JPH09196748A - Acoustic sensor of high-waterproof cylindrical optical fiber - Google Patents
Acoustic sensor of high-waterproof cylindrical optical fiberInfo
- Publication number
- JPH09196748A JPH09196748A JP792896A JP792896A JPH09196748A JP H09196748 A JPH09196748 A JP H09196748A JP 792896 A JP792896 A JP 792896A JP 792896 A JP792896 A JP 792896A JP H09196748 A JPH09196748 A JP H09196748A
- Authority
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- Japan
- Prior art keywords
- optical fiber
- acoustic sensor
- lid
- cylinder
- cavity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Optical Transform (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は円筒型光ファイバ音
響センサに関し、特に音圧を光の位相変化に変換して水
中音波を検出する高耐水圧円筒型光ファイバ音響センサ
に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical optical fiber acoustic sensor, and more particularly, to a high water pressure resistant cylindrical optical fiber acoustic sensor for detecting underwater sound waves by converting sound pressure into a phase change of light.
【０００２】[0002]
【従来の技術】一般的な円筒型光ファイバ音響センサに
ついては、Ｇ．Ｆ．Ｍｃｄｅａｒｍｏｎによる「呼吸振
動型の光ファイバ水中聴音機の理論的解析：Ｔｈｅｏｒ
ｅｔｉｃａｌ Ａｎａｌｙｓｉｓ ｏｆ ａ Ｐｕｓｈ
−Ｐｕｌｌ Ｆｉｂｅｒ−Ｏｐｔｉｃ Ｈｙｄｒｏｐｈ
ｏｎ」と題する下記の文献によって開示されている。 文献名：Ｊｏｕｒｎａｌ ｏｆ Ｌｉｇｈｔｗａｖｅ
Ｔｅｃｈｎｏｌｏｇｙ，［ｖｏｌ．Ｌｔ・５］，Ｎｏ．
５，ｐｐ６４７〜６５２，Ｍａｙ１９８７（米）2. Description of the Related Art A general cylindrical optical fiber acoustic sensor is disclosed in G. K .; F. "Theoretical Analysis of a Respiratory Vibration Type Fiber Optic Underwater Hearing Aid by McDearmon: Theor
electrical Analysis of a Push
-Pull Fiber-Optic Hydroph
and "on". Article name: Journal of Lightwave
Technology, [vol. Lt.5], No.
5, pp 647-652, May 1987 (US)
【０００３】上記の文献に開示されている円筒型光ファ
イバ音響センサは、２つの円筒の呼吸振動を利用したも
ので、図５にこのセンサの模式断面図を示す。図におい
て、センサは所定の長さを持つ外円筒１及び内円筒２の
２つの円筒を同心円状に配置した二重円筒型のもので、
円筒の両端に蓋３を取り付け、各円筒の間に形成される
等間隔な空胴部を空気室４として形成している。外円筒
１の内側面及び内円筒２の外側面には、光ファイバ５，
５ａがそれぞれコイル状に巻回状態で設置されている構
造となっている。[0003] The cylindrical optical fiber acoustic sensor disclosed in the above document utilizes respiratory vibration of two cylinders, and FIG. 5 is a schematic cross-sectional view of this sensor. In the figure, the sensor is a double cylinder type in which two cylinders, an outer cylinder 1 and an inner cylinder 2 having a predetermined length, are concentrically arranged.
The lids 3 are attached to both ends of the cylinders, and the equally spaced cavities formed between the cylinders are formed as air chambers 4. The optical fibers 5, 5 are provided on the inner surface of the outer cylinder 1 and the outer surface of the inner cylinder 2.
5a has a structure in which it is installed in a coiled state.
【０００４】ここで、センサに音圧が加わると、円筒の
内外に圧力差が生じるため、両円筒は振動方向が互いに
逆方向の呼吸振動をする。この時、両円筒に巻き付けた
光ファイバ５，５ａも互いに逆方向に伸び縮みするた
め、光ファイバ５，５ａ内を伝搬しているレーザ光の位
相が変化する。そこで、この音圧に比例するレーザ光の
位相変化量を光の干渉を利用した周知の干渉計の原理に
より、音圧を高感度で検出するようになっている。[0004] When sound pressure is applied to the sensor, a pressure difference is generated between the inside and outside of the cylinder, so that both cylinders perform respiratory vibrations in the opposite directions. At this time, since the optical fibers 5 and 5a wound around the two cylinders also expand and contract in opposite directions, the phase of the laser light propagating in the optical fibers 5 and 5a changes. Therefore, the sound pressure is detected with high sensitivity by the principle of a well-known interferometer that uses the interference of light to detect the phase change amount of the laser light that is proportional to the sound pressure.
【０００５】[0005]
【発明が解決しようとする課題】上述のような従来の円
筒型光ファイバ音響センサは、内・外円筒の間の空胴部
を蓋で閉じ、かつ密閉して空気室を構成しているため、
圧力バランス構造の円筒型光ファイバ音響センサとはな
っていない。従って、これを水中において使用する時は
一般に耐水圧が低くなり、例えば現在要望されるような
深々度の水中では利用できないという問題がある。In the conventional cylindrical optical fiber acoustic sensor as described above, the cavity between the inner and outer cylinders is closed with a lid and sealed to form an air chamber. ,
It is not a cylindrical optical fiber acoustic sensor with a pressure balance structure. Therefore, when it is used in water, the water pressure resistance is generally low, and for example, there is a problem that it cannot be used in deep water as currently required.
【０００６】[0006]
【課題を解決するための手段】本発明に係る高耐水圧円
筒型光ファイバ音響センサは、１つの円筒体による単円
筒型構造で構成され、１つの円筒体の内部を構成する空
胴部をその両端においてそれぞれ閉じる蓋を有し、かつ
円筒体の側面に沿って巻回された光ファイバを備えてな
る円筒型光ファイバ音響センサであって、蓋の内の一方
の側の蓋に形成され、空胴部と円筒体の外周部との静水
圧を等しくする開口部を有するものである。ここで、前
記の開口部の径は、この開口部と空胴部に相当する間隙
部とによって構成されるヘルムホルツ共鳴器におけるヘ
ルムホルツ共振周波数以上の周波数の音波は通過しない
大きさの径であることが必要である。また、光ファイバ
は円筒体の側面及び蓋の内の開口部の形成されていない
蓋の側面に設けられていることが好ましい。A high water pressure resistant cylindrical optical fiber acoustic sensor according to the present invention has a single cylindrical structure composed of one cylindrical body, and has a cavity portion forming the inside of one cylindrical body. A cylindrical optical fiber acoustic sensor having a lid closed at both ends thereof and comprising an optical fiber wound along a side surface of a cylindrical body, which is formed on the lid on one side of the lid. It has an opening that equalizes the hydrostatic pressures of the hollow portion and the outer peripheral portion of the cylindrical body. Here, the diameter of the opening is such that a sound wave having a frequency higher than the Helmholtz resonance frequency in the Helmholtz resonator constituted by the opening and the gap corresponding to the cavity does not pass. is required. Further, it is preferable that the optical fiber is provided on the side surface of the cylindrical body and the side surface of the lid where the opening inside the lid is not formed.
【０００７】なお、ヘルムホルツ共鳴器は、よく知られ
ているように、本発明における蓋及び円筒を剛体とした
時の共振回路を構成する音響回路であり、次のような記
述によって定量的な説明がなされている。この場合、液
体の粘性等が音響抵抗ｒＡ（電気回路の抵抗Ｒに相
当）、開口部（オリフィス）を満たしている液体の質量
ｍＡは音響回路ではイナータンス（電気回路のインダク
タンスＬに相当）、円筒の容量ＣＡは音響コンプライア
ンス（電気回路のキャパシタンスＣに相当）として作用
する。従って、圧力バランスのような構造では、「オリ
フィス−円筒間の容量」により「Ｒ−Ｌ−Ｃ」の共振回
路が構成されたことにより、このような音響回路をヘル
ムホルツ共振器と呼んでいる。そして、ｍＡ、ＣＡ及び
ヘルムホルツ共振周波数ｆは、次式のような式で表され
ている。 ｍＡ＝Ｌρ／Ｓ ＣＡ＝Ｗ／ρｃ２ ｆ＝１／｛２π（ｍＡ×ＣＡ）１／２｝ ここで、Ｌ：オリフィスの長さ、ρ：液体の密度、Ｓ：
オリフィスの面積、Ｗ：円筒の容積、ｃ：音速である。
つまり、開口部と空胴部とは、音響機器（楽器等）の胴
体に設けられた穴と空胴（キャビティ）との関係に擬似
し、この構造は音波（音響）に対して一種のヘルムホル
ツの共鳴器（共振器に同じ）を構成している。As is well known, the Helmholtz resonator is an acoustic circuit that constitutes a resonance circuit when the lid and the cylinder are rigid bodies according to the present invention, and is quantitatively explained by the following description. Has been done. In this case, the viscosity of the liquid is acoustic resistance rA (corresponding to the resistance R of the electric circuit), and the mass mA of the liquid filling the opening (orifice) is the inertance (corresponding to the inductance L of the electric circuit) in the acoustic circuit, the cylinder. The capacitance CA of C acts as an acoustic compliance (corresponding to the capacitance C of the electric circuit). Therefore, in a structure such as a pressure balance, such an acoustic circuit is called a Helmholtz resonator because the "R-L-C" resonant circuit is formed by the "capacity between the orifice and the cylinder". The mA, CA, and Helmholtz resonance frequency f are expressed by the following equations. mA = Lρ / S CA = W / ρc 2 f = 1 / {2π (mA × CA) 1/2 } where L: orifice length, ρ: liquid density, S:
Area of orifice, W: volume of cylinder, c: speed of sound.
In other words, the opening and the cavity are simulated as a relationship between a hole and a cavity provided in the body of an audio device (musical instrument etc.), and this structure is a kind of Helmholtz for sound waves (acoustic). Of the resonator (same as the resonator).
【０００８】本発明においては、１つの円筒（これを以
後単円筒という）の空胴部を円筒の両端部で密閉するよ
うに使用された蓋の内の一方の側の蓋にオリフィス状の
開口部を設けているから、このセンサを水中に設置乃至
浮游させた場合、開口部を介して空胴部内とその外周部
とが通じて、空胴部内と円筒体の外周部とは静水圧が等
しくなるので、圧力バランス構造の光ファイバ音響セン
サが構成される。この場合、上記のような圧力バランス
型の光ファイバ音響センサは前述のヘルムホルツの共振
器として働くことを利用したものに相当し、その周波数
特性は次のように説明される。一般に、ヘルムホルツの
共振器では、ヘルムホルツの共振周波数以下の周波数の
音波（静水圧を含む）はオリフィスを通過する。そのた
め、単円筒型光ファイバ音響センサは、ヘルムホルツ共
振周波数以下の周波数では円筒内側の圧力と音響センサ
周囲の外側圧力が平衡して円筒は呼吸振動は生じない。
従って、それを取り巻く光ファイバは長さの変化は起き
ない。一方、ヘルムホルツ共振周波数以上の周波数の音
波はオリフィスを通過できないので、円筒に呼吸振動が
起き、光ファイバにも長さの変化がおきる。つまり、圧
力バランス型の光ファイバ音響センサの場合の受波感度
の周波数特性は、図４に示すように、遮断周波数（ヘル
ムホルツ共振による）を持つ特性になる。In the present invention, one of the lids used to seal the cavity of one cylinder (hereinafter referred to as a single cylinder) at both ends of the cylinder has an orifice-like opening in the lid. Since the sensor is installed, when the sensor is installed or floated in water, the inside of the cavity and the outer periphery thereof communicate with each other through the opening, and the hydrostatic pressure is generated between the inside of the cavity and the outer periphery of the cylindrical body. Since they are equal to each other, an optical fiber acoustic sensor having a pressure balance structure is constructed. In this case, the pressure-balanced optical fiber acoustic sensor as described above corresponds to one utilizing the fact that it functions as the above-mentioned Helmholtz resonator, and its frequency characteristic is explained as follows. Generally, in a Helmholtz resonator, sound waves (including hydrostatic pressure) at frequencies below the Helmholtz resonance frequency pass through the orifice. Therefore, in the single-cylinder optical fiber acoustic sensor, at a frequency equal to or lower than the Helmholtz resonance frequency, the pressure inside the cylinder and the outside pressure around the acoustic sensor are in equilibrium, and no respiratory vibration occurs in the cylinder.
Therefore, the length of the optical fiber surrounding it does not change. On the other hand, since a sound wave having a frequency higher than the Helmholtz resonance frequency cannot pass through the orifice, respiratory vibration occurs in the cylinder, and the length of the optical fiber also changes. That is, the frequency characteristic of the wave receiving sensitivity in the case of the pressure balance type optical fiber acoustic sensor has a cutoff frequency (due to Helmholtz resonance) as shown in FIG.
【０００９】換言すると、開口部と空胴部とは、音響機
器（楽器等）の穴と空胴との関係に擬似し、この構造は
前述のように音波（音響）に対して一種のヘルムホルツ
の共鳴器を構成している。従って、空胴部の容積と開口
部の径で決まるヘルムホルツ共振周波数以下の周波数の
音波はこの開口部を通過するが、ヘルムホルツ共振周波
数以上の周波数の音波は開口部を通過しない。そこで、
この構成において、ヘルムホルツ共振周波数以上の周波
数の音波をセンサのプローブとして使用すると、センサ
の外側には「静水圧＋この音波の音圧」が印加される
が、空胴部には静水圧のみしか加わらない。従って、円
筒の内側と外側に圧力不平衡が生じ、内・外筒はこの音
波の音圧で呼吸振動をするようになる。In other words, the opening and the cavity are simulated as the relationship between the hole of the acoustic device (musical instrument etc.) and the cavity, and this structure is a kind of Helmholtz against a sound wave (acoustic) as described above. Constitutes the resonator of. Therefore, a sound wave having a frequency equal to or lower than the Helmholtz resonance frequency determined by the volume of the cavity and the diameter of the opening passes through the opening, but a sound wave having a frequency higher than the Helmholtz resonance frequency does not pass through the opening. Therefore,
In this configuration, if a sound wave with a frequency higher than the Helmholtz resonance frequency is used as a probe for the sensor, "hydrostatic pressure + sound pressure of this sound wave" is applied to the outside of the sensor, but only hydrostatic pressure is applied to the cavity. Do not join. Therefore, pressure imbalance occurs between the inside and the outside of the cylinder, and the inner and outer cylinders respire and vibrate at the sound pressure of this sound wave.
【００１０】[0010]
［第１の実施形態］図１は本発明による高耐水圧円筒型
光ファイバ音響センサ（以下センサという）の第１の実
施形態を示す模式断面図である。図１において、所定の
長さ・径を持つ単円筒１０の両端に蓋１１及び蓋１２取
り付け、単円筒１０の内側空胴によって空胴部１３が形
成されている。この場合、蓋１１は、図示のように、円
板で形成され、蓋１２は蓋１１よりも厚さの厚い円板で
形成されている。また、単円筒１０の外側面には光ファ
イバ１４が、蓋１２の外側面には光ファイバ１５がそれ
ぞれコイル状に巻回されて、干渉計（後述の図２参照）
を構成する構造となっている。[First Embodiment] FIG. 1 is a schematic sectional view showing a first embodiment of a high water-resistant cylindrical optical fiber acoustic sensor (hereinafter referred to as a sensor) according to the present invention. In FIG. 1, a lid 11 and a lid 12 are attached to both ends of a single cylinder 10 having a predetermined length and diameter, and a hollow portion 13 is formed by an inner cavity of the single cylinder 10. In this case, the lid 11 is formed of a disc as shown, and the lid 12 is formed of a disc thicker than the lid 11. Further, an optical fiber 14 is wound around the outer surface of the single cylinder 10 and an optical fiber 15 is wound around the outer surface of the lid 12, respectively, and an interferometer (see FIG. 2 described later) is provided.
It has a structure that constitutes.
【００１１】そして、上下に２つある蓋１１，１２の
内、いずれか一方の蓋すなわち本実施例の場合蓋１１の
中心に空胴部１３に通ずるオリフィス１６が開口部とし
て設けられたセンサ構造となっている。この構造によ
り、このセンサを例えば水中に設置乃至浮游させた場
合、空胴部１３にもオリフィス１６を介して水（図に示
したセンサ周囲の液体と同じ液体）が充満するので、セ
ンサ周囲の媒体と同じ媒体で、かつ同じ静水圧で空胴部
１３を満たすことができるようになっている。A sensor structure in which an orifice 16 communicating with the cavity 13 is provided as an opening at the center of either one of the two upper and lower lids 11 and 12, that is, the lid 11 in this embodiment. Has become. With this structure, when this sensor is installed or floated in water, for example, the cavity 13 is also filled with water (the same liquid as the liquid around the sensor shown in the figure) through the orifice 16, so The cavity 13 can be filled with the same medium as the medium and with the same hydrostatic pressure.
【００１２】次に動作について、図３に示す前記の干渉
計の構成説明図を参照しながら説明する。まず、図３に
おいて、１０〜１６は図１で説明したセンサを構成する
部品と同一部品番号であるので、その説明は省略する。
１７はレーザダイオード（ＬＤ）１８からのレーザ光を
分岐して光ファイバ１１及び光ファイバ１２に入射させ
る光カプラであり、１７ａは光ファイバ１１及び光ファ
イバ１２から出力される各レーザ光を光電気変換器（Ｏ
／Ｅ）１９に送信するための光カプラである。Next, the operation will be described with reference to the configuration diagram of the interferometer shown in FIG. First, in FIG. 3, since 10 to 16 are the same part numbers as the parts constituting the sensor described in FIG. 1, the description thereof will be omitted.
Reference numeral 17 is an optical coupler that splits the laser light from the laser diode (LD) 18 and makes it enter the optical fiber 11 and the optical fiber 12, and 17a is an opto-electrical converter that outputs the laser light output from the optical fiber 11 and the optical fiber 12. Converter (O
/ E) 19 is an optical coupler for transmitting to.
【００１３】一方図１において、片側の蓋１１にオリフ
ィス１６を設けておき、このセンサを例えば水中に設置
乃至浮游させた場合、空胴部１３には外周部と同じ液が
満たされる構造となっているため、空胴部１３の容積と
オリフィス１６の径で決まる静水圧を含むヘルムホルツ
共振周波数以下の周波数の音波はオリフィス１６を通過
する。従って、空胴部１３には「静水圧＋この音波の音
圧」が加わるが、センサ（円筒）の外側も同じ「静水圧
＋この音波の音圧」が印加されるので、円筒の内側と外
側の圧力が平衡し、単円筒１０はこの音波では呼吸振動
しない。しかし、この構成では、静水圧で潰れることの
ない圧力バランス構造が得られる。On the other hand, in FIG. 1, when the lid 16 on one side is provided with an orifice 16 and this sensor is installed or floated in water, for example, the cavity portion 13 is filled with the same liquid as the outer peripheral portion. Therefore, a sound wave having a frequency equal to or lower than the Helmholtz resonance frequency including the hydrostatic pressure determined by the volume of the cavity 13 and the diameter of the orifice 16 passes through the orifice 16. Therefore, "hydrostatic pressure + sound pressure of this sound wave" is applied to the cavity 13, but the same "hydrostatic pressure + sound pressure of this sound wave" is applied to the outside of the sensor (cylinder), so The outer pressure is balanced and the single cylinder 10 does not breathe with this sound wave. However, this configuration provides a pressure balance structure that does not collapse under hydrostatic pressure.
【００１４】そこで、この構成において、ヘルムホルツ
共振周波数以上の周波数の音波をセンサのプローブとし
て使用すると、この音波はオリフィス１６を通過しなく
なるので、センサの外側には「静水圧＋この音波の音
圧」が印加されるが、空胴部１３には静水圧のみしか加
わらない。従って、円筒の内側と外側に圧力不平衡が生
じ、単円筒１０はこの音波の音圧で呼吸振動をするよう
になり、それにつれて円筒に巻き付けられた光ファイバ
１４は伸び縮みする。一方、蓋１１，１２は中空でない
剛体であるから音波による呼吸振動は生じないので、蓋
１２に巻き付けられた光ファイバ１５には長さの変化は
生じない。従って、光ファイバ１４及び光ファイバ１５
中を伝搬する光（図３のレーザダイオート１８から入射
された二筋のレーザ光）の間に位相差が生ずるようにな
る。従って、従来の技術で説明したと同様に音響センサ
として機能するようになる。つまり、、ヘルムホルツ共
振周波数以上の周波数の音波を通さない大きさの径を有
するオリフィス１６を蓋１１に設けて音響センサを構成
すればよい。このようにして、蓋１１にオリフィス１６
を有し、単円筒１０の空胴部１３に液体が満たされる構
造を有する圧力バランス構造の単円筒型の光ファイバ音
響センサは耐水圧が高く、深々度の水中でも適用できる
ようになる。Therefore, in this configuration, when a sound wave having a frequency higher than the Helmholtz resonance frequency is used as a probe of the sensor, this sound wave does not pass through the orifice 16. Therefore, "hydrostatic pressure + sound pressure of this sound wave" is provided outside the sensor. Is applied, but only hydrostatic pressure is applied to the cavity 13. Therefore, a pressure imbalance occurs inside and outside the cylinder, causing the single cylinder 10 to vibrate with the sound pressure of this sound wave, and the optical fiber 14 wound around the cylinder expands and contracts accordingly. On the other hand, since the lids 11 and 12 are rigid bodies that are not hollow, breathing vibration due to sound waves does not occur, so that the length of the optical fiber 15 wound around the lid 12 does not change. Therefore, the optical fiber 14 and the optical fiber 15
A phase difference is generated between the light propagating in the inside (the two lines of laser light incident from the laser die-auto 18 in FIG. 3). Therefore, it functions as an acoustic sensor as described in the related art. In other words, the acoustic sensor may be configured by providing the lid 11 with the orifice 16 having a diameter that does not allow passage of a sound wave having a frequency higher than the Helmholtz resonance frequency. In this way, the lid 16 is provided with the orifice 16
The single-cylinder type optical fiber acoustic sensor having a pressure balance structure having a structure in which the cavity 13 of the single cylinder 10 is filled with liquid has a high water pressure resistance and can be applied even in deep water.
【００１５】以上のように第１の実施形態によれば、円
筒型光ファイバ音響センサの単円筒１０の空胴部１３を
密閉する蓋１１にオリフィス１６で形成される開口部を
設け、前述の空胴部１３に液体を満たすことができるよ
うな圧力バランス構造とすることにより、空胴部１３の
静水圧とセンサ外部の静水圧とを一致させることができ
るので、深々度の海中等において使用可能な高耐水圧の
単円筒型光ファイバ音響センサ（ハイドロホン）を得る
ことができる。As described above, according to the first embodiment, the opening formed by the orifice 16 is provided in the lid 11 for sealing the cavity 13 of the single cylinder 10 of the cylindrical optical fiber acoustic sensor, and By using a pressure balance structure capable of filling the cavity 13 with liquid, the hydrostatic pressure of the cavity 13 and the hydrostatic pressure outside the sensor can be matched, so that it can be used in the deep sea. It is possible to obtain a possible single cylinder type optical fiber acoustic sensor (hydrophone) with high water pressure resistance.
【００１６】［第２の実施形態］図２は本発明による高
耐水圧円筒型光ファイバ音響センサの第２の実施形態を
示す模式断面図である。図２において、所定の長さ・径
を持つ単円筒１０の両端に蓋１１，１２を取り付け、円
筒内が空胴部１３となるように形成している。また、本
実施例では単円筒１０内側面に、光ファイバ２０がコイ
ル状に巻回され、蓋１２の外側面には、図１の実施形態
の場合と同様に光ファイバ１５が巻回されていて、本実
施形態の干渉計を構成する構造となっている。そして、
図１の実施形態の場合と同様に、蓋１１にはオリフィス
１６が設けられているが、その基本的な構成・構造は第
１の実施例で説明したものと同様である。[Second Embodiment] FIG. 2 is a schematic sectional view showing a second embodiment of a high water pressure resistant cylindrical optical fiber acoustic sensor according to the present invention. In FIG. 2, lids 11 and 12 are attached to both ends of a single cylinder 10 having a predetermined length and diameter, so that the inside of the cylinder becomes a cavity 13. Further, in this embodiment, the optical fiber 20 is wound in a coil shape on the inner side surface of the single cylinder 10, and the optical fiber 15 is wound on the outer side surface of the lid 12 as in the embodiment of FIG. Thus, the interferometer of the present embodiment is structured. And
As in the case of the embodiment of FIG. 1, the lid 11 is provided with the orifice 16, but the basic configuration and structure are the same as those described in the first embodiment.
【００１７】そして、本実施形態では、光ファイバ２０
が単円筒１０の内側面にコイル状に巻回され、光ファイ
バ１５が蓋１２の外側面に巻回されて、本実施形態の干
渉計を構成する構造となっていることを特徴としている
が、その他の構成、作用動作及び効果乃至利点は、前述
の第１の実施形態の場合と同様であるので、詳細な説明
は省略する。In the present embodiment, the optical fiber 20
Is wound around the inner surface of the single cylinder 10 in a coil shape, and the optical fiber 15 is wound around the outer surface of the lid 12 to form the interferometer of the present embodiment. The other configurations, operations, effects, and advantages are the same as those in the first embodiment described above, and detailed description thereof will be omitted.
【００１８】[0018]
【発明の効果】以上のように本発明によれば、１つの円
筒体からなる単円筒型構造で構成され、この単円筒体の
内部が形成する空胴部をその両端においてそれぞれ閉じ
る蓋を備え、さらにこの円筒体の側面に沿って巻回され
た光ファイバを有してなる円筒型光ファイバ音響センサ
の蓋の内の１方の側の蓋に、空胴部内と円筒体の外周部
との静水圧を等しくする開口部を設けたものとしたか
ら、間隙部の静水圧とセンサ外部の静水圧を一致させる
ことができるので、高感度で、かつ高耐水圧の円筒型光
ファイバ音響センサを得ることができる。As described above, according to the present invention, a single-cylinder structure composed of one cylinder is provided, and a lid for closing the cavity formed inside the single-cylinder at both ends thereof is provided. Further, in the lid on one side of the lid of the cylindrical optical fiber acoustic sensor having an optical fiber wound along the side surface of the cylindrical body, the inside of the cavity and the outer peripheral portion of the cylindrical body are provided. Since the opening for equalizing the hydrostatic pressure of the sensor is provided, it is possible to match the hydrostatic pressure in the gap with the hydrostatic pressure outside the sensor. Therefore, the cylindrical optical fiber acoustic sensor with high sensitivity and high water pressure resistance is provided. Can be obtained.
【図１】本発明による高耐水圧円筒型光ファイバ音響セ
ンサの第１の実施形態を示す模式断面図である。FIG. 1 is a schematic cross-sectional view showing a first embodiment of a high water pressure resistant cylindrical optical fiber acoustic sensor according to the present invention.
【図２】本発明による高耐水圧円筒型光ファイバ音響セ
ンサの第２の実施形態を示す模式断面図である。FIG. 2 is a schematic cross-sectional view showing a second embodiment of a high water pressure resistant cylindrical optical fiber acoustic sensor according to the present invention.
【図３】図１の実施形態の干渉計構成を示す模式説明図
である。FIG. 3 is a schematic explanatory view showing the interferometer configuration of the embodiment of FIG.
【図４】図１の実施形態の干渉計構成の周波数特性を示
す線図である。FIG. 4 is a diagram showing frequency characteristics of the interferometer configuration of the embodiment of FIG.
【図５】従来の円筒型光ファイバ音響センサを示す模式
断面図である。FIG. 5 is a schematic sectional view showing a conventional cylindrical optical fiber acoustic sensor.
１ 外円筒 ２ 内円筒 ３ 蓋 ４ 空気室 ５，５ａ 光ファイバ １０ 単円筒 １１，１２ 蓋 １３ 空胴部 １４，１５，２０ 光ファイバ １６ オリフィス １７，１７ａ 光カプラ １８ レーザダイオード（ＬＤ） １９ 光電気変換器（Ｏ／Ｅ） 1 Outer Cylinder 2 Inner Cylinder 3 Lid 4 Air Chamber 5, 5a Optical Fiber 10 Single Cylinder 11, 12 Lid 13 Cavity 14, 15, 20 Optical Fiber 16 Orifice 17, 17a Optical Coupler 18 Laser Diode (LD) 19 Photoelectricity Converter (O / E)
Claims (3)
され、前記１つの円筒体の内部を構成する空胴部をその
両端においてそれぞれ閉じる蓋を有し、かつ前記円筒体
の側面に沿って巻回された光ファイバを備えてなる円筒
型光ファイバ音響センサであって、 前記蓋の内の一方の側の蓋に形成され、前記空胴部と前
記円筒体の外周部との静水圧を等しくする開口部を有す
ることを特徴とする高耐水圧円筒型光ファイバ音響セン
サ。1. A single-cylinder structure having a single cylindrical body, each of which has a lid that closes a cavity forming the inside of the single cylindrical body at both ends thereof, and extends along a side surface of the cylindrical body. A cylindrical optical fiber acoustic sensor comprising a wound optical fiber, wherein the hydrostatic pressure is formed on the lid on one side of the lid, the hydrostatic pressure between the cavity portion and the outer peripheral portion of the cylindrical body. A high water pressure resistant cylindrical optical fiber acoustic sensor having an opening for making the same.
胴部によって構成されるヘルムホルツ共鳴器におけるヘ
ルムホルツ共振周波数以上の周波数の音波は通過しない
大きさの径であることを特徴とする請求項１記載の高耐
水圧円筒型光ファイバ音響センサ。2. The diameter of the opening is such that a sound wave having a frequency higher than the Helmholtz resonance frequency in a Helmholtz resonator formed by the opening and the cavity does not pass through. The high water pressure resistant cylindrical optical fiber acoustic sensor according to claim 1.
前記蓋の内の前記開口部の形成されていない蓋の側面に
設けられていることを特徴とする請求項１又は請求項２
記載の高耐水圧円筒型光ファイバ音響センサ。3. The optical fiber is provided on a side surface of the cylindrical body and a side surface of the lid in which the opening is not formed in the lid.
The high water pressure resistant cylindrical optical fiber acoustic sensor described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00792896A JP3263897B2 (en) | 1996-01-22 | 1996-01-22 | High water pressure cylindrical optical fiber acoustic sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00792896A JP3263897B2 (en) | 1996-01-22 | 1996-01-22 | High water pressure cylindrical optical fiber acoustic sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09196748A true JPH09196748A (en) | 1997-07-31 |
| JP3263897B2 JP3263897B2 (en) | 2002-03-11 |
Family
ID=11679193
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00792896A Expired - Fee Related JP3263897B2 (en) | 1996-01-22 | 1996-01-22 | High water pressure cylindrical optical fiber acoustic sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3263897B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012068087A (en) * | 2010-09-22 | 2012-04-05 | Technical Research & Development Institute Ministry Of Defence | Optical fiber hydrophone having high water pressure resistance |
| JP2012145596A (en) * | 2012-05-07 | 2012-08-02 | Technical Research & Development Institute Ministry Of Defence | Optical fiber magnetic sensor |
| JP2016099242A (en) * | 2014-11-21 | 2016-05-30 | 住友電気工業株式会社 | Interference type optical fiber sensor system and interference type optical fiber sensor head |
-
1996
- 1996-01-22 JP JP00792896A patent/JP3263897B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012068087A (en) * | 2010-09-22 | 2012-04-05 | Technical Research & Development Institute Ministry Of Defence | Optical fiber hydrophone having high water pressure resistance |
| JP2012145596A (en) * | 2012-05-07 | 2012-08-02 | Technical Research & Development Institute Ministry Of Defence | Optical fiber magnetic sensor |
| JP2016099242A (en) * | 2014-11-21 | 2016-05-30 | 住友電気工業株式会社 | Interference type optical fiber sensor system and interference type optical fiber sensor head |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3263897B2 (en) | 2002-03-11 |
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