JPS63205531A - Measuring method for temperature by optical fiber - Google Patents
Measuring method for temperature by optical fiberInfo
- Publication number
- JPS63205531A JPS63205531A JP62038517A JP3851787A JPS63205531A JP S63205531 A JPS63205531 A JP S63205531A JP 62038517 A JP62038517 A JP 62038517A JP 3851787 A JP3851787 A JP 3851787A JP S63205531 A JPS63205531 A JP S63205531A
- Authority
- JP
- Japan
- Prior art keywords
- optical fiber
- light
- temperature
- wavelength
- loss
- 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.)
- Granted
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 57
- 238000000034 method Methods 0.000 title claims description 13
- 230000031700 light absorption Effects 0.000 claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 3
- 239000000835 fiber Substances 0.000 claims description 3
- 239000011521 glass Substances 0.000 claims description 3
- 239000011159 matrix material Substances 0.000 claims description 2
- 238000010521 absorption reaction Methods 0.000 abstract description 30
- 239000000654 additive Substances 0.000 abstract description 11
- 230000000996 additive effect Effects 0.000 abstract description 5
- 230000004907 flux Effects 0.000 abstract 1
- 230000009102 absorption Effects 0.000 description 26
- 230000003287 optical effect Effects 0.000 description 20
- 229910052761 rare earth metal Inorganic materials 0.000 description 6
- 238000009529 body temperature measurement Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 3
- -1 Nd3◆ Chemical class 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000253 optical time-domain reflectometry Methods 0.000 description 1
- 230000001151 other effect Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Landscapes
- Light Guides In General And Applications Therefor (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は光フアイバ自身の光透過特性の変化を利用した
温度測定方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a temperature measuring method that utilizes changes in the light transmission characteristics of an optical fiber itself.
（従来技術）
近年、光ファイバの応用技術の一環として光フアイバ温
度センサの開発が盛んになっている。光フアイバ温度セ
ンサとしては対象物体からの放射光（赤外線）を光ファ
イバで導き、その光強度値から温度を測定する放射形光
ファイバ温度計が開発されている。(Prior Art) In recent years, optical fiber temperature sensors have been actively developed as part of optical fiber application technology. As an optical fiber temperature sensor, a radiation type optical fiber thermometer has been developed that guides radiation light (infrared rays) from a target object through an optical fiber and measures the temperature from the light intensity value.
最近は光フアイバ自体にトランスデユーサの機能を持た
せたファイバ型温度形の検討もなされている。Recently, consideration has been given to fiber-type temperature sensors in which the optical fiber itself has the function of a transducer.
後者のタイプのセンサとして、光ファイバの母体ガラス
中にＮｄ３◆、Ｓｍ”、Ｅｕ’◆、Ｈｏ３・などの希土
類元素イオンをドーピングし、これら希土類元素イオン
の゛光吸収特性の温度変化をファイバ中の損失値の増減
として検出し、光ファイバに沿った周囲環境の温度分布
を測定する手段が考案されている。As the latter type of sensor, rare earth element ions such as Nd3◆, Sm", Eu'◆, Ho3. Means have been devised to detect the increase or decrease in the loss value of the optical fiber and measure the temperature distribution of the surrounding environment along the optical fiber.
具体的例として第５図にＮｄ３・をドーピングした石英
系光ファイバの損失スペクトルを、また第６図に第５図
中に存在する９００ｎｍ付近の吸収ピークの温度に対す
る損失値の変化を示した。第５図で観察される５９０ｎ
ｍ、７５０ｎｍ、８９０ｎｍなどを中心とする光吸収帯
は、各々Ｎｄ３・に固有の電子準位間遷移に基づく吸収
であり、これらの吸収帯において、例えば５９０ｎｍ付
近に中心をもつ吸収帯に含まれる波長６００ｎｍにおけ
る吸収特性は、第６図に示すように温度の上昇に対して
単調に変化するので、この光吸収量即ち光損失量を検出
することにより温度を測定することができる。As a specific example, FIG. 5 shows the loss spectrum of a silica-based optical fiber doped with Nd3., and FIG. 6 shows the change in loss value with respect to temperature at the absorption peak near 900 nm present in FIG. 590n observed in Figure 5
The optical absorption bands centered at m, 750 nm, 890 nm, etc. are absorptions based on inter-electronic level transitions unique to Nd3, and among these absorption bands, for example, light absorption bands centered around 590 nm include absorption bands centered around 590 nm. Since the absorption characteristic at a wavelength of 600 nm changes monotonically as the temperature increases, as shown in FIG. 6, the temperature can be measured by detecting the amount of light absorption, that is, the amount of light loss.
光７フイバの場合、０ｐｔｉｃａｌ ＴｉｍｅＤｏｍ
ａｉｎ Ｒｅｆｒｅｃｔｍｅｔｅｒ（ＯＴＤＲ）法と
呼ばれる、光ファイバの損失評価手法が確立している。For optical 7 fiber, 0ptical TimeDom
An optical fiber loss evaluation method called the overlapping reflectmeter (OTDR) method has been established.
この方法は光フアイバ内に入力された光パルスの光フア
イバ内の後方レーり散乱光強度を測定し、光ファイバの
長手方向に沿った入力光パルスの波長での損失値を１ｍ
以内の空間分解能で評価する手法である。従ってこの手
法を用いてＮ ｄ３−の吸収帯に含まれる波長の光パル
スを入力し、その波長での吸収損失の距離方向の変化を
調べることにより、布設した光ファイバに沿ったファイ
バの近傍での温度分布が測定できる（従来技術の問題点
）
第６図のＮｄ３°の例に示されているように一般に希土
類元素イオンの吸収特性は約１００℃以下の温度域で一
義的に変化する０種種の希土類元素を添加物として選ぶ
ことにより一２００℃から１００℃の間の温度測定がで
きる。この場合、光フアイバ自体がセンサであるため、
光フアイバ自体をその温度環境にごく必要がある。しか
しそのようにすると保護のために光ファイバに施されて
いる各種のコーティングＦ３（一般にポリマー）もその
温度になり、コーティング層の温度変化（収縮、膨張な
ど）が生じ、それによっても光ファイバの損失が変化し
てしまう、従って光ファイバの周囲の温度環境による損
失変化には、温度と対応する希土類元素の吸収特性によ
る変化以外の要因も含まれ、その変化が温度測定の誤差
要因となる。This method measures the backscattered light intensity within the optical fiber of the optical pulse input into the optical fiber, and calculates the loss value at the wavelength of the input optical pulse along the longitudinal direction of the optical fiber.
This is a method that evaluates with a spatial resolution within Therefore, using this method, by inputting an optical pulse with a wavelength included in the N d3- absorption band and examining the change in absorption loss at that wavelength in the distance direction, it is possible to temperature distribution can be measured (problem with conventional technology) As shown in the example of Nd3° in Figure 6, the absorption characteristics of rare earth ions generally change uniquely in the temperature range of about 100°C or less. By selecting various rare earth elements as additives, it is possible to measure temperatures between -200°C and 100°C. In this case, the optical fiber itself is the sensor, so
The optical fiber itself must be exposed to that temperature environment. However, when doing so, the various coatings F3 (generally polymers) applied to optical fibers for protection also reach that temperature, causing temperature changes (shrinkage, expansion, etc.) of the coating layer, which also causes damage to the optical fiber. Changes in loss due to the temperature environment around the optical fiber include factors other than changes due to temperature and the corresponding absorption characteristics of rare earth elements, and these changes become a cause of error in temperature measurement.
（発明の目的）
本発明の目的は、光ファイバの周囲温度により光フアイ
バケーブルの構造に起因して生ずる損失変化と、トラン
スデユーサとしての機能を持たすために光ファイバに添
加した添加剤の吸収特性の変化とを分離して、正確な温
度を求める方法を実現することにある。(Objective of the Invention) The object of the present invention is to reduce the loss change caused by the structure of the optical fiber cable depending on the ambient temperature of the optical fiber, and the absorption of additives added to the optical fiber to function as a transducer. The objective is to realize a method for determining accurate temperature by separating changes in characteristics.
（問題点を解決するための手段）
本発明の光ファイバによる温度測定方法は第１図のよう
に、温度により光吸収特性が変化する光吸収帯を持つ不
純物がガラス母体中に添加された光ファイバ６の一端も
しくは両端から、上記の光吸収帯に含まれる波長入ｌの
光パルスと、その光吸収帯に含まれない波長入２の光パ
ルスとを入力し、夫々の波長の光パルスの後方散乱強度
と、光ファイバ６への入力時から後方散乱光として出射
されるまでの時間差とを測定して、光ファイバ６の一端
からの長さに対する夫々の波長での損失値を求め、この
両波長での損失値を比較演算して測定対象の温度を測定
するようにしたものである。(Means for Solving the Problems) As shown in Figure 1, the temperature measurement method using an optical fiber of the present invention uses light that is added to a glass matrix with impurities having a light absorption band whose light absorption characteristics change depending on the temperature. An optical pulse with wavelength 1 included in the above-mentioned optical absorption band and an optical pulse with wavelength 2 not included in the optical absorption band are inputted from one or both ends of the fiber 6, and the optical pulses of the respective wavelengths are The backscattered intensity and the time difference from the time of input to the optical fiber 6 until it is emitted as backscattered light are measured, and the loss value at each wavelength for the length from one end of the optical fiber 6 is determined. The temperature of the object to be measured is measured by comparing and calculating the loss values at both wavelengths.
（実施例１）
第１図は本発明の一実施例である。この図において６は
温度計測のトランスデユーサとなる光フアイバケーブル
で、その光ファイバ６の母体のガラス中Ｋ、例えば希土
類元素イオンなどのような周囲温度によって光吸収特性
が変わるような吸収帯を持つ添加剤が含まれている。(Example 1) FIG. 1 shows an example of the present invention. In this figure, 6 is an optical fiber cable that serves as a transducer for temperature measurement, and the optical fiber 6 has an absorption band whose light absorption characteristics change depending on the ambient temperature, such as K in the glass of the base material, such as rare earth element ions. Contains additives that have
第１図の１は上記の吸収帯に含まれる波長成分λ１を持
つ光パルス光源、２は上記の吸収帯に含まれない波長入
２の光パルス光源である。これらの光パルス光源１．２
から発生される光パルスは合波器３により１本の光束４
とされ、ビームスプリッタ−５、レンズ或いは球面ミラ
ーなどの集光器１５を通して光ファイバ６に入射される
。なお、この集光器１５は未発ＩＪでは不可欠な構成要
素ではない。In FIG. 1, reference numeral 1 indicates an optical pulse light source having a wavelength component λ1 included in the above absorption band, and reference numeral 2 indicates an optical pulse light source having a wavelength component λ1 included in the above absorption band. These optical pulse light sources 1.2
The optical pulses generated from
The light is input into the optical fiber 6 through a beam splitter 5 and a condenser 15 such as a lens or a spherical mirror. Note that this condenser 15 is not an essential component in an unfired IJ.
光ファイバ６に入力された波長の異なる二つの光は、夫
々光ファイバ６の内部でのレーり散乱により入射方向と
は反対方向の後方にも散乱される、この場合、その散乱
光は入力端まで戻る間に、戻る光ファイバの長さに応じ
た損失を受けて同光ファイバ６の入射端面より出力され
る。Two lights with different wavelengths input into the optical fiber 6 are each scattered backward in the opposite direction to the direction of incidence due to Ray scattering inside the optical fiber 6. In this case, the scattered lights are scattered at the input end. During the return, the signal is outputted from the input end face of the optical fiber 6 after receiving a loss depending on the length of the returning optical fiber.
出力された光７はビームスプリッタ５でその一部が反射
され、更に分波器８により波長に応じて分離され、その
うち一方は吸収帯に含まれる波長成分入１の光、他方は
吸収帯に含まれない波長成分λ２の光となる。それらの
光は夫々光検出器９．１０で検出され、図示されていな
い増幅器、平均化処理器を通して第２図に示したような
、時間に対する光強度値の関係が得られる。A portion of the output light 7 is reflected by the beam splitter 5, and is further separated according to wavelength by the demultiplexer 8, one of which is the light of wavelength component 1 included in the absorption band, and the other is the light of wavelength component 1 included in the absorption band. The light has a wavelength component λ2 that is not included. These lights are detected by photodetectors 9 and 10, respectively, and are passed through an amplifier and an averaging processor (not shown) to obtain the relationship of the light intensity value with respect to time as shown in FIG. 2.
この場合の時間は光パルスの光フアイバ中の走行時間で
あるから、光ファイバの長さ、即ち測定点の位置に対応
する。また、その位置での光ファイバの損失値は光強度
の値を時間（即ち光ファイバの長さ）で微分することに
よって与えられる。Since the time in this case is the travel time of the optical pulse in the optical fiber, it corresponds to the length of the optical fiber, that is, the position of the measurement point. Further, the loss value of the optical fiber at that position is given by differentiating the light intensity value with respect to time (that is, the length of the optical fiber).
つまり曲線の勾配が損失を表している。この勾配が一定
ならば損失値は一定であるが、急峻に変化するところは
何らかの要因で他と損失値が異なる位置であり、その勾
配（微分値）の大きさにより損失値を求めることができ
る。In other words, the slope of the curve represents the loss. If this slope is constant, the loss value is constant, but where it changes sharply, the loss value is different due to some reason, and the loss value can be determined by the magnitude of the slope (differential value). .
本発明ではこのような時間に対する光温度値の関係の特
性が、添加剤の吸収帯に含まれる波長成分入１の光パル
スによるものと、吸収帯に含まれない波長成分入２の光
パルスによるものとの２種類得られる。このうち後者の
特性は希土類元素イオンなどの温度計測のために添加し
た添加剤の吸収の温度による変化情報が含まれず、その
他の影響、例えば、光ファイバのコーテイング材の周囲
温度変化による収縮、Ｗ張の変化に基づくような周囲温
度との一意的な対応がつきにくい損失変化による影響の
みを受けている。前者の特性は、後者の特性に加えて添
加材の吸収の温度特性の影響も合せて含まれている。こ
のため前者と後者の２種類の特性を比較し、補正１例え
ば減算や除算をおこなうことにより、添加剤の吸収の温
度特性のみを摘出することができる。In the present invention, the characteristics of the relationship between the light temperature value and the time are determined by a light pulse with wavelength component 1 included in the absorption band of the additive and a light pulse with wavelength component 2 not included in the absorption band. You can get two types. Of these, the latter characteristic does not include information on temperature-related changes in the absorption of additives added for temperature measurement, such as rare earth element ions, and is affected by other effects, such as shrinkage due to changes in the ambient temperature of the coating material of optical fibers, W It is affected only by changes in loss, which are difficult to uniquely correspond to changes in ambient temperature, such as those based on changes in tension. In addition to the latter characteristics, the former characteristics include the influence of the temperature characteristics of absorption of additives. Therefore, by comparing the former and latter two types of characteristics and performing correction 1, such as subtraction or division, it is possible to extract only the temperature characteristics of absorption of the additive.
（実施例２）
第３図は本発明の他の実施例である。第１図では添加剤
の吸収帯に含まれる波長成分入ｌの光パルスと、吸収帯
に含まれない波長成分λ２の光パルスが共に光ファイバ
６の同一の入射端面から入力されているが、第３図に示
したものは波長成分入蔦の光パルスと、吸収帯に含まれ
ない波長成分λ２の光パルスとを光ファイバ６の逆方向
から入力するようにしたものである。(Embodiment 2) FIG. 3 shows another embodiment of the present invention. In FIG. 1, an optical pulse with a wavelength component λ included in the absorption band of the additive and an optical pulse with a wavelength component λ2 not included in the absorption band are both input from the same input end face of the optical fiber 6. What is shown in FIG. 3 is such that a light pulse with a wavelength component input and a light pulse with a wavelength component λ2 not included in the absorption band are input from opposite directions of the optical fiber 6.
（実施例３）
第４図は本発明の更に他実施例である。これは時間に対
する後方レーり散乱光強度を観測する際に、ビームスプ
リッタ５の一方に反射ミラー１４を設け、光ファイバ６
に入力する直前の光パルスを反射ミラー１４により光検
出器内９．ｌＧへ入力し、この信号をトリガとして時間
掃引をさせるようにしたものである。この方法では反射
ミラー１４の位置を変化させることにより、光フアイバ
６内のうち特に観測したい部分のみを時間掃引して温度
測定をすることができる。このようにすれば応答時間を
短縮することができる。また光パルスの発振器からの外
部出力をトリガとして時間掃引を開始する場合では時間
遅延器を用いることもできる。(Embodiment 3) FIG. 4 shows still another embodiment of the present invention. When observing the backscattered light intensity with respect to time, a reflecting mirror 14 is provided on one side of the beam splitter 5, and the optical fiber 6 is
The optical pulse just before being input to the photodetector 9 is reflected by the reflecting mirror 14. This signal is input to the IG and used as a trigger to perform a time sweep. In this method, by changing the position of the reflecting mirror 14, it is possible to time-sweep only the part of the optical fiber 6 that is particularly desired to observe and measure the temperature. In this way, response time can be shortened. Further, a time delay device can also be used when the time sweep is started using an external output from an optical pulse oscillator as a trigger.
（発明の効果）
本発明の光ファイバによる温度測定方法は、光フアイバ
６中に温度測定のために添加した添加剤の吸収の温度特
性に基づく損失変化と、それ以外の原因による光ファイ
バの損失変化とを観測し、両者の差から添加剤による温
度に対する吸収損失を摘出するので、正確な温度を光フ
ァイバの長手方向に沿って測定することがｕｆ能となる
。(Effects of the Invention) The method for measuring temperature using an optical fiber of the present invention is characterized by changes in loss based on the temperature characteristics of absorption of additives added into the optical fiber 6 for temperature measurement, and losses in the optical fiber due to other causes. Since the absorption loss due to the additive due to the temperature is extracted from the difference between the two, it becomes possible to accurately measure the temperature along the longitudinal direction of the optical fiber.
第１図は本発明の温度測定方法の一実施例を示す説明図
、第２図は第１図の温度測定方法による時間差−後方散
乱光強度の特性説明図、第３図、第４図は本発明の他の
実施例の説明図、第５図はＮｄ３・をドーピングした石
英系光ファイバの損失スペクトルの説明図１．第６図は
６００ｎｍの吸収損失による出力変化と温度との関係を
示す説ＩＪ１図である。
ｌ、２は光パルス光源
３は合波器
５はビームスプリッター
６は光ファイバ
７は後方散乱光
８は分波器
９、ｌＯは光検出器
１４は反射ミラー
藪 憂
＋ｓ Ｎ ＯＮ 寸
Ｗ堰五Ｒ−２！FIG. 1 is an explanatory diagram showing an embodiment of the temperature measuring method of the present invention, FIG. 2 is an explanatory diagram of the time difference-backscattered light intensity characteristic according to the temperature measuring method of FIG. 1, and FIGS. 3 and 4 are An explanatory diagram of another embodiment of the present invention, FIG. 5 is an explanatory diagram of a loss spectrum of a silica-based optical fiber doped with Nd3.1. FIG. 6 is a theory IJ1 diagram showing the relationship between output change due to absorption loss at 600 nm and temperature. 1, 2 is an optical pulse light source 3 is a multiplexer 5 is a beam splitter 6 is an optical fiber 7 is a backscattered light 8 is a demultiplexer 9, IO is a photodetector 14 is a reflection mirror. R-2!
Claims (1)
がガラス母体中に混入された光ファイバの一端もしくは
両端から、上記の光吸収帯に含まれる波長の光パルスと
、その光吸収帯に含まれない波長の光パルスとを入力し
、夫々の波長の光パルスの後方散乱強度と、光ファイバ
への入力時から後方散乱光として出射されるまでの時間
差とを測定して、光ファイバの一端からの長さに対する
夫々の波長での損失値を求め、この両波長での損失値を
比較演算して測定対象の温度を測定するようにしたこと
を特徴とする光ファイバによる温度測定方法。A light pulse with a wavelength included in the above light absorption band and a light pulse with a wavelength included in the above light absorption band are generated from one or both ends of an optical fiber in which an impurity having a light absorption band whose light absorption characteristics change depending on temperature is mixed into the glass matrix. At one end of the optical fiber, we measure the backscattering intensity of the light pulses at each wavelength and the time difference from when they enter the optical fiber until they are emitted as backscattered light. 1. A method for measuring temperature using an optical fiber, characterized in that the temperature of the object to be measured is measured by calculating the loss value at each wavelength with respect to the length of the fiber and comparing the loss values at both wavelengths.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62038517A JP2516613B2 (en) | 1987-02-21 | 1987-02-21 | Optical fiber temperature measurement method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62038517A JP2516613B2 (en) | 1987-02-21 | 1987-02-21 | Optical fiber temperature measurement method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63205531A true JPS63205531A (en) | 1988-08-25 |
| JP2516613B2 JP2516613B2 (en) | 1996-07-24 |
Family
ID=12527463
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62038517A Expired - Fee Related JP2516613B2 (en) | 1987-02-21 | 1987-02-21 | Optical fiber temperature measurement method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2516613B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH045136A (en) * | 1990-04-23 | 1992-01-09 | Hitachi Cable Ltd | Optical fiber compound trolley wire, abnormal exothermicity detecting system for trolley line using such trolley wire and optical fiber compound trolley wire stringing method |
| US5263776A (en) * | 1992-09-25 | 1993-11-23 | International Business Machines Corporation | Multi-wavelength optical thermometry |
| JP2006023260A (en) * | 2004-07-09 | 2006-01-26 | J-Power Systems Corp | Method and instrument for measuring temperature distribution in optical fiber |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57173732A (en) * | 1981-04-18 | 1982-10-26 | Omron Tateisi Electronics Co | Optical temperature measuring method |
| JPS61202131A (en) * | 1985-03-06 | 1986-09-06 | Agency Of Ind Science & Technol | Distribution type optical fiber temperature sensor |
| JPS61225627A (en) * | 1985-03-29 | 1986-10-07 | Mitsubishi Electric Corp | Photometer |
-
1987
- 1987-02-21 JP JP62038517A patent/JP2516613B2/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57173732A (en) * | 1981-04-18 | 1982-10-26 | Omron Tateisi Electronics Co | Optical temperature measuring method |
| JPS61202131A (en) * | 1985-03-06 | 1986-09-06 | Agency Of Ind Science & Technol | Distribution type optical fiber temperature sensor |
| JPS61225627A (en) * | 1985-03-29 | 1986-10-07 | Mitsubishi Electric Corp | Photometer |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH045136A (en) * | 1990-04-23 | 1992-01-09 | Hitachi Cable Ltd | Optical fiber compound trolley wire, abnormal exothermicity detecting system for trolley line using such trolley wire and optical fiber compound trolley wire stringing method |
| US5263776A (en) * | 1992-09-25 | 1993-11-23 | International Business Machines Corporation | Multi-wavelength optical thermometry |
| JP2006023260A (en) * | 2004-07-09 | 2006-01-26 | J-Power Systems Corp | Method and instrument for measuring temperature distribution in optical fiber |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2516613B2 (en) | 1996-07-24 |
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