JP2002267537A - Diffraction grating reflected wavelength measuring method and device, and physical quantity measuring method and device - Google Patents

Diffraction grating reflected wavelength measuring method and device, and physical quantity measuring method and device

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Publication number
JP2002267537A
JP2002267537A JP2001068220A JP2001068220A JP2002267537A JP 2002267537 A JP2002267537 A JP 2002267537A JP 2001068220 A JP2001068220 A JP 2001068220A JP 2001068220 A JP2001068220 A JP 2001068220A JP 2002267537 A JP2002267537 A JP 2002267537A
Authority
JP
Japan
Prior art keywords
wavelength
reflected light
light
diffraction grating
optical fiber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2001068220A
Other languages
Japanese (ja)
Inventor
Keisuke Fukuchi
圭介 福地
Original Assignee
Hitachi Cable Ltd
日立電線株式会社
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hitachi Cable Ltd, 日立電線株式会社 filed Critical Hitachi Cable Ltd
Priority to JP2001068220A priority Critical patent/JP2002267537A/en
Publication of JP2002267537A publication Critical patent/JP2002267537A/en
Pending legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01DMEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infra-red, visible, or ultra-violet light
    • G01D5/32Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infra-red, visible, or ultra-violet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infra-red, visible, or ultra-violet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infra-red, visible, or ultra-violet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35306Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infra-red, visible, or ultra-violet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
    • G01D5/35309Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infra-red, visible, or ultra-violet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer
    • G01D5/35316Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infra-red, visible, or ultra-violet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer using a Bragg gratings

Abstract

PROBLEM TO BE SOLVED: To measure the wavelength and physical quantity of light reflected by a diffraction grating with high accuracy. SOLUTION: Pulse light having a designated wavelength obtained by modulating output light of a wide band light source 1 by an external modulator 2 enters from one end of an optical fiber having a diffraction grating FBG in the midway of an optical path, reflected light returned from the diffraction grating FBG to one end of the optical fiber is received through a wavelength inclined type optical filter 5 having a designated wavelength transmission characteristic by a photo detector 6, and the light intensity of the reflected light is measured to obtain the wavelength of reflected light from the light intensity of the reflected light.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION
【0001】[0001]
【発明の属する技術分野】本発明は、回折格子反射波長
計測方法及びその装置並びにそれを利用した物理量計測
方法及びその装置に関するものである。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffraction grating reflection wavelength measuring method and apparatus, and a physical quantity measuring method and apparatus using the same.
【0002】[0002]
【従来の技術】これまでの波長計測技術の代表的な方法
としては、第1に光スペクトラムアナライザを用いる方
法、第2に干渉計を利用した波長計を用いる方法があ
る。
2. Description of the Related Art As a typical method of the conventional wavelength measurement technology, there are a first method using an optical spectrum analyzer and a second method using a wavelength meter using an interferometer.
【0003】光スペクトラムアナライザには、その測定
方法を大別すると、回折格子を用いたものと、光フィル
タを用いたものの2種類の方式がある。両者ともに測定
する光を波長毎に細かく区切ってその分解した波長の強
度を逐一測定していくことにより、波長測定を行うもの
である。この波長毎に細かく区切る方法として、回折格
子を用いたり、光フィルタを用いたりする。
[0003] Optical spectrum analyzers can be roughly classified into two types, those using a diffraction grating and those using an optical filter. In both cases, wavelength measurement is performed by finely dividing the light to be measured for each wavelength and measuring the intensity of the decomposed wavelength one by one. As a method of finely dividing each wavelength, a diffraction grating or an optical filter is used.
【0004】回折格子は、光ファイバや光導波路基板な
どの反射基体上(実際には光を伝搬するコア)に光の波
長程度の間隔で格子が切ってあるものであり、これを入
射光に対してある角度を傾けておくことにより、隣同士
の格子で反射した光が干渉し、ある特有な選択された波
長の光のみを取り出すことができる。知りたい波長範囲
で掃引を行い、それぞれの波長においてこれを光電変換
して逐次電圧強度を求めることにより、波長計測を行う
ことができる。回折格子からの反射光は波長幅が約0.
1〜1nm程度であり、これと同等の波長分解能で測定
することによって、そのスペクトル形状、およびピーク
波長を測定することができる。この方法では最高で約±
20pm(pmはピコメートル=10-12m)程度の精
度でピーク波長を測定することができる。
[0004] A diffraction grating is a grating that is cut on a reflective substrate such as an optical fiber or an optical waveguide substrate (actually, a core that propagates light) at an interval of about the wavelength of light, and is converted into incident light. By inclining a certain angle with respect to the light, light reflected by adjacent gratings interferes with each other, so that only light having a certain specific selected wavelength can be extracted. Wavelength measurement can be performed by performing sweeping in a wavelength range to be known and performing photoelectric conversion on each wavelength to sequentially determine voltage intensity. The reflected light from the diffraction grating has a wavelength width of about 0.2.
It is about 1 to 1 nm, and the spectrum shape and the peak wavelength can be measured by measuring with the same wavelength resolution. With this method, at most ±
The peak wavelength can be measured with an accuracy of about 20 pm (pm is picometer = 10 −12 m).
【0005】光フィルタ型の光スペクトラムアナライザ
は、前記回折格子の代わりに、特有の波長のみを透過さ
せ、他の波長は反射、あるいは吸収する光のフィルタを
用いることにより、前記と同様の作用を得、波長計測を
行う。この方式によっても、最高で約±数十pm程度の
精度でピーク波長を測定することができる。
An optical spectrum analyzer of the optical filter type has the same effect as described above by using a filter of light that transmits only specific wavelengths and reflects or absorbs other wavelengths instead of the diffraction grating. Then, wavelength measurement is performed. Even with this method, the peak wavelength can be measured with an accuracy of about ± several tens pm at the maximum.
【0006】次に、干渉計を利用した波長計には、測定
目的に応じて大別して次の2種類の方式がある。
[0006] Wavelength meters using an interferometer are roughly classified into the following two types according to the purpose of measurement.
【0007】まず、ひとつは、一般にレーザダイオード
やガスレーザなどの線幅が狭い波長の精密計測を行う方
式であり、マイケルソン干渉計などを利用して、単一の
発振波長のピーク値にロックした後、その微小な波長変
化を時間継続的に測定する。干渉計を利用することによ
り、比較的容易にpmオーダーの精密な波長計測を行う
ことが可能である。
First, there is a method of performing precise measurement of a wavelength having a narrow line width such as a laser diode or a gas laser in general, and locked to a peak value of a single oscillation wavelength using a Michelson interferometer or the like. Thereafter, the minute wavelength change is continuously measured over time. By using an interferometer, it is possible to relatively easily perform precise wavelength measurement on the order of pm.
【0008】他方、ファブリ・ペロー干渉計を利用して
比較的広帯域の波長範囲を高速で測定する方式がある。
ファブリ・ペロー干渉計では、共振器を構成する向かい
合って置いた2枚の反射板の反射率と、その共振器間隔
を変えることによって、比較的自由にフィルタ特性を設
計することができる。このとき、フィルタ特性の波長透
過幅を回折格子の反射波長幅と同等程度かそれ以下に設
定することによって、反射ピーク波長を正確に測定する
ことができる。ファブリ・ペロー共振器を構成する反射
板の片方をピエゾ振動子に搭載して振動させ、その共振
器長を伸縮させて干渉計による透過波長を掃引させ、そ
の透過分の光強度を逐一測定することによって波長計測
を行う。この方式では、40〜50nm程度の広い波長
範囲を100Hz以下程度の比較的高速な掃引で測定す
ることができる。このとき、ピーク波長精度は約±10
pmが可能であるという報告がある。
On the other hand, there is a method of measuring a relatively wide wavelength range at high speed using a Fabry-Perot interferometer.
In the Fabry-Perot interferometer, the filter characteristics can be designed relatively freely by changing the reflectance of two opposing reflectors constituting the resonator and the interval between the resonators. At this time, the reflection peak wavelength can be accurately measured by setting the wavelength transmission width of the filter characteristic to be equal to or less than the reflection wavelength width of the diffraction grating. One of the reflectors constituting the Fabry-Perot resonator is mounted on a piezo oscillator and vibrated, the length of the resonator is expanded and contracted, the transmission wavelength is swept by an interferometer, and the light intensity of the transmitted light is measured one by one. In this way, wavelength measurement is performed. In this method, a wide wavelength range of about 40 to 50 nm can be measured by a relatively high-speed sweep of about 100 Hz or less. At this time, the peak wavelength accuracy is about ± 10
There are reports that pm is possible.
【0009】[0009]
【発明が解決しようとする課題】しかしながら、光ファ
イバに回折格子を形成したFBG(Fiber Bragg Gratin
g:光ファイバブラッグ回折型フィルタ)を直列に複数
個つなげて、その反射光の波長を回折格子や光フィルタ
を用いた光スペクトラムアナライザにより計測しようと
した場合には、測定波長のスペクトル形状を詳しく分析
するには有利でも、広範囲の波長帯域において、そのピ
ーク波長を正確に測定することはほとんど不可能であ
る。その理由は、最高の精度である±20pmの精度で
安定して測定するには、1nmあたり10秒程度での掃
引測定が必要となるのに対し、実際には40〜50nm
の範囲を掃引するために5〜6分程度の時間が必要であ
り、時々刻々変化するようなFBGの反射波長を計測し
ようとしても、その変化に追随することができず測定不
能となってしまう。
However, an FBG (Fiber Bragg Gratin) in which a diffraction grating is formed on an optical fiber is used.
g: an optical fiber Bragg diffraction filter) connected in series and the wavelength of the reflected light is measured by an optical spectrum analyzer using a diffraction grating or an optical filter. Although advantageous for analysis, it is almost impossible to accurately measure its peak wavelength over a wide wavelength band. The reason is that in order to stably measure with the highest accuracy of ± 20 pm, a sweep measurement of about 10 seconds per 1 nm is required, but in practice, 40 to 50 nm
It takes about 5 to 6 minutes to sweep the range, and even if it is attempted to measure the reflection wavelength of the FBG that changes every moment, it cannot follow the change and cannot be measured. .
【0010】また、回折格子や光フィルタの波長特性を
変化させる場合にそれを動かす機構が必要になってしま
い、更に、可動部があるということはその寿命を含めた
長期信頼性が問題となる。
Further, when changing the wavelength characteristics of the diffraction grating or the optical filter, a mechanism for moving the wavelength characteristics is required. Further, the presence of the movable portion poses a problem of long-term reliability including its life. .
【0011】干渉計を用いた波長計で、精密計測に利用
されているものは、前項で述べたように単一の波長にロ
ックしてその経時変化を計測するものであり、広帯域な
範囲で複数のFBGの反射波長を計測することはできな
い。
A wavelength meter using an interferometer, which is used for precision measurement, locks to a single wavelength and measures the change with time, as described in the previous section. The reflection wavelength of a plurality of FBGs cannot be measured.
【0012】ファブリ・ペロー干渉計を利用したピエゾ
素子波長掃引方式では、広帯域な波長範囲において複数
のFBG反射ピーク波長を計測することが可能であるた
め有用であるが、ピエゾ素子による可動部の長期信頼性
が低い。また、ピエゾ素子の位置決め精度が周囲電磁ノ
イズにより劣化する傾向があり、堅牢な電磁シールド等
が必要となる。
A piezo element wavelength sweeping method using a Fabry-Perot interferometer is useful because a plurality of FBG reflection peak wavelengths can be measured in a wide wavelength range. Low reliability. In addition, the positioning accuracy of the piezo element tends to be deteriorated by ambient electromagnetic noise, and a robust electromagnetic shield or the like is required.
【0013】このように、広帯域な波長範囲で複数のF
BG反射ピーク波長を、精度良く、長期信頼性・安定性
を満足して計測することができる方法及び装置は現状で
は見当たらない。
As described above, a plurality of Fs in a wide wavelength range
At present, there is no method or apparatus that can accurately measure the BG reflection peak wavelength with satisfactory long-term reliability and stability.
【0014】本発明は、上記した従来技術に鑑みなされ
たものであり、その目的とするところは、回折格子で反
射される光の波長、物理量を高精度に計測することがで
きる回折格子反射波長計測方法及びその装置並びに物理
量計測方法及びその装置を提供することにある。
The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide a diffraction grating reflection wavelength capable of measuring a wavelength and a physical quantity of light reflected by the diffraction grating with high accuracy. It is an object of the present invention to provide a measuring method and its device, and a physical quantity measuring method and its device.
【0015】[0015]
【課題を解決するための手段】上記課題を解決するた
め、本発明は、光路途中に回折格子が設けられた光ファ
イバの一端から所定の波長を有するパルス光を入射し、
上記回折格子から上記光ファイバの一端に戻ってくる反
射光を所定の波長透過特性を有する波長傾斜型光フィル
タを通して受光して上記反射光の光強度を測定し、該反
射光の光強度から該反射光の波長を求めることを特徴と
する回折格子反射波長計測方法である。
According to the present invention, a pulse light having a predetermined wavelength is incident from one end of an optical fiber provided with a diffraction grating in an optical path.
The reflected light returning from the diffraction grating to one end of the optical fiber is received through a wavelength gradient optical filter having a predetermined wavelength transmission characteristic, and the light intensity of the reflected light is measured. This is a diffraction grating reflection wavelength measuring method characterized by determining the wavelength of reflected light.
【0016】上記回折格子反射波長計測方法は、上記反
射光を分岐してそれぞれ波長透過特性が異なる波長傾斜
型フィルタを通した後に受光して上記反射光の各光強度
を測定した後、該各光強度の強度比から上記反射光の波
長を求めることにより上記反射光中に含まれる光強度変
動誤差成分を除去するように構成することができる。
In the diffraction grating reflection wavelength measuring method, the reflected light is branched, passed through a wavelength gradient filter having different wavelength transmission characteristics, received, measured, and each light intensity of the reflected light is measured. By obtaining the wavelength of the reflected light from the intensity ratio of the light intensity, it is possible to remove the light intensity fluctuation error component contained in the reflected light.
【0017】更に、上記回折格子反射波長計測方法は、
上記回折格子が、反射光の中心波長がそれぞれ異なる複
数の回折格子からなり、上記光ファイバの一端に戻って
くる反射光を波長選択フィルタにより所定の帯域毎に分
割した後に各帯域毎に上記波長傾斜型光フィルタを通す
ように構成することができる。
Further, the method for measuring the reflection wavelength of the diffraction grating includes:
The diffraction grating is composed of a plurality of diffraction gratings each having a different center wavelength of the reflected light, and the reflected light returning to one end of the optical fiber is divided into predetermined bands by a wavelength selection filter, and then the wavelength is set for each band. It can be configured to pass through an inclined optical filter.
【0018】また、本発明は、光路途中に回折格子が設
けられた光ファイバと、該光ファイバの一端に所定の波
長を有するパルス光を入射する光源と、上記回折格子か
ら上記光ファイバの一端に戻って来た反射光を受光する
受光器と、上記光ファイバの一端と上記受光器との間に
設けられた所定の波長透過特性を有する波長傾斜型光フ
ィルタと、上記受光器により測定した上記反射光の光強
度から該反射光の波長を求める演算回路とを有すること
を特徴とする回折格子反射波長計測装置である。
Further, the present invention provides an optical fiber having a diffraction grating provided in the middle of an optical path, a light source for inputting a pulsed light having a predetermined wavelength to one end of the optical fiber, A light receiving device that receives the reflected light that has returned to the optical fiber, a wavelength gradient optical filter having a predetermined wavelength transmission characteristic provided between one end of the optical fiber and the light receiving device, and measurement was performed by the light receiving device. An arithmetic circuit for calculating the wavelength of the reflected light from the light intensity of the reflected light.
【0019】上記回折格子反射波長計測装置は、上記光
ファイバの一端と上記波長傾斜型光フィルタとの間に上
記反射光を分岐して出力する光分岐器が設けられると共
に、該光分岐器の各出力に波長透過特性が異なる波長傾
斜型フィルタがそれぞれ設けられており、上記演算回路
により上記波長傾斜型フィルタを通した後の上記分岐さ
れた各反射光の光強度の強度比から上記反射光の波長を
求めるように構成することができる。
In the diffraction grating reflection wavelength measuring device, an optical splitter for splitting and outputting the reflected light is provided between one end of the optical fiber and the wavelength tilt type optical filter. Each output is provided with a wavelength gradient filter having a different wavelength transmission characteristic, and the arithmetic circuit determines the reflected light based on the intensity ratio of the branched reflected light after passing through the wavelength gradient filter. Can be determined.
【0020】更に、上記回折格子反射波長計測装置は、
上記回折格子が、反射光の中心波長がそれぞれ異なる複
数の回折格子からなり、上記光ファイバの一端に戻って
くる反射光を波長選択フィルタにより所定の帯域毎に分
割した後に各帯域毎に上記波長傾斜型光フィルタを通す
ように構成することができる。
Further, the above-mentioned diffraction grating reflection wavelength measuring device comprises:
The diffraction grating is composed of a plurality of diffraction gratings each having a different center wavelength of the reflected light, and the reflected light returning to one end of the optical fiber is divided into predetermined bands by a wavelength selection filter, and then the wavelength is set for each band. It can be configured to pass through an inclined optical filter.
【0021】また、本発明は、光路途中に回折格子が設
けられた光ファイバの一端から所定の波長を有するパル
ス光を入射し、上記回折格子から上記光ファイバの一端
に戻ってくる反射光を所定の波長透過特性を有する波長
傾斜型光フィルタを通して受光して上記反射光の光強度
を測定し、該反射光の光強度から該反射光の波長を求め
ると共に、上記入射光の波長に対する上記反射光の波長
の変化量から物理量を求めることを特徴とする物理量計
測方法である。
Further, according to the present invention, a pulsed light having a predetermined wavelength is incident from one end of an optical fiber having a diffraction grating provided in the middle of an optical path, and reflected light returning from the diffraction grating to one end of the optical fiber is generated. The reflected light is received through a wavelength gradient optical filter having a predetermined wavelength transmission characteristic, the light intensity of the reflected light is measured, the wavelength of the reflected light is determined from the light intensity of the reflected light, and the reflection of the reflected light with respect to the wavelength of the incident light is measured. This is a physical quantity measuring method characterized in that a physical quantity is obtained from a change amount of the wavelength of light.
【0022】上記物理量計測方法は、上記反射光を分岐
してそれぞれ波長透過特性が異なる波長傾斜型フィルタ
を通した後に受光して上記反射光の各光強度を測定した
後、該各光強度の強度比から上記反射光の波長を求める
ことにより上記反射光中に含まれる光強度変動誤差成分
を除去するように構成することができる。
In the physical quantity measuring method, the reflected light is branched, passed through a wavelength gradient type filter having different wavelength transmission characteristics, received, measured for each light intensity of the reflected light, and then measured for each light intensity. By obtaining the wavelength of the reflected light from the intensity ratio, it is possible to remove the light intensity fluctuation error component contained in the reflected light.
【0023】更に、上記物理量計測方法は、上記回折格
子が、反射光の中心波長がそれぞれ異なる複数の回折格
子からなり、上記光ファイバの一端に戻ってくる反射光
を波長選択フィルタにより所定の帯域毎に分割した後に
各帯域毎に上記波長傾斜型光フィルタを通すように構成
することができる。
Further, in the physical quantity measuring method, the diffraction grating may include a plurality of diffraction gratings having different center wavelengths of reflected light, and the reflected light returning to one end of the optical fiber may be transmitted to a predetermined band by a wavelength selection filter. It is possible to configure so as to pass through the above-mentioned wavelength-graded optical filter for each band after dividing for each band.
【0024】また、本発明は、光路途中に回折格子が設
けられた光ファイバと、該光ファイバの一端に所定の波
長を有するパルス光を入射する光源と、上記回折格子か
ら上記光ファイバの一端に戻って来た反射光を受光する
受光器と、上記光ファイバの一端と上記受光器との間に
設けられた所定の波長透過特性を有する波長傾斜型光フ
ィルタと、上記受光器により測定した上記反射光の光強
度から該反射光の波長を求めて上記入射光の波長に対す
る上記反射光の波長の変化量から物理量を求める演算回
路とを有することを特徴とする物理量計測装置である。
Also, the present invention provides an optical fiber having a diffraction grating provided in the middle of an optical path, a light source for inputting a pulse light having a predetermined wavelength to one end of the optical fiber, A light receiving device that receives the reflected light that has returned to the optical fiber, a wavelength gradient optical filter having a predetermined wavelength transmission characteristic provided between one end of the optical fiber and the light receiving device, and measurement was performed by the light receiving device. A physical quantity measuring device, comprising: an arithmetic circuit for determining a wavelength of the reflected light from the light intensity of the reflected light and obtaining a physical quantity from an amount of change in the wavelength of the reflected light with respect to the wavelength of the incident light.
【0025】上記物理量計測装置は、上記光ファイバの
一端と上記波長傾斜型光フィルタとの間に上記反射光を
分岐して出力する光分岐器が設けられると共に、該光分
岐器の各出力に波長透過特性が異なる波長傾斜型フィル
タがそれぞれ設けられており、上記演算回路により上記
波長傾斜型フィルタを通した後の上記分岐された各反射
光の光強度の強度比から上記反射光の波長及び物理量を
求めるように構成することができる。
In the physical quantity measuring device, an optical splitter for splitting and outputting the reflected light is provided between one end of the optical fiber and the wavelength tilt type optical filter, and each output of the optical splitter is provided at each output of the optical splitter. Each of the wavelength gradient filters having different wavelength transmission characteristics is provided, and the wavelength of the reflected light and the wavelength of the reflected light are determined based on the intensity ratio of the respective reflected lights branched through the wavelength gradient filter by the arithmetic circuit. It can be configured to determine a physical quantity.
【0026】更に、上記物理量計測装置は、上記回折格
子が、反射光の中心波長がそれぞれ異なる複数の回折格
子からなり、上記光ファイバの一端に戻ってくる反射光
を波長選択フィルタにより所定の帯域毎に分割した後に
各帯域毎に上記波長傾斜型光フィルタを通すように構成
することができる。
Further, in the physical quantity measuring device, the diffraction grating comprises a plurality of diffraction gratings each having a different center wavelength of reflected light, and the reflected light returning to one end of the optical fiber is subjected to a predetermined band by a wavelength selection filter. It is possible to configure so as to pass through the above-mentioned wavelength-graded optical filter for each band after dividing for each band.
【0027】[0027]
【発明の実施の態様】以下、本発明の好適な実施の態様
を図示した図面に基づいて詳細に説明する。
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
【0028】図1は本発明の一実施形態を示す説明図で
ある。
FIG. 1 is an explanatory diagram showing one embodiment of the present invention.
【0029】図1において、1は広帯域光源であり、3
乃至4から20nm程度の広い波長範囲の光を出すこと
ができ、またその出力が1nmあたり約1μWから1m
W程度のものを用いることが好ましい。外部変調器2
は、連続出力である広帯域光源1の出力をパルス状(パ
ルス光)に変調するものである。本発明においては、広
帯域光源1と外部変調器2とを合わせて光源と定義する
ことができる。
In FIG. 1, reference numeral 1 denotes a broadband light source;
Light of a wide wavelength range of about 4 to 20 nm and an output of about 1 μW to 1 m per nm.
It is preferable to use a material having a size of about W. External modulator 2
Is for modulating the output of the broadband light source 1 which is a continuous output into a pulse shape (pulse light). In the present invention, the broadband light source 1 and the external modulator 2 together can be defined as a light source.
【0030】ここで、パルス光として、短パルス、ある
いは疑似ランダムパルス変調された(M系列で変調され
た)パルス列を用いることにより、FBGからの戻り光
をOTDR(Optical Time Domain Reflectometry:光
学的時間領域反射測定方法)の原理によって測定するこ
とができる。
Here, by using a short pulse or a pulse train subjected to pseudo-random pulse modulation (modulated by an M sequence) as the pulse light, the return light from the FBG can be converted to optical time domain reflectometry (OTDR). Area reflection measurement method).
【0031】OTDRとは、光ファイバ中にパルスを入
射したとき、光ファイバ中で散乱、または反射した光の
入射から経過した時間を測定することによって、その位
置(距離)を知り、さらにその位置での戻り光の波長変
化や強度変化から、光ファイバに沿った長手方向の物理
量の多点検知を可能とするものである。このOTDRに
よる物理量計測方式は、1本の光ファイバで数十以上の
位置の多点の物理量計測が可能である、測定地点の現場
に電源が必要ない、といった利点がある。測定対象とな
る物理量として一般的なものは、光ファイバの伝送損
失、温度、歪み等である。
The OTDR means that when a pulse is incident on an optical fiber, its position (distance) is known by measuring the time elapsed from the incidence of the light scattered or reflected in the optical fiber, and the position is further determined. This makes it possible to detect multiple points of the physical quantity in the longitudinal direction along the optical fiber from the change in the wavelength and the change in the intensity of the return light. The physical quantity measurement method using the OTDR has the advantages that a single optical fiber can measure multiple physical quantities at several tens or more positions, and that no power source is required at the site of the measurement point. Typical physical quantities to be measured are transmission loss, temperature, distortion, and the like of an optical fiber.
【0032】図1に示した本実施態様では、1本の光フ
ァイバ10の光路途中に3つのFBG(FBG1、FB
G2及びFBG3)が直列に設けられており、サーキュ
レータ3のポート1からポート2を通じて光ファイバ1
0の一端にパルス光が入射される。入射されたパルス光
は、FBG1、FBG2及びFBG3で反射し、その反
射光はサーキュレータ3のポート2からポート3を通じ
て光電変換器(受光器)6で受光される。このとき、例
えば図2に示すような、波長によって透過光強度が変わ
る特性を有する波長傾斜型光フィルタ5を光電変換器6
の前段に設けることにより、FBG反射波長を光強度に
変換して測定する。そして、図2の波長透過率特性に基
づいて、測定した光強度から図示しない演算回路により
FBG1、FBG2及びFBG3の各反射光の波長を求
める。ここで、光源に近いほどパルス光が入射後に反射
して戻ってくる時間が早いため、OTDRの原理を用い
ることで、計測装置からの距離が異なる位置に設けられ
ている複数のFBGの反射波長を測定することができ
る。
In the embodiment shown in FIG. 1, three FBGs (FBG 1, FB
G2 and FBG3) are provided in series, and an optical fiber 1 is connected from port 1 of circulator 3 through port 2.
The pulse light is incident on one end of the zero. The incident pulse light is reflected by the FBG 1, FBG 2, and FBG 3, and the reflected light is received by the photoelectric converter (light receiver) 6 from the port 2 to the port 3 of the circulator 3. At this time, for example, as shown in FIG.
The FBG reflection wavelength is converted into a light intensity and measured before it is provided. Then, based on the measured light intensity, the wavelengths of the respective reflected lights of FBG1, FBG2 and FBG3 are obtained from the measured light intensity based on the wavelength transmittance characteristics of FIG. Here, the closer the light source is to the light source, the shorter the time it takes for the pulsed light to return after being incident. Therefore, by using the OTDR principle, the reflection wavelengths of a plurality of FBGs provided at different distances from the measurement device are measured. Can be measured.
【0033】ただし、OTDRには距離分解能(または
応答距離)と呼ばれる複数の測定点の距離差に対する最
小分解能があり、それは測定装置毎に任意に設計するこ
とができるが、おおよそ数十cmから数m程度である。
従って、使用するOTDR装置の距離分解能以下の距離
で二つ以上のFBGを設置した場合には、どのFBGか
らの反射光か区別して測定することができない。そのた
め、FBGは使用する装置の距離分解能以上の距離差を
持って設置する必要がある。実用上は、FBGを光ファ
イバに沿って連続的に設けて使用することはほとんどな
く、次のFBGまでの距離をOTDRの距離分解能以上
の余裕を持って使用すれば何ら問題ない。
However, the OTDR has a minimum resolution, called a distance resolution (or response distance), for a distance difference between a plurality of measurement points, which can be arbitrarily designed for each measurement device. m.
Therefore, when two or more FBGs are installed at a distance equal to or less than the distance resolution of the OTDR device to be used, it is impossible to distinguish and measure the reflected light from which FBG. Therefore, the FBGs need to be installed with a distance difference greater than the distance resolution of the device used. Practically, the FBG is rarely used continuously along the optical fiber, and there is no problem if the distance to the next FBG is used with a margin equal to or greater than the distance resolution of the OTDR.
【0034】このように、比較的単純な方法を使用する
ことにより多数のFBG波長を計測することができる。
As described above, a large number of FBG wavelengths can be measured by using a relatively simple method.
【0035】本実施態様においては、光源の出力強度変
動や光ファイバの伝送損失の変動等によりFBGの反射
特性も変化するので、光電変換後の電圧強度変動が、F
BGの反射波長の変化によるものか、光源出力強度の変
動や伝送損失の変動等によるものか、区別が付かないこ
ともあり得る。
In this embodiment, since the reflection characteristics of the FBG also change due to fluctuations in the output intensity of the light source, fluctuations in the transmission loss of the optical fiber, etc.
It may not be possible to distinguish between a change in the BG reflection wavelength, a change in the light source output intensity, a change in the transmission loss, and the like.
【0036】そこで、波長傾斜特性が異なる二つ以上の
波長傾斜型光フィルタを用いることにより、雑音となる
変動要因を取り除くことができる。図3にその構成例を
示す。
Therefore, by using two or more wavelength-gradient optical filters having different wavelength-gradient characteristics, it is possible to eliminate a fluctuation factor that causes noise. FIG. 3 shows an example of the configuration.
【0037】図3は本発明の他の実施態様を示す説明図
である。
FIG. 3 is an explanatory view showing another embodiment of the present invention.
【0038】本実施態様において、上述の図1に示した
実施態様とは、サーキュレータ3のポート3から後段の
構成が異なる。即ち、サーキュレータ3のポート3から
出力されたFBG1、FBG2及びFBG3の各反射光
を、カプラ4により分岐して、各分岐光を、それぞれ異
なった波長透過特性を有する波長傾斜型光フィルタ5−
1、5−2にそれぞれ通した後、光電変換器6−1、6
−2でそれぞれ受光するように構成したものである。
The present embodiment differs from the embodiment shown in FIG. 1 in the configuration of the circulator 3 from the port 3 to the subsequent stage. That is, each reflected light of FBG1, FBG2, and FBG3 output from the port 3 of the circulator 3 is branched by the coupler 4, and each branched light is converted into a wavelength gradient optical filter 5 having a different wavelength transmission characteristic.
After passing through the photoelectric converters 6-1 and 6-2, respectively.
-2, respectively.
【0039】図4は、波長傾斜型光フィルタ5−1、5
−2のそれぞれの波長透過特性の一例を示す説明図であ
る。図4において、長鎖線と一点鎖線で示した波長特性
がそれぞれ5−1や5−2で有する波長透過特性をリニ
アスケールで示したものである。この二つの特性は、図
3中にも書き込んである通りである。この波長傾斜型光
フィルタ5−1、5−2の二つの特性の強度比を取って
ログスケールで示すと、図4に直線で示したような波長
特性を得ることができる。このようにして、途中の光フ
ァイバの伝送損失変動や光源の出力強度変動等による誤
差の影響を除去することができる。
FIG. 4 shows a wavelength-graded optical filter 5-1, 5
2 is an explanatory diagram illustrating an example of each wavelength transmission characteristic of FIG. In FIG. 4, the wavelength characteristics indicated by the long chain line and the dashed line indicate the wavelength transmission characteristics of 5-1 and 5-2, respectively, on a linear scale. These two characteristics are as written in FIG. If the intensity ratio of the two characteristics of the wavelength-graded optical filters 5-1 and 5-2 is taken and shown on a log scale, the wavelength characteristics shown by a straight line in FIG. 4 can be obtained. In this way, it is possible to remove the influence of errors due to fluctuations in transmission loss of the optical fiber and fluctuations in the output intensity of the light source on the way.
【0040】図5に受光した反射光の一例を示す。入射
したパルス光に対するFBG1、FBG2及びFBG3
からのそれぞれの反射光は、横軸を時間=距離と取る
と、離散的に測定される。そして、各反射光の強度は、
図4に示す波長透過特性を持った波長傾斜型光フィルタ
5−1、5−2を通過した後、光電変換器6−1、6−
2で測定される。そして、FBG1を例に取ると、測定
された二つの光強度P11とP12について10×Log
(P11/P12)を求めた後、図4に示す関係からFBG
1の反射光の波長を求めることができる。以下、FBG
2、FBG3についても同様に二つの光強度比から反射
光の波長を求めればよい。
FIG. 5 shows an example of the reflected light received. FBG1, FBG2 and FBG3 for the incident pulse light
Are measured discretely, taking the horizontal axis as time = distance. And the intensity of each reflected light is
After passing through the wavelength-graded optical filters 5-1 and 5-2 having the wavelength transmission characteristics shown in FIG.
Measured at 2. Then, taking as an example the FBG 1, measured two light intensity P 11 and P 12 10 × Log
After obtaining (P 11 / P 12 ), the FBG is obtained from the relationship shown in FIG.
The wavelength of the reflected light can be determined. Hereinafter, FBG
2. For FBG3, the wavelength of the reflected light may be similarly obtained from the two light intensity ratios.
【0041】図6は本発明の他の実施態様を示す説明図
である。
FIG. 6 is an explanatory view showing another embodiment of the present invention.
【0042】本実施例では、反射波長が異なる複数のF
BGを基幹の光ファイバ10からカプラ4により分岐し
た枝線の光ファイバ11a,11bに設けた構成として
いる。カプラ4の分岐比を最適化することによって、計
測可能なFBGを30以上とすることも可能である。ま
た、枝線の光ファイバ11a,11bのいずれかが断線
しても全体のシステムには影響を与えないという利点も
ある。
In this embodiment, a plurality of Fs having different reflection wavelengths are used.
The BG is provided on the branch optical fibers 11a and 11b branched from the main optical fiber 10 by the coupler 4. By optimizing the branching ratio of the coupler 4, the measurable FBG can be made 30 or more. Further, there is an advantage that even if any of the branch optical fibers 11a and 11b is broken, the entire system is not affected.
【0043】本実施態様では、サーキュレータ3から出
力された反射光を波長選択フィルタ41に入射すること
により、λ1、λ2の反射波長を持つFBG1、FBG2
からの反射光は、それぞれの信号成分が波長選択フィル
タ41でチャンネルch1とチャンネルch2に分割さ
れるため、FBG1、FBG2をODTRの測定距離分
解能以下の近接した位置に置くことが可能である。この
例では、各枝線の光ファイバ11a,11bに設置する
FBGの数(即ち反射波長)が2つの例を示したもので
あるが、FBGの設置数(即ち反射波長)が3つ以上の
場合には、それに合わせて波長選択フィルタ41のチャ
ンネル数を設定すればよい。
In the present embodiment, the reflected light output from the circulator 3 is made incident on the wavelength selection filter 41, so that the FBG1 and FBG2 having the reflection wavelengths of λ 1 and λ 2 are provided.
In the reflected light from, the respective signal components are divided into the channel ch1 and the channel ch2 by the wavelength selection filter 41, so that the FBG1 and the FBG2 can be placed at close positions less than the measurement distance resolution of the ODTR. In this example, the number of FBGs (ie, reflection wavelengths) installed in the optical fibers 11a and 11b of each branch line is two, but the number of FBGs installed (ie, reflection wavelengths) is three or more. In this case, the number of channels of the wavelength selection filter 41 may be set accordingly.
【0044】波長選択フィルタ41より後段の構成は図
3の実施態様と同様であり、各波長(チャンネルch
1、ch2)毎に波長傾斜型光フィルタ5−1、5−2
を通過した後、光電変換器6−1、6−2で光強度が測
定され、その測定された光強度の比から図示しない演算
回路により、FBG1、FBG2の反射光の波長を求め
ることができる。
The configuration subsequent to the wavelength selection filter 41 is the same as that of the embodiment of FIG.
1, ch2) wavelength-graded optical filters 5-1 and 5-2
, The light intensity is measured by the photoelectric converters 6-1 and 6-2, and the wavelength of the reflected light of the FBG1 and the FBG2 can be obtained from the ratio of the measured light intensity by an arithmetic circuit (not shown). .
【0045】図7は他の実施態様を示す説明図であり、
図6の実施態様では各チャンネルch1、ch2に波長
傾斜型光フィルタ5−1、5−2及び光電変換器6−
1、6−2を一組ずつ合計二組設けたが、本実施態様で
は、波長選択フィルタ41の後段にスイッチ7を設け
て、一組の波長傾斜型光フィルタ5−1、5−2及び光
電変換器6−1、6−2で交互に各チャンネルch1、
ch2からの反射光の波長を計測するよう構成したもの
である。この場合、波長傾斜フィルタ5−1、5−2と
しては、その検出波長が被測定のFBGの反射波長
λ1、λ2の両方をカバーできる範囲のものを使用する必
要がある。このように複数の波長帯域の反射光を計測す
る場合でも、スイッチ7を用いることにより、一組の波
長傾斜型光フィルタ及び光電変換器を共用でき、装置構
成を簡略化できる。
FIG. 7 is an explanatory view showing another embodiment.
In the embodiment shown in FIG. 6, wavelength-graded optical filters 5-1 and 5-2 and a photoelectric converter 6--6 are provided for each channel ch1 and ch2.
In this embodiment, the switch 7 is provided at the subsequent stage of the wavelength selection filter 41, and one set of the wavelength gradient optical filters 5-1, 5-2 and Each of the channels ch1 and 6 is alternately switched by the photoelectric converters 6-1 and 6-2.
It is configured to measure the wavelength of the reflected light from ch2. In this case, it is necessary to use a filter whose detection wavelength can cover both the reflection wavelengths λ 1 and λ 2 of the measured FBG as the wavelength gradient filters 5-1 and 5-2. Thus, even when measuring the reflected light in a plurality of wavelength bands, the use of the switch 7 allows the use of a single set of wavelength gradient optical filters and photoelectric converters, thereby simplifying the device configuration.
【0046】図8は、他の実施態様を示す説明図であ
る。図3に示した実施態様では、幹線の光ファイバ10
の光路途中に複数のFBGが設けられていたが、本実施
態様では、幹線の光ファイバ10にカプラ4を介して、
反射波長が同じλ1である複数のFBGを設けた光ファ
イバ11a,11bが枝線として接続されている。この
場合、同一枝線内の各FBG間の距離をOTDRの測定
距離分解能以上とする必要がある。また、隣接する枝線
間のFBGについてもOTDRの測定距離分解能以上と
するために、各カプラ4間の距離を枝線の長さよりも充
分長くする必要がある。このように、複数のFBGが設
けられた枝線を幹線に複数本接続した場合であっても、
全てのFBGの反射光の戻り時間が異なるため、波長選
択フィルタを用いる必要がなく、また波長傾斜型光フィ
ルタ及び光電変換器も一組設けるだけでよい。
FIG. 8 is an explanatory diagram showing another embodiment. In the embodiment shown in FIG. 3, the main optical fiber 10
Although a plurality of FBGs are provided in the middle of the optical path, in this embodiment, the trunk optical fiber 10 is
Optical fibers 11a and 11b provided with a plurality of FBGs having the same reflection wavelength of λ 1 are connected as branch lines. In this case, the distance between the FBGs in the same branch line must be equal to or greater than the OTDR measurement distance resolution. In addition, the distance between the couplers 4 needs to be sufficiently longer than the length of the branch line so that the FBG between adjacent branch lines is equal to or greater than the OTDR measurement distance resolution. Thus, even when a plurality of branch lines provided with a plurality of FBGs are connected to a trunk line,
Since the return times of the reflected lights of all the FBGs are different, it is not necessary to use a wavelength selection filter, and it is sufficient to provide only one set of a wavelength-graded optical filter and a photoelectric converter.
【0047】次に本発明の物理量の計測方法及び計測装
置について説明する。計測したい物理量(絶対量、若し
くは変化量)は、上述した反射波長の計測方法及び計測
装置により求めた反射波長から、演算回路を用いて公知
の手法により算出可能である。即ち、一般的な光ファイ
バを用いてFBGを構成している場合、その反射波長に
対する物理量の係数は、例えば、温度係数:10pm/
℃、歪み係数:1.2nm/Nであることが知られてい
る。なお、歪み量については、歪み量1000με=反
射波長1nmという関係式がある。よって、入射光の波
長に対する反射光の波長の変化量から、物理量を算出す
ることができる。
Next, a method and an apparatus for measuring a physical quantity according to the present invention will be described. The physical quantity (absolute amount or change amount) to be measured can be calculated by a known method using an arithmetic circuit from the above-described method of measuring the reflection wavelength and the reflection wavelength obtained by the measurement device. That is, when the FBG is configured using a general optical fiber, the coefficient of the physical quantity with respect to the reflection wavelength is, for example, a temperature coefficient: 10 pm /
It is known that the temperature and the distortion coefficient are 1.2 nm / N. As for the amount of distortion, there is a relational expression that the amount of distortion is 1000 με = the reflection wavelength is 1 nm. Therefore, the physical quantity can be calculated from the amount of change in the wavelength of the reflected light with respect to the wavelength of the incident light.
【0048】[0048]
【発明の効果】以上に説明したように、本発明は回折格
子で反射される光の波長、物理量を高精度に計測するこ
とができる。
As described above, according to the present invention, the wavelength and physical quantity of light reflected by a diffraction grating can be measured with high accuracy.
【図面の簡単な説明】[Brief description of the drawings]
【図1】本発明の一実施態様を示す説明図である。FIG. 1 is an explanatory diagram showing one embodiment of the present invention.
【図2】波長傾斜型光フィルタの波長透過特性の一例を
示す。
FIG. 2 shows an example of a wavelength transmission characteristic of a wavelength tilt type optical filter.
【図3】本発明の他の実施態様を示す説明図である。FIG. 3 is an explanatory view showing another embodiment of the present invention.
【図4】複数の波長傾斜型光フィルタの波長透過特性と
その組み合わせの一例を示す。
FIG. 4 shows an example of wavelength transmission characteristics of a plurality of wavelength-graded optical filters and combinations thereof.
【図5】図3に示す実施態様の受光信号の一例を示す。FIG. 5 shows an example of a light receiving signal of the embodiment shown in FIG.
【図6】本発明の他の実施態様を示す説明図である。FIG. 6 is an explanatory view showing another embodiment of the present invention.
【図7】本発明の他の実施態様を示す説明図である。FIG. 7 is an explanatory view showing another embodiment of the present invention.
【図8】本発明の他の実施態様を示す説明図である。FIG. 8 is an explanatory view showing another embodiment of the present invention.
【符号の説明】[Explanation of symbols]
1 広帯域光源 2 外部変調器 3 サーキュレータ 4 カプラ 5 波長傾斜型光フィルタ 6 光電変換器(受光器) 7 光スイッチ 10 幹線(光ファイバ) 11 枝線(光ファイバ) 41 WDMカプラ FBG ファイバブラッググレーティング(回折格子) REFERENCE SIGNS LIST 1 broadband light source 2 external modulator 3 circulator 4 coupler 5 wavelength-graded optical filter 6 photoelectric converter (light receiver) 7 optical switch 10 trunk line (optical fiber) 11 branch line (optical fiber) 41 WDM coupler FBG fiber Bragg grating (diffraction) lattice)

Claims (12)

    【特許請求の範囲】[Claims]
  1. 【請求項1】光路途中に回折格子が設けられた光ファイ
    バの一端から所定の波長を有するパルス光を入射し、前
    記回折格子から前記光ファイバの一端に戻ってくる反射
    光を所定の波長透過特性を有する波長傾斜型光フィルタ
    を通して受光して前記反射光の光強度を測定し、該反射
    光の光強度から該反射光の波長を求めることを特徴とす
    る回折格子反射波長計測方法。
    1. A pulse light having a predetermined wavelength is incident from one end of an optical fiber provided with a diffraction grating in the middle of an optical path, and reflected light returning from the diffraction grating to one end of the optical fiber is transmitted through a predetermined wavelength. A method of measuring a reflection wavelength of a diffraction grating, comprising: receiving a light through a wavelength gradient optical filter having characteristics; measuring the light intensity of the reflected light; and obtaining the wavelength of the reflected light from the light intensity of the reflected light.
  2. 【請求項2】前記反射光を分岐してそれぞれ波長透過特
    性が異なる波長傾斜型フィルタを通した後に受光して前
    記反射光の各光強度を測定した後、該各光強度の強度比
    から前記反射光の波長を求めることにより前記反射光中
    に含まれる光強度変動誤差成分を除去することを特徴と
    する請求項1記載の回折格子反射波長計測方法。
    2. After the reflected light is branched and passed through a wavelength gradient filter having different wavelength transmission characteristics, the reflected light is received and each light intensity of the reflected light is measured. 2. The diffraction grating reflection wavelength measuring method according to claim 1, wherein a light intensity fluctuation error component contained in the reflected light is removed by obtaining a wavelength of the reflected light.
  3. 【請求項3】前記回折格子が、反射光の中心波長がそれ
    ぞれ異なる複数の回折格子からなり、前記光ファイバの
    一端に戻ってくる反射光を波長選択フィルタにより所定
    の帯域毎に分割した後に各帯域毎に前記波長傾斜型光フ
    ィルタを通すことを特徴とする請求項1又は請求項2に
    記載の回折格子反射波長計測方法。
    3. The diffraction grating comprises a plurality of diffraction gratings each having a different center wavelength of the reflected light, and after dividing the reflected light returning to one end of the optical fiber into predetermined bands by a wavelength selection filter, 3. The method of measuring a reflection wavelength of a diffraction grating according to claim 1, wherein the wavelength-graded optical filter is passed through each band.
  4. 【請求項4】光路途中に回折格子が設けられた光ファイ
    バと、該光ファイバの一端に所定の波長を有するパルス
    光を入射する光源と、前記回折格子から前記光ファイバ
    の一端に戻って来た反射光を受光する受光器と、上記光
    ファイバの一端と前記受光器との間に設けられた所定の
    波長透過特性を有する波長傾斜型光フィルタと、前記受
    光器により測定した前記反射光の光強度から該反射光の
    波長を求める演算回路とを有することを特徴とする回折
    格子反射波長計測装置。
    4. An optical fiber having a diffraction grating provided in the middle of an optical path, a light source for inputting pulsed light having a predetermined wavelength to one end of the optical fiber, and returning from the diffraction grating to one end of the optical fiber. A light receiving device for receiving the reflected light, a wavelength gradient optical filter having a predetermined wavelength transmission characteristic provided between one end of the optical fiber and the light receiving device, and the reflected light measured by the light receiving device. A calculation circuit for calculating the wavelength of the reflected light from the light intensity.
  5. 【請求項5】前記光ファイバの一端と前記波長傾斜型光
    フィルタとの間に前記反射光を分岐して出力する光分岐
    器が設けられると共に、該光分岐器の各出力に波長透過
    特性が異なる波長傾斜型フィルタがそれぞれ設けられて
    おり、前記演算回路により前記波長傾斜型フィルタを通
    した後の前記分岐された各反射光の光強度の強度比から
    前記反射光の波長を求めることを特徴とする請求項4記
    載の回折格子反射波長計測装置。
    5. An optical splitter for splitting and outputting the reflected light between one end of the optical fiber and the wavelength gradient optical filter, and each output of the optical splitter has a wavelength transmission characteristic. Different wavelength gradient filters are provided, and the arithmetic circuit calculates the wavelength of the reflected light from the intensity ratio of the light intensity of each of the branched reflected lights after passing through the wavelength gradient filter. The diffraction grating reflection wavelength measuring device according to claim 4, wherein
  6. 【請求項6】前記回折格子が、反射光の中心波長がそれ
    ぞれ異なる複数の回折格子からなり、前記光ファイバの
    一端に戻ってくる反射光を波長選択フィルタにより所定
    の帯域毎に分割した後に各帯域毎に前記波長傾斜型光フ
    ィルタを通すように構成したことを特徴とする請求項4
    又は請求項5に記載の回折格子反射波長計測装置。
    6. A diffraction grating comprising a plurality of diffraction gratings each having a different center wavelength of the reflected light, and dividing the reflected light returning to one end of the optical fiber into predetermined bands by a wavelength selection filter. 5. The apparatus according to claim 4, wherein said filter is configured to pass through said wavelength gradient optical filter for each band.
    Or the diffraction grating reflection wavelength measuring device according to claim 5.
  7. 【請求項7】光路途中に回折格子が設けられた光ファイ
    バの一端から所定の波長を有するパルス光を入射し、前
    記回折格子から前記光ファイバの一端に戻ってくる反射
    光を所定の波長透過特性を有する波長傾斜型光フィルタ
    を通して受光して前記反射光の光強度を測定し、該反射
    光の光強度から該反射光の波長を求めると共に、前記入
    射光の波長に対する前記反射光の波長の変化量から物理
    量を求めることを特徴とする物理量計測方法。
    7. A pulse light having a predetermined wavelength is incident from one end of an optical fiber provided with a diffraction grating in the middle of an optical path, and reflected light returning from the diffraction grating to one end of the optical fiber is transmitted through a predetermined wavelength. Received through a wavelength gradient optical filter having characteristics, measures the light intensity of the reflected light, obtains the wavelength of the reflected light from the light intensity of the reflected light, and calculates the wavelength of the reflected light with respect to the wavelength of the incident light. A physical quantity measurement method characterized by obtaining a physical quantity from a change amount.
  8. 【請求項8】前記反射光を分岐してそれぞれ波長透過特
    性が異なる波長傾斜型フィルタを通した後に受光して前
    記反射光の各光強度を測定した後、該各光強度の強度比
    から前記反射光の波長を求めることにより前記反射光中
    に含まれる光強度変動誤差成分を除去することを特徴と
    する請求項7記載の物理量計測方法。
    8. After the reflected light is branched and passed through a wavelength gradient filter having different wavelength transmission characteristics, the reflected light is received and each light intensity of the reflected light is measured. 8. The physical quantity measuring method according to claim 7, wherein a light intensity fluctuation error component included in the reflected light is removed by obtaining a wavelength of the reflected light.
  9. 【請求項9】前記回折格子が、反射光の中心波長がそれ
    ぞれ異なる複数の回折格子からなり、前記光ファイバの
    一端に戻ってくる反射光を波長選択フィルタにより所定
    の帯域毎に分割した後に各帯域毎に前記波長傾斜型光フ
    ィルタを通すことを特徴とする請求項7又は請求項8に
    記載の物理量計測方法。
    9. A diffraction grating comprising a plurality of diffraction gratings each having a different center wavelength of reflected light, and after dividing the reflected light returning to one end of the optical fiber into predetermined bands by a wavelength selection filter, 9. The physical quantity measuring method according to claim 7, wherein the wavelength-graded optical filter is passed through each band.
  10. 【請求項10】光路途中に回折格子が設けられた光ファ
    イバと、該光ファイバの一端に所定の波長を有するパル
    ス光を入射する光源と、前記回折格子から前記光ファイ
    バの一端に戻って来た反射光を受光する受光器と、上記
    光ファイバの一端と前記受光器との間に設けられた所定
    の波長透過特性を有する波長傾斜型光フィルタと、前記
    受光器により測定した前記反射光の光強度から該反射光
    の波長を求めて前記入射光の波長に対する前記反射光の
    波長の変化量から物理量を求める演算回路とを有するこ
    とを特徴とする物理量計測装置。
    10. An optical fiber having a diffraction grating provided in the middle of an optical path, a light source for inputting pulse light having a predetermined wavelength to one end of the optical fiber, and returning from the diffraction grating to one end of the optical fiber. A light receiving device for receiving the reflected light, a wavelength gradient optical filter having a predetermined wavelength transmission characteristic provided between one end of the optical fiber and the light receiving device, and the reflected light measured by the light receiving device. A physical quantity measuring device, comprising: an arithmetic circuit for determining the wavelength of the reflected light from the light intensity and calculating the physical quantity from the amount of change in the wavelength of the reflected light with respect to the wavelength of the incident light.
  11. 【請求項11】前記光ファイバの一端と前記波長傾斜型
    光フィルタとの間に前記反射光を分岐して出力する光分
    岐器が設けられると共に、該光分岐器の各出力に波長透
    過特性が異なる波長傾斜型フィルタがそれぞれ設けられ
    ており、前記演算回路により前記波長傾斜型フィルタを
    通した後の前記分岐された各反射光の光強度の強度比か
    ら前記反射光の波長及び物理量を求めることを特徴とす
    る請求項10記載の物理量計測装置。
    11. An optical splitter for splitting and outputting said reflected light between one end of said optical fiber and said wavelength gradient optical filter, and each output of said optical splitter has a wavelength transmission characteristic. Different wavelength gradient filters are provided, and the arithmetic circuit calculates the wavelength and physical quantity of the reflected light from the intensity ratio of the light intensity of each of the branched reflected lights after passing through the wavelength gradient filter. The physical quantity measuring device according to claim 10, wherein:
  12. 【請求項12】前記回折格子が、反射光の中心波長がそ
    れぞれ異なる複数の回折格子からなり、前記光ファイバ
    の一端に戻ってくる反射光を波長選択フィルタにより所
    定の帯域毎に分割した後に各帯域毎に前記波長傾斜型光
    フィルタを通すように構成したことを特徴とする請求項
    10又は請求項11に記載の物理量計測装置。
    12. The diffraction grating includes a plurality of diffraction gratings each having a different center wavelength of reflected light, and the reflected light returning to one end of the optical fiber is divided into predetermined bands by a wavelength selection filter, and then each is divided. The physical quantity measuring device according to claim 10, wherein the wavelength gradient optical filter is configured to pass through each band.
JP2001068220A 2001-03-12 2001-03-12 Diffraction grating reflected wavelength measuring method and device, and physical quantity measuring method and device Pending JP2002267537A (en)

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Publication number Priority date Publication date Assignee Title
KR100470911B1 (en) * 2002-06-05 2005-02-21 주식회사 아이세스 FBG sensor system
JP2007535674A (en) * 2004-05-01 2007-12-06 センサーネットリミテッドSensornet Lemited Direct measurement of Brillouin frequency in distributed optical sensing systems.
JP2010502967A (en) * 2006-09-06 2010-01-28 シーメンス アクチエンゲゼルシヤフトSiemens Aktiengesellschaft Optical device for monitoring a rotatable shaft with a directional axis
JP2010043892A (en) * 2008-08-11 2010-02-25 Ihi Inspection & Instrumentation Co Ltd Measurement method and device using fbg sensor
CN102124306A (en) * 2008-08-20 2011-07-13 株式会社渡边制作所 Optical fiber sensing system
KR101247575B1 (en) 2011-10-04 2013-03-26 국방과학연구소 Physical quantity high speed measuring system of structure using optical spectrometer
EP2600114A3 (en) * 2011-12-01 2016-07-06 Hitachi, Ltd. Multi-point measuring method of fbg sensor and multi-point measuring apparatus
WO2020194856A1 (en) * 2019-03-27 2020-10-01 沖電気工業株式会社 Optical coherent sensor and optical coherent sensing method

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US5680489A (en) * 1996-06-28 1997-10-21 The United States Of America As Represented By The Secretary Of The Navy Optical sensor system utilizing bragg grating sensors
JPH10141922A (en) * 1996-11-12 1998-05-29 Hitachi Cable Ltd Multipoint strain and temperature sensor

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JPH0658817A (en) * 1992-08-12 1994-03-04 Yokogawa Electric Corp Light wavelength meter
JPH08145736A (en) * 1994-11-22 1996-06-07 Sumitomo Electric Ind Ltd Optical fiber sensor
US5680489A (en) * 1996-06-28 1997-10-21 The United States Of America As Represented By The Secretary Of The Navy Optical sensor system utilizing bragg grating sensors
JPH10141922A (en) * 1996-11-12 1998-05-29 Hitachi Cable Ltd Multipoint strain and temperature sensor

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100470911B1 (en) * 2002-06-05 2005-02-21 주식회사 아이세스 FBG sensor system
JP2007535674A (en) * 2004-05-01 2007-12-06 センサーネットリミテッドSensornet Lemited Direct measurement of Brillouin frequency in distributed optical sensing systems.
JP4943320B2 (en) * 2004-05-01 2012-05-30 センサーネットリミテッドSensornet Limited Direct measurement of Brillouin frequency in distributed optical sensing systems.
EP1756527B1 (en) * 2004-05-01 2014-08-06 Sensornet Limited Direct measurement of brillouin frequency in distributed optical sensing systems
JP2010502967A (en) * 2006-09-06 2010-01-28 シーメンス アクチエンゲゼルシヤフトSiemens Aktiengesellschaft Optical device for monitoring a rotatable shaft with a directional axis
JP2010043892A (en) * 2008-08-11 2010-02-25 Ihi Inspection & Instrumentation Co Ltd Measurement method and device using fbg sensor
CN102124306A (en) * 2008-08-20 2011-07-13 株式会社渡边制作所 Optical fiber sensing system
KR101247575B1 (en) 2011-10-04 2013-03-26 국방과학연구소 Physical quantity high speed measuring system of structure using optical spectrometer
EP2600114A3 (en) * 2011-12-01 2016-07-06 Hitachi, Ltd. Multi-point measuring method of fbg sensor and multi-point measuring apparatus
WO2020194856A1 (en) * 2019-03-27 2020-10-01 沖電気工業株式会社 Optical coherent sensor and optical coherent sensing method

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