JP2552603B2 - Fiber optic gyro - Google Patents
Fiber optic gyroInfo
- Publication number
- JP2552603B2 JP2552603B2 JP4009652A JP965292A JP2552603B2 JP 2552603 B2 JP2552603 B2 JP 2552603B2 JP 4009652 A JP4009652 A JP 4009652A JP 965292 A JP965292 A JP 965292A JP 2552603 B2 JP2552603 B2 JP 2552603B2
- Authority
- JP
- Japan
- Prior art keywords
- optical fiber
- light
- optical
- fiber coil
- depolarizer
- 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.)
- Expired - Fee Related
Links
Description
【０００１】[0001]
【産業上の利用分野】この発明は、光ファイバコイルに
右回り光と左回り光とを伝搬させ、これら右回り光と左
回り光との位相差を検出して光ファイバコイルに印加さ
れるその中心回りの角速度を検出する光ファイバジャイ
ロに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention propagates clockwise light and counterclockwise light through an optical fiber coil, detects the phase difference between the clockwise light and counterclockwise light, and applies the phase difference to the optical fiber coil. The present invention relates to an optical fiber gyro for detecting an angular velocity around the center.
【０００２】[0002]
【従来の技術】図２に従来の光ファイバジャイロを示
す。光源１１からの光は光ファイバカプラなどの光分岐
器１２を通り、更に偏光子１３を通って所定の偏光方向
の成分のみが取り出され、その偏光子１３からの光は光
ファイバカプラなどの光分岐器１４で２分配され、その
一方の光は光ファイバコイル１６の一端に右回り光とし
て入射され、他方の光は光位相変調器１７を通って光フ
ァイバコイル１６の他端に左回り光として入射される。2. Description of the Related Art FIG. 2 shows a conventional optical fiber gyro. The light from the light source 11 passes through an optical branching device 12 such as an optical fiber coupler, and further passes through a polarizer 13 to extract only a component in a predetermined polarization direction. The light from the polarizer 13 is a light such as an optical fiber coupler. The light is split into two by the branching device 14, one light of which is incident on one end of the optical fiber coil 16 as a clockwise light, and the other light passes through the optical phase modulator 17 and is counterclockwise light on the other end of the optical fiber coil 16. Is incident as.
【０００３】光ファイバコイル１６を伝搬した右回り光
と左回り光とは光分岐器１４に戻って合成されて干渉
し、その干渉光は偏光子１３で所定の偏光方向の成分の
みが取り出され、その偏光子１３を通過した光は光分岐
器１２で分岐されて光検出器１８に入射され、その光の
強度に応じた電気信号に変換される。変調信号発生器１
９からの周期関数、例えば正弦波信号により光位相変調
器１７が駆動され、これを通過する光が位相変調され
る。光検出器１８の出力は同期検波回路２１で変調信号
発生器１９からの基準信号により同期検波され、その検
波出力は出力端子２２に出力される。The clockwise light and the counterclockwise light that have propagated through the optical fiber coil 16 return to the optical splitter 14 and are combined and interfere with each other. The light that has passed through the polarizer 13 is split by the optical splitter 12 and is incident on the photodetector 18, where it is converted into an electric signal corresponding to the intensity of the light. Modulation signal generator 1
The optical phase modulator 17 is driven by a periodic function from No. 9, for example, a sine wave signal, and the light passing therethrough is phase-modulated. The output of the photodetector 18 is synchronously detected by the synchronous detection circuit 21 based on the reference signal from the modulation signal generator 19, and the detection output is output to the output terminal 22.
【０００４】光ファイバコイル１６に、その軸心回りの
角速度が印加されていない状態では、光ファイバコイル
１６を伝搬した右回り光と、左回り光との位相差はゼロ
であり、同期検波回路２１の出力もゼロであるが、光フ
ァイバコイル１６に、その軸心回りの角速度が印加され
ると、これに応じて右回り光と左回り光とに位相差が生
じ、同期検波回路２１から、前記印加角速度の方向およ
び大きさに応じた極性およびレベルの出力が生じ、印加
角速度を検出することができる。When the angular velocity around the axis of the optical fiber coil 16 is not applied to the optical fiber coil 16, the phase difference between the clockwise light and the counterclockwise light propagated through the optical fiber coil 16 is zero, and the synchronous detection circuit The output of the counter 21 is also zero, but when an angular velocity around the axis is applied to the optical fiber coil 16, a phase difference is generated between the clockwise light and the counterclockwise light in response to this, and the synchronous detection circuit 21 outputs The output of the polarity and the level corresponding to the direction and the magnitude of the applied angular velocity is generated, and the applied angular velocity can be detected.
【０００５】光ファイバコイル１６中を伝搬する光の偏
波面ゆらぎによって生ずるジャイロ出力変動を低減する
ために、従来においては光ファイバコイル１６として偏
波面保存光ファイバが主として用いられていた。しか
し、偏波面保存光ファイバは高価であるため、安価な単
一モード光ファイバで光ファイバコイル１６を構成し、
その光ファイバコイル１６の一端と光分岐器１４との間
にデポラライザ２３を挿入し、同一方向回りの垂直偏光
成分と水平偏光成分とが互いに干渉しないように十分位
相をずらし、無偏光状態とすることが行われている。デ
ポラライザ２３としては偏波面保存光ファイバで構成さ
れたものを用いることにより、容易に製品化することが
できる。図４にこの型のデポラライザの構成例を示す。In order to reduce the gyro output fluctuation caused by the polarization plane fluctuation of the light propagating through the optical fiber coil 16, a polarization plane preserving optical fiber has been mainly used as the optical fiber coil 16 in the past. However, since the polarization-maintaining optical fiber is expensive, the optical fiber coil 16 is composed of an inexpensive single-mode optical fiber,
The depolarizer 23 is inserted between the one end of the optical fiber coil 16 and the optical branching device 14, and the phases thereof are sufficiently shifted so that the vertical polarization component and the horizontal polarization component in the same direction do not interfere with each other, and a non-polarization state is obtained. Is being done. The depolarizer 23 can be easily commercialized by using a polarization-maintaining optical fiber. FIG. 4 shows a configuration example of this type of depolarizer.
【０００６】[0006]
【発明が解決しようとする課題】しかし、光ファイバコ
イル１６およびデポラライザ２３に加わる温度変動によ
って非相反な位相差が生じ、その結果、ジャイロ出力が
変動することが知られている。このジャイロ出力変動量
ΔＶは、光ファイバコイル１６の長さをＬとすると、次
式で表せる。However, it is known that a nonreciprocal phase difference occurs due to temperature fluctuations applied to the optical fiber coil 16 and the depolarizer 23, and as a result, the gyro output fluctuates. This gyro output fluctuation amount ΔV can be expressed by the following equation, where L is the length of the optical fiber coil 16.
【０００７】 ΔＶ＝ｋ∫（ｄφ／ｄＴ）｛Ｔ（Ｌ−ｌ）−Ｔ（ｌ）｝ｄｌ …… (1) ｋは定数、ｄφ／ｄＴは温度変動に伴う位相量変化で、
屈折率の温度係数による変化分と光ファイバ長の変動に
よる変化分の２つの原因を有する、Ｔ（ｌ）は光ファイ
バコイル１６の一端からｌだけ離れた点の温度変化率、
∫は０からＬ／２までである。ΔV = k∫ (dφ / dT) {T (L−1) −T (l)} dl (1) k is a constant, and dφ / dT is the change in the phase amount due to temperature fluctuation,
There are two causes for the change due to the temperature coefficient of the refractive index and the change due to the change in the optical fiber length. T (l) is the temperature change rate at a point separated by 1 from one end of the optical fiber coil 16,
∫ is from 0 to L / 2.
【０００８】光ファイバコイル１６の温度変動によるジ
ャイロ出力の変動を低減するために、図３Ａに光ファイ
バコイル１６を展開して示すように、光ファイバコイル
１６の中心、つまり全長の２分の１の点（Ｌ／２）を中
心に対称な温度分布となるように実装することが提案さ
れている。しかし、図３Ｂに示すように、一端にデポラ
ライザ２３が位置している場合は、対称な温度分布とな
るような実装としても単一モード光ファイバコイル１６
とデポラライザ２３との温度変動による位相変化量の違
いからデポラライザ２３と、これが接続されていない側
の光ファイバコイル１６の端部との間に位相量変動差が
発生し、結果としてジャイロ出力の変動が生じる。この
ジャイロ出力変動ΔＶ′は、デポラライザ２３の長さを
ｌ1 ，∫は０からｌ 1 ，デポラライザ２３で生じる温度
変動に伴う位相量変化をｄφ′／ｄＴとすると、 ΔＶ′＝ｋ∫｛（ｄφ／ｄＴ）Ｔ(Ｌ−ｌ)−(ｄφ′／ｄＴ)Ｔ(ｌ)｝ｄｌ …… (2) となる。従って、単一モード光ファイバを光ファイバコ
イル１６として使用すると、安価に構成できるが、温度
変動によりジャイロ出力が変動する問題があった。In order to reduce the fluctuation of the gyro output due to the temperature fluctuation of the optical fiber coil 16, the optical fiber coil 16 is expanded and shown in FIG. 3A. It is proposed that the temperature distribution is symmetrical with respect to the point (L / 2). However, as shown in FIG. 3B, when the depolarizer 23 is located at one end, the single mode optical fiber coil 16 can be mounted even if the temperature distribution is symmetrical.
And the depolarizer 23, the difference in the amount of phase change due to the temperature change causes a difference in the amount of phase change between the depolarizer 23 and the end of the optical fiber coil 16 on the side where the depolarizer 23 is not connected. Occurs. This gyro output fluctuation ΔV ′ is ΔV ′ = k∫ {(when the length of the depolarizer 23 is l 1 , ∫ is 0 to l 1 , and the phase amount change due to temperature fluctuation caused by the depolarizer 23 is dφ ′ / dT. dφ / dT) T (L−1) − (dφ ′ / dT) T (l)} dl (2) Therefore, if a single mode optical fiber is used as the optical fiber coil 16, the cost can be reduced, but there is a problem that the gyro output fluctuates due to temperature fluctuation.
【０００９】[0009]
【課題を解決するための手段】この発明によれば、光フ
ァイバコイルは単一モード光ファイバで構成され、その
単一モード光ファイバコイルの一端に、光ファイバ、も
しくは光ファイバと光ＩＣで構成されたデポラライザが
接続され、他端に、そのデポラライザと光の位相量変化
に関して同一温度係数を有する、光軸が一端から他端ま
で同一で非接続構成光軸が一端から他端まで同一で非接
続構成の補償用光ファイバが接続される。According to the present invention, an optical fiber coil is composed of a single mode optical fiber, and one end of the single mode optical fiber coil is composed of an optical fiber or an optical fiber and an optical IC. Depolarizer is connected to the other end, and the optical axis from the one end to the other end has the same temperature coefficient with respect to the phase change of the depolarizer and the light at the other end.
The optical axes are the same and are not connected.
A compensating optical fiber having a continuous configuration is connected.
【００１０】[0010]
【実施例】図１にこの発明の実施例を示し、図２と対応
する部分に同一符号を付けてある。この発明において
は、単一モード光ファイバのコイル１６のデポラライザ
２３が接続されていない側の端と、光分岐器１４との間
に補償用光ファイバ２４が接続される。補償用光ファイ
バ２４は光軸が一端から他端まで同一で非接続構成光軸
が一端から他端まで同一で非接続構成であり、デポララ
イザ２３と温度変動に対する光の位相量変化が等しい。
例えば、デポラライザ２３を構成している偏波面保存光
ファイバと同一の温度係数を有する単一モード光ファイ
バを同一長で用いる。FIG. 1 shows an embodiment of the present invention, in which parts corresponding to those in FIG. 2 are denoted by the same reference numerals. In the present invention, the compensating optical fiber 24 is connected between the optical branching device 14 and the end of the coil 16 of the single-mode optical fiber to which the depolarizer 23 is not connected. The compensating optical fiber 24 has the same optical axis from one end to the other end, and the optical axis is not connected.
Is the same from one end to the other end and is not connected, and the change in the phase amount of light with respect to the temperature change is the same as that of the depolarizer 23.
For example, a single-mode optical fiber having the same temperature coefficient as the polarization-maintaining optical fiber forming the depolarizer 23 is used with the same length.
【００１１】光ファイバコイル１６をその中心（２分の
１の長さの点）に対し対称に巻き、かつデポラライザ２
３と補償用光ファイバ２４とを近接して平行に配置す
る。この光ファイバコイル１６，デポラライザ２３，補
償用光ファイバ２４に温度変動が加わると、光ファイバ
コイル１６においては、（１）式においてＴ（ｌ）＝Ｔ
（Ｌ−ｌ）が成立するから光ファイバコイル１６の温度
変動にもとづくジャイロ出力の変動はない。またデポラ
ライザ２３と補償用光ファイバ２４とは同一位相量変化
パラメータをもっており、かつ近接して配置されている
から、（２）式でｄφ′／ｄＴ＝ｄφ／ｄＴ，Ｔ（ｌ）
＝Ｔ（Ｌ−ｌ）が成立し、この部分での温度変動にもと
づくジャイロ出力変動はない。The optical fiber coil 16 is wound symmetrically with respect to its center (a point having a half length), and the depolarizer 2 is used.
3 and the compensating optical fiber 24 are arranged in parallel with each other. When temperature fluctuations are applied to the optical fiber coil 16, the depolarizer 23, and the compensation optical fiber 24, T (l) = T in the equation (1) in the optical fiber coil 16.
Since (L-1) is established, the gyro output does not fluctuate due to the temperature fluctuation of the optical fiber coil 16. Further, since the depolarizer 23 and the compensation optical fiber 24 have the same phase amount change parameter and are arranged close to each other, dφ ′ / dT = dφ / dT, T (l) in the equation (2).
= T (L-1) holds, and there is no gyro output fluctuation due to temperature fluctuation in this portion.
【００１２】上述において、デポラライザ２３および補
償用光ファイバ２４も光ファイバコイル１６と共にコイ
ルに巻いてもよい。上述では、この発明を開ループ光フ
ァイバジャイロに適用したが、閉ループ光ファイバジャ
イロに適用することもできる。光分岐器１２，１４とし
ては光ファイバカプラのみならず、光ＩＣで構成してよ
い。In the above description, the depolarizer 23 and the compensating optical fiber 24 may be coiled together with the optical fiber coil 16. In the above description, the present invention is applied to the open loop optical fiber gyro, but it can also be applied to the closed loop optical fiber gyro. The optical branching devices 12 and 14 may be not only optical fiber couplers but also optical ICs.
【００１３】さらにデポライザ２３として、例えばプロ
トン交換法によって作成された高い消光比を持つ光導波
路の光軸と、偏波面保存光ファイバの光軸とを４５°傾
けて接続した構造のものを用いてもよい。Further, as the depolarizer 23, one having a structure in which an optical axis of an optical waveguide having a high extinction ratio created by a proton exchange method and an optical axis of a polarization-maintaining optical fiber are connected at an angle of 45 ° Good.
【００１４】[0014]
【発明の効果】以上述べたように、この発明によれば単
一モード光ファイバを光ファイバコイル１６として用い
るため安価に構成することができ、しかも補償用光ファ
イバ２４を用いて、デポラライザと対称な関係とするこ
とにより、温度変動の影響を受け難い、温度安定性の優
れた精度の高い、光ファイバジャイロを得ることができ
る。As described above, according to the present invention, since the single mode optical fiber is used as the optical fiber coil 16, it can be constructed at a low cost, and the compensating optical fiber 24 is used to be symmetrical with the depolarizer. With such a relationship, it is possible to obtain an optical fiber gyro that is not easily affected by temperature fluctuations, has excellent temperature stability, and is highly accurate.
【図１】この発明の実施例を示すブロック図。FIG. 1 is a block diagram showing an embodiment of the present invention.
【図２】従来の光ファイバジャイロを示すブロック図。FIG. 2 is a block diagram showing a conventional optical fiber gyro.
【図３】光ファイバコイルを展開して対称構成を示す
図。FIG. 3 is a diagram showing a symmetrical configuration by expanding an optical fiber coil.
【図４】光ファイバ型デポラライザの構成例を示す図。FIG. 4 is a diagram showing a configuration example of an optical fiber type depolarizer.
Claims (1)
て、光ファイバコイルの両端に右回り光、左回り光とし
て入射し、これら右回り光および左回り光の上記光ファ
イバコイルを伝搬した光を上記光分岐手段で干渉させ、
その干渉光の光強度を光検出器で電気信号に変換し、そ
の電気信号から上記光ファイバコイルに、その軸心回り
に印加される角速度を検出する光ファイバジャイロにお
いて、 上記光ファイバコイルは単一モード光ファイバよりな
り、 その単一モード光ファイバコイルの一端と上記光分岐手
段との間に光ファイバで構成されたデポラライザが挿入
され、 上記単一モード光ファイバコイルの他端と上記光分岐手
段との間に上記デポラライザと中を通過する光の位相量
変化に関して同一温度係数を有し、光軸が一端から他端
まで同一であり、非接続構成の補償用光ファイバが挿入
されている、ことを特徴とする光ファイバジャイロ。1. A light from a light source is distributed by an optical branching means, and is incident on both ends of an optical fiber coil as right-handed light and left-handed light. The propagated light is caused to interfere by the optical branching means,
In an optical fiber gyro that converts the light intensity of the interference light into an electric signal with a photodetector and detects the angular velocity applied to the optical fiber coil from the electric signal to the optical fiber coil, the optical fiber coil is A single mode optical fiber, a depolarizer composed of an optical fiber is inserted between one end of the single mode optical fiber coil and the optical branching means, and the other end of the single mode optical fiber coil and the optical branch have a same temperature coefficient with respect to the phase change in the amount of light passing through a medium and the depolarizer between the means and the other end the optical axis from one end
The optical fiber gyro is characterized in that a compensating optical fiber having a non-connection configuration is inserted thereinto.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4009652A JP2552603B2 (en) | 1992-01-23 | 1992-01-23 | Fiber optic gyro |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4009652A JP2552603B2 (en) | 1992-01-23 | 1992-01-23 | Fiber optic gyro |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05196471A JPH05196471A (en) | 1993-08-06 |
| JP2552603B2 true JP2552603B2 (en) | 1996-11-13 |
Family
ID=11726150
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4009652A Expired - Fee Related JP2552603B2 (en) | 1992-01-23 | 1992-01-23 | Fiber optic gyro |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2552603B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6990269B2 (en) | 2002-11-01 | 2006-01-24 | Japan Aviation Electronics Industry Limited | Fiber optic gyroscope |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6211963B1 (en) * | 1998-12-29 | 2001-04-03 | Honeywell Inc. | Low drift depolarizer for fiber optic gyroscope having legs wound in a winding pattern |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61175518A (en) * | 1985-01-31 | 1986-08-07 | Mitsubishi Heavy Ind Ltd | Optical fiber sensor |
| JPH04344417A (en) * | 1991-05-22 | 1992-12-01 | Matsushita Electric Ind Co Ltd | Optical fiber gyro |
-
1992
- 1992-01-23 JP JP4009652A patent/JP2552603B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6990269B2 (en) | 2002-11-01 | 2006-01-24 | Japan Aviation Electronics Industry Limited | Fiber optic gyroscope |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05196471A (en) | 1993-08-06 |
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