JPS6344174B2 - - Google Patents
Info
- Publication number
- JPS6344174B2 JPS6344174B2 JP57081251A JP8125182A JPS6344174B2 JP S6344174 B2 JPS6344174 B2 JP S6344174B2 JP 57081251 A JP57081251 A JP 57081251A JP 8125182 A JP8125182 A JP 8125182A JP S6344174 B2 JPS6344174 B2 JP S6344174B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- beam splitter
- optical fiber
- polarizing beam
- polarization
- 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
Links
- 239000013307 optical fiber Substances 0.000 claims description 20
- 230000010287 polarization Effects 0.000 claims description 15
- 239000000835 fiber Substances 0.000 claims description 4
- 230000001902 propagating effect Effects 0.000 claims description 4
- 230000000644 propagated effect Effects 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 238000001514 detection method Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 230000008033 biological extinction Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/58—Turn-sensitive devices without moving masses
- G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
- G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Optics & Photonics (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Gyroscopes (AREA)
- Lasers (AREA)
Description
【発明の詳細な説明】
本発明は光フアイバレーザジヤイロに関するも
のである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber laser gyroscope.
従来、リング干渉計を利用した光フアイバーレ
ーザジヤイロの干渉状態の変化を検出する方法と
しては大別とすると次の２つである。 Conventionally, methods for detecting changes in the interference state of an optical fiber laser gyroscope using a ring interferometer can be broadly classified into the following two methods.
(1) 干渉縞変化検出法
(2) 干渉光強度変化検出法
これらの方法のうち、(1)は縞を作るために片方
の回転の光の入射条件焦点を最適結合点からはず
すため結合損が大きく、また干渉光の１部のみ利
用するため雑音の影響を受けやすく、光学系の波
長オーダの位置ズレで誤差が発生するという欠点
があつた。(1) Method for detecting changes in interference fringes (2) Method for detecting changes in interference light intensity Among these methods, method (1) uses coupling loss because the incident condition focus of the light of one rotation is shifted from the optimal coupling point in order to create fringes. However, since only a portion of the interference light is used, it is susceptible to noise, and errors occur due to positional deviations on the order of wavelength in the optical system.
(2)の方法では回転による両方向回転光の位相差
をθとするとcos θに比例した干渉光出力が得ら
れるためθが微小量のときは、感度が悪く、θが
正負に変化しても、回転の向きが不明であるとい
う欠点がある。 In method (2), if θ is the phase difference of the bidirectionally rotated light due to rotation, an interference light output proportional to cos θ is obtained, so when θ is a minute amount, the sensitivity is poor, and even if θ changes to positive or negative , the disadvantage is that the direction of rotation is unknown.
更に、伝送路として使用する従来の単一モード
フアイバは偏波保存性が悪く、偏波の不安定性が
干渉光のゆらぎの原因になつていた。 Furthermore, conventional single mode fibers used as transmission lines have poor polarization preservation, and instability of polarization causes fluctuations in interference light.
上記の欠点を解消するため、sinθに比例した出
力を得ようとする案もあるが、位相差が±（π／
２）を越えた場合にはやはり不都合がある。 In order to solve the above drawback, there is a plan to obtain an output proportional to sinθ, but the phase difference is ±(π/
If 2) is exceeded, there will still be inconveniences.
本発明は斯かる状況に鑑み、回転方向の検出が
でき、回転による位相差が小さい場合にも検出感
度が優れており、さらに位相差が大きい場合にも
不都合が生じない光フアイバレーザジヤイロの提
供を目的とする。 In view of this situation, the present invention provides an optical fiber laser gyro that can detect the direction of rotation, has excellent detection sensitivity even when the phase difference due to rotation is small, and does not cause any inconvenience even when the phase difference is large. For the purpose of providing.
本発明の構成の一実施例を図面を参照して以下
具体的に説明する。 An embodiment of the configuration of the present invention will be specifically described below with reference to the drawings.
図において、５は偏光ビームスプリツタ８であ
り、コイル状偏波面保存光フアイバ６の両端が固
定されている。偏波面保存光フアイバとは、固有
偏光軸を有し伝搬する光の偏波面を保存する機能
を有する光フアイバである。 In the figure, 5 is a polarizing beam splitter 8, and both ends of a coiled polarization-maintaining optical fiber 6 are fixed. A polarization-maintaining optical fiber is an optical fiber that has a unique polarization axis and has the function of preserving the polarization plane of propagating light.
レーザ光源１からの光は1/2波長板２によつて、
偏光ビームスプリツタ５に対して約45゜の方位の
直線偏光として入射するように設定される。３は
ビームスプリツタである。 The light from the laser light source 1 is passed through the 1/2 wavelength plate 2,
The light is set to be incident on the polarizing beam splitter 5 as linearly polarized light with an orientation of about 45°. 3 is a beam splitter.
偏光ビームスプリツタ５では45゜方位の直線偏
光のＳ偏光、Ｐ偏光成分がそれぞれ反射、透過す
る。それらの光はコイル状偏波面保存光フアイバ
６の両端より相互に逆向きに入射されるが、コイ
ル状偏波面保存光フアイバコイルはその両端で偏
光ビームスプリツタ５に対し固有偏光軸を空間的
に直交させるように90゜ねじつて配置されており、
従つていずれの偏光成分も例えばコイル状偏波面
保存光フアイバ６の長軸方位に入射されるよう構
成してある。尚、長軸方位ではなく短軸方位に入
射されるようにしても勿論かまわない。 The polarizing beam splitter 5 reflects and transmits the S-polarized light component and the P-polarized light component of the linearly polarized light in the 45° direction, respectively. These lights are incident in mutually opposite directions from both ends of the coiled polarization-maintaining optical fiber 6, but the coiled polarization-maintaining optical fiber coil spatially directs the unique polarization axis to the polarization beam splitter 5 at both ends. It is arranged with a 90° twist so that it is perpendicular to the
Therefore, the structure is such that any polarized light component is incident on the long axis direction of the coiled polarization preserving optical fiber 6, for example. Of course, the light may be incident on the short axis direction instead of the long axis direction.
偏光ビームスプリツタ５と偏波面保存光フアイ
バ６とはマイクロレンズを介して固定することが
望ましい。 It is desirable that the polarizing beam splitter 5 and the polarization maintaining optical fiber 6 be fixed via a microlens.
このようにすると時計方向の伝搬光（CW）は
Ｐ偏光で伝搬し再び偏光ビームスプリツタ５に入
射するときにはＳ偏光で入射するのでビームスプ
リツタ３に向かつて反射される。このとき短軸方
位のモードに変換された成分は偏光ビームスプリ
ツタ５を透過してしまい検出器側にはいかない。
そのため消光比劣化によるノイズの原因にはなら
ない。同様に反時計方向の伝搬光（CCW）はＳ
偏光で伝搬しＰ偏光として偏光ビームスプリツタ
５に入射するため、ビームスプリツタ３に向かつ
て透過される。 In this way, the clockwise propagating light (CW) propagates as P-polarized light, and when it enters the polarizing beam splitter 5 again, it enters as S-polarized light, so that it is reflected toward the beam splitter 3. At this time, the component converted into the mode in the short axis direction passes through the polarizing beam splitter 5 and does not reach the detector side.
Therefore, it does not cause noise due to extinction ratio deterioration. Similarly, counterclockwise propagating light (CCW) is S
Since the light propagates as polarized light and enters the polarizing beam splitter 5 as P-polarized light, it is transmitted toward the beam splitter 3.
従つてビームスプリツタ３ではCW，CCW方
向の光の偏波が空間的に直交するような向きで取
り出せることになる。 Therefore, the beam splitter 3 can take out the polarized waves of light in the CW and CCW directions in directions that are spatially orthogonal to each other.
このようにするとコイル状偏波面保存光フアイ
バが回転しないときにはCCW，CWの光の位相
差は等しいから、ビームスプリツタ３でとり出さ
れた光は直線偏光である。 In this way, when the coiled polarization-maintaining optical fiber does not rotate, the phase difference between CCW and CW light is equal, so the light taken out by the beam splitter 3 is linearly polarized light.
この状態の光をビームスプリツタ４で分岐し、
一方は光の直交偏光軸に方位を一致させて設置さ
れた1/4波長板７を介して当該1/4波長板７と45゜
回転した方位に置いた偏光ビームスプリツタ８に
入射する。 The light in this state is split by a beam splitter 4,
One of the beams enters a polarizing beam splitter 8, which is placed at a direction rotated by 45 degrees from the quarter-wave plate 7, through a quarter-wave plate 7 whose orientation is aligned with the orthogonal polarization axes of the light.
また、他方は光の直交偏光軸に対して方位を
45゜回転して設置された偏光ビームスプリツタ９
に直接入射する。 On the other hand, the orientation is relative to the orthogonal polarization axis of the light.
Polarizing beam splitter 9 installed with 45° rotation
directly incident on the
偏光ビームスプリツタ４，９の透過側、出射側
には光電変換器１２，１２が置かれており、受光
した光強度を電気信号に変換し、それぞれの出力
を差動増幅器１１，１１に導きその出力を観測す
る。 Photoelectric converters 12, 12 are placed on the transmission side and output side of the polarization beam splitters 4, 9, which convert the received light intensity into electrical signals, and guide the respective outputs to differential amplifiers 11, 11. Observe its output.
今、コイル状偏波面保存光フアイバ６が回転角
速度Ωで回転したとすると、Ｐ偏光とＳ偏光との
間にはサグナツクの位相差θが発生する。このθ
はΩと次の関係にあることが知られている。 Now, if the coiled polarization-maintaining optical fiber 6 is rotated at a rotational angular velocity Ω, a sagnac phase difference θ will occur between the P-polarized light and the S-polarized light. This θ
is known to have the following relationship with Ω.
θ＝4πFl／λCΩ ……(1)
但し、Ｒはコイルのループ半径、ｌはフアイバ
長、λは波長、Ｃは光速である。 θ=4πFl/λCΩ (1) where R is the loop radius of the coil, l is the fiber length, λ is the wavelength, and C is the speed of light.
従つてビームスプリツタ３でとり出された光
（Ｐ偏光とＳ偏光）の電界ベクトルは上記θを用
いて次式で表せる。 Therefore, the electric field vector of the light (P-polarized light and S-polarized light) taken out by the beam splitter 3 can be expressed by the following equation using the above θ.
ep＝Acos（wt−θ）
es＝Acos wt ……(2)
但し、Ａは定数、ｗは光角周波数である。つま
り光は一般に楕円偏光となる。 ep=Acos(wt-θ) es=Acos wt...(2) However, A is a constant and w is the optical angular frequency. In other words, light is generally elliptically polarized.
この状態でビームスプリツタ４により分岐さ
れ、かつ1/4波長板７を透過させると、強度は1/2
になるとともに、Ｐ偏光とＳ偏光との間には90゜
の位相差が付加される。ここが本発明の第１のミ
ソである。1/4波長板１０を透過後の光は次式で
与えられる。 In this state, if the beam is split by the beam splitter 4 and transmitted through the 1/4 wavelength plate 7, the intensity will be 1/2.
At the same time, a phase difference of 90° is added between the P-polarized light and the S-polarized light. This is the first secret of the present invention. The light after passing through the quarter-wave plate 10 is given by the following equation.
ep′＝Ａ／２sin（wt−θ）
es′＝Ａ／２cos wt ……(3)
この透過光に対し、偏光ビームスプリツタ８が
１／４波長板と45゜回転した方位に置いてあるため、
偏光ビームスプリツタ８の透過側出射光および反
射側出射光は
で与えられるものであり、従つて光電変換器１
２，１２で受光される光強度として
P1＝ｋ／８A2（１＋sin θ）
P2＝ｋ／８A2（１＋sin θ） ……(5)
の電気信号を得ることができる。但しｋは定数で
ある。ゆえに差動増幅器１１で観測される出力は
次式により表すことができる。 ep'=A/2sin(wt-θ) es'=A/2cos wt...(3) With respect to this transmitted light, the polarizing beam splitter 8 is placed at an orientation rotated by 45 degrees with respect to the quarter-wave plate. For,
The transmission side output light and the reflection side output light of the polarizing beam splitter 8 are Therefore, the photoelectric converter 1
As the light intensity received at 2 and 12, an electric signal of P 1 =k/8A 2 (1+sin θ) P 2 =k/8A 2 (1+sin θ) (5) can be obtained. However, k is a constant. Therefore, the output observed by the differential amplifier 11 can be expressed by the following equation.
P1＝P1−P2＝ｋ／４A2 sin θ ……(6)
このように、出力がsin θに比例して変化する
ようにしたので、コイル状偏波面保存光フアイバ
６が回転しないときは出力が０、回転するとその
方向によつて正負の極性をもつて変化するものと
なり、かつθが微妙量のときでも変化が顕著に表
れるので、感度は大幅に向上する。 P 1 = P 1 − P 2 = k/4A 2 sin θ ...(6) In this way, since the output changes in proportion to sin θ, the coiled polarization-maintaining optical fiber 6 does not rotate. When the output is 0, the output changes with positive and negative polarity depending on the direction of rotation, and the change is noticeable even when θ is a small amount, so the sensitivity is greatly improved.
しかし、この出力だけでは回転角速度Ωが大き
くなりθが±90゜に近づくと感度が低下するし、±
90゜を越えると、θを特定できなくなつてしまう。
そこで、ビームスプリツタ４で分岐したもう一方
の光を利用する。これが本発明の第２のミソであ
る。 However, with only this output, the sensitivity decreases as the rotational angular velocity Ω increases and θ approaches ±90°, and the sensitivity decreases with ±90°.
If it exceeds 90°, it becomes impossible to specify θ.
Therefore, the other beam split by the beam splitter 4 is used. This is the second secret of the present invention.
偏光ビームスプリツタ９は、光の直交偏光軸に
対し45゜回転した方位に置いてあるため、その透
過側出力光および反射側出力光は、
で与えられるものであり、従つて光電変換器１
２，１２で受光される光強度として
P3＝Ｒ／８A2（１＋cos θ）
P4＝Ｒ／８A2（１＋cos θ） ……(8)
の電気信号を得ることができる。ゆえにもう一方
の差動増幅器１１で観測される出力は、次式で表
される。 Since the polarizing beam splitter 9 is placed in an orientation rotated by 45 degrees with respect to the orthogonal polarization axis of the light, its transmission side output light and reflection side output light are Therefore, the photoelectric converter 1
As the light intensity received at 2 and 12, an electric signal of P 3 =R/8A 2 (1+cos θ) P 4 =R/8A 2 (1+cos θ) (8) can be obtained. Therefore, the output observed by the other differential amplifier 11 is expressed by the following equation.
P″＝P3−P4＝ｋ／４A2 cos θ ……(9)
この出力によればθが±90゜近くの感度に優れ
ているので、前記差動増幅器１１の出力P′とこの
P″の双方を用いれば、検出範囲を大幅に拡大す
ることができる。すなわち、P′、P″の極性も考
慮するように適当な演算を行えばよい。演算処理
回路にはこのような演算処理を行うものであり、
その演算方法は特に限定するものではないが、例
えばP′／P″を計算し、tan θを求めることが考
えられる。このようにすれば、出力を規格化する
ことができ、光源１や光フアイバの温度特性の変
動等の影響を受けない高精度の検出が可能とな
る。 P″=P 3 −P 4 =k/4A 2 cos θ (9) According to this output, the sensitivity of θ is close to ±90°, so the output P′ of the differential amplifier 11 and the
If both P'' are used, the detection range can be greatly expanded. That is, an appropriate calculation may be performed to take into account the polarities of P' and P''. The arithmetic processing circuit performs such arithmetic processing,
The calculation method is not particularly limited, but for example, it is possible to calculate P′/P″ and find tan θ.In this way, the output can be normalized, and the light source 1 and light Highly accurate detection is possible without being affected by changes in the temperature characteristics of the fiber.
なお、図において各素子間に空気を媒体として
光を伝搬しているが、この媒体として偏波面保存
光フアイバを用いてもよく、この場合振動に対す
る信頼性が高くなる。 Note that in the figure, light is propagated between each element using air as a medium, but a polarization-maintaining optical fiber may be used as the medium, and in this case, reliability against vibrations is increased.
以上説明したように、本発明の光フアイバーレ
ーザジヤイロであれば、次のような顕著な効果を
奏する。 As explained above, the optical fiber laser gyroscope of the present invention has the following remarkable effects.
(1) sin θに比例した出力とcos θに比例した出
力とが同時に得られるので、回転方向の検出が
でき、回転による位相差θが微小な場合にも検
出感度が良好であり、位相差θが大きい場合に
も不都合を生じない。(1) Since an output proportional to sin θ and an output proportional to cos θ can be obtained at the same time, the direction of rotation can be detected, and the detection sensitivity is good even when the phase difference θ due to rotation is minute. No problem occurs even when θ is large.
(2) 光源や光フアイバの温度特性による変動の影
響が問題とならず、消光比の劣化が出力に影響
しないため、検出感度が良好であり信頼性が高
い。(2) The influence of fluctuations due to the temperature characteristics of the light source and optical fiber does not pose a problem, and deterioration of the extinction ratio does not affect the output, so detection sensitivity is good and reliability is high.
図は本発明の一実施例を示す説明図である。
１：レーザ光源、２：1/2波長板、３，４：ビ
ームスプリツタ、５，８，９：偏光ビームスプリ
ツタ、６：コイル状偏波面保存光フアイバ、７：
１／４波長板、１０：光電変換器、１１：差動増幅
器、１２：演算処理回路。
The figure is an explanatory diagram showing one embodiment of the present invention. 1: Laser light source, 2: 1/2 wavelength plate, 3, 4: Beam splitter, 5, 8, 9: Polarizing beam splitter, 6: Coiled polarization preserving optical fiber, 7:
1/4 wavelength plate, 10: photoelectric converter, 11: differential amplifier, 12: arithmetic processing circuit.
Claims (1)
45゜の方位で入射し、該偏光ビームスプリツタ５
の反射光と透過光とをコイル状偏波面保存光フア
イバ６のひとつの固有偏光軸に両端から入射し
て、コイル状偏波面保存フアイバ６を両方向に伝
搬させ、出射した光を分岐して一方は当該分岐光
の直交偏光軸に対し方位を一致させて配置した1/
４波長板７を介して該1/4波長板７に対し45゜方位
を傾けて設置した偏光ビームスプリツタ８に導い
て当該偏光ビームスプリツタ８の透過光と反射光
との差動出力を得、他方は1/4波長板を介さずに
当該分岐光の直流偏光軸に対し45゜方位を傾けて
設置した偏光ビームスプリツタ９に直接導いて当
該偏光ビームスプリツタ９の透過光と反射光との
差動出力を得、双方の差動出力を演算処理するこ
とにより前記両方向伝搬光の位相差を検出するよ
うに構成したことを特徴とする光フアイバレーザ
ジヤイロ。1 Direct the linearly polarized light to the polarizing beam splitter 5
The polarizing beam splitter 5
The reflected light and the transmitted light are incident on one characteristic polarization axis of the coiled polarization-maintaining optical fiber 6 from both ends, and the coiled polarization-maintaining fiber 6 is propagated in both directions, and the emitted light is split into one direction. is a 1/
The beam is guided through a 4-wave plate 7 to a polarizing beam splitter 8 installed at an angle of 45 degrees with respect to the 1/4-wave plate 7, and the differential output between the transmitted light and reflected light of the polarized beam splitter 8 is generated. The other beam is directly guided to a polarizing beam splitter 9 installed at an angle of 45 degrees with respect to the DC polarization axis of the branched light without passing through a quarter-wave plate, and is then separated from the transmitted light of the polarizing beam splitter 9 and reflected light. 1. An optical fiber laser gyroscope characterized in that the optical fiber laser gyroscope is configured to obtain a differential output with light and to detect a phase difference of the bidirectionally propagating light by calculating and processing the differential outputs.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57081251A JPS58198715A (en) | 1982-05-14 | 1982-05-14 | Optical fiber laser gyro |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57081251A JPS58198715A (en) | 1982-05-14 | 1982-05-14 | Optical fiber laser gyro |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58198715A JPS58198715A (en) | 1983-11-18 |
| JPS6344174B2 true JPS6344174B2 (en) | 1988-09-02 |
Family
ID=13741167
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57081251A Granted JPS58198715A (en) | 1982-05-14 | 1982-05-14 | Optical fiber laser gyro |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58198715A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02132394A (en) * | 1988-11-14 | 1990-05-21 | Kenwood Corp | Moving body identifying device |
-
1982
- 1982-05-14 JP JP57081251A patent/JPS58198715A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02132394A (en) * | 1988-11-14 | 1990-05-21 | Kenwood Corp | Moving body identifying device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58198715A (en) | 1983-11-18 |
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