voltage source to be measured to the optical waveguide 2 to give a phase change to the propagating light. The electrodes 5 and 6 are connected to probe terminals 9 and 10, respectively. As the substrate 1, for example, Li
NbO 3 or GaAs is used.
【００１８】ここで本実施例の特徴とするところは、光
導波路２は一つの光入出射導波路に対して二つの分岐導
波路３、４が設けられたＹ字型導波路であり、二つの分
岐導波路３、４の一端にそれぞれ反射手段としての反射
板７、８が設けられ、電極５、６が分岐導波路４に沿っ
て設けられ、光導波路２の光入射端と光出射端とが共通
化されたことにある。The feature of this embodiment is that the optical waveguide 2 is a Y-shaped waveguide in which two branch waveguides 3 and 4 are provided for one light input / output waveguide. Reflecting plates 7 and 8 as reflecting means are provided at one ends of the two branching waveguides 3 and 4, respectively, and electrodes 5 and 6 are provided along the branching waveguide 4, and a light incident end and a light emitting end of the optical waveguide 2 are provided. And is common.
【００１９】この電圧センサは一つのユニットとしてパ
ッケージングされ、そのパッケージから、光導波路２の
入出射端に一端が結合された光ファイバ２０が引き出さ
れる。この光ファイバ２０の他端は測定部２１に結合さ
れる。測定部２１には、半導体レーザ光源２２、アイソ
レータ２３、ビームスプリッタ２４および光検出器２５
を備える。The voltage sensor is packaged as one unit, and the optical fiber 20 having one end coupled to the input / output end of the optical waveguide 2 is pulled out from the package. The other end of the optical fiber 20 is coupled to the measuring section 21. The measuring unit 21 includes a semiconductor laser light source 22, an isolator 23, a beam splitter 24, and a photodetector 25.
Equipped with.
【００２０】この実施例の動作を説明する。半導体レー
ザ光源２２から出射されたレーザ光は、アイソレータ２
３、ビームスプリッタ２４および光ファイバ２０を介し
て光導波路２に結合する。光導波路２に結合した光は分
岐導波路３、４に分岐して伝搬し、反射板７、８により
反射され、再び合波されて光ファイバ２０を逆方向に伝
搬する。この逆方向の伝搬光はビームスプリッタ２４に
より光検出器２５に導かれる。プローブ端子９、１０か
ら電極５、６間に電圧が印加されると、分岐導波路４に
電界が印加され、電気光学効果によりその伝搬光の位相
が変化する。このため、分岐導波路３、４の伝搬光を合
波すれば、位相の違いから、干渉による光強度変化を起
こす。この光強度変化を光検出器２５で測定することに
より、プローブ端子９、１０間の電圧を検出できる。The operation of this embodiment will be described. The laser light emitted from the semiconductor laser light source 22 is transmitted to the isolator 2
3, coupled to the optical waveguide 2 via the beam splitter 24 and the optical fiber 20. The light coupled to the optical waveguide 2 branches and propagates in the branching waveguides 3 and 4, is reflected by the reflection plates 7 and 8, is recombined, and propagates in the optical fiber 20 in the opposite direction. The light propagating in the opposite direction is guided to the photodetector 25 by the beam splitter 24. When a voltage is applied between the probe terminals 9 and 10 and the electrodes 5 and 6, an electric field is applied to the branching waveguide 4, and the phase of the propagating light changes due to the electro-optic effect. Therefore, when the propagating lights in the branching waveguides 3 and 4 are combined, a change in phase causes a change in light intensity due to interference. By measuring this change in light intensity with the photodetector 25, the voltage between the probe terminals 9 and 10 can be detected.
【００２１】この実施例では、電圧センサのパッケージ
内で光ファイバ２０を曲げる必要がなく、パッケージを
小型化できる。また、電極５、６を基板１の端部近くま
で形成でき、プローブ端子９、１０とを直結でき、入力
容量を減らすことができる。具体的な数値をあげると、
パッケージの大きさを従来の１７ｍｍ×５ｍｍから７ｍ
ｍ×５ｍｍ程度、すなわち１／２程度に小型化でき、入
力容量を３〜５ｐＦから２〜４ｐＦ程度に減らすことが
できる。In this embodiment, it is not necessary to bend the optical fiber 20 inside the package of the voltage sensor, and the package can be miniaturized. Further, the electrodes 5 and 6 can be formed near the end of the substrate 1, the probe terminals 9 and 10 can be directly connected, and the input capacitance can be reduced. If you give specific numbers,
The size of the package is 7m from the conventional 17mm x 5mm
The size can be reduced to about m × 5 mm, that is, about ½, and the input capacitance can be reduced from about 3 to 5 pF to about 2 to 4 pF.
【００２２】この実施例において、構造を明確にするた
め反射手段が板状であるように説明したが、実用的には
反射膜が便利である。また、他の光反射構造を用いるこ
ともできる。In this embodiment, the reflecting means is described as a plate for clarifying the structure, but the reflecting film is practically convenient. Also, other light reflecting structures can be used.
【００２３】図２は本発明第二実施例の電圧センサを示
す斜視図である。この実施例は電極の配置が第一実施例
と異なる。FIG. 2 is a perspective view showing a voltage sensor according to the second embodiment of the present invention. This embodiment differs from the first embodiment in the arrangement of electrodes.
【００２４】この実施例は、第一実施例と同様に、電気
光学効果を示す基板１に形成された光導波路２と、この
光導波路２に被測定電圧源からの電圧を印加してその伝
搬光に位相変化を与える電極５、６とを備え、電極５、
６は各々プローブ端子９、１０に接続される。光導波路
２は一つの光入出射導波路に対して二つの分岐導波路
３、４が設けられたＹ字型導波路であり、二つの分岐導
波路３、４の一端にそれぞれ反射手段としての反射板
７、８が設けられる。In this embodiment, similarly to the first embodiment, an optical waveguide 2 formed on a substrate 1 exhibiting an electro-optical effect, and a voltage from a voltage source to be measured are applied to the optical waveguide 2 to propagate the same. And electrodes 5 and 6 for giving a phase change to the light.
6 are connected to probe terminals 9 and 10, respectively. The optical waveguide 2 is a Y-shaped waveguide in which two branch waveguides 3 and 4 are provided for one light input / output waveguide, and one end of each of the two branch waveguides 3 and 4 serves as a reflection means. Reflecting plates 7 and 8 are provided.
【００２５】ここで本実施例が第一実施例と異なるの
は、分岐導波路３、４の間に接地電極１１が設けられ、
電極５と接地電極１１とで分岐導波路３を挟み、電極６
と接地電極１１とで分岐導波路４を挟んだことにある。
したがって、プローブ端子９、１０の電圧は差動入力と
なり、分岐導波路３、４のそれぞれの伝搬光に位相変化
を生じさせる。この位相変化による干渉光の強度変化を
測定することは第一実施例と同等であり、同等の測定系
によりプローブ端子９、１０間の電圧を検出できる。Here, the present embodiment is different from the first embodiment in that the ground electrode 11 is provided between the branch waveguides 3 and 4,
The branch waveguide 3 is sandwiched between the electrode 5 and the ground electrode 11, and the electrode 6
And the grounding electrode 11 sandwiches the branch waveguide 4.
Therefore, the voltage of the probe terminals 9 and 10 becomes a differential input, and causes a phase change in each of the propagating lights of the branch waveguides 3 and 4. Measuring the intensity change of the interference light due to this phase change is the same as in the first embodiment, and the voltage between the probe terminals 9 and 10 can be detected by the same measurement system.
【００２６】図３は本発明第三実施例の電圧センサを示
す斜視図である。FIG. 3 is a perspective view showing the voltage sensor of the third embodiment of the present invention.
【００２７】この実施例は、第一実施例および第二実施
例と同様に、電気光学効果を示す基板１に形成された光
導波路２と、この光導波路２に被測定電圧源からの電圧
を印加してその伝搬光に位相変化を与える電極５、６と
を備え、電極５、６は各々プローブ端子９、１０に接続
される。光導波路２の一端には反射手段としての反射板
７が設けられる。In this embodiment, like the first and second embodiments, the optical waveguide 2 formed on the substrate 1 exhibiting the electro-optical effect and the voltage from the voltage source to be measured are applied to the optical waveguide 2. The electrodes 5 and 6 are provided to apply a phase change to the propagating light, and the electrodes 5 and 6 are connected to the probe terminals 9 and 10, respectively. A reflection plate 7 as a reflection means is provided at one end of the optical waveguide 2.
【００２８】ここで本実施例が第一実施例および第二実
施例と異なるのは、光導波路２が一本の導波路であり、
その入出射端に偏光板１２が配置されたことである。こ
の構成により、干渉による光強度の変化を得るのではな
く、位相変化による偏波面の回転による偏光板１２の透
過光強度を得る。測定系については第一実施例と同等の
ものを用いることができる。The present embodiment differs from the first and second embodiments in that the optical waveguide 2 is a single waveguide,
That is, the polarizing plate 12 is arranged at the entrance and exit ends. With this configuration, not the change in the light intensity due to the interference but the transmitted light intensity of the polarizing plate 12 due to the rotation of the polarization plane due to the phase change is obtained. As the measurement system, the same one as in the first embodiment can be used.
【００２９】[0029]
【発明の効果】以上説明したように、本発明の電圧セン
サは、外部の測定系に結合するための光ファイバを曲げ
る必要がないためパッケージを小型化でき、しかも、プ
ローブ端子と電極との距離が非常に短いので入力容量が
小さくなる効果がある。As described above, according to the voltage sensor of the present invention, it is not necessary to bend the optical fiber for coupling to the external measurement system, so that the package can be downsized and the distance between the probe terminal and the electrode can be reduced. Is very short, which has the effect of reducing the input capacitance.
【図１】本発明第一実施例の電圧センサとその測定系を
示す図。FIG. 1 is a diagram showing a voltage sensor and its measurement system according to a first embodiment of the present invention.
【図２】本発明第二実施例の電圧センサを示す斜視図。FIG. 2 is a perspective view showing a voltage sensor according to a second embodiment of the present invention.
【図３】本発明第三実施例の電圧センサを示す斜視図。FIG. 3 is a perspective view showing a voltage sensor according to a third embodiment of the present invention.
【図４】従来例の電圧センサを示す斜視図。FIG. 4 is a perspective view showing a conventional voltage sensor.
１、３１ 基板 ２、３２ 光導波路 ３、４ 分岐導波路 ５、６、３３ 電極 ７、８ 反射板 ９、１０、３４ プローブ端子 １１ 接地電極 １２ 偏光板 ２０、３５、３６ 光ファイバ ２１ 測定部 ２２ 半導体レーザ光源 ２３ アイソレータ ２４ ビームスプリッタ ２５ 光検出器 1, 31 Substrate 2, 32 Optical Waveguide 3, 4 Branched Waveguide 5, 6, 33 Electrode 7, 8 Reflector 9, 10, 34 Probe Terminal 11 Grounding Electrode 12 Polarizer 20, 35, 36 Optical Fiber 21 Measuring Section 22 Semiconductor laser light source 23 Isolator 24 Beam splitter 25 Photodetector
Claims (4)
た光導波路と、 この光導波路に被測定電圧源からの電圧を印加してその
伝搬光に位相変化を与える電極とを備えた電圧センサに
おいて、 前記光導波路は一端に反射手段が設けられた光入射端と
光出射端とが共通の導波路であることを特徴とする電圧
センサ。1. A voltage sensor provided with an optical waveguide formed of a material exhibiting an electro-optical effect, and an electrode for applying a voltage from a voltage source to be measured to the optical waveguide to change the phase of the propagating light. A voltage sensor, wherein the optical waveguide has a common light-incident end and light-exiting end having a reflecting means provided at one end.
て二つの分岐導波路が設けられたＹ字型導波路であり、
前記二つの分岐導波路にそれぞれ反射手段が設けられ、
前記二つの分岐導波路の少なくとも一方に沿って電極が
設けられた請求項１記載の電圧センサ。2. The optical waveguide is a Y-shaped waveguide in which two branch waveguides are provided for one light input / output waveguide.
Reflecting means is provided on each of the two branch waveguides,
The voltage sensor according to claim 1, wherein an electrode is provided along at least one of the two branch waveguides.
差により光入出射導波路で生じる干渉光の強度変化を測
定する手段を備えた請求項２記載の電圧センサ。3. The voltage sensor according to claim 2, further comprising means for measuring a change in intensity of the interference light generated in the light incident / exited waveguide by the phase difference of the propagating light generated in the two branch waveguides.
出射端には偏光板が配置された請求項１記載の電圧セン
サ。4. The voltage sensor according to claim 1, wherein the optical waveguide is a single waveguide, and a polarizing plate is arranged at an input / output end thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7194292A JPH05273260A (en) | 1992-03-30 | 1992-03-30 | Voltage sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7194292A JPH05273260A (en) | 1992-03-30 | 1992-03-30 | Voltage sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05273260A true JPH05273260A (en) | 1993-10-22 |
Family
ID=13475066
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7194292A Pending JPH05273260A (en) | 1992-03-30 | 1992-03-30 | Voltage sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05273260A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0664460A1 (en) * | 1993-07-07 | 1995-07-26 | Tokin Corporation | Electric field sensor |
| EP0668507A1 (en) * | 1993-07-07 | 1995-08-23 | Tokin Corporation | Electric field sensor |
| JPH08233881A (en) * | 1995-02-27 | 1996-09-13 | Tokin Corp | System for detecting surge waveform |
| EP0866356A1 (en) * | 1997-03-19 | 1998-09-23 | Tokin Corporation | Optical modulator having a reflection plate mounted on a reflection end with an inclined angle against the reflection end |
| JP2011128092A (en) * | 2009-12-21 | 2011-06-30 | Japan Ae Power Systems Corp | Single-phase optical current transformer |
| JP2013032968A (en) * | 2011-08-02 | 2013-02-14 | Toyota Industries Corp | Optical fiber type voltage sensor |
-
1992
- 1992-03-30 JP JP7194292A patent/JPH05273260A/en active Pending
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0664460A1 (en) * | 1993-07-07 | 1995-07-26 | Tokin Corporation | Electric field sensor |
| EP0668507A1 (en) * | 1993-07-07 | 1995-08-23 | Tokin Corporation | Electric field sensor |
| EP0668507A4 (en) * | 1993-07-07 | 1996-09-11 | Tokin Corp | Electric field sensor. |
| EP0664460A4 (en) * | 1993-07-07 | 1996-09-11 | Tokin Corp | Electric field sensor. |
| US5625284A (en) * | 1993-07-07 | 1997-04-29 | Tokin Corporation | Electric field sensor having sensor head with unbalanced electric field shield to shield branched optical waveguides against an applied electric field |
| US5781003A (en) * | 1993-07-07 | 1998-07-14 | Tokin Corporation | Electric field sensor |
| US5850140A (en) * | 1993-07-07 | 1998-12-15 | Tokin Corporation | Electric field sensor having sensor head with unbalanced electric field shield to shield branched optical waveguides against an applied electric field |
| JPH08233881A (en) * | 1995-02-27 | 1996-09-13 | Tokin Corp | System for detecting surge waveform |
| EP0866356A1 (en) * | 1997-03-19 | 1998-09-23 | Tokin Corporation | Optical modulator having a reflection plate mounted on a reflection end with an inclined angle against the reflection end |
| US6038354A (en) * | 1997-03-19 | 2000-03-14 | Tokin Corporation | Optical modulator having a reflection plate mounted on a reflection end with an inclined angle against the reflection end |
| JP2011128092A (en) * | 2009-12-21 | 2011-06-30 | Japan Ae Power Systems Corp | Single-phase optical current transformer |
| JP2013032968A (en) * | 2011-08-02 | 2013-02-14 | Toyota Industries Corp | Optical fiber type voltage sensor |
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