JP4467842B2 - Optical applied measuring equipment - Google Patents

Description

この式(3)からわかるように、バイアス成分のｘ成分Ｖｘとｙ成分Ｖｙから温度による旋光の変化Δαを求めることができるため、温度とΔαとの関係が既知であれば、温度を求めることができる。
【００３４】
また、電流による変調成分のｘ成分Ｖｘとｙ成分Ｖｙは、電流によるファラデー旋光角をＦとすると、変調成分次の式(4)、(5)でそれぞれ表される。
【数３】
Ｖｘ＝Ｋ・{ｓｉｎ（４５°＋Δα＋Ｆ）−ｓｉｎ（４５°＋Δα）}²
… (4)
Ｖｙ＝Ｋ・{ｃｏｓ（４５°＋Δα＋Ｆ）−ｃｏｓ（４５°＋Δα）}²
… (5)
ここで、Δαは式(3)から求められるので、式(4)、(5)から、ファラデー旋光角Ｆを求めることにより、電流を求めることができる。
【００３５】
［作用効果］
以上のように、本実施の形態においては、旋光性を有するファラデー素子６という同一のセンサで電流と温度の両方を測定することができる。そのため、構成が単純化してコストの低減、信頼性の向上が期待できることに加えて、次のような効果が得られる。
【００３６】
すなわち、例えば、センサのヴェルデ定数に温度依存性がある場合でも、このセンサがセンサ素子そのものの温度を測定していることから、電流センサ近辺に温度センサを取り付けた場合に問題となる電流センサと温度センサの取付位置での温度差を考慮する必要がなく、電流測定時の温度による影響の補正を高精度に行うことができる。もちろん、温度測定時の磁界による影響の補正についても同様に高精度化が図れることはいうまでもない。
【００３７】
また、電流測定が不要で、温度測定のみを必要とする場合であっても、電流測定装置と同一の機器構成で温度測定装置を実現できるため、機器の共通化が図れ、コスト低減と機器の信頼性の確保というメリットが得られる。
【００３８】
［第２の実施の形態］
［構成］
図２は、本発明による光応用測定装置を適用した第２の実施の形態として、電流測定装置の別の形態を示す構成図である。この電流測定装置は、前述した第１の実施の形態に係る図１の装置において、光源２と２つの検出器８，９との間の部分を全て光ファイバ型の素子で構成したものである。
【００３９】
すなわち、光源２には、送信ファイバ３、第１のファイバ偏光子１１、センサファイバ１２、偏波面保持カプラ１３が順次接続されている。この偏波面保持カプラ１３の各出射ポートには、第２のファイバ偏光子１４と第３のファイバ偏光子１５がそれぞれ接続され、これらの偏光子１４，１５は、受信ファイバ１６，１７を介して２つの検出器８，９にそれぞれ接続されている。以下には、この装置の構成の詳細について、光源２からの光が電子回路１０から信号として出力されるまでの流れに沿って順次説明する。
【００４０】
まず、光源ドライバ１によって駆動される光源２からの光は、送信ファイバ３を伝播して第１のファイバ偏光子１１で直線偏光にされ、この直線偏光がセンサファイバ１２へ入射されるようになっている。ここで、センサファイバ１２は、捻りを加えることで旋光性を持たせた光ファイバ、望ましくは、アニーリングの施されていない石英ファイバであり、被測定電流の流れる導体Ｃの周りを周回して配置されている。すなわち、ファイバを透過する直線偏光が、導体Ｃを流れる電流によって発生する磁界に比例したファラデー旋光を受けるようになっている。
【００４１】
偏波面保持カプラ１３は、その軸が第１のファイバ偏光子１１の出射偏光軸に対して電流がゼロで基準温度の場合に４５°傾くように設置されている。この偏波面保持カプラ１３の一方の出射ポートに接続された第２のファイバ偏光子１４は、偏波面保持カプラ１３の軸と一致した偏光成分のみを透過するようになっており、偏波面保持カプラ１３の他方の出射ポートに接続された第３のファイバ偏光子１５は、偏波面保持カプラ１３の軸と直交した成分のみを透過するようになっている。すなわち、これらの第２、第３のファイバ偏光子１４，１５は、センサファイバ１２で生じた偏波面の回転を、直交する２方位の偏光成分の光強度信号に変換するようになっている。
【００４２】
そして、第２、第３のファイバ偏光子１４，１５で得られた２方向の偏光成分の光強度信号は、受信ファイバ１６，１７によって２つの検出器８，９まで伝送され、これらの検出器８，９でそれぞれ光電変換されるようになっている。なお、２つの検出器８，９で得られた２つの信号から、電子回路１０によって電流値を演算し、得られた信号を出力する点は、前述した第１の実施の形態と同様である。
【００４３】
［作用効果］
以上のような構成の光電流測定装置によれば、第１の実施の形態の作用効果に加えて、次のような作用効果が得られる。
まず、光源２と２つの検出器８，９との間の部分を全て光ファイバ型の素子で構成したことにより、光の伝播経路中に空間が全く存在しないことになる。そのため、光電流測定装置が振動等を受けた場合でも、振動による光量の変化を生じることがなく、安定した出力を得ることができる。
【００４４】
また、この光電流測定装置において、電流に対するセンサの感度Ｓ_Iは、ヴェルデ定数（°／Ａ）をＶ、ファイバの巻き数をｎとすると、次の式(6)で表される。
【数４】
Ｓ_I＝Ｖ・ｎ … (6)
この式(6)からわかるように、センサファイバ１２の巻き数ｎを変えることによって、センサの感度を自由に変更することができ、様々な電流レンジの計測に容易に対応することができる。
【００４５】
また、この光電流測定装置において、温度に対するセンサの感度Ｓ_Tは、旋光の温度依存性（°／℃）をｄα／ｄＴ、ファイバの捻り回数をｍとすると、次の式(7)で表される。
【数５】
Ｓ_T＝ｄα／ｄＴ・ｍ … (7)
この式(7)からわかるように、温度に対するセンサの感度Ｓ_Tは、電流に対するセンサの感度Ｓ_Iとは何ら関係なしに、任意の感度を得ることができる。
【００４６】
［第３の実施の形態］
［構成］
図３は、本発明による光応用測定装置を適用した第３の実施の形態として、電圧測定装置の１つの形態を示す構成図である。この電圧測定装置は、前述した第１の実施の形態に係る図１の装置において、旋光性を有するファラデー素子６の代わりに、位相差板２１と旋光性を有するポッケルス素子２２を配置したものであり、他の部分は第１の実施の形態と同様に構成されている。以下には、この装置の構成の詳細について、光源２からの光が電子回路１０から信号として出力されるまでの流れに沿って順次説明する。
【００４７】
まず、光源２からの光が、送信ファイバ３を伝播して結合レンズ４で平行光にされ、偏光子５により直線偏光として出射される点は第１の実施の形態と同様である。本実施の形態において、偏光子５からの直線偏光は、位相差板２１を介してセンサとなるポッケルス素子２２に入射されるようになっている。
【００４８】
すなわち、偏光子５からの直線偏光をそのままポッケルス素子２２に入射して出射偏光状態を測定することによって電圧を測定した場合には、電圧が正の時と負の時で同じ信号が出力されてしまうため、位相差板２１を用いて光学的なバイアスを予め加えておくことが、一般的に行われている。位相差板２１から出射した光は、ポッケルス素子２２に入射され、ポッケルス素子２２を透過する間に、電圧によって発生する電界に比例した位相差を受け、ポッケルス素子２２から出射した光は、ＰＢＳ７に入射されるようになっている。ここで、センサとなるポッケルス素子２２としては、旋光性を有し、かつ、旋光の大きさが温度に依存する素子が使用されている。
【００４９】
なお、ＰＢＳ７によって、直交する２方位の偏光成分の光強度信号を得て、これらの光強度信号を２つの検出器８，９でそれぞれ光電変換する点は、第１の実施の形態と同様であるが、本実施の形態においては、検出器８，９で得られた２つの信号から、電子回路１０によって電圧値を演算し、信号を出力するようになっている。
【００５０】
この場合、電子回路１０では、次のような信号処理を行うことにより、温度および電圧を求めるようになっている。
２つの検出器８，９で光電変換された２つの信号は、電圧ゼロのときに出力されているバイアス成分と電流による変調成分に分けて考えることができる。
【００５１】
まず、電圧がゼロのときに出力されているバイアス成分のｘ成分Ｖｘとｙ成分Ｖｙは、Ｋは損失も含めた入射光強度をＫ、温度による旋光の変化（°）をΔαとすると、次の式(8)、(9)でそれぞれ表される。
【数６】
Ｖｘ＝Ｋ・ｓｉｎ（４５°＋Δα） … (8)
Ｖｙ＝Ｋ・ｃｏｓ（４５°＋Δα） … (9)
【００５２】
これらの式(8)、(9)式から、次の式(10)が得られる。
【数７】

この式(10)からわかるように、バイアス成分のｘ成分Ｖｘとｙ成分Ｖｙから温度による旋光の変化Δαを求めることができるため、温度とΔαとの関係が既知であれば、温度を求めることができる。
【００５３】
また、電圧は、ポッケルス効果によって生じる位相変化による偏光度の変化を測定することによって求めることができる。
【００５４】
［作用効果］
以上のように、本実施の形態においては、旋光性を有するファラデー素子６という同一のセンサで電圧と温度の両方を測定することができる。そのため、構成が単純化してコストの低減、信頼性の向上が期待できることに加えて、次のような効果が得られる。
【００５５】
すなわち、センサがセンサ素子そのものの温度を測定していることから、電圧センサ近辺に温度センサを取り付けた場合に問題となる取付位置での温度差を考慮する必要がなく、電圧測定時の温度による影響の補正を高精度に行うことができ、温度測定時の電界による影響の補正についても同様に高精度化が図れる。
【００５６】
また、電圧測定が不要で、温度測定のみを必要とする場合であっても、電圧測定装置と同一の機器構成で温度測定装置を実現できるため、機器の共通化が図れ、コスト低減と機器の信頼性の確保というメリットが得られる。
【００５７】
［他の実施の形態］
なお、本発明は、前述した実施の形態に限定されるものではなく、本発明の範囲内で他にも多種多様な形態が実施可能である。
例えば、第３の実施の形態の変形例として、第２の実施の形態と同様に、光源２と検出器８，９との間の部分を光ファイバ型の素子で構成することにより、第２の実施の形態と同様の作用効果を得ることができる。
【００５８】
すなわち、センサとなる光学素子として旋光性を有する光学素子を使用し、この光学素子の旋光性を補正することができる限り、直線偏光を出射する光源、センサとなる光学素子、光学素子を出射した光を光強度信号に変換する変換手段、光強度信号から特定の物理量を求める処理手段、等の各部の具体的な構成は自由に選択可能である。
【００５９】
【発明の効果】
以上説明したように、本発明においては、センサとなる光学素子として旋光性を有する光学素子を使用し、この光学素子の旋光性を補正することにより、温度による影響の補正を高精度に実現して電流・電圧を高精度に測定可能な、あるいは、温度自体を高精度に測定可能な、高精度で安定性に優れた小型の光応用測定装置を提供することができる。
【図面の簡単な説明】
【図１】本発明による光応用測定装置を適用した第１の実施の形態として、電流測定装置の１つの形態を示す構成図である。
【図２】本発明による光応用測定装置を適用した第２の実施の形態として、電流測定装置の別の形態を示す構成図である。
【図３】本発明による光応用測定装置を適用した第３の実施の形態として、電圧測定装置の１つの形態を示す構成図である。
【図４】従来技術による光応用電流測定装置の一例を示す構成図である。
【符号の説明】
Ｃ…導体
１…光源ドライバ
２…光源
３…送信ファイバ
４…結合レンズ
５…偏光子
６…ファラデー素子
７…ＰＢＳ
８，９…検出器
１０…電子回路
１１…第１のファイバ偏光子
１２…センサファイバ
１３…偏波面保持カプラ
１４…第２のファイバ偏光子
１５…第３のファイバ偏光子
１６，１７…受信ファイバ
２１…位相差板
２２…ポッケルス素子
３１…光源
３２…第１の光ファイバ
３３…第２の光ファイバ
３４…第１のＰＺファイバ
３５…ファイバコイル
３６…第２のＰＺファイバ
３７…検出器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical applied measurement device that measures changes in physical quantities using changes in polarization characteristics of optical elements, and more particularly to an optical applied measurement device suitable for current / voltage measurement and temperature measurement. It is.
[0002]
[Prior art]
Conventionally, photocurrent measuring devices that measure current using optical elements are small, highly insulating, have no degradation in linearity due to saturation, and are nonflammable with high-speed response. Has attracted attention as an ideal measuring device used for current measurement. A typical photocurrent measuring device using optics uses an optical element arranged in the vicinity of an electric conductor or a fiber coil made of a single mode fiber surrounding the electric conductor as a sensor.
[0003]
In these photocurrent measuring devices, as a result of the magneto-optical Faraday effect, the polarization direction of light passing through an optical element such as a fiber coil changes according to the change in the current flowing through the conductor. Here, the Faraday effect is that when a linearly polarized beam passes through a substance in the magnetic field direction, the plane of polarization of the linearly polarized light rotates, and is a result of Faraday birefringence. Faraday birefringence is a difference in refractive index between left circularly polarized light and right circularly polarized light that passes through a material parallel to a magnetic field.
[0004]
On the other hand, the sensitivity of the optical current measuring device, varies greatly with the temperature change, for example, a very accurate optical current measuring device used in an environment having a temperature range varying widely as -40 ℃ ~ + 80 ℃ Are recognized to fluctuate unacceptably.
[0005]
In the technical literature, it has been recognized that the influence of temperature on the sensitivity of a fiber coil is related to the following three different phenomena for a photocurrent measuring device using a fiber coil as a sensor. That is, (i) change in linear birefringence of the detection fiber, (ii) change in linear birefringence due to stress induced by the material protecting the detection fiber, and (iii) change in the Verde constant of the fiber core material.
[0006]
Here, the Verde constant is an equation representing the Faraday effect, and is a proportional constant V of θ = μNVI. Where θ is the rotation angle of the polarization plane, μ is the transmittance of the fiber core material, N is the number of turns of the surrounding fiber loop, and I is the current of the conductor. In other words, the Verde constant is equal to the rotation angle of plane polarized light in a material with a given magnetic field divided by the product of the optical path length of the material and the strength of the magnetic field, and the temperature and wavelength of the optical signal. Are both functions.
[0007]
Conventionally, several techniques have been proposed in order to correct sensitivity fluctuations caused by such temperature fluctuations in the photocurrent measuring device.
For example, devices are known that monitor the temperature near the sensor and adjust the value of the detector output according to empirical data related to the temperature dependence of the Verde constant. Such an apparatus complicates electronic processing and increases the number of optoelectronic components, which generally increases the cost of the apparatus.
[0008]
On the other hand, as a method for correcting the variation in sensitivity due to temperature without increasing the cost, for example, JP-A-11-512826 proposes a method using optical rotation of a fiber. FIG. 4 is a block diagram showing the configuration of this conventional photocurrent measuring device.
[0009]
In the photocurrent measuring apparatus shown in FIG. 4, the input end of the fiber coil 35 is connected to the light source 31 via the first optical fiber 32, the second optical fiber 33, and the first PZ fiber 34. The output end of the fiber coil 35 is connected to a detector 37 via a second PZ fiber 36 that is adjusted to a predetermined preferred bias angle.
[0010]
In this photocurrent measuring device, the pre-selected channel of the output of the fiber coil 35 is adjusted by the axis of the second PZ fiber 32 to correct the variation of the Verde constant due to temperature. That is, the change in the sensor sensitivity due to the temperature dependence of the Verde constant is corrected using the change in the bias angle due to the temperature dependence of the belly phase of the fiber coil.
[0011]
[Problems to be solved by the invention]
However, the conventional photocurrent measuring apparatus as described above has the following problems.
[0012]
That is, in the photocurrent measuring apparatus of FIG. 4, as described above, in order to correct the sensor sensitivity variation due to the temperature dependence of the Verde constant, the physical rotation and detection of the input polarizer, the output polarizer, or the detection element are performed. so-called Berry phase is circular birefringence contribute apparent shape of the coil utilizes the temperature dependence of (Berry phase). In this case, both the temperature dependence of the Verde constant and the temperature dependence of the belly phase generally change almost linearly with respect to the temperature, whereas the relationship between the belly phase and the sensitivity of the photocurrent measuring device is Non-linear.
[0013]
Therefore, there is a limit to the accuracy that can be realized by the apparatus shown in FIG. 4, and if the operating temperature range exceeds a certain limit, the error is increased. Furthermore, since it is difficult to grasp the temperature characteristics of the belly phase at the time of design, this also makes it difficult to improve the accuracy of the photocurrent measuring device.
In addition, when performing correction using a temperature sensor arranged in the vicinity of the current sensor of the photocurrent measuring device, it is difficult to accurately grasp the temperature difference due to the mounting position of the current sensor and the temperature sensor. Also in this case, it is difficult to perform highly accurate current measurement.
[0014]
On the other hand, this problem of the accuracy limit due to the temperature fluctuation as described above is not limited to the photocurrent measuring device but also exists in the photovoltage measuring device, and is generally used in these optical application measuring devices. It is a problem to be solved.
[0015]
The present invention has been proposed in order to eliminate the above-described drawbacks of the prior art, and its purpose is to enable accurate measurement of current and voltage with high-precision correction of the influence of temperature. Alternatively, it is to provide a small-sized optical application measuring apparatus that can measure the temperature itself with high accuracy and has high accuracy and excellent stability.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the present invention uses an optical element having optical rotation as an optical element serving as a sensor, and corrects the optical rotation of the optical element, thereby adjusting physical quantities such as current, voltage, and temperature. It is possible to measure with high accuracy.
[0017]
The invention described in claim 1
(a) one light source that emits linearly polarized light;
(b) an optical rotation that changes the polarization direction of the incident linearly polarized light, an optical element that changes the polarization direction of the incident linearly polarized light in proportion to a specific physical quantity, and
(c) When the specific physical quantity is zero, the light emitted linearly polarized light passes through the optical element, and when the specific physical quantity exists, the light emitted linearly polarized light passes through the optical element, Conversion means for converting into light intensity signals of polarization components in two directions,
(d) When the specific physical quantity is zero, based on the light intensity signal of the polarized light component in two directions obtained by the conversion means based on the light emitted through the optical element through the linearly polarized light, the optical element A processing means for determining an optical rotation change amount depending on the temperature, and determining a temperature of the optical element based on the optical rotation change amount;
(e) Based on the light emitted from the linearly polarized light that has passed through the optical element in the presence of the specific physical quantity, the processing means uses the light intensity signal of the polarization component in two directions obtained by the conversion means. In determining the specific physical quantity, the polarization azimuth amount of the optical element based on the specific physical quantity is corrected based on the temperature determined based on the optical rotation.
[0018]
According to the present invention, even if an optical element having optical rotation is used by acquiring the light intensity signal of the polarization component in two directions from the light emitted from the optical element having optical rotation and correcting it by the processing means, Since the optical rotation can be corrected, physical quantities such as current, voltage and temperature can be measured with high accuracy.
[0019]
According to a second aspect of the present invention, in the optical applied measurement apparatus according to the first aspect, the optical element having optical rotation is an optical element whose magnitude of optical rotation depends on temperature, and the processing means is an optical rotation of the optical element. It is characterized in that the temperature is obtained from the size.
According to the present invention, by using an optical element having a temperature dependency on the magnitude of the optical rotation, temperature measurement with high accuracy can be performed based on the magnitude of the optical rotation of the optical element.
[0020]
According to a third aspect of the present invention, in the optical applied measurement apparatus according to the second aspect, the optical element having optical rotation is a Faraday element that makes linearly polarized light from a light source incident and changes its polarization direction in proportion to a magnetic field. And the processing means is configured to obtain the magnitude of the applied magnetic field or the magnitude of the current that generated the magnetic field from the light intensity signal of the polarization component in two directions obtained by the converting means. It is characterized by that.
[0021]
According to the present invention, it is possible to measure two kinds of physical quantities, that is, a magnetic field or current and temperature, with one sensor called a Faraday element having optical rotation, and the sensitivity of the sensor itself to the magnetic field and temperature can be mutually adjusted. By correcting each other, highly accurate measurement is possible.
[0022]
According to a fourth aspect of the present invention, in the optical applied measuring apparatus according to the second aspect, the optical element having optical rotation is a Pockels element that makes linearly polarized light from a light source incident and changes its polarization state in proportion to an electric field. And the processing means is configured to obtain the magnitude of the applied electric field or the voltage that generated the electric field from the light intensity signal of the polarization component in two directions obtained by the converting means. It is said.
[0023]
According to the present invention, it is possible to measure two kinds of physical quantities, that is, an electric field or voltage and temperature, with a single sensor called a Pockels element having optical rotation, and the sensitivity of the sensor itself to the electric field and temperature can be mutually adjusted. By correcting each other, highly accurate measurement is possible.
[0024]
According to a fifth aspect of the present invention, in the optical applied measuring apparatus according to any one of the first to fourth aspects, the optical element having optical rotation is an optical fiber to which twisting is applied.
According to a sixth aspect of the present invention, in the optical applied measuring apparatus according to the fifth aspect, the twisted optical fiber is an unannealed quartz fiber.
[0025]
According to these inventions of claims 5 and 6, by using an optical fiber having optical rotation as a sensor, in particular, a twisted optical fiber, the magnetic field / current, electric field / voltage, or temperature to be measured is measured. Since the sensitivity to physical quantities such as these can be arbitrarily adjusted, the range of use of the sensor can be greatly expanded.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
[Constitution]
FIG. 1 is a block diagram showing one form of a current measuring apparatus as a first embodiment to which an optical applied measuring apparatus according to the present invention is applied. This current measuring device includes a light source driver 1, a light source 2, a transmission fiber 3, a coupling lens 4, a polarizer 5, a Faraday element 6, a PBS (polarizing beam splitter) 7, two detectors 8 and 9, and an electronic circuit 10. It has. Below, the detail of the structure of this apparatus is demonstrated sequentially along the flow until the light from the light source 2 is output as a signal from the electronic circuit 10. FIG.
[0027]
First, light from the light source 2 driven by the light source driver 1 propagates through the transmission fiber 3 and is collimated by the coupling lens 4, and only one linearly polarized component in the axial direction of the polarizer is emitted by the polarizer 5. And is incident on the Faraday element 6. That is, these components 1 to 5 constitute the “light source that emits linearly polarized light” in the present invention.
[0028]
Further, as the Faraday element 6 serving as a sensor, an element having optical activity and whose optical rotation depends on temperature is used, and this Faraday element 6 is in the vicinity of the conductor C through which the current to be measured flows. Is installed. That is, the linearly polarized light incident on the Faraday element 6 from the polarizer 5 receives Faraday rotation in proportion to the magnetic field generated by the current flowing through the conductor C while passing through the Faraday element 6. The light emitted from the Faraday element 6 enters the PBS 7.
[0029]
Here, the PBS 7 is installed so that the incident polarization azimuth is 45 ° when the Faraday optical rotation angle is zero and the reference temperature, and the light from the Faraday element 6 that is a sensor is incident to be orthogonal to two directions. A light intensity signal of the polarization component is obtained. That is, this PBS 7 corresponds to the conversion means in the present invention.
[0030]
Then, the light intensity signals of the two-directional polarization components obtained by the PBS 7 are photoelectrically converted by the two detectors 8 and 9, respectively, and the current value is calculated by the electronic circuit 10 from the obtained two signals. The output signal is output. That is, the detectors 8 and 9 and the electronic circuit 10 constitute processing means in the present invention.
[0031]
In this case, the electronic circuit 10 obtains the temperature and current by performing the following signal processing.
The two signals photoelectrically converted by the two detectors 8 and 9 can be divided into a bias component output when the current is zero and a modulation component due to the current.
[0032]
First, the x component Vx and the y component Vy of the bias component that are output when the current is zero are as follows. If K is the incident light intensity including loss and K is the change in optical rotation (°) with temperature, Δα Represented by equations (1) and (2), respectively.
[Expression 1]
Vx = K · sin ² (45 ° + Δα) (1)
Vy = K · cos ² (45 ° + Δα) (2)
[0033]
From these equations (1) and (2), the following equation (3) is obtained.
[Expression 2]

As can be seen from this equation (3), since the change Δα of the optical rotation due to the temperature can be obtained from the x component Vx and the y component Vy of the bias component, the temperature is obtained if the relationship between the temperature and Δα is known. Can do.
[0034]
Further, the x component Vx and the y component Vy of the modulation component due to the current are expressed by the following equations (4) and (5), respectively, where F is the Faraday rotation angle due to the current.
[Equation 3]
Vx = K · {sin (45 ° + Δα + F) −sin (45 ° + Δα)} ²
… (Four)
Vy = K · {cos (45 ° + Δα + F) −cos (45 ° + Δα)} ²
… (Five)
Here, since Δα is obtained from the equation (3), the current can be obtained by obtaining the Faraday rotation angle F from the equations (4) and (5).
[0035]
[Function and effect]
As described above, in the present embodiment, both the current and the temperature can be measured by the same sensor called the Faraday element 6 having optical rotation. Therefore, in addition to the simplification of the configuration that can be expected to reduce costs and improve reliability, the following effects can be obtained.
[0036]
That is, for example, even if the sensor's Verde constant is temperature-dependent, since this sensor measures the temperature of the sensor element itself, a current sensor that is problematic when a temperature sensor is attached in the vicinity of the current sensor It is not necessary to consider the temperature difference at the temperature sensor mounting position, and the influence of temperature during current measurement can be corrected with high accuracy. Of course, it goes without saying that high accuracy can be achieved for the correction of the influence of the magnetic field during temperature measurement as well.
[0037]
Even if current measurement is not required and only temperature measurement is required, the temperature measurement device can be realized with the same device configuration as the current measurement device. The merit of ensuring reliability is obtained.
[0038]
[Second Embodiment]
[Constitution]
FIG. 2 is a block diagram showing another embodiment of the current measuring device as the second embodiment to which the optical applied measuring device according to the present invention is applied. This current measuring device is a device in which the portion between the light source 2 and the two detectors 8 and 9 in the device of FIG. 1 according to the first embodiment described above is composed of optical fiber elements. .
[0039]
That is, the transmission fiber 3, the first fiber polarizer 11, the sensor fiber 12, and the polarization plane holding coupler 13 are sequentially connected to the light source 2. A second fiber polarizer 14 and a third fiber polarizer 15 are connected to each output port of the polarization-maintaining coupler 13, and these polarizers 14 and 15 are connected via receiving fibers 16 and 17. It is connected to two detectors 8 and 9, respectively. Below, the detail of the structure of this apparatus is demonstrated sequentially along the flow until the light from the light source 2 is output as a signal from the electronic circuit 10. FIG.
[0040]
First, light from the light source 2 driven by the light source driver 1 propagates through the transmission fiber 3 and is linearly polarized by the first fiber polarizer 11, and this linearly polarized light enters the sensor fiber 12. ing. Here, the sensor fiber 12 is an optical fiber having optical rotation by twisting, preferably a quartz fiber that is not annealed, and is arranged around the conductor C through which the current to be measured flows. Has been. That is, the linearly polarized light transmitted through the fiber is subjected to Faraday rotator proportional to the magnetic field generated by the current flowing through the conductor C.
[0041]
The polarization plane holding coupler 13 is installed such that its axis is inclined by 45 ° with respect to the output polarization axis of the first fiber polarizer 11 when the current is zero and the reference temperature. The second fiber polarizer 14 connected to one output port of the polarization-maintaining coupler 13 transmits only the polarization component that coincides with the axis of the polarization-maintaining coupler 13. The third fiber polarizer 15 connected to the other output port 13 transmits only the component orthogonal to the axis of the polarization-maintaining coupler 13. That is, the second and third fiber polarizers 14 and 15 convert the rotation of the polarization plane generated in the sensor fiber 12 into light intensity signals of polarization components in two orthogonal directions.
[0042]
Then, the light intensity signals of the polarization components in the two directions obtained by the second and third fiber polarizers 14 and 15 are transmitted to the two detectors 8 and 9 by the receiving fibers 16 and 17, and these detectors. The photoelectric conversion is performed at 8 and 9, respectively. The point that the electronic circuit 10 calculates the current value from the two signals obtained by the two detectors 8 and 9 and outputs the obtained signal is the same as in the first embodiment. .
[0043]
[Function and effect]
According to the photocurrent measuring device configured as described above, the following operational effects can be obtained in addition to the operational effects of the first embodiment.
First, since all portions between the light source 2 and the two detectors 8 and 9 are configured by optical fiber type elements, there is no space in the light propagation path. Therefore, even when the photocurrent measuring device receives vibration or the like, a stable output can be obtained without causing a change in the amount of light due to the vibration.
[0044]
In this photocurrent measuring device, the sensitivity S _I of the sensor with respect to the current is expressed by the following equation (6), where V is the Verde constant (° / A) and n is the number of turns of the fiber.
[Expression 4]
S _I = V · n (6)
As can be seen from this equation (6), by changing the number of turns n of the sensor fiber 12, the sensitivity of the sensor can be freely changed, and the measurement of various current ranges can be easily handled.
[0045]
In this photocurrent measuring device, the sensitivity S _T of the sensor with respect to temperature is expressed by the following equation (7), where dα / dT is the temperature dependency of optical rotation (° / ° C.) and m is the number of twists of the fiber. Is done.
[Equation 5]
S _T = dα / dT · m (7)
As can be seen from this equation (7), the sensitivity S _T of the sensor with respect to the temperature can obtain an arbitrary sensitivity regardless of the sensitivity S _I of the sensor with respect to the current.
[0046]
[Third Embodiment]
[Constitution]
FIG. 3 is a configuration diagram showing one form of a voltage measuring apparatus as a third embodiment to which the optical applied measuring apparatus according to the present invention is applied. This voltage measuring device is a device in which a phase difference plate 21 and a Pockels element 22 having optical activity are arranged instead of the Faraday element 6 having optical activity in the device of FIG. 1 according to the first embodiment described above. Yes, and other parts are configured in the same manner as in the first embodiment. Below, the detail of the structure of this apparatus is demonstrated sequentially along the flow until the light from the light source 2 is output as a signal from the electronic circuit 10. FIG.
[0047]
First, the light from the light source 2 propagates through the transmission fiber 3, is converted into parallel light by the coupling lens 4, and is emitted as linearly polarized light by the polarizer 5, as in the first embodiment. In the present embodiment, the linearly polarized light from the polarizer 5 is made incident on the Pockels element 22 serving as a sensor via the phase difference plate 21.
[0048]
That is, when the voltage is measured by directly entering the linearly polarized light from the polarizer 5 into the Pockels element 22 and measuring the outgoing polarization state, the same signal is output when the voltage is positive and negative. Therefore, it is common practice to apply an optical bias in advance using the phase difference plate 21. The light emitted from the phase difference plate 21 is incident on the Pockels element 22, receives a phase difference proportional to the electric field generated by the voltage while passing through the Pockels element 22, and the light emitted from the Pockels element 22 enters the PBS 7. It is designed to be incident. Here, as the Pockels element 22 serving as a sensor, an element having optical activity and whose optical rotation depends on temperature is used.
[0049]
Note that the PBS 7 obtains light intensity signals of polarized components in two orthogonal directions and photoelectrically converts these light intensity signals by the two detectors 8 and 9, respectively, as in the first embodiment. However, in this embodiment, a voltage value is calculated by the electronic circuit 10 from the two signals obtained by the detectors 8 and 9, and a signal is output.
[0050]
In this case, the electronic circuit 10 obtains the temperature and voltage by performing the following signal processing.
The two signals photoelectrically converted by the two detectors 8 and 9 can be divided into a bias component output when the voltage is zero and a modulation component due to current.
[0051]
First, the x component Vx and the y component Vy of the bias component output when the voltage is zero, K is the incident light intensity including loss and K is the change of optical rotation (°) due to temperature. (8) and (9), respectively.
[Formula 6]
Vx = K · sin (45 ° + Δα) (8)
Vy = K · cos (45 ° + Δα) (9)
[0052]
From these equations (8) and (9), the following equation (10) is obtained.
[Expression 7]

As can be seen from this equation (10), since the change of optical rotation Δα due to temperature can be obtained from the x component Vx and the y component Vy of the bias component, the temperature is obtained if the relationship between the temperature and Δα is known. Can do.
[0053]
The voltage can be obtained by measuring a change in the degree of polarization due to a phase change caused by the Pockels effect.
[0054]
[Function and effect]
As described above, in the present embodiment, both the voltage and the temperature can be measured by the same sensor called the Faraday element 6 having optical rotation. Therefore, in addition to the simplification of the configuration that can be expected to reduce costs and improve reliability, the following effects can be obtained.
[0055]
In other words, since the sensor measures the temperature of the sensor element itself, it is not necessary to consider the temperature difference at the mounting position that becomes a problem when a temperature sensor is mounted in the vicinity of the voltage sensor. The influence can be corrected with high accuracy, and the correction of the influence due to the electric field at the time of temperature measurement can be similarly improved.
[0056]
Even when voltage measurement is unnecessary and only temperature measurement is required, the temperature measurement device can be realized with the same device configuration as the voltage measurement device, so that the devices can be shared, cost reduction and device The merit of ensuring reliability is obtained.
[0057]
[Other embodiments]
The present invention is not limited to the above-described embodiments, and various other forms can be implemented within the scope of the present invention.
For example, as a modification of the third embodiment, as in the second embodiment, the portion between the light source 2 and the detectors 8 and 9 is configured by an optical fiber type element, so that the second The same effect as the embodiment can be obtained.
[0058]
In other words, an optical element having optical activity is used as an optical element serving as a sensor, and a light source that emits linearly polarized light, an optical element serving as a sensor, and an optical element are emitted as long as the optical rotation of the optical element can be corrected. Specific configurations of each unit such as a conversion unit that converts light into a light intensity signal and a processing unit that obtains a specific physical quantity from the light intensity signal can be freely selected.
[0059]
【The invention's effect】
As described above, in the present invention, an optical element having optical rotation is used as an optical element serving as a sensor, and the optical rotation of this optical element is corrected, thereby correcting the influence of temperature with high accuracy. Therefore, it is possible to provide a small optical application measuring apparatus that can measure current and voltage with high accuracy or can measure temperature itself with high accuracy and has high accuracy and excellent stability.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing one form of a current measuring device as a first embodiment to which an optical applied measuring device according to the present invention is applied.
FIG. 2 is a configuration diagram showing another embodiment of a current measuring device as a second embodiment to which the optical applied measuring device according to the present invention is applied.
FIG. 3 is a configuration diagram showing one form of a voltage measuring apparatus as a third embodiment to which the optical applied measuring apparatus according to the present invention is applied.
FIG. 4 is a configuration diagram showing an example of an optical applied current measuring device according to the prior art.
[Explanation of symbols]
C ... Conductor 1 ... Light source driver 2 ... Light source 3 ... Transmission fiber 4 ... Coupling lens 5 ... Polarizer 6 ... Faraday element 7 ... PBS
8, 9 ... Detector 10 ... Electronic circuit 11 ... First fiber polarizer 12 ... Sensor fiber 13 ... Polarization plane maintaining coupler 14 ... Second fiber polarizer 15 ... Third fiber polarizer 16, 17 ... Reception fiber DESCRIPTION OF SYMBOLS 21 ... Phase difference plate 22 ... Pockels element 31 ... Light source 32 ... 1st optical fiber 33 ... 2nd optical fiber 34 ... 1st PZ fiber 35 ... Fiber coil 36 ... 2nd PZ fiber 37 ... Detector

Claims (5)

One light source that emits linearly polarized light;
An optical rotation that changes the polarization direction of the incident linearly polarized light, an optical element that changes the polarization direction of the incident linearly polarized light in proportion to a specific physical quantity, and
When the specific physical quantity is zero, the linearly polarized light exits through the optical element, and when the specific physical quantity exists, the linearly polarized light exits through the optical element in two directions. Conversion means for converting into a light intensity signal of the polarization component of
Depends on the temperature of the optical element from the light intensity signal of the polarization component in two directions obtained by the conversion means based on the light emitted by the linearly polarized light passing through the optical element when the specific physical quantity is zero And a processing means for determining the optical rotation change amount and determining the temperature of the optical element based on the optical rotation change amount,
Based on the light emitted by the linearly polarized light passing through the optical element in the presence of the specific physical quantity, the processing means determines the specific intensity from the light intensity signals of the two-directional polarization components obtained by the conversion means. In determining a physical quantity, an optical applied measurement apparatus , wherein the polarization azimuth amount of an optical element based on the specific physical quantity is corrected based on a temperature determined based on the optical rotation . The optical element having optical rotatory power is a Faraday element that receives linearly polarized light from the light source and changes the polarization direction in proportion to a magnetic field, and the processing means has two directions obtained by the converting means. 2. The applied optical measurement apparatus according to claim 1, wherein the apparatus is configured to obtain a magnitude of a given magnetic field or a magnitude of a current that generates the magnetic field from a light intensity signal of a polarization component. . The optical element having optical rotatory power is a Pockels element that enters linearly polarized light from the light source and changes its polarization state in proportion to an electric field, and the processing means has two directions obtained by the converting means. 2. The optical applied measurement apparatus according to claim 1, wherein the apparatus is configured to obtain a magnitude of a given electric field or a voltage generating the electric field from a light intensity signal of a polarization component. The optical applied measuring apparatus according to claim 1 , wherein the optical element having optical rotation is an optical fiber to which twisting is applied. Optical fiber plus the twist is applied optical measurement apparatus according to claim 4, characterized in that a quartz fiber which was not subjected to annealing.

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