JPH07159281A - Reflection measuring apparatus for optical frequency region - Google Patents
Reflection measuring apparatus for optical frequency regionInfo
- Publication number
- JPH07159281A JPH07159281A JP5309311A JP30931193A JPH07159281A JP H07159281 A JPH07159281 A JP H07159281A JP 5309311 A JP5309311 A JP 5309311A JP 30931193 A JP30931193 A JP 30931193A JP H07159281 A JPH07159281 A JP H07159281A
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- JP
- Japan
- Prior art keywords
- optical
- light
- frequency
- directional coupler
- 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.)
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、光ファイバー通信線路
における反射光及び後方散乱光の発生箇所を高い距離分
解能で同定し、故障箇所、異常箇所を発見するための測
定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 measuring device for identifying a location where reflected light and backscattered light are generated in an optical fiber communication line with a high distance resolution and for finding a fault location or an abnormal location.
【０００２】[0002]
【従来の技術】高い距離分解能で、光部品または光ファ
イバーからの反射光及び後方散乱光の強度分布を測定す
ることが可能な分布型光センサーとして、Ｃ−ＯＦＤＲ
（Coherent Optical Frequency Domain Reflectometry
）が知られている。2. Description of the Related Art As a distributed optical sensor capable of measuring the intensity distribution of reflected light and backscattered light from an optical component or an optical fiber with high distance resolution, a C-OFDR is available.
(Coherent Optical Frequency Domain Reflectometry
)It has been known.
【０００３】Ｃ−ＯＦＤＲでは、周波数が時間に対して
直線的に繰り返し掃引されたコヒーレントな光を用いる
ことにより、光周波数領域における反射光及び後方散乱
光の強度分布測定を可能にしている。具体的には、図５
に示すように、光源Ｌからの直線周波数掃引された光を
信号光Ａと参照光Ｂとに分けた後、信号光Ａを被測定光
部品、例えば光ファイバー１００に入射し、反射、又は
後方散乱された反射光Ｃと参照光Ｂとの間のビート周波
数信号を受信器Ｄで受信し、スペクトラムアナライザー
Ｅで解析している。このとき、両光の周波数差は、その
遅延時間差に比例するため、反射光強度分布を光周波数
領域で測定することができる。特に距離分解能が高い場
合には、受信帯域幅を狭く設定することができるため、
低雑音で測定が行なえるという方式上の利点を有する。
このときの周波数掃引波形図を図６ａに、測定波形を図
６ｂに示した。図６ａの縦軸ｆは光周波数、横軸ｔは時
間を表し、図６ｂの縦軸Ｉは強度、横軸Δｆは周波数差
を表す。In C-OFDR, by using coherent light whose frequency is repeatedly swept linearly with respect to time, it is possible to measure the intensity distribution of reflected light and backscattered light in the optical frequency region. Specifically, FIG.
As shown in FIG. 1, after the linear frequency swept light from the light source L is divided into the signal light A and the reference light B, the signal light A is incident on the measured optical component, for example, the optical fiber 100, and reflected or backscattered. The received beat frequency signal between the reflected light C and the reference light B is received by the receiver D and analyzed by the spectrum analyzer E. At this time, since the frequency difference between the two lights is proportional to the delay time difference, the reflected light intensity distribution can be measured in the optical frequency range. Especially when the distance resolution is high, the reception bandwidth can be set narrow,
It has a system advantage that measurement can be performed with low noise.
The frequency sweep waveform diagram at this time is shown in FIG. 6a, and the measured waveform is shown in FIG. 6b. The vertical axis f in FIG. 6a represents optical frequency, the horizontal axis t represents time, the vertical axis I in FIG. 6b represents intensity, and the horizontal axis Δf represents frequency difference.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、Ｃ−Ｏ
ＦＤＲにおける周波数掃引には、極めて高精度な線形性
が要求され、且つ周波数掃引速度として、１〜１００Ｔ
Ｈｚ／秒程度の高い値が必要とされる。また反射光と参
照光との干渉によるビード信号を継続的に得るために
は、それらの間の光路長差が光の可干渉距離内に入って
いなければならない。しかしながら半導体レーザーを光
源として用い、注入電流制御により周波数を掃引する場
合には、可干渉距離が短いために測定可能範囲を広くと
れないという問題、及び線形周波数掃引が難しく充分な
測定精度がとれないという問題があり、充分な長さを有
する光ファイバーの測定は不可能であった。However, C--O
The frequency sweep in FDR requires extremely accurate linearity, and the frequency sweep speed is 1 to 100T.
Values as high as Hz / sec are required. Further, in order to continuously obtain the bead signal due to the interference between the reflected light and the reference light, the optical path length difference between them must be within the coherence length of the light. However, when a semiconductor laser is used as a light source and the frequency is swept by controlling the injection current, there is a problem that the measurable range cannot be widened due to the short coherence distance, and the linear frequency sweep is difficult and sufficient measurement accuracy cannot be obtained. However, it is impossible to measure an optical fiber having a sufficient length.
【０００５】またコヒーレント光源としてＹＡＧレーザ
ー等の狭帯域幅光源を用い、外部変調器により光周波数
を掃引する方式では、外部変調器により１０〜数１０Ｇ
Ｈｚ周波数を変調掃引するが、変調時における０次成分
及び高次変調成分の除去が難しく測定を困難にしてい
た。In a system in which a narrow bandwidth light source such as a YAG laser is used as a coherent light source and an optical frequency is swept by an external modulator, 10 to several tens of G are supplied by the external modulator.
Although the Hz frequency is modulated and swept, it is difficult to remove the 0th-order component and the higher-order modulation component during the modulation, which makes the measurement difficult.
【０００６】本発明は、以上の問題点を解決し、広い範
囲にわたって、高い距離分解能が可能になる光周波数領
域反射測定装置を提供することを目的とする。An object of the present invention is to solve the above problems and to provide an optical frequency domain reflectometer capable of achieving high distance resolution over a wide range.
【０００７】[0007]
【課題を解決するための手段】上記課題を解決するため
に、本発明は、１）極めてコヒーレントな光を発生する
レーザー光源と、２）該光源より生じた光の強度もしく
は位相に周波数変調をかけるための高速外部変調器と、
３）該高速部変調器からの出力光の周波数変調成分の中
から、０次光及び高次変調成分を除去し、１次変調成分
のみを取り出すための光フィルターと、４）該光フィル
ターからの出力光を２波に分波するための第１の光方向
性結合器と、５）該第１の光方向性結合器の片方の出力
光を被測定光ファイバーに導き、且つ該被測定光ファイ
バーからの反射もしくは後方散乱光を取り出すための第
２の光方向性結合器と、６）該第２の光方向性結合器を
介して取り出された反射光、及び後方散乱光を、前記第
１の光方向性結合器の残りの出力ポートより出力される
光波と合波しヘテロダイン検波するためのヘテロダイン
受信器と、７）ヘテロダイン受信器からの電気信号を周
波数解析するためのスペクトラムアナライザーと、８）
該スペクトラムアナライザーの測定値を加算平均化する
ための信号処理系と、９）光フィルターの共振線を光周
波数に合わせて同期制御するための同期制御系とから測
定系を構成し、前記高速外部変調器により光の周波数を
時間に対して直線的に掃引することにより、被測定光フ
ァイバーからの反射光及び後方散乱光の強度分布を高い
距離分解能で測定することを可能にした。In order to solve the above-mentioned problems, the present invention provides 1) a laser light source for generating extremely coherent light, and 2) frequency modulation for the intensity or phase of the light generated by the light source. A high-speed external modulator for applying
3) An optical filter for removing 0th-order light and higher-order modulation components from the frequency-modulation component of the output light from the high-speed modulator and extracting only the 1st-order modulation component; 4) From the optical filter A first optical directional coupler for demultiplexing the output light of the above into two waves, and 5) guiding one output light of the first optical directional coupler to the optical fiber to be measured, and the optical fiber to be measured. A second optical directional coupler for extracting reflected or backscattered light from the light source, and 6) the reflected light and the backscattered light extracted via the second optical directional coupler, , A heterodyne receiver for combining with the light waves output from the remaining output ports of the optical directional coupler for heterodyne detection, 7) a spectrum analyzer for frequency-analyzing the electric signal from the heterodyne receiver, and )
A signal processing system for averaging the measured values of the spectrum analyzer and 9) a synchronous control system for synchronously controlling the resonance line of the optical filter according to the optical frequency to constitute a measuring system, and the high-speed external By sweeping the frequency of the light linearly with time by the modulator, it became possible to measure the intensity distribution of the reflected light and the backscattered light from the optical fiber to be measured with high distance resolution.
【０００８】[0008]
【作用】基本的な構成を図１に示す。極めてコヒーレン
トな光を発生するレーザー光源１により生じた光は、高
速外部変調器２により振幅、もしくは位相変調を受け、
その光周波数は時間に対して繰り返し直線掃引される。
変調時に生じた０次変調成分及び高次変調成分は、鋭い
共振ピークを有する光フィルター３により除去され、１
次変調成分だけが取り出される。The basic structure is shown in FIG. The light generated by the laser light source 1 that generates extremely coherent light undergoes amplitude or phase modulation by the high-speed external modulator 2,
The optical frequency is repeatedly swept linearly with respect to time.
The 0th-order modulation component and the higher-order modulation component generated at the time of modulation are removed by the optical filter 3 having a sharp resonance peak, and 1
Only the next modulation component is extracted.
【０００９】次に、光フィルターを透過した１次変調光
成分は、第１の光方向性結合器４により、信号光と参照
光とに分波され、信号光は第２の光方向性結合器５を介
して被測定光ファイバー１００に導かれる。被測定光フ
ァイバー１００からの反射または後方散乱光は、第２の
光方向性結合器を介して取り出され、第１の光方向性結
合器で分波された参照光と合波され、ヘテロダイン受信
器６によりヘテロダイン検波される。ヘテロダイン受信
器の出力信号はスペクトラムアナライザー７により周波
数解析され、更に信号処理装置８により加算平均化され
る。９は高速外部変調器と光フィルターとを同期制御す
るための同期制御系であり、光フィルターの共振線が１
次変調光の光周波数に追従するように制御する。Next, the primary modulated light component transmitted through the optical filter is demultiplexed into a signal light and a reference light by the first optical directional coupler 4, and the signal light is second optical directional coupling. It is guided to the optical fiber 100 to be measured via the device 5. The reflected or backscattered light from the optical fiber 100 to be measured is taken out through the second optical directional coupler, combined with the reference light demultiplexed by the first optical directional coupler, and the heterodyne receiver. 6 for heterodyne detection. The output signal of the heterodyne receiver is frequency-analyzed by the spectrum analyzer 7 and further averaged by the signal processor 8. Reference numeral 9 is a synchronous control system for synchronously controlling the high-speed external modulator and the optical filter, and the resonance line of the optical filter is 1
The control is performed so as to follow the optical frequency of the next modulated light.
【００１０】このようにして、可干渉距離の長いコヒー
レント光の周波数を極めて正確に線形掃引し、且つ他の
０次及び高次変調成分を除去することが可能になるた
め、高距離分解能、及び広い測定範囲を有する光周波数
領域反射測定装置を構成することができる。In this way, the frequency of the coherent light having a long coherence length can be swept extremely accurately and the other 0th-order and higher-order modulation components can be removed. An optical frequency domain reflectometry device having a wide measurement range can be constructed.
【００１１】[0011]
【実施例】図１は、本発明の実施例の構成を示す図であ
る。１は極めてコヒーレントな光を発生するレーザー光
源（例えばＹＡＧレーザー）であり、その可干渉距離は
１０数ｋｍ程度であるとする。２は、レーザー光源１か
ら生じた光の振幅もしくは位相に変調をかけ周波数変調
するための高速外部変調器（具体的にはＬｉＮｂＯ 3 変
調素子等）であり、光周波数は一定値Ｆ［Ｈｚ］を基準
変調周波数として、時間Ｔの間に、Ｆ＋Δｆ［Ｈｚ］ま
で時間に対して直線掃引される。図２に、周波数変調の
様子を図示する。ここで周波数掃引速度はΔｆ／Ｔで表
される。FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.
It 1 is a laser beam that generates extremely coherent light
Source (eg YAG laser) and its coherence length is
It is assumed that the distance is about 10 km. 2 is the laser light source 1
Frequency modulation by modulating the amplitude or phase of the generated light
High-speed external modulator (specifically LiNbO 3Strange
The optical frequency is a constant value F [Hz] as a reference.
As the modulation frequency, during time T, F + Δf [Hz] or
Is swept linearly with time. Figure 2 shows the frequency modulation
The situation is illustrated. Here, the frequency sweep speed is expressed as Δf / T.
To be done.
【００１２】３は鋭い共振ピークを有する光フィルター
（具体的にはファブリーペロー干渉計）であり、変調時
に生じた０次変調成分及び高次変調成分を除去し、１次
変調成分だけを取り出す。ここでファブリーペロー干渉
計の共振線Ｒの位置は１次変調成分の変調周波数に追随
して同期掃引される。図３にこの模様を示した。同図で
Ｇ（−１），Ｇ（０），Ｇ（＋１）はそれぞれ、−１次
光、０次光、１次光を示す。このような外部制御且つ高
速制御可能なファブリーペロー干渉計の具体例として
は、ＬｉＮｂＯ3 素子を用いたものがあり、ミリ秒以下
で１０数ＧＨｚの共振線のシフトが可能である。更に、
図４に示すように、共振線のシフトに伴う、０次または
高次変調成分のクロストークを避けるために、共振線間
隔が異なる複数の高速制御可能なファブリーペロー干渉
計を重ね合わせて使用する。同図でＫ（１）及びＫ
（２）はそれぞれ第１及び第２のファブリーペロー干渉
計の透過特性を示し、Ｆ（１）は１次光変調周波数を示
す。このようにして、可干渉距離の長いコヒーレント光
の周波数を極めて正確に線形掃引し、且つ他の０次及び
高次変調成分を除去することが可能になる。これはＣ−
ＯＦＤＲにおける理想周波数掃引光である。Reference numeral 3 is an optical filter having a sharp resonance peak (specifically, a Fabry-Perot interferometer), which removes the 0th-order modulation component and the higher-order modulation component generated at the time of modulation and extracts only the 1st-order modulation component. Here, the position of the resonance line R of the Fabry-Perot interferometer is synchronously swept following the modulation frequency of the primary modulation component. This pattern is shown in FIG. In the figure, G (-1), G (0), and G (+1) represent -1st order light, 0th order light, and 1st order light, respectively. A specific example of such a Fabry-Perot interferometer capable of external control and high-speed control is one using a LiNbO 3 element, which can shift the resonance line of 10's GHz in milliseconds or less. Furthermore,
As shown in FIG. 4, in order to avoid crosstalk of 0th-order or higher-order modulation components due to the shift of the resonance line, a plurality of high-speed controllable Fabry-Perot interferometers having different resonance line intervals are used in combination. . In the figure, K (1) and K
(2) shows the transmission characteristics of the first and second Fabry-Perot interferometers, respectively, and F (1) shows the primary optical modulation frequency. In this way, the frequency of the coherent light having a long coherence length can be extremely accurately linearly swept, and other 0th-order and higher-order modulation components can be removed. This is C-
It is an ideal frequency sweep light in OFDR.
【００１３】４は第１の光方向性結合器であり、ファブ
リーペロー干渉計を透過した光を信号光と参照光とに分
波する。信号光は第２の光方向性結合器５を介して被測
定光ファイバー１００に導かれ、被測定光ファイバー１
００からの反射または後方散乱光は、第２の光方向性結
合器を介して取り出され、第１の光方向性結合器で分波
された参照光と合波され、ヘテロダイン受信器６により
ヘテロダイン検波される。ヘテロダイン受信器６の出力
信号はスペクトラムアナライザー７により周波数解析さ
れ、更に信号処理装置８により加算平均化される。９は
高速外部変調器とファブリーペロー干渉計とを同期制御
するための同期制御系であり、ファブリーペロー干渉計
の共振線が、１次変調光の光周波数に追従するように制
御する。Reference numeral 4 is a first optical directional coupler, which splits the light transmitted through the Fabry-Perot interferometer into a signal light and a reference light. The signal light is guided to the optical fiber under measurement 100 via the second optical directional coupler 5, and the optical fiber under measurement 1 is measured.
The reflected or backscattered light from 00 is extracted via the second optical directional coupler, is combined with the reference light demultiplexed by the first optical directional coupler, and is heterodyne by the heterodyne receiver 6. Is detected. The output signal of the heterodyne receiver 6 is frequency-analyzed by the spectrum analyzer 7 and further averaged by the signal processor 8. Reference numeral 9 is a synchronous control system for synchronously controlling the high-speed external modulator and the Fabry-Perot interferometer, and controls so that the resonance line of the Fabry-Perot interferometer follows the optical frequency of the primary modulated light.
【００１４】ここで周波数掃引時間Ｔ＝１０ｍｓ、周波
数掃引範囲ｆ＝１０ＧＨｚ、基準変調周波数１５ＧＨｚ
とすると、共振線間隔が〜１０ＧＨｚと、〜１５ＧＨｚ
の二つの異なるファブリーペロー干渉計を組み合わせて
用いることにより０次及び高次変調成分の低減、除去が
可能になる。更に周波数掃引速度は１ＴＨｚ／秒であ
り、距離１ｍに対する割り当て周波数は５ｋＨｚとな
り、Ｃ−ＯＦＤＲとしては充分である。また周波数掃引
周期に起因する周期振幅変調成分の周波数も〜１００Ｈ
ｚ程度であり、割り当て周波数は５ｋＨｚに対して充分
小さな値である。Here, frequency sweep time T = 10 ms, frequency sweep range f = 10 GHz, reference modulation frequency 15 GHz
Then, the resonance line spacing is -10 GHz and -15 GHz.
By using two different Fabry-Perot interferometers in combination, it is possible to reduce and remove the 0th-order and higher-order modulation components. Furthermore, the frequency sweep speed is 1 THz / sec, and the assigned frequency for a distance of 1 m is 5 kHz, which is sufficient for C-OFDR. The frequency of the periodic amplitude modulation component caused by the frequency sweep period is also up to 100H.
z, and the assigned frequency is a sufficiently small value for 5 kHz.
【００１５】以上、実施例に述べた構成、パラメータ設
定に基づいて、高距離分解能、広い測定範囲を有する光
周波数領域反射測定装置を構成することができる。As described above, an optical frequency domain reflectometry device having a high distance resolution and a wide measurement range can be constructed based on the configuration and parameter setting described in the embodiments.
【００１６】[0016]
【発明の効果】以上説明したように、本発明における光
周波数領域反射測定装置は、高距離分解能と、極めて広
い測定可能距離を同時に実現することが可能であるとい
う点で従来の方法とは全く異なる新規高性能な測定装置
であり、実用に供して極めて優れた効果を奏するもので
ある。As described above, the optical frequency domain reflectometry apparatus according to the present invention is completely different from the conventional method in that it can realize a high distance resolution and an extremely wide measurable distance at the same time. It is a different new high-performance measuring device, and has an extremely excellent effect in practical use.
【図１】本発明における光周波数領域反射測定装置の実
施例を示す図である。FIG. 1 is a diagram showing an embodiment of an optical frequency domain reflectometry device according to the present invention.
【図２】高速外部変調器による変調周波数掃引を説明す
る図である。FIG. 2 is a diagram illustrating modulation frequency sweeping by a high-speed external modulator.
【図３】ファブリーペロー干渉計による１次変調成分の
取り出しを説明する図である。FIG. 3 is a diagram illustrating extraction of a primary modulation component by a Fabry-Perot interferometer.
【図４】ファブリーペロー干渉計の重ね合わせによる１
次変調成分の取り出しと、０次変調成分、高次変調成分
の除去を説明する図である。[Fig. 4] 1 by superposition of Fabry-Perot interferometers
It is a figure explaining extraction of a secondary modulation component, and removal of a zero-order modulation component and a high-order modulation component.
【図５】従来のＣ−ＯＦＤＲの概念図である。FIG. 5 is a conceptual diagram of a conventional C-OFDR.
【図６】ａは周波数掃引波形を示す図、ｂは測定波形を
示す図である。6A is a diagram showing a frequency sweep waveform, and FIG. 6B is a diagram showing a measurement waveform.
１ レーザー光源 ２ 高速外部変調器 ３ ファブリーペロー干渉計 ４ 第１の光方向性結合器 ５ 第２の光方向性結合器 ６ ヘテロダイン受信器 ７ スペクトラムアナライザー ８ 信号処理系 ９ 同期制御系 1 laser light source 2 high-speed external modulator 3 Fabry-Perot interferometer 4 first optical directional coupler 5 second optical directional coupler 6 heterodyne receiver 7 spectrum analyzer 8 signal processing system 9 synchronization control system
Claims (2)
レーザー光源と、 ２）該光源より生じた光の強度もしくは位相に周波数変
調をかけるための高速外部変調器と、 ３）該高速外部速変調器からの出力光の周波数変調成分
の中から、０次光及び高次変調成分を除去し、１次変調
成分のみを取り出すための光フィルターと、 ４）該光フィルターからの出力光を２波に分波するため
の第１の光方向性結合器と、 ５）該第１の光方向性結合器の片方の出力光を被測定光
ファイバーに導き、且つ該被測定光ファイバーからの反
射もしくは後方散乱光を取り出すための第２の光方向性
結合器と、 ６）該第２の光方向性結合器を介して取り出された反射
光及び後方散乱光を、前記第１の光方向性結合器の残り
の出力ポートより出力される光波と合波しヘテロダイン
検波するための平衡型ヘテロダイン受信器と、 ７）該平衡型ヘテロダイン受信器からの電気信号を周波
数解析するためのスペクトラムアナライザーと、 ８）該スペクトラムアナライザーの測定値を加算平均化
するための信号処理系と、 ９）ファブリーペロー干渉計の共振線を光周波数に合わ
せて同期制御するための同期制御系とから構成され、 前記高速外部変調器により光の周波数を時間に対して直
線的に掃引するように構成したことを特徴とする光周波
数領域反射測定装置。1. A laser light source for generating extremely coherent light, 2) a high-speed external modulator for frequency-modulating the intensity or phase of light generated by the light source, and 3) the high-speed external speed modulation. An optical filter for removing the 0th-order light and higher-order modulation components from the frequency-modulated component of the output light from the optical device and extracting only the 1st-order modulation component; 4) 2 waves of output light from the optical filter A first optical directional coupler for demultiplexing the optical fiber into light, and 5) guiding the output light from one of the first optical directional couplers to the optical fiber to be measured, and reflecting or backscattering from the optical fiber to be measured. A second optical directional coupler for extracting light, and 6) the reflected light and the backscattered light extracted through the second optical directional coupler of the first optical directional coupler. Combined with the light waves output from the remaining output ports Balanced heterodyne receiver for telodyne detection, 7) Spectrum analyzer for frequency analysis of electric signals from the balanced heterodyne receiver, and 8) Signal for averaging the measured values of the spectrum analyzer. It is composed of a processing system and 9) a synchronous control system for synchronously controlling the resonance line of the Fabry-Perot interferometer according to the optical frequency, and sweeps the optical frequency linearly with time by the high-speed external modulator. An optical frequency domain reflectometry device characterized by being configured as follows.
置において、前記光フィルターが複数の光フィルターを
組み合わせて構成されたことを特徴とする光周波数領域
反射測定装置。2. The optical frequency domain reflectometry device according to claim 1, wherein the optical filter is configured by combining a plurality of optical filters.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30931193A JP3306815B2 (en) | 1993-12-09 | 1993-12-09 | Optical frequency domain reflectometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30931193A JP3306815B2 (en) | 1993-12-09 | 1993-12-09 | Optical frequency domain reflectometer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07159281A true JPH07159281A (en) | 1995-06-23 |
| JP3306815B2 JP3306815B2 (en) | 2002-07-24 |
Family
ID=17991491
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30931193A Expired - Fee Related JP3306815B2 (en) | 1993-12-09 | 1993-12-09 | Optical frequency domain reflectometer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3306815B2 (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0754939A1 (en) * | 1995-02-02 | 1997-01-22 | Yokogawa Electric Corporation | Optical fibre detecting device |
| KR100406862B1 (en) * | 1996-07-30 | 2004-01-24 | 삼성전자주식회사 | Apparatus and method for measuring reflectivity of optical fiber reflector |
| KR100691871B1 (en) * | 2005-03-25 | 2007-03-12 | 광주과학기술원 | Apparatus and Method for Compensation of the Nonlinearity of an OFDR system |
| JP2008089515A (en) * | 2006-10-04 | 2008-04-17 | Nippon Telegr & Teleph Corp <Ntt> | Optical frequency domain reflection measuring method and device |
| JP2009014456A (en) * | 2007-07-03 | 2009-01-22 | Nippon Telegr & Teleph Corp <Ntt> | Method and device for measuring optical reflectance distribution |
| JP2011158330A (en) * | 2010-01-29 | 2011-08-18 | Nippon Telegr & Teleph Corp <Ntt> | Apparatus and method for measurement of optical path |
| JP2016109624A (en) * | 2014-12-09 | 2016-06-20 | 日本電信電話株式会社 | Light reflection measurement device and light reflection measurement method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62230073A (en) * | 1986-03-31 | 1987-10-08 | Yokogawa Electric Corp | Variable wavelength light source |
| JPH04248434A (en) * | 1991-02-04 | 1992-09-03 | Nippon Telegr & Teleph Corp <Ntt> | Remote tester of optical line |
| JPH05118954A (en) * | 1991-10-25 | 1993-05-14 | Nippon Telegr & Teleph Corp <Ntt> | Device for measuring reflection in optical frequency area |
| JPH05322699A (en) * | 1992-05-25 | 1993-12-07 | Nippon Telegr & Teleph Corp <Ntt> | High distance-resolution optical transmission line measuring device |
-
1993
- 1993-12-09 JP JP30931193A patent/JP3306815B2/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62230073A (en) * | 1986-03-31 | 1987-10-08 | Yokogawa Electric Corp | Variable wavelength light source |
| JPH04248434A (en) * | 1991-02-04 | 1992-09-03 | Nippon Telegr & Teleph Corp <Ntt> | Remote tester of optical line |
| JPH05118954A (en) * | 1991-10-25 | 1993-05-14 | Nippon Telegr & Teleph Corp <Ntt> | Device for measuring reflection in optical frequency area |
| JPH05322699A (en) * | 1992-05-25 | 1993-12-07 | Nippon Telegr & Teleph Corp <Ntt> | High distance-resolution optical transmission line measuring device |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0754939A1 (en) * | 1995-02-02 | 1997-01-22 | Yokogawa Electric Corporation | Optical fibre detecting device |
| EP0754939A4 (en) * | 1995-02-02 | 1999-01-27 | Yokogawa Electric Corp | Optical fibre detecting device |
| KR100406862B1 (en) * | 1996-07-30 | 2004-01-24 | 삼성전자주식회사 | Apparatus and method for measuring reflectivity of optical fiber reflector |
| KR100691871B1 (en) * | 2005-03-25 | 2007-03-12 | 광주과학기술원 | Apparatus and Method for Compensation of the Nonlinearity of an OFDR system |
| JP2008089515A (en) * | 2006-10-04 | 2008-04-17 | Nippon Telegr & Teleph Corp <Ntt> | Optical frequency domain reflection measuring method and device |
| JP2009014456A (en) * | 2007-07-03 | 2009-01-22 | Nippon Telegr & Teleph Corp <Ntt> | Method and device for measuring optical reflectance distribution |
| JP2011158330A (en) * | 2010-01-29 | 2011-08-18 | Nippon Telegr & Teleph Corp <Ntt> | Apparatus and method for measurement of optical path |
| JP2016109624A (en) * | 2014-12-09 | 2016-06-20 | 日本電信電話株式会社 | Light reflection measurement device and light reflection measurement method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3306815B2 (en) | 2002-07-24 |
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