JPH03233319A - Optical fiber measuring instrument - Google Patents
Optical fiber measuring instrumentInfo
- Publication number
- JPH03233319A JPH03233319A JP2844490A JP2844490A JPH03233319A JP H03233319 A JPH03233319 A JP H03233319A JP 2844490 A JP2844490 A JP 2844490A JP 2844490 A JP2844490 A JP 2844490A JP H03233319 A JPH03233319 A JP H03233319A
- Authority
- JP
- Japan
- Prior art keywords
- optical fiber
- bending
- waveform
- optical
- sensors
- 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 32
- 230000003287 optical effect Effects 0.000 claims description 8
- 239000000835 fiber Substances 0.000 claims description 4
- 238000005259 measurement Methods 0.000 claims description 4
- 238000005452 bending Methods 0.000 abstract description 11
- 238000004804 winding Methods 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 6
- 238000005253 cladding Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000253 optical time-domain reflectometry Methods 0.000 description 2
- 241000190020 Zelkova serrata Species 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Landscapes
- Length Measuring Devices By Optical Means (AREA)
- Optical Transform (AREA)
Abstract
Description
【発明の詳細な説明】
〈産業上の利用分野〉
本発明は、例えばバルブの開閉状態の検知、ケーブルの
浸水や落雷などの環境の検知等、単一地点のみならず多
数地点の状況を検知する光ファイバ応力付与型センサを
用いた測定装置に関する。[Detailed Description of the Invention] <Industrial Application Field> The present invention is capable of detecting situations not only at a single point but also at multiple points, such as detecting the open/closed state of a valve or detecting environments such as cable flooding or lightning strikes. The present invention relates to a measuring device using an optical fiber stress-applying sensor.
〈従来の技術とその課題〉
光ファイバ応力付与型センサは、検知する量に応じて光
ファイバに曲げ応力を加え、その結果光伝送損失が生ず
るものである。そして、とのセンサは浸水検知や落雷検
知に用いられて多数地点での検知量に相応する伝送損失
の測定に用いられる。<Prior art and its problems> Optical fiber stress applying sensors apply bending stress to an optical fiber depending on the amount to be detected, resulting in optical transmission loss. The sensor is used for flood detection and lightning detection, and is used to measure transmission loss corresponding to the amount detected at multiple points.
測定に当っては、光伝送損失を光時間領域反射測定器（
Ｏｐｔｉｃａｌ Ｔｉｍｅ Ｄｏｍａｉｎ Ｒｅｆｌｅ
ｅｔｍｅｔｅｒ）（ＯＴＤＲ装置という）により、光レ
ベルの段差として検出するものである。For measurement, optical transmission loss is measured using an optical time domain reflectance measuring instrument (
Optical Time Domain Refle
ETmeter (referred to as an OTDR device), it is detected as a difference in light level.
ところが、第３図（ａ）、第４図（ａ）に示すように光
ファイバ１の途中に備えられた光ファイバ応力付与型セ
ンサ２に応力が加えられた場合、第３図（ｂｌに示す如
くその応力付加部分から後方にＺの範囲数十ｍにわたっ
てデッドゾ−ンが生ずる。このデッドゾーンは後方散乱
光を取り込むタイミングより広いパルスを光源として使
用した場合必ず生ずるが、この取り込みタイミングより
狭いパルスを使用した場合でも応力を加えた場所にて生
ずるクラッドモードのため生じてしまう。すなわち、光
ファイバ応力付与型センサでは、このセンサ間の間隔を
数十ｍ以下にすると、曲げなど応力付与部で生ずるクラ
ッドモードの影響による過渡的な測定点内となって、異
なるセンサの信号が重なり合って個々のセンサからの信
号が分離しに＜＜、シたがって多数のセンサを近接して
配置できないという問題がある。However, when stress is applied to the optical fiber stress-applying sensor 2 provided in the middle of the optical fiber 1 as shown in FIGS. 3(a) and 4(a), A dead zone occurs rearward from the stress-applying part over a Z range of several tens of meters.This dead zone always occurs when a pulse wider than the timing to capture the backscattered light is used as a light source, but when a pulse narrower than the timing to capture backscattered light is used as a light source. Even when using an optical fiber stress-applying sensor, it occurs due to the cladding mode that occurs at the location where stress is applied.In other words, with an optical fiber stress-applying sensor, if the distance between the sensors is less than several tens of meters, the stress-applying part such as bending Due to the influence of the cladding mode that occurs, signals from different sensors overlap and signals from individual sensors become separated within a transient measurement point.Therefore, a large number of sensors cannot be placed close together. There is.
第３図（ａ）、第４図（ａｌに示す例では、クラッドモ
ードの影響長が２０ｍ〜５０ｍ生じ、その影響長よりも
接近させてセンサ２を配置すると、−例として第３図（
Ｃ）、第４図（ｂｌのようにどのセンサか判明しないこ
とになる。In the examples shown in FIGS. 3(a) and 4(al), the influence length of the cladding mode occurs from 20 m to 50 m, and if the sensor 2 is placed closer than the influence length, as shown in FIG.
C), as shown in Figure 4 (bl), it is not clear which sensor it is.
本発明は、上述の１ｇ１題に鑑みクラッドモードの影響
を極力小さ（して、多数のセンサを近接して配置できろ
ようにした光ファイバ測定装置の提供を目的とする。SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an optical fiber measuring device that minimizes the influence of cladding modes and allows a large number of sensors to be placed close to each other.
く課題を解決するための手段〉
上述の目的を達成する本発明は、光ファイバの途中に応
力付与部を備え上記光ファイバに光源・検出器及び光学
系を接続した光ファイバ測定装置において、
上記応力付与部に上記光ファイバを急峻に曲げて反射光
を発生させる手段を備えたことを特徴とする。Means for Solving the Problems> The present invention achieves the above-mentioned objects in an optical fiber measuring device in which a stress applying section is provided in the middle of an optical fiber and a light source, a detector, and an optical system are connected to the optical fiber. The present invention is characterized in that the stress applying section is provided with means for sharply bending the optical fiber to generate reflected light.
く作 用〉
光ファイバを急峻に曲げると、この曲げにより第２図に
示すような鋭い反射波形Ｒが生じ、しかもこの反射波形
はそれ以前の信号レベルにより突出している特徴がある
。そして、この反射波形を、例えばセンサが動作してい
ない信号を基準として基準レベルより大きな突発入力と
してとらえれば、相互に近接したセンサの動作検出が容
易にできる。Effect> When an optical fiber is bent sharply, this bending causes a sharp reflected waveform R as shown in FIG. 2, and this reflected waveform is characterized by being more prominent than the previous signal level. If this reflected waveform is taken as a sudden input that is higher than a reference level, for example, with a signal in which the sensor is not operating as a reference, it is possible to easily detect the operation of sensors that are close to each other.
施 例〉
ここで、第１図、第３図、第４図を参照して本発明の詳
細な説明する。Example> The present invention will now be described in detail with reference to FIGS. 1, 3, and 4.
第１図は本発明装置の一例であり、１は光ファイバ、２
（よ例えば棒にまきつけるようにして例えば約１０ｃｍ
の曲げを与え急峻な曲げ発生のための応力付与部、３は
反射波形を測定する０ＴＤＲ装置、４はコンピュータで
ある。FIG. 1 shows an example of the device of the present invention, where 1 is an optical fiber, 2 is an optical fiber, and 2 is an optical fiber.
(For example, wrap it around a stick, for example, about 10 cm.)
3 is an OTDR device for measuring the reflected waveform, and 4 is a computer.
かかる構成にて欅への光ファイバ１のまきつけにより、
曲げによる段差が例えば約０．１ｄＢ程度の鋭い反射状
波形が生ずる。そして、この反射状の波形は、光ファイ
バ１を強く曲げるに従って強く突出する。このまきつけ
によるクラッドモードの影響は約３０ｍであったが、反
射状の波形は特異なものであり容易に判定可能である。With this configuration, by winding the optical fiber 1 around the keyaki,
A sharp reflected waveform with a step difference of, for example, about 0.1 dB due to bending is generated. This reflected waveform protrudes more strongly as the optical fiber 1 is bent more strongly. The influence of the cladding mode due to this winding was about 30 m, but the reflected waveform is unique and can be easily determined.
かかる曲げ測定を発生させ検出する装置を４台のセンサ
及び３台のセンサを備え、しかも影響炎内５ｍの間隔で
設定した。この場合３００ｍ１程度の弱い曲げでは第３
図（Ｃ）、第４図く実
（ｂｌの如く判定不可能であったが、約１０ｃｍの急峻
な曲げを発生させると第３図（ｄｌ 、第４図（ｃｌの
ように鋭い反射状の波形が生じた。The apparatus for generating and detecting such bending measurements was equipped with four sensors and three sensors, and was set at intervals of 5 m within the influence flame. In this case, for a weak bend of about 300 m1, the third
Although it was impossible to judge as shown in Figure (C) and Figure 4 (bl), if a steep bend of about 10 cm is generated, a sharp reflective shape as shown in Figure 3 (dl) and Figure 4 (cl) can be generated. A waveform occurred.
なお、光ファイバ１の曲げを強くすると反射が顕著にな
るが、その際曲げ疲労によるファイバ破断が信頼性の点
から問題となる。この場合、ハーメチックファイバなど
疲労指数の大きなファイバを用いることにより問題が解
決できろ。Incidentally, when the optical fiber 1 is bent more strongly, reflection becomes more noticeable, but in this case, fiber breakage due to bending fatigue becomes a problem from the viewpoint of reliability. In this case, the problem can be solved by using a fiber with a large fatigue index, such as a hermetic fiber.
また、上記実施例では検査者が波形を直接判定している
が、コンピュータを用いてソフトウェア上にて自動的に
検査を行うようにすると効果的である。Further, in the above embodiments, the tester directly judges the waveform, but it is effective to automatically perform the test using software using a computer.
〈発明の効果〉
以上説明したように本発明によれば、曲げにて生ずる反
射形状波形は階段状の損失を検出する従来と異なりセン
サが接近しても容易に特徴付けられて検出できるので、
センサの近接配置も可能となる。<Effects of the Invention> As explained above, according to the present invention, the reflected waveform caused by bending can be easily characterized and detected even when the sensor approaches, unlike the conventional method that detects step-like loss.
Sensors can also be placed close together.
第１図は本発明の一実施例の構成図、第２図は反射波形
の発生状態図、第３図は４個のセンサを配置状態図とそ
の波形図、第４図は３個のセンサの配置状態図とその波
形図である。
図 中
１は光ファイバ、
２は応力付与部、
３は０ＴＤＲ装置である。Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is a diagram of the generation state of reflected waveforms, Fig. 3 is a diagram of the arrangement of four sensors and their waveforms, and Fig. 4 is a diagram of the arrangement of four sensors. FIG. 2 is an arrangement state diagram and its waveform diagram. In the figure, 1 is an optical fiber, 2 is a stress applying section, and 3 is an 0TDR device.
Claims (3)
イバに光源・検出器及び光学系を接続した光ファイバ測
定装置において、 上記応力付与部に上記光ファイバを急峻に 曲げて反射光を発生させる手段を備えたことを特徴とす
る光ファイバ測定装置。(1) In an optical fiber measurement device that has a stress applying part in the middle of the optical fiber and connects a light source, a detector, and an optical system to the optical fiber, the optical fiber is bent sharply to the stress applying part to generate reflected light. 1. An optical fiber measuring device characterized by comprising means for causing
光時間領域反射測定器を備えたことを特徴とする請求項
（１）の光ファイバ測定装置。(2) The optical fiber measuring device according to claim 1, further comprising an optical time-domain reflectometer as a light source/detector and optical system for detecting reflected light.
特徴とする請求項（１）又は（２）の光ファイバ測定装
置。(3) The optical fiber measuring device according to claim (1) or (2), wherein the optical fiber is a hermetic fiber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2028444A JP2755461B2 (en) | 1990-02-09 | 1990-02-09 | Optical fiber measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2028444A JP2755461B2 (en) | 1990-02-09 | 1990-02-09 | Optical fiber measuring device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03233319A true JPH03233319A (en) | 1991-10-17 |
| JP2755461B2 JP2755461B2 (en) | 1998-05-20 |
Family
ID=12248849
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2028444A Expired - Lifetime JP2755461B2 (en) | 1990-02-09 | 1990-02-09 | Optical fiber measuring device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2755461B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005241459A (en) * | 2004-02-26 | 2005-09-08 | Furukawa Electric Co Ltd:The | Optical fiber sensor |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58501336A (en) * | 1981-08-27 | 1983-08-11 | テイア−ルダブリユ− インコ−ポレ−テツド | How to monitor forces acting on a structure |
| JPH01225911A (en) * | 1988-03-07 | 1989-09-08 | Fujikura Ltd | Manufacture of hermetic-coat optical fiber |
| JPH0237394U (en) * | 1988-08-31 | 1990-03-12 |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2599493A1 (en) | 1986-05-30 | 1987-12-04 | Comp Generale Electricite | FIBER OPTICAL MULTIPOINT MEASURING DEVICE WITH TEMPORAL MULTIPLEXING |
-
1990
- 1990-02-09 JP JP2028444A patent/JP2755461B2/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58501336A (en) * | 1981-08-27 | 1983-08-11 | テイア−ルダブリユ− インコ−ポレ−テツド | How to monitor forces acting on a structure |
| JPH01225911A (en) * | 1988-03-07 | 1989-09-08 | Fujikura Ltd | Manufacture of hermetic-coat optical fiber |
| JPH0237394U (en) * | 1988-08-31 | 1990-03-12 |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005241459A (en) * | 2004-02-26 | 2005-09-08 | Furukawa Electric Co Ltd:The | Optical fiber sensor |
| JP4609836B2 (en) * | 2004-02-26 | 2011-01-12 | 古河電気工業株式会社 | Optical fiber sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2755461B2 (en) | 1998-05-20 |
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