JPH05203410A - Method and device for measuring reflecting point in optical frequency domain - Google Patents
Method and device for measuring reflecting point in optical frequency domainInfo
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- JPH05203410A JPH05203410A JP1216692A JP1216692A JPH05203410A JP H05203410 A JPH05203410 A JP H05203410A JP 1216692 A JP1216692 A JP 1216692A JP 1216692 A JP1216692 A JP 1216692A JP H05203410 A JPH05203410 A JP H05203410A
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- beat signal
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、光ファイバや光導波路
内での反射点分布をその発振周波数が時間的に変化する
レーザ光を用いて高空間分解能で測定する方法及び装置
（ＯＦＤＲと呼ぶ）に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus (OFDR) for measuring the distribution of reflection points in an optical fiber or an optical waveguide with high spatial resolution by using laser light whose oscillation frequency changes with time. ).
【０００２】[0002]
【従来の技術】図５は従来の技術を示す図であって、１
は周波数が時間的に変化する光を出射するレーザ、２は
ファイバカプラ、３は反射鏡、４は被測定導波路、５は
光検出器、６はスペクトラムアナライザである。レーザ
１からの出射光はカプラ２により２分される。一方は反
射鏡３で全反射されて一定時間遅延した参照光となり、
他方は被測定導波路４内を伝搬する。導波路４内に存在
する屈折率の揺らぎや導波路−空気間のフレネル反射に
よって生じた後方反射光は、ファイバカプラ２により参
照光と合波される。ビート信号Ｓ（ｔ）は実時間により
サンプリングされた場合（実時間クロックを使用した場
合）、時刻ｔにおけるサンプル値は次式で与えられる。2. Description of the Related Art FIG. 5 is a diagram showing a conventional technique.
Is a laser that emits light whose frequency changes with time, 2 is a fiber coupler, 3 is a reflecting mirror, 4 is a waveguide to be measured, 5 is a photodetector, and 6 is a spectrum analyzer. The emitted light from the laser 1 is split into two by the coupler 2. One of them becomes a reference light which is totally reflected by the reflecting mirror 3 and delayed for a certain time,
The other propagates in the measured waveguide 4. The back-reflected light generated by the fluctuation of the refractive index existing in the waveguide 4 and the Fresnel reflection between the waveguide and the air is combined with the reference light by the fiber coupler 2. When the beat signal S (t) is sampled in real time (when a real time clock is used), the sample value at time t is given by the following equation.
【０００３】 ここで、ａｋｅｘｐ（ｉεk ）、τk はそれぞれｋ番目
の散乱点によって生じた反射光の複素振幅値、参照光に
対する遅延時間差であり、ν(t) は時間ｔにおける光周
波数である。入射光の発振周波数が時間的に変化してい
るため、後方反射光を発生させた散乱点に応じて参照光
との時間差が異なり、生じるビート周波数が異なる。合
波光の干渉強度Ｓ（ｔ）を光検出器５で受光し、これを
スペクトラムアナライザ６でスペクトル分解すると、図
６に示す様に、被測定導波路４内で発生した後方散乱分
布が測定される。ここで、横軸のビート周波数はファイ
バ各点に対応し、縦軸は後方散乱強度分布に対応する。
発振周波数が時間に対して直線的に変化すれば、後方散
乱光と参照光との遅延時間差と、生じるビート周波数が
一対一に対応するので、周波数掃引幅によって決定され
た最大分解能が実現される。[0003] Here, a k exp (iε k ), τ k are the complex amplitude value of the reflected light generated by the k-th scattering point, the delay time difference with respect to the reference light, and ν (t) is the optical frequency at time t. .. Since the oscillation frequency of the incident light changes with time, the time difference from the reference light differs depending on the scattering point that generated the back-reflected light, and the generated beat frequency also differs. When the interference intensity S (t) of the combined light is received by the photodetector 5 and is spectrally decomposed by the spectrum analyzer 6, the backscattering distribution generated in the measured waveguide 4 is measured as shown in FIG. It Here, the beat frequency on the horizontal axis corresponds to each point of the fiber, and the vertical axis corresponds to the backscattering intensity distribution.
If the oscillation frequency changes linearly with respect to time, the delay time difference between the backscattered light and the reference light and the resulting beat frequency have a one-to-one correspondence, so that the maximum resolution determined by the frequency sweep width is realized. ..
【０００４】[0004]
【発明が解決しようとする課題】しかし実際には発振周
波数は直線的に変化せず、生じるビート周波数と遅延時
間差が一対一に対応せず、実際の空間分解能は最大分解
能に比して劣化するという問題があった。また、発振周
波数を直線的に変化させようとすれば、高精度温度コン
トローラ（半導体レーザ光源の場合）等の制御装置が必
要となり、システム全体のコストアップにつながるとい
う問題があった。However, in reality, the oscillation frequency does not change linearly, the generated beat frequency and the delay time difference do not correspond one-to-one, and the actual spatial resolution deteriorates compared to the maximum resolution. There was a problem. Further, if the oscillation frequency is to be changed linearly, a control device such as a high-accuracy temperature controller (in the case of a semiconductor laser light source) is required, which causes a problem of increasing the cost of the entire system.
【０００５】本発明の目的は、発振周波数が非線形的に
変化する光源を使用した場合でも、その全周波数変化量
によって制限される最大空間分解能が実現されるＯＦＤ
Ｒを提供することにある。An object of the present invention is to realize an OFD that realizes a maximum spatial resolution limited by the total frequency change amount even when a light source whose oscillation frequency changes nonlinearly is used.
To provide R.
【０００６】[0006]
【課題を解決するための手段】本発明は上記目的を達成
するため、請求項１では、光周波数が時間的に掃引する
光源を使用し、該光源出射光を二分し、二分された一方
を参照光、他方を被測定導波路への入射光とし、該参照
光と被測定導波路からの反射光とを干渉せしめ、生じる
干渉強度中のビート信号のスペクトル解析により該測定
導波路中の反射分布を測定する光周波数領域反射点測定
方法において、光源からの出射光の一部または全部を二
分し、二分された一方にまたは他方に対して一定の遅延
時間を与えた後に再び合波することにより光周波数の掃
引と共に新たにビート信号（参照ビート信号と呼ぶ）を
生ぜしめ、該参照ビート信号より光源出射光が一定の周
波数増加ないし減少するごとにサンプリングパルスを発
生せしめ、これを外部クロックとして前記ビート信号を
サンプリングし、該サンプリングデータのフーリエ解析
により該導波路中の反射分布を求める。請求項２では、
光周波数が時間的に掃引する光源を使用し、該光源出射
光を二分し、二分された一方を参照光、他方を被測定導
波路への入射光とし、該参照光と被測定導波路からの反
射光とを干渉せしめ、生じる干渉強度中のビート信号の
スペクトル解析により該測定導波路中の反射分布を測定
する光周波数領域反射点測定装置において、光源からの
出射光の一部または全部を二分し、二分された一方にま
たは他方に対して一定の遅延時間を与えた後に再び合波
することにより光周波数の掃引と共に新たにビート信号
（参照ビート信号と呼ぶ）を生ぜしめる手段と、該参照
ビート信号より光源出射光が一定の周波数増加ないし減
少するごとにサンプリングパルスを発生せしめる手段
と、これを外部クロックとして前記ビート信号をサンプ
リングし、該サンプリングデータのフーリエ解析により
該導波路中の反射分布を求める手段とを有する。請求項
３では、請求項１において、外部クロックの発生装置と
して、アーム長の異なるファイバ型のマッハ・ツェンダ
干渉計を用いる。請求項４では、請求項１において、外
部クロックの発生装置として、前記光源からの出射光を
二分する光学部分と被測定導波路を結ぶ光学経路上に伝
搬光の一部を反射する部分を設置し、該反射光と前記参
照光とのビート信号を参照ビート信号とする。In order to achieve the above object, the present invention uses, in claim 1, a light source whose optical frequency is swept with time, divides the light emitted from the light source into two, and divides one of the divided light into two. The reference light and the other is the incident light to the measured waveguide, the reference light and the reflected light from the measured waveguide are caused to interfere with each other, and the reflection in the measured waveguide is performed by spectrum analysis of the beat signal in the generated interference intensity. In the optical frequency domain reflection point measuring method for measuring the distribution, dividing part or all of the light emitted from the light source into two parts, giving a certain delay time to one or the other of the two parts, and then combining them again. Causes a new beat signal (referred to as a reference beat signal) to be generated together with the sweeping of the optical frequency, and a sampling pulse is generated every time the light emitted from the light source increases or decreases by a certain frequency from the reference beat signal. The beat signal is sampled as part clock, obtaining the reflection distribution in the waveguide by a Fourier analysis of the sampled data. In claim 2,
A light source whose optical frequency is swept in time is used, and the light emitted from the light source is divided into two parts, one of the two divided parts is used as a reference light, and the other part is used as an incident light to the waveguide to be measured. In the optical frequency domain reflection point measuring device for measuring the reflection distribution in the measurement waveguide by interfering with the reflected light of, and analyzing the spectrum of the beat signal in the generated interference intensity, a part or all of the light emitted from the light source is measured. A means for generating a new beat signal (referred to as a reference beat signal) together with sweeping of the optical frequency by halving the light frequency and then again multiplexing after giving a constant delay time to one of the two halves or to the other; Means for generating a sampling pulse each time the light emitted from the light source increases or decreases by a certain frequency from the reference beat signal, and the beat signal is sampled by using this as an external clock, And means for determining the reflection distribution in the waveguide by a Fourier analysis of the ring data. According to a third aspect, in the first aspect, a fiber type Mach-Zehnder interferometer having different arm lengths is used as the external clock generator. According to a fourth aspect of the present invention, in the first aspect, as the external clock generator, a portion that reflects a part of the propagating light is provided on an optical path that connects the optical portion that divides the light emitted from the light source and the waveguide to be measured. Then, the beat signal of the reflected light and the reference light is used as a reference beat signal.
【０００７】[0007]
【作用】光周波数が時間的に掃引する光源を使用し、光
源からの出射光の一部または全部を二分し、二分された
一方にまたは他方に対して一定の遅延時間を与えた後に
再び合波することにより光周波数の掃引と共に新たにビ
ート信号（参照ビート信号と呼ぶ）を生ぜしめ、該参照
ビート信号より光源出射光が一定の周波数増加ないし減
少するごとにサンプリングパルスを発生せしめ、これを
外部クロックとして参照光と反射光によって生じるビー
ト信号をサンプリングし、該サンプリングデータのフー
リエ解析により該導波路中の反射分布を求める。By using a light source whose optical frequency is swept in time, a part or all of the light emitted from the light source is divided into two parts, and a constant delay time is given to one of the two parts or the other part, and then they are combined again. By waving, a beat signal (referred to as a reference beat signal) is newly generated together with the sweep of the optical frequency, and a sampling pulse is generated each time the light emitted from the light source increases or decreases by a certain frequency from the reference beat signal. The beat signal generated by the reference light and the reflected light is sampled as an external clock, and the reflection distribution in the waveguide is obtained by Fourier analysis of the sampling data.
【０００８】[0008]
【実施例】図１は、本発明の第１の実施例であって、１
は周波数が時間的に変化する光を出射するレーザ、２は
ファイバカプラ、３は反射鏡、４は被測定導波路、５は
光検出器、７は０．４ＧＨｚ毎にＴＴＬレベルのパルス
を発生させるクロックパルス発生装置、８は波形デジタ
イザー／フーリエ変換器である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the first embodiment of the present invention.
Is a laser that emits light whose frequency changes with time, 2 is a fiber coupler, 3 is a reflecting mirror, 4 is a waveguide to be measured, 5 is a photodetector, and 7 is a pulse of TTL level every 0.4 GHz. The clock pulse generator 8 is a waveform digitizer / Fourier transformer.
【０００９】これを動作させるには、クロックパルス発
生装置７からのパルスに同期して波形デジタイザー８に
入力するビート信号をサンプリングしこれをフーリエ変
換する。周波数νi において、サンプリングされたビー
ト信号Ｓ（ｔ）のサンプル値Ｓi は(1) 式より となる。(2) 式より、サンプリングデータ｛Ｓi ｝（ｊ
＝１，２，，，Ｎ）と後方散乱振幅値｛ ak exp(i
εk ) ｝（ｋ＝１，２，，，Ｎ）は複素フーリエ変換に
よって一対一に対応するため、本方式における空間分解
能は周波数掃引幅で決定される最大空間分解能となる。To operate this, the beat signal input to the waveform digitizer 8 in synchronization with the pulse from the clock pulse generator 7 is sampled and Fourier-transformed. At the frequency ν i , the sampled value S i of the sampled beat signal S (t) is Becomes From equation (2), sampling data {Si} (j
= 1,2 ,,, N) and the backscattering amplitude value { ak exp (i
Since ε k )} (k = 1, 2, ..., N) corresponds one-to-one by the complex Fourier transform, the spatial resolution in this method is the maximum spatial resolution determined by the frequency sweep width.
【００１０】図２は被測定物として厚さ１ｍｍのガラス
板の両面からの反射光を本発明の実施例（図１）と従来
の実施例（図５）で測定したときの比較を示す。横軸は
反射光と参照光との光路長差を示し、散乱点の相対位置
はこれを２ｎ（ｎは屈折率）で割った値となる。光源に
１．５５μｍの半導体レーザを用いその発振周波数を４
００ＧＨｚ連続変化させた。本方式を用いると、両面か
らの反射光がはっきりと分解されたのに対し、従来方式
では分解できなかった。本方式の分解能は、ピーク波形
の半値６９０μｍを２ｎで割った２４０μｍとなり、全
発振周波数変位４００ＧＨｚからの予想値２６０μｍと
ほぼ一致し、最大分解能が実現されたことが確認され
た。FIG. 2 shows a comparison between the light reflected from both sides of a glass plate having a thickness of 1 mm as an object to be measured in the embodiment of the present invention (FIG. 1) and the conventional embodiment (FIG. 5). The horizontal axis represents the optical path length difference between the reflected light and the reference light, and the relative position of the scattering point is a value obtained by dividing this by 2n (n is the refractive index). A 1.55 μm semiconductor laser is used as the light source and its oscillation frequency is set to 4
It was continuously changed at 00 GHz. Using this method, the reflected light from both sides was clearly decomposed, but it could not be decomposed by the conventional method. The resolution of this system was 240 μm obtained by dividing the peak waveform half-value of 690 μm by 2n, which was almost the same as the expected value 260 μm from the total oscillation frequency displacement of 400 GHz, and it was confirmed that the maximum resolution was achieved.
【００１１】図３は本実施例で使用したクロックパルス
発生装置を示す。系は、本装置はファイバ型のマッハ・
ツェンダ干渉計９と光検出器１０、パルス発生回路１１
で構成される。干渉計９では、一方のアームが２４ｃｍ
長い為、周波数の変化する光がこの干渉計９内を伝搬す
ると、出射ビート信号は(1) 式より Ｓ（ｔ）＝Ｓ0 COS[２πν（ｔ）τ0 ］ (3) となる。ここで、τ0 は両アーム間の遅延時間差であ
り、τ0 ＝１．１nsecである。(3) 式より、ビート信号
は周波数の変化とともに１／τ0 ＝０．４ＧＨｚの周期
で変化する。そこで、パルス発生回路１１は、ビート信
号Ｓ（ｔ）がゼロクロスする時にＴＴＬレベルのパルス
発生する。このような構成であるため、本装置により
０．４２４ＧＨｚサンプリング用のクロックパルスが得
られる。FIG. 3 shows the clock pulse generator used in this embodiment. This system is a fiber type Mach
Zehnder interferometer 9, photodetector 10, pulse generation circuit 11
Composed of. In the interferometer 9, one arm is 24 cm
Since the light having a long frequency propagates in the interferometer 9, the output beat signal is S (t) = S 0 COS [2πν (t) τ 0 ] (3) according to the equation (1). Here, τ 0 is the delay time difference between both arms, and τ 0 = 1.1 nsec. From the equation (3), the beat signal changes with a change in frequency at a cycle of 1 / τ 0 = 0.4 GHz. Therefore, the pulse generation circuit 11 generates a TTL level pulse when the beat signal S (t) crosses zero. Due to such a configuration, this apparatus can obtain a clock pulse for 0.424 GHz sampling.
【００１２】図４は本発明の第２の実施例であって、第
１の実施例との違いは、ファイバアーム内の一点に反射
発生器１２（具体的には、コネクタによるファイバ接続
部）を設け、反射発生器１２で生じた反射光と参照光と
のビート信号をクロックパルス発生用のための入力とし
たものである。すなわち、第１の実施例では、マッハ・
ツェンダ干渉計とＯＦＤＲ本体が別々であったのに対
し、第２の実施例では、両者が一体となっている。本装
置では、クロックパルス発生用のビート信号と被測定物
からの反射光で生じたビート信号を分離するための電気
的フィルターと、サンプリング定理を満足するためにク
ロクパルス発生用ビート信号をてい倍する回路が不可欠
である。FIG. 4 shows a second embodiment of the present invention. The difference from the first embodiment is that a reflection generator 12 (specifically, a fiber connecting portion by a connector) is provided at one point in the fiber arm. Is provided, and the beat signal of the reflected light generated by the reflection generator 12 and the reference light is used as an input for clock pulse generation. That is, in the first embodiment, Mach
While the Zender interferometer and the OFDR main body are separate, in the second embodiment, both are integrated. In this device, the beat signal for clock pulse generation and the beat signal for separating the beat signal generated by the reflected light from the DUT are separated, and the beat signal for clock pulse generation is doubled to satisfy the sampling theorem. Circuits are essential.
【００１３】本実施例では、参照ビート信号のゼロクロ
スの点からのサンプリング用のクロックパルスを発生さ
せたため、周波数の増減方向が識別できないという欠点
がある。しかし、下記参考文献１に示したように、マッ
ハ・ツェンダ干渉計のファイバアームの一方に位相変調
を印加しビート信号中の変調周波数ｆに対する基本成分
（周波数ｆ）と第２高調波成分（２ｆ）の振幅を検波す
ると、それぞれ Ｓf （ｔ）＝ａ0 sin ［２πν(t) τ］， (4) Ｓf （ｔ）＝ａ0 cos ［２πν(t) τ］， (5) となることから、ロータリーエンコーダ等で使われてい
るアップ／ダウン弁別器により周波数の増減方向が識別
できる。このため、周波数がジグザグに変化した場合で
も、一定周波数間隔のサンプリングが可能となる。ま
た、両アーム内を伝搬する光の位相を調整し、一方のア
ームを伝搬した光の出射光を直線偏光、他方を円偏光と
し、合波光を偏光ビームスプリッタで分岐しても(4) −
(5) と同様な信号が得られる（参考文献２）。In this embodiment, since the clock pulse for sampling is generated from the zero-cross point of the reference beat signal, there is a drawback that the increasing / decreasing direction of the frequency cannot be identified. However, as shown in Reference Document 1 below, phase modulation is applied to one of the fiber arms of the Mach-Zehnder interferometer, and the fundamental component (frequency f) and the second harmonic component (2f) with respect to the modulation frequency f in the beat signal are applied. ), S f (t) = a 0 sin [2πν (t) τ], (4) S f (t) = a 0 cos [2πν (t) τ], (5) Therefore, the increasing / decreasing direction of the frequency can be identified by the up / down discriminator used in the rotary encoder or the like. Therefore, even if the frequency changes zigzag, sampling can be performed at constant frequency intervals. In addition, the phase of the light propagating in both arms is adjusted, the outgoing light of the light propagating in one arm is linearly polarized, the other is circularly polarized, and the combined light is split by a polarization beam splitter (4)-
The same signal as in (5) is obtained (reference 2).
【００１４】参考文献１：K. Takada, M. Kobayashi, a
nd J. Noda, "Fiber-optic Fourier transform spectro
meter with a coherent interferogram averaging sche
me," Appl. Opt., 29, pp. 5170-5176, 1990. 参考文献２：S. K. Sheem, T. G. Giallorenzi, and K.
Koo, "Optical technique to solve the signal fadin
g problem in fiber interferometers, "Appl. Opt., 2
1, pp. 689-693. 1982.Reference 1: K. Takada, M. Kobayashi, a
nd J. Noda, "Fiber-optic Fourier transform spectro
meter with a coherent interferogram averaging sche
me, "Appl. Opt., 29, pp. 5170-5176, 1990. Reference 2: SK Sheem, TG Giallorenzi, and K.
Koo, "Optical technique to solve the signal fadin
g problem in fiber interferometers, "Appl. Opt., 2
1, pp. 689-693. 1982.
【００１５】[0015]
【発明の効果】以上説明した如く、請求項１の発明によ
れば、発振周波数の掃引を精密に制御する回路を使用す
ることなく高空間分解能ＯＦＤＲが実現できることか
ら、光ファイバコネクタ、光アイソレータ等のバックリ
フレクションが重要となる光部品の反射率分布測定装置
を低価格で供給できるという効果がある。また請求項２
乃至４の発明によれば、請求項１による方法を適確に実
現できる。As described above, according to the first aspect of the invention, the high spatial resolution OFDR can be realized without using a circuit for precisely controlling the sweep of the oscillation frequency. Therefore, an optical fiber connector, an optical isolator, etc. There is an effect that it is possible to supply a reflectance distribution measuring device for optical parts, in which back reflection is important, at a low price. Claim 2
According to the inventions of to 4, it is possible to accurately realize the method according to claim 1.
【図１】本発明の第１の実施例を示す構成図FIG. 1 is a configuration diagram showing a first embodiment of the present invention.
【図２】同一のサンプルに対して、本実施例と従来の装
置で得られた反射分布の比較図FIG. 2 is a comparison diagram of reflection distributions obtained by the present embodiment and a conventional device for the same sample.
【図３】本発明の実施例で使用したクロックパルス発生
装置の構成図FIG. 3 is a configuration diagram of a clock pulse generator used in an embodiment of the present invention.
【図４】本発明の第２の実施例を示す構成図FIG. 4 is a configuration diagram showing a second embodiment of the present invention.
【図５】従来の装置を説明する構成図FIG. 5 is a configuration diagram illustrating a conventional device.
【図６】図５の装置によって得られた被測定導波路内の
反射分布図FIG. 6 is a reflection distribution map inside the measured waveguide obtained by the apparatus of FIG.
１…レーザ、２…ファイバカプラ、３…反射鏡、４…被
測定導波路、５…光検出器、６…スペクトラムアナライ
ザ、７…サンプリングパルス発生回路、８…波形デジタ
イザ／フーリエ変換器、９…ファイバ型マッハ・ツェン
ダ干渉計、１０…光検出器、１１…パルス発生回路、１
２…反射点発生器。1 ... Laser, 2 ... Fiber coupler, 3 ... Reflector, 4 ... Waveguide to be measured, 5 ... Photodetector, 6 ... Spectrum analyzer, 7 ... Sampling pulse generating circuit, 8 ... Waveform digitizer / Fourier converter, 9 ... Fiber type Mach-Zehnder interferometer, 10 ... Photodetector, 11 ... Pulse generation circuit, 1
2 ... Reflection point generator.
Claims (4)
し、該光源出射光を二分し、二分された一方を参照光、
他方を被測定導波路への入射光とし、該参照光と被測定
導波路からの反射光とを干渉せしめ、生じる干渉強度中
のビート信号のスペクトル解析により該測定導波路中の
反射分布を測定する光周波数領域反射点測定方法におい
て、 光源からの出射光の一部または全部を二分し、二分され
た一方にまたは他方に対して一定の遅延時間を与えた後
に再び合波することにより光周波数の掃引と共に新たに
ビート信号（参照ビート信号と呼ぶ）を生ぜしめ、 該参照ビート信号より光源出射光が一定の周波数増加な
いし減少するごとにサンプリングパルスを発生せしめ、 これを外部クロックとして前記ビート信号をサンプリン
グし、 該サンプリングデータのフーリエ解析により該導波路中
の反射分布を求めることを特徴とする光周波数領域反射
点測定方法。1. A light source whose optical frequency is swept in time is used, the light emitted from the light source is divided into two, and one of the two divided light beams is a reference light.
The other is used as incident light to the measured waveguide, the reference light and the reflected light from the measured waveguide are caused to interfere with each other, and the reflection distribution in the measured waveguide is measured by spectrum analysis of the beat signal in the generated interference intensity. In the optical frequency domain reflection point measurement method described above, a part or all of the light emitted from the light source is divided into two parts, and a certain delay time is given to one of the two parts or the other part, and then they are combined again to obtain the optical frequency. A new beat signal (referred to as a reference beat signal) is generated together with the sweep of the reference signal, and a sampling pulse is generated each time the light emitted from the light source increases or decreases by a certain frequency from the reference beat signal, and the beat signal is used as an external clock. Is sampled and the reflection distribution in the waveguide is obtained by Fourier analysis of the sampling data. Law.
し、該光源出射光を二分し、二分された一方を参照光、
他方を被測定導波路への入射光とし、該参照光と被測定
導波路からの反射光とを干渉せしめ、生じる干渉強度中
のビート信号のスペクトル解析により該測定導波路中の
反射分布を測定する光周波数領域反射点測定装置におい
て、 光源からの出射光の一部または全部を二分し、二分され
た一方にまたは他方に対して一定の遅延時間を与えた後
に再び合波することにより光周波数の掃引と共に新たに
ビート信号（参照ビート信号と呼ぶ）を生ぜしめる手段
と、 該参照ビート信号より光源出射光が一定の周波数増加な
いし減少するごとにサンプリングパルスを発生せしめる
手段と、 これを外部クロックとして前記ビート信号をサンプリン
グし、該サンプリングデータのフーリエ解析により該導
波路中の反射分布を求める手段とを有することを特徴と
する光周波数領域反射点測定装置。2. A light source whose optical frequency is swept in time is used, the light emitted from the light source is divided into two, and one of the two divided light beams is a reference light.
The other is used as incident light to the measured waveguide, the reference light and the reflected light from the measured waveguide are caused to interfere with each other, and the reflection distribution in the measured waveguide is measured by spectrum analysis of the beat signal in the generated interference intensity. In the optical frequency domain reflection point measuring device, a part or the whole of the light emitted from the light source is divided into two parts, and a certain delay time is given to one or the other of the two parts, and then they are combined again to obtain the optical frequency. Means for newly generating a beat signal (referred to as a reference beat signal) together with the sweep of, a means for generating a sampling pulse each time the light emitted from the light source increases or decreases by a certain frequency from the reference beat signal, and an external clock As means for sampling the beat signal, and obtaining the reflection distribution in the waveguide by Fourier analysis of the sampling data. Optical frequency domain reflection point measuring apparatus.
の異なるファイバ型のマッハ・ツェンダ干渉計を用いる
ことを特徴とする請求項１記載の光周波数領域反射点測
定装置。3. The optical frequency domain reflection point measuring apparatus according to claim 1, wherein a fiber type Mach-Zehnder interferometer having different arm lengths is used as the external clock generator.
からの出射光を二分する光学部分と被測定導波路を結ぶ
光学経路上に伝搬光の一部を反射する部分を設置し、該
反射光と前記参照光とのビート信号を参照ビート信号と
することを特徴とする請求項１記載の光周波数領域反射
点測定装置。4. As an external clock generator, a portion for reflecting a part of propagating light is provided on an optical path connecting an optical portion for dividing light emitted from the light source and a waveguide to be measured, and the reflected light is provided. The optical frequency domain reflection point measuring device according to claim 1, wherein a beat signal between the reference light and the reference light is used as a reference beat signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1216692A JPH05203410A (en) | 1992-01-27 | 1992-01-27 | Method and device for measuring reflecting point in optical frequency domain |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1216692A JPH05203410A (en) | 1992-01-27 | 1992-01-27 | Method and device for measuring reflecting point in optical frequency domain |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05203410A true JPH05203410A (en) | 1993-08-10 |
Family
ID=11797855
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1216692A Pending JPH05203410A (en) | 1992-01-27 | 1992-01-27 | Method and device for measuring reflecting point in optical frequency domain |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05203410A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0692705A1 (en) * | 1994-07-16 | 1996-01-17 | Felten & Guilleaume Energietechnik AG | Method for evaluating backscattered optical signals for determining a position depending measuring profile of a backscatting medium |
| WO1996024038A1 (en) * | 1995-02-02 | 1996-08-08 | Yokogawa Electric Corporation | Optical fibre detecting device |
| KR100691871B1 (en) * | 2005-03-25 | 2007-03-12 | 광주과학기술원 | Apparatus and Method for Compensation of the Nonlinearity of an OFDR system |
| CN105783763A (en) * | 2016-05-17 | 2016-07-20 | 安徽师范大学 | High precision dynamic optical fiber strain sensing device and sensing method thereof |
| US10718658B2 (en) | 2014-08-07 | 2020-07-21 | Furukawa Electric Co., Ltd. | Optical fiber sensor, seismic prospecting method, method of measuring distribution of petroleum/natural gas reservoir layer, strain detection method, and method of specifying position of a fissure in stratum |
| JP2023067611A (en) * | 2021-11-01 | 2023-05-16 | キヤノントッキ株式会社 | Reflection rate measuring device and film forming device |
-
1992
- 1992-01-27 JP JP1216692A patent/JPH05203410A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0692705A1 (en) * | 1994-07-16 | 1996-01-17 | Felten & Guilleaume Energietechnik AG | Method for evaluating backscattered optical signals for determining a position depending measuring profile of a backscatting medium |
| WO1996024038A1 (en) * | 1995-02-02 | 1996-08-08 | Yokogawa Electric Corporation | Optical fibre detecting device |
| KR100691871B1 (en) * | 2005-03-25 | 2007-03-12 | 광주과학기술원 | Apparatus and Method for Compensation of the Nonlinearity of an OFDR system |
| US10718658B2 (en) | 2014-08-07 | 2020-07-21 | Furukawa Electric Co., Ltd. | Optical fiber sensor, seismic prospecting method, method of measuring distribution of petroleum/natural gas reservoir layer, strain detection method, and method of specifying position of a fissure in stratum |
| CN105783763A (en) * | 2016-05-17 | 2016-07-20 | 安徽师范大学 | High precision dynamic optical fiber strain sensing device and sensing method thereof |
| CN105783763B (en) * | 2016-05-17 | 2018-08-31 | 安徽师范大学 | A kind of Dynamic High-accuracy fiber strain sensing device and its method for sensing |
| JP2023067611A (en) * | 2021-11-01 | 2023-05-16 | キヤノントッキ株式会社 | Reflection rate measuring device and film forming device |
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