JP5743200B2 - Optical fiber temperature distribution measuring device - Google Patents

Optical fiber temperature distribution measuring device Download PDF

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JP5743200B2
JP5743200B2 JP2011109567A JP2011109567A JP5743200B2 JP 5743200 B2 JP5743200 B2 JP 5743200B2 JP 2011109567 A JP2011109567 A JP 2011109567A JP 2011109567 A JP2011109567 A JP 2011109567A JP 5743200 B2 JP5743200 B2 JP 5743200B2
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和司 大石
和司 大石
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所定長に敷設された光ファイバの一端側から光パルスを入射し、前記光ファイバから得られる後方ラマン散乱光よりストークス光とアンチストークス光を抽出して夫々の強度を電気信号に変換した受信信号レベルと、前記一端側で測定される基準温度信号を入力する演算制御部により前記所定長の温度分布を演算する光ファイバ温度分布測定装置に関するものであり、ユーザが温度校正をより容易にかつ正確に実施できる環境を提供する。
A received signal in which an optical pulse is incident from one end side of an optical fiber laid in a predetermined length, and Stokes light and anti-Stokes light are extracted from backward Raman scattered light obtained from the optical fiber and converted into electric signals. The present invention relates to an optical fiber temperature distribution measuring device that calculates the temperature distribution of the predetermined length by a calculation control unit that inputs a level and a reference temperature signal measured at the one end side, and allows a user to perform temperature calibration more easily and accurately. Provide an environment that can be implemented.

図６は、従来の光ファイバ温度分布測定装置の構成例を示す機能ブロック図である。所定長に敷設された光ファイバ１０の一端側から、ドライブ回路２０で駆動されるレーザ光源３０よりの光パルスを、サーキュレータ４０および温度基準部５０を経由して入射させる。   FIG. 6 is a functional block diagram showing a configuration example of a conventional optical fiber temperature distribution measuring apparatus. A light pulse from the laser light source 30 driven by the drive circuit 20 is incident through the circulator 40 and the temperature reference unit 50 from one end side of the optical fiber 10 laid in a predetermined length.

入射された光パルスは、温度基準部５０を介して光ファイバ１０中を伝播すると同時に、後方散乱光を発生させる。後方散乱光にはレイリー散乱光、ブリルアン散乱光、ラマン散乱光などがあるが、温度と相関のあるラマン散乱光のみをサーキュレータ４０を経由して波長分波器６０によって切り出し、受光部７０のフォトダイオードで受光して電気信号変換し、制御演算部８０に入力する。   The incident light pulse propagates through the optical fiber 10 via the temperature reference unit 50 and simultaneously generates backscattered light. Backscattered light includes Rayleigh scattered light, Brillouin scattered light, Raman scattered light, etc., but only the Raman scattered light correlated with temperature is cut out by the wavelength demultiplexer 60 via the circulator 40, and the photo of the light receiving unit 70 is obtained. Light is received by the diode, converted into an electrical signal, and input to the control calculation unit 80.

図７は、入射光と後方ラマン散乱光の周波数スペクトル図である。ラマン散乱光は、光ファイバ入射光のスペクトルに対して所定波長離れた周波数(波長)にシフトする。長波長側にシフトした散乱光をストークス（以下、ＳＴ）光と呼び、短波長側にシフトした散乱光をアンチストークス（以下、ＡＳ）光と呼ぶ。   FIG. 7 is a frequency spectrum diagram of incident light and backward Raman scattered light. The Raman scattered light shifts to a frequency (wavelength) that is a predetermined wavelength away from the spectrum of the optical fiber incident light. The scattered light shifted to the long wavelength side is referred to as Stokes (hereinafter referred to as ST) light, and the scattered light shifted to the short wavelength side is referred to as anti-Stokes (hereinafter referred to as AS) light.

制御演算部８０は、受光部７０から入力するＳＴ光およびＡＳ光の夫々の強度に比例した電気信号をＡＤコンバータでディジタル信号に変換し、温度分布演算手段８１の信号処理によって温度分布に変換する。変換された温度分布Ｆ１は、表示手段９０で表示される。   The control calculation unit 80 converts an electrical signal proportional to the intensity of each of the ST light and AS light input from the light receiving unit 70 into a digital signal by an AD converter, and converts it into a temperature distribution by signal processing of the temperature distribution calculation means 81. . The converted temperature distribution F1 is displayed on the display means 90.

受光されたラマン散乱光が光ファイバ１０のどの位置で散乱されたものかは、パルスを発光して受光部７０で受信するまでの時間から換算できる。任意の距離における温度計算式は次式で表される。   The position in the optical fiber 10 where the received Raman scattered light is scattered can be converted from the time until the light receiving unit 70 receives the pulse and receives it. The temperature calculation formula at an arbitrary distance is expressed by the following formula.

Figure 0005743200
Figure 0005743200

ここで、h：プランク定数、c：光速、Δν：ラマンシフト波数、k：ボルツマン定数とする。また温度θにおけるＡＳ光強度とＳＴ光強度の比をＲ（θ）とし、同様に、温度ＴにおけるＡＳ光強度とＳＴ光強度の比をＲ（Ｔ）とする。   Here, h: Planck constant, c: speed of light, Δν: Raman shift wave number, k: Boltzmann constant. Further, the ratio of the AS light intensity and the ST light intensity at the temperature θ is R (θ), and similarly, the ratio of the AS light intensity and the ST light intensity at the temperature T is R (T).

したがって、温度θが既知であれば温度Ｔを求めることができる。つまり、光ファイバ１０の一端側に温度基準部５０を設け、その温度を温度センサ５１で測定した温度をθとして取得すれば、光ファイバ１０の任意の箇所での温度Ｔを求めることができる。   Therefore, if the temperature θ is known, the temperature T can be obtained. That is, if the temperature reference part 50 is provided on one end side of the optical fiber 10 and the temperature measured by the temperature sensor 51 is obtained as θ, the temperature T at an arbitrary position of the optical fiber 10 can be obtained.

特開２００７−２４０１７４号公報JP 2007-240174 A

図８は、ＳＴ光とＡＳ光の強度分布差を説明する周波数特性図である。図８（Ａ）はＳＴ光とＡＳ光の強度分布を示す。ＳＴ光とＡＳ光は、図７に示すように波長が異なるため、ファイバ伝送損失が異なる。したがって、全光ファイバ区間において温度が一定であったとしてもＳＴ光とＡＳ光のファイバ伝送損失の差によって、図８（Ｂ）に示すように温度勾配を持ってしまう。   FIG. 8 is a frequency characteristic diagram illustrating an intensity distribution difference between ST light and AS light. FIG. 8A shows the intensity distribution of ST light and AS light. Since ST light and AS light have different wavelengths as shown in FIG. 7, fiber transmission loss is different. Therefore, even if the temperature is constant in the entire optical fiber section, a temperature gradient is caused as shown in FIG. 8B due to the difference in fiber transmission loss between ST light and AS light.

この温度誤差を解消するために、ＳＴ光とＡＳ光のファイバ伝送損失差を補正する処理が必要になる。この補正処理は、図６の制御演算部８０における温度分布補正手段８２に実装されるアプリケーションソフトウェアで実行される。次式は、ＡＳ光を補正する場合の式である。この場合、ＳＴ光を補正してもよいが、ここではＡＳ光を補正する場合を示す。   In order to eliminate this temperature error, it is necessary to correct the fiber transmission loss difference between the ST light and the AS light. This correction processing is executed by application software installed in the temperature distribution correction means 82 in the control calculation unit 80 of FIG. The following expression is an expression for correcting AS light. In this case, ST light may be corrected, but here, a case where AS light is corrected is shown.

ＡＳ２（Ｌ）＝ＡＳ（Ｌ）＋Ｌｏｓｓ×Ｌ （式２）   AS2 (L) = AS (L) + Loss × L (Formula 2)

ここで、各パラメータの意味は次の通りとする。
ＡＳ２（Ｌ）：距離Ｌ（ｍ）での補正後のＡＳ光強度
ＡＳ（Ｌ）：距離Ｌ（ｍ）での補正前のＡＳ光強度
Ｌｏｓｓ：補正値（ＡＳ光とＳＴ光のファイバ伝送損失差（ｄＢ／ｍ））
Ｌ：距離（ｍ） Here, the meaning of each parameter is as follows.
AS2 (L): AS light intensity after correction at distance L (m) AS (L): AS light intensity before correction at distance L (m) Loss: Correction value (fiber transmission loss of AS light and ST light) Difference (dB / m))
L: Distance (m)

式２によって補正されたＡＳ光強度を用いて式１で温度計算を再度行うことで、温度分布が補正される。実際には、ユーザがアプリケーションソフトウェアの画面上で補正信号ＣによりＬｏｓｓ値を入力し、その結果再計算されて得られた強度分布または温度分布を見ながら、適切なＬｏｓｓ値に調整していく作業が必要となる。   The temperature distribution is corrected by performing the temperature calculation again using Equation 1 using the AS light intensity corrected according to Equation 2. In practice, the user inputs the Loss value by the correction signal C on the screen of the application software, and adjusts to an appropriate Loss value while observing the intensity distribution or temperature distribution obtained as a result of recalculation. Is required.

図９は、ＳＴ光とＡＳ光の強度差の補正を説明する表示画面である。図９（Ａ）は、ＡＳ光を矢印方向に補正してＳＴ光の強度分布勾配と一致させる。例えば、全光ファイバ区間において温度一定という環境の下であれば、図９（Ｂ）に示すように温度が一定になるようにＬｏｓｓ値を設定する。   FIG. 9 is a display screen for explaining correction of an intensity difference between ST light and AS light. In FIG. 9A, the AS light is corrected in the direction of the arrow to match the ST light intensity distribution gradient. For example, if the temperature is constant in the entire optical fiber section, the Loss value is set so that the temperature is constant as shown in FIG. 9B.

図１０（Ａ）は、補正前の温度分布、図１０（Ｂ）は補正後の温度分布を示す表示画面である。実際の温度分布は図１０（Ａ），（Ｂ）に示すようにノイズを含むため、温度が一定であるか、温度勾配があるかの判断が難しく、正確なＬｏｓｓ値をユーザが設定することは容易ではない。   FIG. 10A is a display screen showing the temperature distribution before correction, and FIG. 10B is a display screen showing the temperature distribution after correction. Since the actual temperature distribution includes noise as shown in FIGS. 10A and 10B, it is difficult to determine whether the temperature is constant or there is a temperature gradient, and the user must set an accurate Loss value. Is not easy.

本発明の目的は、ユーザが温度分布を見ながら適切なＬｏｓｓ値をより容易かつ正確に設定できるような補助機能を備える光ファイバ温度分布測定装置を実現することにある。   An object of the present invention is to realize an optical fiber temperature distribution measuring apparatus having an auxiliary function that allows a user to set an appropriate Loss value more easily and accurately while viewing a temperature distribution.

このような課題を達成するために、本発明は次の通りの構成になっている。
（１）所定長に敷設された光ファイバの一端側から光パルスを入射し、前記光ファイバから得られる後方ラマン散乱光よりストークス光とアンチストークス光を抽出して夫々の強度を電気信号に変換した受信信号レベルと、前記一端側で測定される基準温度信号を入力する演算制御部により前記所定長の温度分布を演算する光ファイバ温度分布測定装置において、
前記温度分布を表示する表示手段と、
前記温度分布を示す複数のデータに基づいて近似直線を演算して前記表示手段に前記温度分布と重ねて表示させる近似直線生成手段と、
前記ストークス光とアンチストークス光のファイバ伝送損失差を補正するための補正信号を入力して前記近似直線を既知の温度分布特性に一致させるための温度分布補正手段と、
を備えることを特徴とする光ファイバ温度分布測定装置。

In order to achieve such a subject, the present invention has the following configuration.
(1) An optical pulse is incident from one end side of an optical fiber laid at a predetermined length, and Stokes light and anti-Stokes light are extracted from backward Raman scattered light obtained from the optical fiber, and each intensity is converted into an electric signal. In the optical fiber temperature distribution measuring device that calculates the temperature distribution of the predetermined length by the calculation control unit that inputs the received signal level and the reference temperature signal measured on the one end side,
Display means for displaying the temperature distribution;
An approximate straight line generating unit that calculates an approximate straight line based on a plurality of data indicating the temperature distribution and displays the approximated straight line on the display unit with the temperature distribution ;
A temperature distribution correction means for inputting a correction signal for correcting a fiber transmission loss difference between the Stokes light and the anti-Stokes light to match the approximate straight line with a known temperature distribution characteristic;
An optical fiber temperature distribution measuring device comprising:

（２）前記光ファイバを恒温槽に収容して前記光ファイバの温度測定区間全体を同一温度に保持すると共に、前記恒温槽の温度測定信号を前記演算制御部に入力し、
前記温度分布補正手段は、前記補正信号により、前記恒温槽の一定温度分布を示す前記表示手段の直線に前記近似直線を一致させることを特徴とする（１）に記載の光ファイバ温度分布測定装置。 (2) The optical fiber is housed in a thermostat and the entire temperature measurement section of the optical fiber is held at the same temperature, and a temperature measurement signal of the thermostat is input to the arithmetic control unit,
The optical fiber temperature distribution measuring device according to (1), wherein the temperature distribution correcting means matches the approximate straight line with a straight line of the display means indicating a constant temperature distribution of the thermostatic bath based on the correction signal. .

（３）前記光ファイバの温度測定区間の一端側温度を測定した第１温度信号を前記演算制御部に出力する第１温度センサと、前記光ファイバの温度測定区間の他端側温度を測定した第２温度信号を前記演算制御部に出力する第２温度センサを備え、
前記温度分布補正手段は、前記補正信号により、前記第１温度信号および前記第２温度信号を示す前記表示手段のスポットに前記近似直線を一致させることを特徴とする（１）に記載の光ファイバ温度分布測定装置。 (3) A first temperature sensor that outputs a first temperature signal obtained by measuring a temperature at one end of the temperature measurement section of the optical fiber to the calculation control unit, and a temperature at the other end of the temperature measurement section of the optical fiber were measured. A second temperature sensor for outputting a second temperature signal to the arithmetic control unit;
The optical fiber according to (1), wherein the temperature distribution correcting means matches the approximate straight line to the spot of the display means indicating the first temperature signal and the second temperature signal by the correction signal. Temperature distribution measuring device.

（４）前記温度分布補正手段は、ユーザの手動操作により前記補正信号を入力することを特徴とする（１）乃至（３）のいずれかに記載の光ファイバ温度分布測定装置。 (4) The optical fiber temperature distribution measuring device according to any one of (1) to (3), wherein the temperature distribution correction means inputs the correction signal by a user's manual operation.

（５）前記温度分布補正手段は、前記光ファイバの温度測定区間全体を一定温度に保持した環境において、前記近似直線の勾配をゼロに収斂させるための前記補正信号を生成し、前記近似直線を、前記一定温度分布を示す直線に自動的に一致させることを特徴とする（２）に記載の光ファイバ温度分布測定装置。 (5) The temperature distribution correction unit generates the correction signal for converging the slope of the approximate line to zero in an environment in which the entire temperature measurement section of the optical fiber is held at a constant temperature, and the approximate line is The optical fiber temperature distribution measuring device according to (2), wherein the optical fiber temperature distribution measuring apparatus automatically matches the straight line indicating the constant temperature distribution.

（６）温度分布補正手段は、前記所定長に敷設された光ファイバが、複数種類の光ファイバの直列接続形態とる場合に、各光ファイバによる温度測定区間毎に前記補正信号を入力し、温度測定区間毎に前記近似直線を既知の温度分布特性に一致させることを特徴とする（１）乃至（５）のいずれかに記載の光ファイバ温度分布測定装置。 (6) The temperature distribution correction means inputs the correction signal for each temperature measurement section of each optical fiber when the optical fiber laid in the predetermined length takes a series connection form of a plurality of types of optical fibers, The optical fiber temperature distribution measuring device according to any one of (1) to (5), wherein the approximate straight line is matched with a known temperature distribution characteristic for each measurement section.

本発明によれば、温度分布上に近似直線を表示させる補助機能により、温度勾配がより明確になる。したがって、温度分布がノイズを含む場合でももの近似直線を既知の温度分布特性に正確に一致させるためのＬｏｓｓ値の調整が容易になる。   According to the present invention, the temperature gradient becomes clearer by the auxiliary function of displaying the approximate straight line on the temperature distribution. Therefore, even when the temperature distribution includes noise, it is easy to adjust the Loss value to accurately match the approximate straight line with the known temperature distribution characteristics.

本発明を適用した光ファイバ温度分布測定装置の一実施例を示す機能ブロック図である。It is a functional block diagram which shows one Example of the optical fiber temperature distribution measuring apparatus to which this invention is applied. 本発明の信号処理手順を示すフローチャートである。It is a flowchart which shows the signal processing procedure of this invention. 温度分布上に近似直線を表示した表示画面である。It is the display screen which displayed the approximate straight line on the temperature distribution. 本発明を適用した光ファイバ温度分布測定装置の他の実施例を示す機能ブロック図である。It is a functional block diagram which shows the other Example of the optical fiber temperature distribution measuring apparatus to which this invention is applied. 図４の実施例における近似直線の生成と温度プロファイルへの一致操作の表示画面である。FIG. 5 is a display screen for generating an approximate straight line and for matching a temperature profile in the embodiment of FIG. 従来の光ファイバ温度分布測定装置の構成例を示す機能ブロック図である。It is a functional block diagram which shows the structural example of the conventional optical fiber temperature distribution measuring apparatus. 入射光と後方ラマン散乱光の周波数スペクトル図である。It is a frequency spectrum figure of incident light and back Raman scattered light. ＳＴ光とＡＳ光の強度分布差を説明する周波数特性図である。It is a frequency characteristic figure explaining the intensity distribution difference of ST light and AS light. ＳＴ光とＡＳ光の強度差の補正を説明する表示画面である。It is a display screen explaining correction | amendment of the intensity difference of ST light and AS light. 補正前と補正後の温度分布を示す表示画面である。It is a display screen which shows the temperature distribution before correction | amendment and after correction | amendment.

以下本発明を、図面を用いて詳細に説明する。図１は、本発明を適用した光ファイバ温度分布測定装置の一実施例を示す機能ブロック図である。図６で説明した従来構成と同一要素には同一符号を付して説明を省略する。   Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of an optical fiber temperature distribution measuring apparatus to which the present invention is applied. The same elements as those in the conventional configuration described with reference to FIG.

図６に示した従来構成に追加される本発明の特徴部は、制御演算部８０に設けられた近似直線生成手段１００およびこの近似直線を用いた温度分布補正手段２００を備える構成にある。表示手段９０には、温度分布Ｆ１に追加されて、この温度分布のデータに基づいて生成された近似直線Ｆ２が重ねて表示される。   A feature of the present invention added to the conventional configuration shown in FIG. 6 is a configuration including an approximate straight line generating unit 100 provided in the control calculation unit 80 and a temperature distribution correcting unit 200 using the approximate straight line. On the display unit 90, an approximate straight line F2 generated based on the temperature distribution data is superimposed and displayed in addition to the temperature distribution F1.

図１の実施例では、敷設予定の光ファイバの温度測定区間全体を温度一定の恒温槽３００に収納し、予め光ファイバのＬｏｓｓ値（ＳＴ光とＡＳ光のファイバ伝送損失差)を求めておく例である。   In the embodiment of FIG. 1, the entire temperature measurement section of the optical fiber to be laid is housed in a constant temperature bath 300 with a constant temperature, and the Loss value of the optical fiber (fiber transmission loss difference between ST light and AS light) is obtained in advance. It is an example.

すでに井戸などに光ファイバが敷設されている状態で温度一定の環境を作ることは難しいが、敷設前であれば恒温槽で容易に光ファイバ全体を一定温度に保持することが可能である。よって、この環境下で近似直線の勾配がセロになるように前記温度分布補正手段２００に補正信号Ｃを入力してＬｏｓｓ値を調整する。   Although it is difficult to create an environment where the temperature is constant when the optical fiber is already laid in a well or the like, the entire optical fiber can be easily maintained at a constant temperature in a thermostatic bath before laying. Therefore, the correction signal C is input to the temperature distribution correction unit 200 to adjust the Loss value so that the slope of the approximate straight line becomes zero under this environment.

図２は、発明の信号処理手順を示すフローチャートであり、Ｌｏｓｓ値の補正を実行してグラフを再描画するまでのフローを示す。処理が開始されると、ステップＳ１でユーザにより近視直線の勾配がチェックされ、ステップＳ２で正しくないと判断された場合には、ステップＳ３でユーザ操作による補正信号Ｃの入力でＬｏｓｓ値が変更される。   FIG. 2 is a flowchart showing the signal processing procedure of the invention, and shows a flow from the correction of the Loss value to the redrawing of the graph. When the process is started, the slope of the myopic straight line is checked by the user in step S1, and if it is determined that it is not correct in step S2, the loss value is changed by inputting the correction signal C by the user operation in step S3. The

次にステップＳ４で変更されたＬｏｓｓ値に基づき再度温度計算を実施する。温度計算の過程は、リニアデータ(生データ)から強度データに変換し、さらに強度データから温度データに変換するという流れになる。   Next, the temperature calculation is performed again based on the Loss value changed in step S4. In the temperature calculation process, linear data (raw data) is converted into intensity data, and then the intensity data is converted into temperature data.

強度データに変換する際に、Ｌｏｓｓ値の補正を実行する。次に、ステップＳ５で補正された温度分布データに基づいて近似直線を生成する。このとき、近似直線を生成するために使用するデータの範囲を指定する(光ファイバの温度測定範囲のみ)。近似直線を生成する手法としては次に示す周知の最小二乗法を用いることができる。   When converting into intensity data, correction of the Loss value is executed. Next, an approximate straight line is generated based on the temperature distribution data corrected in step S5. At this time, the range of data used to generate the approximate straight line is specified (only the temperature measurement range of the optical fiber). As a method for generating the approximate straight line, the following known least squares method can be used.

求めたい近似式をｙ＝ａｘ＋ｂとすると、係数ａ，ｂは次式で表される。ここで、ｘは距離データを示し、ｙは温度データを示す。   If an approximate expression to be obtained is y = ax + b, the coefficients a and b are expressed by the following expressions. Here, x represents distance data, and y represents temperature data.

Figure 0005743200
Figure 0005743200

Figure 0005743200
Figure 0005743200

上式によって係数が求まると、近似直線が求まる。次にステップＳ６で温度分布と、その近似直線を同一グラフ上に再描画し、ステップＳ１に戻る。ステップＳ２で正しいと判断された場合には処理を終了する。   When the coefficient is obtained by the above equation, an approximate straight line is obtained. Next, in step S6, the temperature distribution and the approximate straight line are redrawn on the same graph, and the process returns to step S1. If it is determined in step S2 that it is correct, the process is terminated.

図３は、温度分布上に近似直線を表示した表示画面である。図３（Ａ）は温度勾配がある場合、図３（Ｂ）は温度一定の場合を示す。   FIG. 3 is a display screen displaying approximate lines on the temperature distribution. FIG. 3A shows a case where there is a temperature gradient, and FIG. 3B shows a case where the temperature is constant.

図４は、本発明を適用した光ファイバ温度分布測定装置の他の実施例を示す機能ブロック図であり、すでに敷設されている光ファイバに対しても本発明を適用してＬｏｓｓ値補正が可能な例を示している。   FIG. 4 is a functional block diagram showing another embodiment of an optical fiber temperature distribution measuring apparatus to which the present invention is applied. The present invention can be applied to an already installed optical fiber to correct the Loss value. An example is shown.

すでに光ファイバ１０が井戸４００等に敷設されている場合でも、測定範囲に温度センサが設置されていれば、その温度測定値に合わせてＬｏｓｓ値を調整することができる。即ち、予め温度プロファイルが分かっている場合には、そのプロファイルに合わせることでＬｏｓｓ値の調整が可能である。   Even when the optical fiber 10 is already laid in the well 400 or the like, the Loss value can be adjusted according to the temperature measurement value if a temperature sensor is installed in the measurement range. That is, when the temperature profile is known in advance, the loss value can be adjusted by adjusting to the profile.

図４では、井戸４００の入口部に配置された第１温度センサ５００の温度検出信号Ｔｓ１と、井戸４００の底部に配置された第２温度センサ６００の温度検出信号Ｔｓ２が制御演算部８０に入力され、表示部９０に各温度センサによる２点の温度測定スポットが表示される。   In FIG. 4, the temperature detection signal Ts1 of the first temperature sensor 500 disposed at the inlet of the well 400 and the temperature detection signal Ts2 of the second temperature sensor 600 disposed at the bottom of the well 400 are input to the control calculation unit 80. Then, two temperature measurement spots by each temperature sensor are displayed on the display unit 90.

図５は、図４の実施例における近似直線の生成と温度プロファイルへの一致操作の表示画面である。図５（Ａ）では、温度分布Ｆ１および近似直線Ｆ２に加えて前記２点の温度測定スポットＴｓ１およびＴｓ２が画面表示される。   FIG. 5 is a display screen for the generation of the approximate line and the matching operation to the temperature profile in the embodiment of FIG. In FIG. 5A, the two temperature measurement spots Ts1 and Ts2 are displayed on the screen in addition to the temperature distribution F1 and the approximate straight line F2.

図５（Ｂ）では、近似直線Ｆ２が２点の温度測定スポットＴｓ１およびＴｓ２を含んで通過するように、温度分布補正手段２００への補正信号Ｃの変更操作により、Ｌｏｓｓ値を調整して勾配を変更する一致操作を実行する。   In FIG. 5B, the Loss value is adjusted by changing the correction signal C to the temperature distribution correction means 200 so that the approximate line F2 passes through the two temperature measurement spots Ts1 and Ts2, and the gradient is obtained. Perform a match operation that changes

一般に、温度分布にはノイズが重畳しており、温度分布だけでＬｏｓｓ値を調整することは困難であるが、このように、温度測定スポットの２点に近似直線を合わせる操作により、極めて簡単かつ正確にＬｏｓｓ値を調整することができる。   In general, noise is superimposed on the temperature distribution, and it is difficult to adjust the Loss value only by the temperature distribution. In this way, by adjusting the approximate line to the two points of the temperature measurement spot, The Loss value can be adjusted accurately.

図１、図４の実施例では、補正信号Ｃの入力値の変更操作はユーザの手動操作による例を示したが、図１のように恒温槽などにより温度測定区間において光ファイバの温度が一定に保持されている環境下では、近似直線の勾配を自動的で補正することも可能である。   In the embodiment shown in FIGS. 1 and 4, the operation of changing the input value of the correction signal C is an example of manual operation by the user. However, as shown in FIG. It is also possible to automatically correct the gradient of the approximate straight line under the environment maintained in the above.

自動補正の手順は、温度測定データに基づいて温度分布の近似直線を求め、その近似直線の係数ａ(温度勾配)をゼロに収斂させるための補正信号を生成し、近似直線を一定温度分布を示す直線に自動的に一致させる。   The procedure for automatic correction is to obtain an approximate straight line of the temperature distribution based on the temperature measurement data, generate a correction signal for converging the coefficient a (temperature gradient) of the approximate straight line to zero, and convert the approximate straight line to a constant temperature distribution. Automatically match the straight line shown.

図１、図４の実施例では、光ファイバ１０は同一材質の一本構成を例示したが、複数種類の光ファイバが直列接続されている場合でも本発明を応用することが可能である。温度分布補正手段２００は、各光ファイバによる温度測定区間毎に補正信号Ｃを入力し、温度測定区間毎に近似直線を既知の温度分布特性に一致させる。   In the embodiment of FIGS. 1 and 4, the optical fiber 10 has an example of a single material, but the present invention can be applied even when a plurality of types of optical fibers are connected in series. The temperature distribution correction means 200 inputs a correction signal C for each temperature measurement section by each optical fiber, and makes the approximate line coincide with a known temperature distribution characteristic for each temperature measurement section.

この場合、近似直線の係数を求める際に使用するデータ範囲を指定することにより、各ファイバによる温度測定区間に分割して近似直線を生成することができ、これにより区間毎の補正が可能となる。   In this case, by specifying the data range to be used when calculating the coefficient of the approximate line, it is possible to generate an approximate line by dividing the temperature measurement section by each fiber, thereby enabling correction for each section. .

図１、図４の実施例では、近似直線生成手段１００および温度分布補正手段２００の機能が制御演算部８０内に実装されている構成を例示したが、これらの機能並びに表示手段９０を、ネットワークを介して通信可能に接続されたパーソナルコンピュータおよび表示装置により実現することも可能である。   1 and 4 exemplify the configuration in which the functions of the approximate straight line generation unit 100 and the temperature distribution correction unit 200 are mounted in the control calculation unit 80. However, these functions and the display unit 90 are connected to the network. It can also be realized by a personal computer and a display device that are communicably connected to each other.

１０ 光ファイバ
２０ ドライブ回路
３０ レーザ光源
４０ サーキュレータ
５０ 温度基準部
５１ 温度センサ
６０ 波長分波器
７０ 受光部
８０ 制御演算部
８１ 温度分布演算手段
９０ 表示手段
１００ 近似直線生成手段
２００ 温度分布補正手段
３００ 恒温槽
４００ 井戸
５００ 第１温度センサ
６００ 第２温度センサ DESCRIPTION OF SYMBOLS 10 Optical fiber 20 Drive circuit 30 Laser light source 40 Circulator 50 Temperature reference part 51 Temperature sensor 60 Wavelength demultiplexer 70 Light receiving part 80 Control calculation part 81 Temperature distribution calculation means 90 Display means 100 Approximate straight line generation means 200 Temperature distribution correction means 300 Constant temperature Tank 400 Well 500 First temperature sensor 600 Second temperature sensor

Claims (6)

所定長に敷設された光ファイバの一端側から光パルスを入射し、前記光ファイバから得られる後方ラマン散乱光よりストークス光とアンチストークス光を抽出して夫々の強度を電気信号に変換した受信信号レベルと、前記一端側で測定される基準温度信号を入力する演算制御部により前記所定長の温度分布を演算する光ファイバ温度分布測定装置において、
前記温度分布を表示する表示手段と、
前記温度分布を示す複数のデータに基づいて近似直線を演算して前記表示手段に前記温度分布と重ねて表示させる近似直線生成手段と、
前記ストークス光とアンチストークス光のファイバ伝送損失差を補正するための補正信号を入力して前記近似直線を既知の温度分布特性に一致させるための温度分布補正手段と、
を備えることを特徴とする光ファイバ温度分布測定装置。 A received signal in which an optical pulse is incident from one end side of an optical fiber laid in a predetermined length, and Stokes light and anti-Stokes light are extracted from backward Raman scattered light obtained from the optical fiber and converted into electric signals. In the optical fiber temperature distribution measuring device that calculates the temperature distribution of the predetermined length by the calculation control unit that inputs the level and the reference temperature signal measured at the one end side,
Display means for displaying the temperature distribution;
An approximate straight line generating unit that calculates an approximate straight line based on a plurality of data indicating the temperature distribution and displays the approximated straight line on the display unit with the temperature distribution ;
A temperature distribution correction means for inputting a correction signal for correcting a fiber transmission loss difference between the Stokes light and the anti-Stokes light to match the approximate straight line with a known temperature distribution characteristic;
An optical fiber temperature distribution measuring device comprising: 前記光ファイバを恒温槽に収容して前記光ファイバの温度測定区間全体を同一温度に保持すると共に、前記恒温槽の温度測定信号を前記演算制御部に入力し、
前記温度分布補正手段は、前記補正信号により、前記恒温槽の一定温度分布を示す前記表示手段の直線に前記近似直線を一致させることを特徴とする請求項１に記載の光ファイバ温度分布測定装置。 The optical fiber is housed in a thermostat and the entire temperature measurement section of the optical fiber is held at the same temperature, and a temperature measurement signal of the thermostat is input to the arithmetic control unit,
2. The optical fiber temperature distribution measuring device according to claim 1, wherein the temperature distribution correcting unit matches the approximate straight line with a straight line of the display unit indicating a constant temperature distribution of the thermostatic bath based on the correction signal. . 前記光ファイバの温度測定区間の一端側温度を測定した第１温度信号を前記演算制御部に出力する第１温度センサと、前記光ファイバの温度測定区間の他端側温度を測定した第２温度信号を前記演算制御部に出力する第２温度センサを備え、
前記温度分布補正手段は、前記補正信号により、前記第１温度信号および前記第２温度信号を示す前記表示手段のスポットに前記近似直線を一致させることを特徴とする請求項１に記載の光ファイバ温度分布測定装置。 A first temperature sensor that outputs a first temperature signal obtained by measuring a temperature at one end of the temperature measurement section of the optical fiber to the arithmetic control unit; and a second temperature that measures a temperature at the other end of the temperature measurement section of the optical fiber. A second temperature sensor for outputting a signal to the arithmetic control unit;
2. The optical fiber according to claim 1, wherein the temperature distribution correcting unit causes the approximate straight line to coincide with the spot of the display unit indicating the first temperature signal and the second temperature signal by the correction signal. Temperature distribution measuring device. 前記温度分布補正手段は、ユーザの手動操作により前記補正信号を入力することを特徴とする請求項１乃至３のいずれかに記載の光ファイバ温度分布測定装置。   4. The optical fiber temperature distribution measuring device according to claim 1, wherein the temperature distribution correction means inputs the correction signal by a user's manual operation. 前記温度分布補正手段は、前記光ファイバの温度測定区間全体を一定温度に保持した環境において、前記近似直線の勾配をゼロに収斂させるための前記補正信号を生成し、前記近似直線を、前記一定温度分布を示す直線に自動的に一致させることを特徴とする請求項２に記載の光ファイバ温度分布測定装置。   The temperature distribution correction means generates the correction signal for converging the slope of the approximate line to zero in an environment in which the entire temperature measurement section of the optical fiber is held at a constant temperature, and the approximate line is set to the constant 3. The optical fiber temperature distribution measuring apparatus according to claim 2, wherein the optical fiber temperature distribution measuring apparatus automatically matches the straight line indicating the temperature distribution. 温度分布補正手段は、前記所定長に敷設された光ファイバが、複数種類の光ファイバの直列接続形態とる場合に、各光ファイバによる温度測定区間毎に前記補正信号を入力し、温度測定区間毎に前記近似直線を既知の温度分布特性に一致させることを特徴とする請求項１乃至５のいずれかに記載の光ファイバ温度分布測定装置。   The temperature distribution correction means inputs the correction signal for each temperature measurement section by each optical fiber when the optical fiber laid in the predetermined length takes a form of serial connection of a plurality of types of optical fibers, and for each temperature measurement section 6. The optical fiber temperature distribution measuring apparatus according to claim 1, wherein the approximate straight line is made to coincide with a known temperature distribution characteristic.
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