JPS61104235A - Method for measuring strain distribution of optical fiber - Google Patents
Method for measuring strain distribution of optical fiberInfo
- Publication number
- JPS61104235A JPS61104235A JP22419784A JP22419784A JPS61104235A JP S61104235 A JPS61104235 A JP S61104235A JP 22419784 A JP22419784 A JP 22419784A JP 22419784 A JP22419784 A JP 22419784A JP S61104235 A JPS61104235 A JP S61104235A
- Authority
- JP
- Japan
- Prior art keywords
- optical fiber
- optical
- distribution
- core wire
- 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.)
- Pending
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title description 11
- 230000003287 optical effect Effects 0.000 claims abstract description 30
- 238000000691 measurement method Methods 0.000 claims description 2
- 230000005540 biological transmission Effects 0.000 abstract description 5
- 230000035945 sensitivity Effects 0.000 abstract description 2
- 238000005259 measurement Methods 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 239000000835 fiber Substances 0.000 description 4
- 238000004891 communication Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000001902 propagating effect Effects 0.000 description 2
- 238000005452 bending Methods 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000010409 ironing Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000006223 plastic coating Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、通信用光ケーブル内で応力による光ファイバ
歪、特にその歪分布を測定する方法に関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for measuring optical fiber strain due to stress in a communication optical cable, particularly its strain distribution.
（従来の技術）
光ファイバの歪を定量化することは、光ファイバの寿命
を推定し保障する上で極めて重要である。(Prior Art) Quantifying the strain of an optical fiber is extremely important in estimating and guaranteeing the life of the optical fiber.
すでに光ファイバの歪を測定する方法として、光ファイ
バと同じ径を持つ抵抗線にプラスチック被ａを施して、
これを光７アイパ心線の代わりに光２ケーブル内に収容
し、抵抗線の抵抗変化を測定する方法が公開されている
（実願昭５８−０４８８８２ ）。There is already a method for measuring strain in optical fibers, in which a resistance wire with the same diameter as the optical fiber is coated with plastic.
A method has been disclosed in which this is housed in an optical 2 cable instead of an optical 7 eyeglass core wire and the resistance change of the resistance wire is measured (Utility Application No. 58-048882).
また光ケーブル内の光ファイバを伝搬する光パルス信号
の群遅延時間を測定することｋよって、歪を測定する方
法（管厚、他：″光ファイバ心線とケーブルの低温特性
′信学論（Ｃ）、、１Ｔ６２−Ｃ。There is also a method of measuring strain (tube thickness, etc.) by measuring the group delay time of the optical pulse signal propagating through the optical fiber in the optical cable. ),,1T62-C.
１２、ｐｐ、８６４−８７１ （昭５４−１２））が提
案されている。12, pp. 864-871 (Sho 54-12)) has been proposed.
（発明が解決しようとする問題点）
これらの方法では、全長にわたる歪量を測定することは
できても、光ファイバの軸方向にわたる分布を測定する
ことができないという問題があった。この問題に対して
、撚りを与えた光７アイパを光ファイバ内に収容してそ
の光損失を測定することによって、伸び歪の分布を測定
する方法が出願されているが（特願昭５８−１２２０６
０ ） 、この方法ｔは撚りを有する心線の製造および
ケーブル化が難しいという欠点があった。また撚り線は
光ファイバｌ心に被覆した光ファイバ心線と構造が異な
るので、ケーブル内で力学的挙動が異なり、正しい光フ
ァイバの歪を測定することができないという欠点があっ
た。(Problems to be Solved by the Invention) These methods have a problem in that although it is possible to measure the amount of strain over the entire length, it is not possible to measure the distribution over the axial direction of the optical fiber. To solve this problem, an application has been filed for a method of measuring the distribution of elongation strain by accommodating a twisted optical fiber into an optical fiber and measuring its optical loss (Japanese Patent Application No. 1983- 12206
0), this method t had the disadvantage that it was difficult to manufacture twisted core wires and make it into a cable. Furthermore, since the structure of the stranded wire is different from that of the optical fiber core coated on the optical fiber core, the mechanical behavior within the cable is different, resulting in the disadvantage that it is not possible to accurately measure the strain of the optical fiber.
（問題点を解決するための手段）
本発明は、これらの欠点を除去するため、光ケーブル内
に実装したマイクロペンド（微小な曲がり）を有する光
ファイバ心線の損失分布を測定することによって、歪の
分布を測定する。(Means for Solving the Problems) In order to eliminate these drawbacks, the present invention measures the loss distribution of an optical fiber core having micropends (minute bends) mounted in an optical cable, thereby reducing distortion. Measure the distribution of
以下図面により本発明の詳細な説明する。The present invention will be explained in detail below with reference to the drawings.
第４図はマイクロベンドを有する光ファイバ心線の斜視
図であって、１は光ファイバ、２はプラスチック被覆で
ある。この光ファイバ心線の構造および材料は、通常の
光ファイバ心線と相違はないが、第４図に示すよ５１Ｃ
，光ファイバ１は軸方向に沼ってマイクロペンドを有し
ており、光の伝Ｐ４２に対して損失増加を与える。FIG. 4 is a perspective view of a coated optical fiber having a microbend, where 1 is an optical fiber and 2 is a plastic coating. The structure and materials of this optical fiber are the same as those of ordinary optical fiber, but as shown in Figure 4, 51C
, the optical fiber 1 has micropends in the axial direction, which increases the loss of light transmission P42.
本発明による歪測定の効果を説明するため行った実験結
果について述べる。The results of experiments conducted to explain the effects of strain measurement according to the present invention will be described.
第４図に示したマイクロペンドを有する光ファイバ心線
を製造し、伸び歪に対するマイクロベンド損失増を測定
した結果を第６図に示す。この光ファイバ心線は被覆前
の損失が０．８５ ｄＢ／１００ ｍ 。An optical fiber core having the micropend shown in FIG. 4 was manufactured, and the increase in microbending loss with respect to elongation strain was measured. The results are shown in FIG. This optical fiber has a loss of 0.85 dB/100 m before coating.
被覆後の損失は８０．４ ｄＢ／１００ ｍであった。The loss after coating was 80.4 dB/100 m.
損失増加はほとんどマイクロペンドによるものである。Most of the loss increase is due to micropends.
なお伸び歪はマイクロペンドを有する光ファイバ心線に
おもりをぶら下げ張力を与えることによって生じさせて
いる。実験結果から光ファイバ心線に機械的な張力を加
えて伸び歪を生じさせると、この光ファイバを伝搬する
光信号の光損失が減少することと、マイクロペンド損失
の減少と歪はよい直線関係にあることがわかる。この原
因は、心線内で軸方向収縮を生じていたものが張力で緩
和されたためと考えられる。この光ファイバのマイクロ
ベンド損失の減少量を測定すれば、伸び歪を知ることが
できる。さらにマイクロペンド損失の減少量の光ファイ
バの長さ方向分布を測定すれば、光ファイバ歪の分布を
知ることができる。Note that the elongation strain is caused by applying tension by hanging a weight to the optical fiber core wire having micropends. Experimental results show that when mechanical tension is applied to an optical fiber to cause elongation strain, the optical loss of the optical signal propagating through this optical fiber decreases, and that there is a good linear relationship between the reduction in micropend loss and strain. You can see that there is. The reason for this is thought to be that the axial contraction within the core was relaxed by the tension. By measuring the amount of decrease in microbend loss of this optical fiber, the elongation strain can be determined. Furthermore, by measuring the distribution of the amount of reduction in micropend loss in the length direction of the optical fiber, it is possible to know the distribution of optical fiber strain.
なおこのようなマイクロペンドによる光伝送損失の大き
い光ファイバ心線は、硬化収縮率の大きな紫外線硬化樹
脂を心線被覆材に用いる。被覆時の引落し率（ダイス出
口の径と最終的に被覆された樹脂の径の比：樹脂の押し
出しに対しファイバの送りを速くすることによりこの比
は大きくなりファイバに歪を与える）を大きくする、被
覆後の冷却を急激に行う、など被覆の軸方向収縮をあら
かじめ与えることや、比屈折率差の小さい光ファイバを
用いる、などの方法により極めて容易に製造することが
できる。Note that for optical fiber coated wires which have a large optical transmission loss due to such micropends, an ultraviolet curing resin having a large curing shrinkage rate is used as a coated material of the coated wire. Increase the drawdown rate during coating (ratio between the diameter of the die exit and the diameter of the resin that is finally coated: by increasing the speed of fiber feeding relative to resin extrusion, this ratio increases, causing distortion to the fiber). It can be manufactured extremely easily by applying axial shrinkage of the coating in advance, such as by rapidly cooling it after coating, or by using an optical fiber with a small relative refractive index difference.
第１図は本発明による測定系の一実施例の構成図であっ
て、８はマイクロペンドを有する光ファイバ心ｙ−Ｉ
Ｓ４は光ケーブル、５はダミー光ファイバ、６は光パル
ス試験器、７はテータ処理装置、８は出力装置である。FIG. 1 is a block diagram of an embodiment of the measurement system according to the present invention, in which 8 is an optical fiber core y-I having a micropend.
S4 is an optical cable, 5 is a dummy optical fiber, 6 is an optical pulse tester, 7 is a data processing device, and 8 is an output device.
マイクロペンドを有する光７アイパ心へ８が、被測定光
ケーブル４に実装されている。マイクロペンドを有する
光ファイバ心（Ｊｌｌｇの一端はダミー光ファイバ６を
介し【光パルス試験器６に接続されている。この光パル
ス試験器６で発生させたパルス幅の短い光パルス信号を
グミー光ファイバ５を介してマイクロペンドを有する光
ファイバ心線８に入射し、その光７アイパ内で後方散乱
光を発生させる。この後方散乱光をその光ファイバの入
射端で検出しこれを時間軸上に表示することＫより、光
ファイバの長手方向の光伝送損失の分布を観測すること
ができる。An optical 7 to an optical core 8 having a micropend is mounted on the optical cable 4 to be measured. One end of an optical fiber core (Jllg) having a micro pend is connected to an optical pulse tester 6 via a dummy optical fiber 6. The light enters the optical fiber core 8 having a micropend through the fiber 5, and backscattered light is generated within the eyeper 7. This backscattered light is detected at the input end of the optical fiber and is recorded on the time axis. The distribution of optical transmission loss in the longitudinal direction of the optical fiber can be observed from K shown in .
第２図は本発明による測定を実施した結果である。横軸
は時間軸、縦軸は光の反射量を示している。FIG. 2 shows the results of measurement according to the present invention. The horizontal axis shows the time axis, and the vertical axis shows the amount of light reflection.
第８図の横軸は、光ケーブル４内の心線の長さを示し、
マイクロペンドを有する光ファイバ心線ＩＳの光ファイ
バの光伝搬速度から片道の距離に換算させた。縦軸は第
２図の結果に基づいて伝送損失変化量分布と伸び歪の分
布を第５図の結果から対応させた。第８図の測定結果は
、被測定光ケーブルの一端から５０ｍの近傍に、０．２
５％程度の伸び歪が与えられていることを示す。なお現
在の光パルス試験装置の距離分解能は約１ｍであるが、
この分解能をさらに引き上げることにより、歪が極端に
変化する部分の位置と大きさを感度良く検出することが
できる。The horizontal axis in FIG. 8 indicates the length of the core wire in the optical cable 4,
The one-way distance was calculated from the light propagation speed of the optical fiber of the optical fiber IS having the micropend. The vertical axis corresponds to the distribution of transmission loss variation and the distribution of elongation strain based on the results of FIG. 2 based on the results of FIG. 5. The measurement results in Figure 8 show that 0.2
This shows that an elongation strain of about 5% has been applied. Note that the distance resolution of current optical pulse test equipment is approximately 1 m,
By further increasing this resolution, it is possible to detect with high sensitivity the position and size of a portion where distortion changes extremely.
（発明の効果）
以上説明したように、本発明の光ファイバ歪分布測定法
によれば、長尺の通信用光ケーブルの曲げ、しごきなど
による光ファイバの伸び歪の分布を、品感度で容易に測
定観測することができるので、光ケーブルのＱＪ構造設
計が容易になる利点がある。(Effects of the Invention) As explained above, according to the optical fiber strain distribution measurement method of the present invention, it is possible to easily measure the elongation strain distribution of an optical fiber due to bending, ironing, etc. of a long communication optical cable with high quality. Since measurement and observation can be performed, there is an advantage that the QJ structure design of the optical cable is facilitated.
さらに本発明の方法によれば、歪を測定する心線は、従
来からの方法で通信用光ケーブル内に容易に実装できる
ので、布設後のケーブルの保守に利用するには極めて有
効である。Further, according to the method of the present invention, the core wire whose strain is to be measured can be easily mounted in a communication optical cable using a conventional method, and therefore it is extremely effective for use in maintenance of the cable after installation.
第１図は本発明による測定系の一実施例の構成図、第２
図は本発明による方法の実施例によって得られた測定結
果を示す図、第８図は本発明による方法の実施例によっ
て得られた伸び歪分布を示す図、第４図はマイクロベン
ドを有する光ファイバ心線の斜視図、第５図は本発明に
よる光ファイバ心線の伸び歪に対するマイクロベンド損
失増の１Ｑｌｌ定桔呆を示す図であるー
ト・・光ファイバ ２・・・プラスチック被覆８
・・・マイクロベンドを有する光ファイバ心線４・・・
光ケーブル ５・・・ダミー光ファイバ６・・・
光パルス試験器 ７・・・データ処理装置８・・・出
力装置FIG. 1 is a configuration diagram of an embodiment of the measurement system according to the present invention, and FIG.
The figure shows measurement results obtained by an embodiment of the method according to the present invention, Fig. 8 shows an elongation strain distribution obtained by an embodiment of the method according to the present invention, and Fig. 4 shows a light beam having microbends. FIG. 5 is a perspective view of a fiber coated wire, and is a diagram showing the 1Qll constant deviation of the microbend loss increase with respect to the elongation strain of the optical fiber coated wire according to the present invention.
... Optical fiber core wire 4 having micro bends...
Optical cable 5...Dummy optical fiber 6...
Optical pulse tester 7...Data processing device 8...Output device
Claims (1)
ァイバ心線を光ケーブル内に実装し、該光ファイバ心線
のマイクロベンド損失分布を測定することによつて、光
ケーブル内の光ファイバの歪分布を測定することを特徴
とする光ファイバ歪分布測定法。1. By mounting an optical fiber core having a constant microbend loss in the length direction in an optical cable and measuring the microbend loss distribution of the optical fiber core, the strain distribution of the optical fiber in the optical cable can be determined. An optical fiber strain distribution measurement method characterized by measuring.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22419784A JPS61104235A (en) | 1984-10-26 | 1984-10-26 | Method for measuring strain distribution of optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22419784A JPS61104235A (en) | 1984-10-26 | 1984-10-26 | Method for measuring strain distribution of optical fiber |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61104235A true JPS61104235A (en) | 1986-05-22 |
Family
ID=16810041
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22419784A Pending JPS61104235A (en) | 1984-10-26 | 1984-10-26 | Method for measuring strain distribution of optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61104235A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022064597A1 (en) * | 2020-09-24 | 2022-03-31 | 日本電信電話株式会社 | Device and method for detecting trend of increase and decrease of microbending loss in optical fiber |
-
1984
- 1984-10-26 JP JP22419784A patent/JPS61104235A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022064597A1 (en) * | 2020-09-24 | 2022-03-31 | 日本電信電話株式会社 | Device and method for detecting trend of increase and decrease of microbending loss in optical fiber |
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