JP2009053045A - Optical fiber hydrogen sensor and hydrogen detection system using the same - Google Patents

Optical fiber hydrogen sensor and hydrogen detection system using the same Download PDF

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JP2009053045A
JP2009053045A JP2007220097A JP2007220097A JP2009053045A JP 2009053045 A JP2009053045 A JP 2009053045A JP 2007220097 A JP2007220097 A JP 2007220097A JP 2007220097 A JP2007220097 A JP 2007220097A JP 2009053045 A JP2009053045 A JP 2009053045A
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hydrogen
optical fiber
light
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hydrogen sensor
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Eiki Mimura
三村榮紀
Noriyuki Hamada
浜田則幸
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FIBERLABS Inc
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<P>PROBLEM TO BE SOLVED: To realize an optical fiber hydrogen sensor, requiring no optical setting, having a high response speed and high sensitivity and being easy to be mass-produced, and to provide a hydrogen detection system that uses the sensor. <P>SOLUTION: A change in the bending loss produced in a partially thinned constricted part 12 by the volumetric expansion due to the hydrogen occulusion of a hydrogen-occuluding film 13 is detected by an optical fiber 11 equipped with the constricted part 12, the hydrogen-occuluding film 13 adhered to a part of the side surface of the constricted part 12 over the longitudinal direction that includes the constricted part 12, and the reflecting means 14 provided to the end surface near the constricted part 12 of the optical fiber 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、光ファイバを使って水素を検知する光ファイバ水素センサ及びそれを用いた水素検知システムに関し、より具体的には、光ファイバの曲げ損失を検出して水素を検知する光ファイバ水素センサ及びそれを用いた水素検知システムに関する。 The present invention relates to an optical fiber hydrogen sensor that detects hydrogen using an optical fiber and a hydrogen detection system using the same, and more specifically, an optical fiber hydrogen sensor that detects hydrogen by detecting a bending loss of an optical fiber. And a hydrogen detection system using the same.

光ファイバセンサは、防爆性、耐電磁ノイズ特性に優れ、遠隔、多点モニタリングが容易なことから今後幅広い分野での利用が期待されており、光ファイバ水素センサもそれらの利点のため開発が望まれている。   Optical fiber sensors are expected to be used in a wide range of fields because of their excellent explosion-proof and electromagnetic noise resistance characteristics, and easy remote and multi-point monitoring. Optical fiber hydrogen sensors are also expected to be developed because of their advantages. It is rare.

光ファイバ、或いは、光学的手段により水素を検知するセンサが、特許文献１、２、３、４、非特許文献１に記載されている。 Patent Documents 1, 2, 3, 4, and Non-Patent Document 1 describe sensors that detect hydrogen using an optical fiber or optical means.

非特許文献１には、光ファイバのクラッドに、水素により着色するＷＯ３等の調光ガラス材料を用いて、エバネッセント波の光吸収より水素を検知するライン状水素センサが開示されている。 Non-Patent Document 1 discloses a line-shaped hydrogen sensor that detects hydrogen by light absorption of an evanescent wave by using a light control glass material such as WO3 colored with hydrogen in the clad of an optical fiber.

特許文献１には、水素感応調光ミラーの水素化に伴う光の透過率や反射率の変化を光学的に検知する水素センサが開示されている。 Patent Document 1 discloses a hydrogen sensor that optically detects changes in light transmittance and reflectance associated with hydrogenation of a hydrogen-sensitive dimming mirror.

特許文献２には、白金、ロジウムなど水素ガスを吸着解離する触媒金属膜の透過率や反射率の変化を光学的に検出する水素センサが開示されている。 Patent Document 2 discloses a hydrogen sensor that optically detects changes in transmittance and reflectance of a catalytic metal film that adsorbs and dissociates hydrogen gas such as platinum and rhodium.

特許文献３には、Ｍｇ-Ｎｉ合金薄膜の水素化を、表面の光学反射率の変化により検知する水素センサが開示されている。 Patent Document 3 discloses a hydrogen sensor that detects hydrogenation of an Mg—Ni alloy thin film by a change in optical reflectance of the surface.

特許文献４には、水素吸蔵合金膜の体積膨張によって起こるガラス基板の歪みを光学的手法で検出する水素センサが開示されている。
特開２００５−２６５５９０号公報 特開平５−１９６５６９号公報 特開２００５−８３８３２号公報 特許第３８６６００１号公報 岡崎ら、“光ファイバを使ったライン状水素センサの検討”、第２３回光波センシング技術研究会、LST23-22，pp.147-152(1999) Patent Document 4 discloses a hydrogen sensor that detects distortion of a glass substrate caused by volume expansion of a hydrogen storage alloy film by an optical method.
JP 2005-265590 A Japanese Patent Laid-Open No. 5-19669 JP 2005-83832 A Japanese Patent No. 3866001 Okazaki et al., “Examination of line-shaped hydrogen sensor using optical fiber”, 23rd Lightwave Sensing Technology Study Group, LST23-22, pp.147-152 (1999)

しかしながら、非特許文献１に開示されている水素センサでは、酸化タングステンの耐水性が悪いため、センサ寿命が短く、また水素に対する反応特性の経時変化が著しいという問題があった。 However, the hydrogen sensor disclosed in Non-Patent Document 1 has problems in that the water resistance of tungsten oxide is poor, so that the sensor life is short, and the change in the reaction characteristics with respect to hydrogen is significant over time.

特許文献１、２、３、で開示されている水素感応調光ミラー、白金、ロジウムなどの触媒金属、Ｍｇ-Ｎｉ合金薄など、水素感応材料の透過率や反射率変化を検知するセンサでは、基板上に製膜した水素感応膜の透過率や反射率変化を検出するための精密な光学的セッティングが必要であり、光学部品の僅かな位置ずれで検出光強度が変化してしまうという問題があった。 In sensors that detect changes in the transmittance and reflectance of hydrogen-sensitive materials, such as hydrogen-sensitive dimming mirrors disclosed in Patent Documents 1, 2, and 3, catalyst metals such as platinum and rhodium, and Mg-Ni alloy thins, Precise optical settings are required to detect changes in the transmittance and reflectance of the hydrogen-sensitive film formed on the substrate, and the problem is that the detected light intensity changes due to slight displacement of the optical components. there were.

このような光学的セッティングの煩雑さをなくすために、水素感応膜を光ファイバ端面に直接製膜して反射率変化を測定する方法が考えられるが、このような方法は応答速度が遅くなるという問題があった。特許文献３に開示されているように、透過率測定は、膜全体が水素化するのに時間を要すため応答が遅く、膜表面の変化を直ぐに反映できる反射率測定のほうが速い応答が得られる。しかしながら、光ファイバ端面に水素感応膜を直接製膜した場合は、水素に暴露されている膜表面から水素化が起こり、光ファイバ端面に達するまで時間を要すため、反射率測定であっても応答が遅くなってしまうという問題が生じる。 In order to eliminate the complexity of such optical settings, a method of measuring the reflectance change by directly forming a hydrogen sensitive film on the end face of the optical fiber can be considered, but such a method is said to slow down the response speed. There was a problem. As disclosed in Patent Document 3, the transmittance measurement takes a long time to hydrogenate the entire film, so the response is slow, and the reflectance measurement that can immediately reflect changes in the film surface gives a faster response. It is done. However, when a hydrogen sensitive film is formed directly on the end face of an optical fiber, hydrogenation occurs from the surface of the film exposed to hydrogen, and it takes time to reach the end face of the optical fiber. There arises a problem that the response becomes slow.

特許文献４に開示されている水素吸蔵合金膜の体積膨張によって起こるガラス基板の歪みを光学的手法で検出する水素センサでは、基板の歪み測定に光テコ法のような複雑な光学装置を必要とするため、精密な光学的セッティングが必要であり、装置が複雑で高価になるという問題があった。 In a hydrogen sensor that detects distortion of a glass substrate caused by volume expansion of a hydrogen storage alloy film disclosed in Patent Document 4 by an optical method, a complicated optical device such as an optical lever method is required to measure the distortion of the substrate. Therefore, precise optical setting is necessary, and there is a problem that the apparatus is complicated and expensive.

本発明は、上記に鑑みてなされたもので、その目的としては、煩雑な光学的セッティングが不要で、応答速度が早く、高感度で、量産容易な水素センサおよびそれを用いた水素検知システムを提供することにある。 The present invention has been made in view of the above, and has as its purpose a hydrogen sensor that does not require complicated optical settings, has a high response speed, is highly sensitive, and is easily mass-produced, and a hydrogen detection system using the same. It is to provide.

そのため、本発明は、（１）部分的に細くなった括れ部と、当該括れ部を含む長手方向にわたり、側面の一部に付着させた水素吸蔵膜と、当該括れ部に近い端面に反射手段を具備した光ファイバ（１１）からなることを特徴とする光ファイバ水素センサを提供する。 Therefore, the present invention provides (1) a partially narrowed constricted portion, a hydrogen storage film attached to a part of the side surface in the longitudinal direction including the constricted portion, and a reflecting means on an end face close to the constricted portion. An optical fiber hydrogen sensor comprising: an optical fiber (11) comprising:

また、（２）当該水素吸蔵膜がＰｄ、Ｐｄ合金、Ｌａ−Ｎｉ合金、希土類金属−Ｎｉ合金、Ｍｇ−Ｎｉ合金であることを特徴とする光ファイバ水素センサを提供する。   (2) An optical fiber hydrogen sensor characterized in that the hydrogen storage film is Pd, Pd alloy, La—Ni alloy, rare earth metal-Ni alloy, or Mg—Ni alloy.

また、（３）熱膨張率が当該水素吸蔵膜と類似し、且つ、水素により体積変化を起こさない材質からなる熱膨張相殺膜を、当該水素吸蔵膜と対称的に配置することにより、温度による曲げ損失変化の影響を軽減したことを特徴とする光ファイバ水素センサを提供する。 Further, (3) a thermal expansion counterbalance film made of a material having a thermal expansion coefficient similar to that of the hydrogen storage film and not causing a volume change by hydrogen is arranged symmetrically with the hydrogen storage film, thereby depending on the temperature. An optical fiber hydrogen sensor characterized by reducing the influence of a bending loss change is provided.

また、（４）当該水素吸蔵膜の材質がＰｄであり、当該熱膨張相殺膜が炭素鋼或いは純鉄であることを特徴とする光ファイバ水素センサを提供する。 (4) The optical fiber hydrogen sensor is characterized in that the hydrogen storage film is made of Pd and the thermal expansion counterbalance film is carbon steel or pure iron.

また、（５）光ファイバ水素センサと、当該光ファイバ水素センサと計測部の間の光伝送を行う伝送用光ファイバと、当該光ファイバ水素センサに供給すべき測定光を発生する発光手段と、当該光ファイバ水素センサで光量変化を受けた測定光を受光する受光手段と、当該受光手段の出力を閾値処理或いは水素濃度変換する演算処理手段を備えたことを特徴とする水素検知システムを提供する。   (5) an optical fiber hydrogen sensor, a transmission optical fiber that performs optical transmission between the optical fiber hydrogen sensor and the measurement unit, and a light emitting means that generates measurement light to be supplied to the optical fiber hydrogen sensor; Provided is a hydrogen detection system comprising: a light receiving unit that receives measurement light that has undergone a change in light quantity by the optical fiber hydrogen sensor; and an arithmetic processing unit that performs threshold processing or hydrogen concentration conversion on the output of the light receiving unit. .

また、（６）当該水素検知システムに、温度センサ、温度信号伝送路、温度計測部を付加し、予め取得しておいた反射光量の温度依存性データに基づき、当該演算処理手段の温度による影響を除去するようにしたことを特徴とする水素検知システムを提供する。 (6) A temperature sensor, a temperature signal transmission path, and a temperature measurement unit are added to the hydrogen detection system, and the influence of the temperature of the arithmetic processing unit based on the temperature dependence data of the reflected light amount acquired in advance. The present invention provides a hydrogen detection system characterized in that the hydrogen is removed.

更に、特定の波長の光を特定の当該光ファイバ水素センサに分波し、当該光ファイバ水素センサからの反射光を合波する合分波フィルタを介して当該伝送用光ファイバに複数配置した当該光ファイバ水素センサと、当該光ファイバ水素センサに供給すべき複数の波長の測定光を発生する発光手段と、当該光ファイバ水素センサで光量変化を受けた複数の波長からなる測定光を各波長に分岐する波長分岐フィルタと、分岐された各波長の光を受光する複数の当該受光手段と、複数の当該受光手段の出力を閾値処理或いは水素濃度変換するための当該演算処理手段とを具備したことを特徴とする多点水素検知システムを提供する。   Further, a plurality of light beams having specific wavelengths are demultiplexed to the specific optical fiber hydrogen sensor, and a plurality of the optical fibers for transmission are arranged in the transmission optical fiber via a multiplexing / demultiplexing filter that multiplexes the reflected light from the optical fiber hydrogen sensor. An optical fiber hydrogen sensor, a light emitting means for generating measurement light of a plurality of wavelengths to be supplied to the optical fiber hydrogen sensor, and measurement light consisting of a plurality of wavelengths subjected to a change in the amount of light by the optical fiber hydrogen sensor for each wavelength A wavelength branching filter for branching, a plurality of light receiving means for receiving the branched light of each wavelength, and a processing unit for performing threshold processing or hydrogen concentration conversion on outputs of the plurality of light receiving means. A multi-point hydrogen detection system is provided.

本発明により、煩雑な光学的セッティングが不要で、応答速度が早く、高感度で、量産容易な水素センサを実現できる。また、それを用いて、複数地点の水素をリアルタイムで検知できる水素検知システムを簡易な構成で安価に実現できる。 According to the present invention, it is possible to realize a hydrogen sensor that does not require complicated optical settings, has a high response speed, is highly sensitive, and is easily mass-produced. In addition, a hydrogen detection system that can detect hydrogen at a plurality of locations in real time can be realized with a simple configuration at low cost.

以下、図面を参照して、本発明の実施例を詳細に説明する。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

図１（ａ）は本発明の第一実施例である光ファイバ水素センサの構成側面図、（ｂ）は切断面図である。   FIG. 1A is a side view of the configuration of the optical fiber hydrogen sensor according to the first embodiment of the present invention, and FIG.

図中、１は水素センサ部で、構成側面図（ａ）、切断面図（ｂ）に示すように、光ファイバ１１の一部を細くした括れ部1２、水素吸蔵膜１3、及び反射ミラー１４を具備している。 In the figure, reference numeral 1 denotes a hydrogen sensor unit. As shown in the configuration side view (a) and cut-away view (b), a constricted part 12, a hydrogen occlusion film 13 and a reflecting mirror 14 in which a part of the optical fiber 11 is thinned. It has.

光ファイバ１１は、線形性のよい応答を得るためにシングルモードファイバであるのが望ましく、また、伝送距離、コスト面から光通信波長帯に適合したものが望まれる。 The optical fiber 11 is preferably a single mode fiber in order to obtain a response with good linearity, and is preferably adapted to the optical communication wavelength band in terms of transmission distance and cost.

括れ部１２は、光ファイバ１１に、微小な力で、再現性よく、大きな曲率の曲げを与える役割をし、括れ部１２の中央の径が細いほど高感度となる。以下、括れ部１２の中央の径を括れ径と称す。しかし、括れ径が細すぎると光出力が非線形となりやすいため、細すぎる括れ径は望ましくない。例えば、クラッド径が１２５μｍ、ＭＦＤ（モードフィールド径）が１０μｍ（波長：１．５５μｍ）程度である通常のシングルモードファイバの場合、括れ径は５０〜９０μｍの範囲であることが望ましい。括れ径が９０μｍ以上の場合は、曲げによる光の漏洩が殆ど起こらず、５０μｍ以下の場合は、曲げがない場合でも光の漏洩が大きく、また、光出力が非線形で不安定となりやすい。 The constricted portion 12 serves to give the optical fiber 11 a bend with a large curvature with a small force and good reproducibility. The narrower the central diameter of the constricted portion 12, the higher the sensitivity. Hereinafter, the central diameter of the constricted portion 12 is referred to as a constricted diameter. However, if the constricted diameter is too thin, the light output tends to be non-linear, so an excessively constricted diameter is not desirable. For example, in the case of a normal single mode fiber having a cladding diameter of 125 μm and an MFD (mode field diameter) of about 10 μm (wavelength: 1.55 μm), the constriction diameter is desirably in the range of 50 to 90 μm. When the constricted diameter is 90 μm or more, light leakage due to bending hardly occurs. When the constricted diameter is 50 μm or less, light leakage is large even when there is no bending, and the light output tends to be nonlinear and unstable.

１３は水素吸蔵膜で、図１（a）、（b）に示すように、括れ部１２を含むファイバ側面の一部に形成する。水素吸蔵膜１３の長手方向の幅は、括れ部１２の幅よりやや広い程度でよい。また、水素吸蔵膜１３は、水素を吸蔵して体積膨張が起こったときに、括れ部１２に曲げの変化を与えるよう、ファイバ側面の一部に形成する。最も効率よく曲げを起こすには、ファイバ側面の半分に水素吸蔵膜１３を形成するのがよい。水素吸蔵膜１３の材質は、水素を吸蔵して体積膨張が起こる素材であり、例えば、Ｐｄ、Ｐｄ合金、Ｌａ−Ｎｉ合金などの希土類金属合金、Ｍｇ−Ｎｉ合金等を用いることができる。当然、水素吸蔵に対して体積膨張が大きい材質ほど高感度のセンサとなる。水素吸蔵膜１３の形成は、スパッタリグ装置、イオンアシスト蒸着装置など通常の製膜装置で容易に形成でき、膜厚は０．１〜０．５μｍ程度である。 A hydrogen storage film 13 is formed on a part of the side surface of the fiber including the constricted portion 12 as shown in FIGS. 1 (a) and 1 (b). The width of the hydrogen storage film 13 in the longitudinal direction may be slightly wider than the width of the constricted portion 12. Further, the hydrogen storage film 13 is formed on a part of the side surface of the fiber so as to change the bending of the constricted portion 12 when volume expansion occurs due to storage of hydrogen. In order to cause bending most efficiently, it is preferable to form the hydrogen storage film 13 on the half of the side surface of the fiber. The material of the hydrogen storage film 13 is a material that absorbs hydrogen and causes volume expansion. For example, a rare earth metal alloy such as Pd, Pd alloy, La—Ni alloy, Mg—Ni alloy, or the like can be used. Naturally, a material having a larger volume expansion than hydrogen storage has a higher sensitivity. The hydrogen storage film 13 can be easily formed by a normal film forming apparatus such as a sputtering rig apparatus or an ion assist vapor deposition apparatus, and the film thickness is about 0.1 to 0.5 μm.

１４は反射ミラーであり、括れ部１２の曲げ動作に支障を与えないよう軽量のほうがよく、光ファイバ１１の端面にスパッタリング、蒸着などの製膜手段により直接形成するのが望ましい。括れ部１２の中央から反射ミラー１４までの距離は、やはり軽量化のため短いほうが望ましく、通常、10mm以下である。 Reference numeral 14 denotes a reflection mirror, which should be light in weight so as not to hinder the bending operation of the constricted portion 12, and is preferably formed directly on the end face of the optical fiber 11 by film forming means such as sputtering or vapor deposition. The distance from the center of the constricted portion 12 to the reflecting mirror 14 is desirably shorter for weight reduction, and is usually 10 mm or less.

本実施例の光ファイバ水素センサの動作を図２を用いて説明する。図２は、水素センサ部１の曲げの変化を示している。括れ部１２を具備する光ファイバ１１の側面に水素吸蔵膜１３を形成する際、製膜温度を室温より高くしておくと、（ａ）に示すように、製膜時にセンサ部分１を直線状にしておいても、水素吸蔵膜は光ファイバ(石英)より熱膨張率が大きいので、室温では水素吸蔵膜１３がより収縮して水素センサ部１は（ｂ）のように適度に曲がり、一定の漏洩光を発生する状態となる。この漏洩光の強さは、製膜時の温度で調節可能であり、線形的応答性、ダイナミックレンジの観点から、通常、５〜１０ｄＢ程度の漏洩光が発生するようにするのが望ましい。 The operation of the optical fiber hydrogen sensor of this embodiment will be described with reference to FIG. FIG. 2 shows a change in bending of the hydrogen sensor unit 1. When forming the hydrogen storage film 13 on the side surface of the optical fiber 11 having the constricted portion 12, if the film forming temperature is set higher than room temperature, the sensor portion 1 is linearly formed during film formation as shown in FIG. Even so, since the hydrogen storage film has a larger coefficient of thermal expansion than that of the optical fiber (quartz), the hydrogen storage film 13 contracts more at room temperature, and the hydrogen sensor unit 1 bends appropriately as shown in FIG. It will be in the state which generates the leakage light. The intensity of this leakage light can be adjusted by the temperature at the time of film formation, and it is usually desirable to generate leakage light of about 5 to 10 dB from the viewpoint of linear response and dynamic range.

（ｂ）に示すような適度な曲げを持つ水素センサ部１を水素含有ガスに暴露すると、水素吸蔵膜１３が水素を吸蔵して体積膨張を起こすため、センサ部分１の曲げの曲率が小さくなり、漏洩光が減少し、反射光強度が増大するので、この反射光強度の変化を検出すれば、水素漏洩検知器とすることができる。 When the hydrogen sensor part 1 having an appropriate bend as shown in FIG. 5B is exposed to a hydrogen-containing gas, the hydrogen storage film 13 absorbs hydrogen and causes volume expansion, so that the bending curvature of the sensor part 1 is reduced. Since the leakage light is reduced and the reflected light intensity is increased, a hydrogen leakage detector can be obtained by detecting the change in the reflected light intensity.

水素の吸蔵は、水素吸蔵膜１３の表面から起こり、奥に浸透していくが、水素センサ部１の曲率変化は水素吸蔵膜１３表面に水素が吸蔵された時点から始まるので、応答速度の速い水素漏洩検知器となる。   Although the hydrogen occlusion occurs from the surface of the hydrogen occlusion film 13 and penetrates into the back, the change in curvature of the hydrogen sensor unit 1 starts from the time when hydrogen is occluded on the surface of the hydrogen occlusion film 13, so that the response speed is fast. It becomes a hydrogen leak detector.

また、曲率は水素濃度の増大と共に小さくなるので、水素濃度と反射光強度の関係を予め取得しておけば、水素濃度測定に使用することも可能である。 Further, since the curvature decreases as the hydrogen concentration increases, if the relationship between the hydrogen concentration and the reflected light intensity is acquired in advance, it can be used for measuring the hydrogen concentration.

以上、説明したように、括れ部１２を具備する光ファイバ１１と、光ファイバ１１側面に直接形成した水素吸蔵膜１３と、反射ミラー１４で水素センサ部１を構成することにより、部品が一体化したセンサとなるため煩雑な光部品のセッティングが不要であり、薄膜製造プロセスで製造できるため量産容易で、曲げに極めて敏感な括れ部（１２）の曲げロスを利用するため高感度で、簡易な構造で製造容易なため安価な水素センサを実現できる。   As described above, the components are integrated by configuring the hydrogen sensor unit 1 with the optical fiber 11 having the constricted portion 12, the hydrogen storage film 13 formed directly on the side surface of the optical fiber 11, and the reflecting mirror 14. Therefore, complicated optical component setting is not required, and it is easy to mass-produce because it can be manufactured by a thin film manufacturing process. Because it uses the bending loss of the constricted portion (12) that is extremely sensitive to bending, it is highly sensitive and simple. Since the structure is easy to manufacture, an inexpensive hydrogen sensor can be realized.

図３は、図１（ａ）（ｂ）に示す水素センサの第一実施例を発展させた形態を示す。１５は、熱膨張相殺膜で、水素吸蔵膜１３と熱膨張率が類似し、且つ、水素により体積変化を起こさない材質からなる。図３では、括れ部１２を含む長手方向にわたり、光ファイバ１１の側面半分を熱膨張相殺膜１５、残りの側面半分を水素吸蔵膜１３として描いてあるが、両膜は対称的に配置されていればよく、必ず半分ずつ配置される必要はない。これら両膜の膜厚はほぼ同等にする。 FIG. 3 shows a developed form of the first embodiment of the hydrogen sensor shown in FIGS. Reference numeral 15 denotes a thermal expansion counterbalance film, which is made of a material having a thermal expansion coefficient similar to that of the hydrogen storage film 13 and does not cause a volume change due to hydrogen. In FIG. 3, the side half of the optical fiber 11 is drawn as the thermal expansion counterbalance film 15 and the other side half is drawn as the hydrogen storage film 13 over the longitudinal direction including the constricted portion 12, but the two films are arranged symmetrically. They do not have to be arranged in half. The thicknesses of these two films are almost equal.

具体的な材質の例としては、水素吸蔵膜１３を熱膨張率が１１．８×１０−６／ＫのＰｄとした場合、熱膨張率１１．７×１０−６／Ｋの炭素鋼や純鉄を熱膨張率相殺膜１５として使用できる。 Specific examples of the material, a hydrogen storage layer 13 if the thermal expansion coefficient was Pd of 11.8 × 10 -6 / K, the thermal expansion coefficient of 11.7 × 10 -6 / K carbon steel or pure of Iron can be used as the thermal expansion coefficient canceling film 15.

このように、水素吸蔵膜１３と熱膨張率が類似し、且つ、水素により体積変化を起こさない材質の熱膨張相殺膜１５を、水素吸蔵膜１３と対称的に配することにより、温度による水素センサ部１の曲げ変化を減少できるので、温度変化の影響を受けにくい水素センサとなる。   As described above, the thermal expansion canceling film 15 made of a material having a thermal expansion coefficient similar to that of the hydrogen storage film 13 and causing no volume change by hydrogen is arranged symmetrically with the hydrogen storage film 13, so that Since the bending change of the sensor unit 1 can be reduced, the hydrogen sensor is less susceptible to temperature changes.

熱膨張相殺膜１５を具備した水素センサの動作を説明する。   The operation of the hydrogen sensor provided with the thermal expansion counterbalance film 15 will be described.

水素吸蔵膜１３、熱膨張相殺膜１５を同じ製膜温度で形成すると、室温においても水素センサ部１はほぼ直線状態であり、括れ部１２における漏洩光強度はほぼ最小となる。   When the hydrogen storage film 13 and the thermal expansion canceling film 15 are formed at the same film forming temperature, the hydrogen sensor unit 1 is substantially linear even at room temperature, and the leaked light intensity at the constricted part 12 is substantially minimized.

水素センサ部１を水素含有気体中に暴露すると水素吸蔵膜１３が水素を吸蔵して体積膨張するので、括れ分１２に曲げが生じて漏洩光が増大、反射光強度が減少する。従って、反射光強度を測定することにより水素を検知できる。 When the hydrogen sensor unit 1 is exposed to a hydrogen-containing gas, the hydrogen storage film 13 absorbs hydrogen and expands in volume. Therefore, bending occurs in the constricted portion 12, leakage light increases, and reflected light intensity decreases. Therefore, hydrogen can be detected by measuring the reflected light intensity.

図４は、本発明の第三実施例である水素検知システムの概略構成を示す図である。   FIG. 4 is a diagram showing a schematic configuration of a hydrogen detection system according to the third embodiment of the present invention.

図中、２は水素センサ部１への光の伝送および反射してくる信号光を計測部３に導くための伝送用光ファイバである。計測部３の主要構成部品は、発光素子４、光カプラ５、受光素子６、光アイソレータ７、演算処理回路８である。発光素子４は光ファイバに入射可能な光源であり、より遠隔まで信号を伝送するためには、波長帯が１．５μｍ帯、１．３μｍ帯など通信波長帯であることが望ましく、例えば、通信波長帯の半導体レーザを利用できる。 In the figure, reference numeral 2 denotes a transmission optical fiber for guiding the signal light transmitted to the hydrogen sensor unit 1 and reflected signal light to the measuring unit 3. The main components of the measuring unit 3 are a light emitting element 4, an optical coupler 5, a light receiving element 6, an optical isolator 7, and an arithmetic processing circuit 8. The light emitting element 4 is a light source that can be incident on an optical fiber. In order to transmit a signal farther away, the wavelength band is preferably a communication wavelength band such as a 1.5 μm band or a 1.3 μm band. A semiconductor laser in the wavelength band can be used.

発光素子４から出射した測定光は、光アイソレータ７、光カプラ５を通過して光伝送用ファイバ２に送られ、水素センサ部１に入射される。括れ部１２で一部の光を漏洩した後、測定光は反射ミラー１４で反射され、括れ部１２で再度光を漏洩した後、伝送用光ファイバ２を経て光カプラ５に達し、受光素子６で受光される。発光素子４側に戻る一部の光は光アイソレータ７でブロックされる。反射光強度と水素濃度の相関を予め演算処理回路８に入力しておき、受光素子６の出力を演算処理すれば水素濃度検知システムとして動作する。 The measurement light emitted from the light emitting element 4 passes through the optical isolator 7 and the optical coupler 5, is sent to the optical transmission fiber 2, and enters the hydrogen sensor unit 1. After a part of light leaks at the constricted part 12, the measurement light is reflected by the reflecting mirror 14, leaks light again at the constricted part 12, reaches the optical coupler 5 through the transmission optical fiber 2, and receives the light receiving element 6. Is received. A part of the light returning to the light emitting element 4 side is blocked by the optical isolator 7. If the correlation between the reflected light intensity and the hydrogen concentration is input in advance to the arithmetic processing circuit 8 and the output of the light receiving element 6 is arithmetically processed, the system operates as a hydrogen concentration detection system.

また、計測部３の主要構成部品は何れも光通信で使用されている市販品を安価に購入できるため安価なシステムが構成できる。 Moreover, since all the main components of the measuring unit 3 can be purchased at low cost from commercial products used in optical communication, an inexpensive system can be configured.

図５は、図４に示す水素検知システムの第三実施例を発展させ、温度特性を向上させた構成を示す。図中、３１は温度センサ、３２は温度信号伝送路、３３は温度計測部である。温度センサには、光ファイバセンサシステムの特徴を最大限活かすため、例えば、特開２００７−２４５２７に本願発明者等により開示されているような光ファイバ式温度センサが望ましいが、熱電対、白金抵抗体などの一般的センサを利用することも可能である。信号伝送路３２は、温度センサ３２の種類によって異なり、例えば、光ファイバ式温度センサでは光ファイバであり、熱電対では補償導線となる。温度計測部３３も同様に温度センサに適合したものとする。   FIG. 5 shows a configuration in which the third embodiment of the hydrogen detection system shown in FIG. 4 is developed to improve temperature characteristics. In the figure, 31 is a temperature sensor, 32 is a temperature signal transmission path, and 33 is a temperature measurement unit. For the temperature sensor, in order to make the most of the characteristics of the optical fiber sensor system, for example, an optical fiber type temperature sensor as disclosed in Japanese Patent Application Laid-Open No. 2007-24527 by the present inventors is desirable. It is also possible to use a general sensor such as a body. The signal transmission path 32 differs depending on the type of the temperature sensor 32. For example, the optical fiber temperature sensor is an optical fiber, and the thermocouple is a compensating conductor. Similarly, the temperature measuring unit 33 is adapted to the temperature sensor.

予め測定しておいた水素センサ部１の出力の温度依存性を、演算処理回路８に入力しておき、温度センサ２１で測定した温度データを用いて温度の影響を補正することにより、温度の影響を受けない正確な水素検知システムとなる。   The temperature dependence of the output of the hydrogen sensor unit 1 measured in advance is input to the arithmetic processing circuit 8, and the temperature data is measured using the temperature sensor 21 to correct the influence of the temperature. It is an accurate hydrogen detection system that is not affected.

図６は、本発明の第五実施例である多点水素検知システムの概略構成を示す図である。以下、システムの動作を説明する。光源２１は、ＡＳＥ光源、チューナブルレーザなどのように複数の波長を発光する光源で、光源２１から発光された光は、光アイソレータ７、２個の光カプラ５を経て伝送用光ファイバ２に入射される。光アイソレータ７を出た光の一部は、光カプラ５で分岐され光源２１の光強度変化をモニターするパワーモニタ用受光素子２４に入射され、光源の変動を補正するデータとして使われる。 FIG. 6 is a diagram showing a schematic configuration of a multipoint hydrogen detection system according to the fifth embodiment of the present invention. Hereinafter, the operation of the system will be described. The light source 21 is a light source that emits a plurality of wavelengths, such as an ASE light source or a tunable laser, and the light emitted from the light source 21 passes through the optical isolator 7 and the two optical couplers 5 to the transmission optical fiber 2. Incident. A part of the light emitted from the optical isolator 7 is branched by the optical coupler 5 and incident on the power monitor light receiving element 24 for monitoring the light intensity change of the light source 21 and used as data for correcting the fluctuation of the light source.

測定光が合分波フィルタ２２−１に到達すると、波長λ１の光のみ温度センサ部１−１側に分岐され、残りの波長の光は伝送用光ファイバ２を先に進む。合分波フィルタ２２−２ではλ２、合分波フィルタ２２−３ではλ３というように各水素センサ部１−（1〜n）に割り当てられた波長が分岐されていく。各水素センサ部１−（1〜n）で反射された各波長の光は、再度合分波フィルタ２２を経て伝送用光ファイバ２に入射され、光カプラ５を経て波長分岐フィルタ２３に達する。波長分岐フィルタ２３で光は各波長に分岐され、各々割り当てられた受光素子６に入射される。 When the measurement light reaches the demultiplexing filters 22-1, is branched into only the temperature sensor unit 11 side light of the wavelength lambda 1, the light of the remaining wavelength proceed the transmission optical fiber 2. The wavelength assigned to each hydrogen sensor unit 1- (1 to n) is branched, such as λ 2 in the multiplexing / demultiplexing filter 22-2 and λ 3 in the multiplexing / demultiplexing filter 22-3. The light of each wavelength reflected by each hydrogen sensor unit 1-(1 to n) is again incident on the transmission optical fiber 2 through the multiplexing / demultiplexing filter 22, and reaches the wavelength branching filter 23 through the optical coupler 5. The light is branched into each wavelength by the wavelength branching filter 23 and is incident on the assigned light receiving element 6.

演算処理回路８に光量レベルの閾値を設定しておき、各受光素子６の出力が閾値に到達したときに警報を発するようにすれば多点水素漏洩検知システムとして動作する。 If a threshold value of the light amount level is set in the arithmetic processing circuit 8 and an alarm is issued when the output of each light receiving element 6 reaches the threshold value, it operates as a multipoint hydrogen leak detection system.

演算処理回路８に予め取得しておいた水素濃度と反射光強度の関係式を入力しておき、各受光素子６の出力を演算処理すれば、各水素センサ部１−（１〜ｎ）の水素濃度を検知する多点水素濃度検知システムとして動作する。 If the relational expression between the hydrogen concentration and the reflected light intensity acquired in advance is inputted to the arithmetic processing circuit 8 and the output of each light receiving element 6 is arithmetically processed, each hydrogen sensor unit 1- (1 to n) It operates as a multipoint hydrogen concentration detection system that detects the hydrogen concentration.

各水素センサ部１−（１〜ｎ）の識別に異なる波長の光λ１〜λｎを用い、各波長に割り当てた複数の受光素子ＰＤ１〜ＰＤｎで並列に受光することにより、計測時間が短くなり、リアルタイム測定ができる。 By using light λ 1 to λ n of different wavelengths for identification of each hydrogen sensor unit 1-(1 to n) and receiving light in parallel by a plurality of light receiving elements PD 1 to PD n assigned to each wavelength, measurement time Becomes shorter and real-time measurement is possible.

また、伝送用光ファイバ２、光カプラ５、光アイソレータ７、合分波フィルタ２２、波長分岐フィルタ２３、受光素子６など、上記各種の構成部品には光通信用に開発された安価で信頼性の高い市販品を利用できるため、安価で信頼性の高いシステムを構成できる。 The various components such as the transmission optical fiber 2, the optical coupler 5, the optical isolator 7, the multiplexing / demultiplexing filter 22, the wavelength branching filter 23, and the light receiving element 6 are inexpensive and reliable developed for optical communication. Therefore, it is possible to configure an inexpensive and highly reliable system.

特定の実施例を参照して本発明を説明したが、特許請求の範囲に規定される本発明の技術的範囲を逸脱しないで、上述の実施例に種々の変更を加えることは、本発明の属する分野の技術者にとって自明であり、このような変更・修正も本発明の技術的範囲に含まれる。   Although the invention has been described with reference to specific embodiments, various modifications may be made to the above-described embodiments without departing from the scope of the invention as defined in the claims. Such changes and modifications are also within the technical scope of the present invention.

本発明の第１実施例である水素センサの構成を示す図である。It is a figure which shows the structure of the hydrogen sensor which is 1st Example of this invention. センサ部の動作を説明する側面図である。It is a side view explaining operation | movement of a sensor part. 本発明の第２実施例であるセンサ部の側面図と切断面図である。It is the side view and cutaway view of a sensor part which is 2nd Example of this invention. 本発明の第３実施例である水素検知システムの概略構成を示す図である。It is a figure which shows schematic structure of the hydrogen detection system which is 3rd Example of this invention. 本発明の第４実施例である水素検知システムの概略構成を示す図である。It is a figure which shows schematic structure of the hydrogen detection system which is 4th Example of this invention. 本発明の第５実施例である水素検知システムの概略構成を示す図である。It is a figure which shows schematic structure of the hydrogen detection system which is 5th Example of this invention.

符号の説明Explanation of symbols

１：水素センサ部
２：伝送用光ファイバ
３：計測部
４：発光素子
５：光カプラ
６：受光素子
７：光アイソレータ
８：演算処理回路
１１：光ファイバ
１２：括れ部
１３：水素吸蔵膜
１４：反射ミラー
１５：熱膨張率相殺膜
２０：多点計測部
２１：光源
２２：（１〜ｎ）：合分波フィルタ
２３：波長分岐フィルタ
２４：パワーモニタ用受光素子
３１：温度センサ
３２：温度信号伝送路
３３：温度計測部 1: Hydrogen sensor unit 2: Transmission optical fiber 3: Measuring unit 4: Light emitting element 5: Optical coupler
6: light receiving element 7: optical isolator 8: arithmetic processing circuit 11: optical fiber 12: constricted part 13: hydrogen storage film 14: reflecting mirror 15: thermal expansion coefficient canceling film 20: multipoint measuring part 21: light source 22: (1 ˜n): multiplexing / demultiplexing filter 23: wavelength branching filter 24: light receiving element 31 for power monitoring: temperature sensor 32: temperature signal transmission path 33: temperature measuring unit

Claims (7)

部分的に細くなった括れ部（１２）と、当該括れ部（１２）を含む長手方向にわたり、側面の一部に付着させた水素吸蔵膜（１３）と、当該括れ部（１２）に近い端面に反射手段（１４）を具備した光ファイバ（１１）からなることを特徴とする光ファイバ水素センサ。 A partially narrowed constriction (12), a hydrogen storage film (13) attached to a part of the side surface in the longitudinal direction including the constriction (12), and an end face close to the constriction (12) An optical fiber hydrogen sensor comprising an optical fiber (11) provided with a reflecting means (14). 当該水素吸蔵膜（１３）がＰｄ、Ｐｄ合金、Ｌａ−Ｎｉ合金、希土類金属−Ｎｉ合金、Ｍｇ−Ｎｉ合金であることを特徴とする請求項１に記載の光ファイバ水素センサ。   The optical fiber hydrogen sensor according to claim 1, wherein the hydrogen storage film (13) is Pd, Pd alloy, La-Ni alloy, rare earth metal-Ni alloy, Mg-Ni alloy. 熱膨張率が当該水素吸蔵膜（１３）と類似し、且つ、水素による体積変化を起こさない材質からなる熱膨張相殺膜（１５）を、当該水素吸蔵膜（１３）と対称的に配置したことを特徴とする請求項１に記載の光ファイバ水素センサ。 The thermal expansion canceling film (15) made of a material having a thermal expansion coefficient similar to that of the hydrogen storage film (13) and not causing a volume change due to hydrogen is arranged symmetrically with the hydrogen storage film (13). The optical fiber hydrogen sensor according to claim 1. 当該水素吸蔵膜（１３）の材質がＰｄであり、当該熱膨張相殺膜（１５）の材質が炭素鋼或いは純鉄であることを特徴とする請求項３に記載の光ファイバ水素センサ。 The optical fiber hydrogen sensor according to claim 3, wherein the material of the hydrogen storage film (13) is Pd, and the material of the thermal expansion counterbalance film (15) is carbon steel or pure iron. 当該光ファイバ水素センサと、当該光ファイバ水素センサと計測部（３）の間の光伝送を行う伝送用光ファイバ（２）と、当該光ファイバ水素センサに供給すべき測定光を発生する発光手段（４）と、当該光ファイバ水素センサで光量変化を受けた測定光を受光する受光手段（６）と、当該受光手段（６）の出力を水素濃度に変換する演算処理手段（８）とを備えたことを特徴とする水素検知システム。 The optical fiber hydrogen sensor, a transmission optical fiber (2) for performing optical transmission between the optical fiber hydrogen sensor and the measurement unit (3), and a light emitting means for generating measurement light to be supplied to the optical fiber hydrogen sensor (4), a light receiving means (6) for receiving measurement light having undergone a change in light quantity by the optical fiber hydrogen sensor, and an arithmetic processing means (8) for converting the output of the light receiving means (6) into a hydrogen concentration. A hydrogen detection system characterized by comprising. 当該光ファイバ水素センサに加え、温度センサ（３１）、温度信号伝送路（３２）、温度計測部（３３）を具備し、予め取得しておいた温度に対する反射光量変化データに基づき、前記演算処理手段（８）で温度補正を行うようにしたことを特徴とする請求項５に記載の水素検知システム。   In addition to the optical fiber hydrogen sensor, a temperature sensor (31), a temperature signal transmission path (32), and a temperature measurement unit (33) are provided, and the calculation processing is performed based on the reflected light amount change data with respect to the temperature acquired in advance. 6. The hydrogen detection system according to claim 5, wherein temperature correction is performed by means (8). 特定の波長の光を特定の当該光ファイバ水素センサに分波し、当該光ファイバ水素センサからの反射光を合波する合分波フィルタ（２２）を介して当該伝送用光ファイバ（２）に複数配置した当該光ファイバ水素センサと、当該当該光ファイバ水素センサに供給すべき複数の波長の測定光を発生する発光手段（２１）と、当該当該光ファイバ水素センサで光量変化を受けた複数の波長からなる測定光を各波長に分岐する波長分岐フィルタ（２３）と、分岐された各波長の光を受光する複数の当該受光手段（６）と、複数の当該受光手段（６）の出力を閾値処理或いは水素濃度変換するための当該演算処理手段（８）とを具備したことを特徴とする多点水素検知システム。   The light of a specific wavelength is demultiplexed to a specific optical fiber hydrogen sensor, and is reflected to the transmission optical fiber (2) via a multiplexing / demultiplexing filter (22) that multiplexes the reflected light from the optical fiber hydrogen sensor. A plurality of the optical fiber hydrogen sensors arranged, a light emitting means (21) for generating measurement light of a plurality of wavelengths to be supplied to the optical fiber hydrogen sensor, and a plurality of light quantity changes received by the optical fiber hydrogen sensor A wavelength branching filter (23) for branching measurement light having wavelengths to each wavelength, a plurality of light receiving means (6) for receiving the branched light of each wavelength, and outputs of the plurality of light receiving means (6) A multipoint hydrogen detection system comprising the arithmetic processing means (8) for threshold processing or hydrogen concentration conversion.
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JP2011085576A (en) * 2009-09-15 2011-04-28 Mitsubishi Cable Ind Ltd Optical fiber hydrogen sensor, and optical fiber hydrogen sensor system with the same
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8675200B2 (en) 2009-09-03 2014-03-18 Japan Aviation Electronics Industry Limited Hydrogen detecting surface plasmon resonator, surface plasmon resonance optical hydrogen detector and method for optically detecting hydrogen using surface plasmon resonance
JP2011085576A (en) * 2009-09-15 2011-04-28 Mitsubishi Cable Ind Ltd Optical fiber hydrogen sensor, and optical fiber hydrogen sensor system with the same
CN101949829A (en) * 2010-09-07 2011-01-19 中国船舶重工集团公司第七一八研究所 Nuclear power hydrogen concentration detecting device
JP2014059300A (en) * 2012-08-24 2014-04-03 Soka Univ Hydrogen sensor, and detector using the same
KR102056358B1 (en) 2018-02-22 2019-12-16 호남대학교 산학협력단 optical type hydrogen sensor
KR102122946B1 (en) * 2018-12-11 2020-06-26 호남대학교 산학협력단 Temperature compensative fiber-optic hydrogen sensor
KR20220057363A (en) * 2020-10-29 2022-05-09 한국광기술원 temperature calibration type hydrogen concentration measuring apparatus
KR102405456B1 (en) * 2020-10-29 2022-06-07 한국광기술원 temperature calibration type hydrogen concentration measuring apparatus

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