JPS58225301A - Optical type displacement measuring apparatus - Google Patents
Optical type displacement measuring apparatusInfo
- Publication number
- JPS58225301A JPS58225301A JP57108725A JP10872582A JPS58225301A JP S58225301 A JPS58225301 A JP S58225301A JP 57108725 A JP57108725 A JP 57108725A JP 10872582 A JP10872582 A JP 10872582A JP S58225301 A JPS58225301 A JP S58225301A
- Authority
- JP
- Japan
- Prior art keywords
- light
- target
- displacement
- pbs22
- pbs21
- 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
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B2290/00—Aspects of interferometers not specifically covered by any group under G01B9/02
- G01B2290/70—Using polarization in the interferometer
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Instruments For Measurement Of Length By Optical Means (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は、レーザ光を用いてターゲットの変位測定を行
なう光学式変位測定装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical displacement measuring device that measures the displacement of a target using laser light.
第1図は、この種の装置のひとつである公知のマイケル
ソン変位計の構成説明図である。この装置は、レーザ光
源1からのレーザビームを、ビームスプリーツタ(以下
BSと略す)2で分割し、一方を被測定変位が与えられ
るターゲット3のミラー30に照射するとともに、他方
を固定ミラー4に照射し、これらのミラー30及び4か
ら0反射光を、BS2を介して受光器5で受光するよう
に構成されている。受光器5上に照射される各反射光は
、互いに干渉し、ターゲット3が矢印2方向(光軸方向
)にλ/2(λはレーザ光の波長)動くごとに強まシ、
受光器5から得られる出力信号のピーク回数倉計測する
ことによってターゲット3に与えられる変位を知ること
ができる。FIG. 1 is an explanatory diagram of the configuration of a known Michelson displacement meter, which is one of this type of devices. This device splits a laser beam from a laser light source 1 with a beam splitter (hereinafter abbreviated as BS) 2, and irradiates one part to a mirror 30 of a target 3 to which a displacement to be measured is applied, and the other part to a fixed mirror 4. The mirrors 30 and 4 are configured to emit zero reflected light to the light receiver 5 via the BS2. The reflected lights irradiated onto the light receiver 5 interfere with each other and become stronger each time the target 3 moves by λ/2 (λ is the wavelength of the laser beam) in the direction of the arrow 2 (optical axis direction).
By measuring the number of peaks of the output signal obtained from the light receiver 5, the displacement given to the target 3 can be known.
とξろで、仁のような従来装置においては、受光器5か
ら出力される光の強さに対応した信号のレベルが、ミラ
ー30や4が曇つ九場合や、レーザ光源の出力が減衰し
た場合影響を受け、測定誤差を生ずるという欠点がある
。また、変位方向の判別がつかないこと、λ/2 以上
の変位変化を正確に測定できないこと等の欠点がある。However, in a conventional device like the one described above, the level of the signal corresponding to the intensity of the light output from the photoreceiver 5 is reduced when the mirrors 30 and 4 become cloudy or when the output of the laser light source is attenuated. This has the disadvantage that it may be influenced by the sensor and cause measurement errors. Further, there are drawbacks such as the inability to determine the direction of displacement and the inability to accurately measure displacement changes of λ/2 or more.
ここにおいて、本発明は、従来装置におけるこれらの欠
点をなくすることを目的としてなされたものである。The present invention has been made with the object of eliminating these drawbacks of conventional devices.
本発明に係る装置は、マイクルソンの干渉針において、
ターゲットからの反射光及びミラーからの反射光をそれ
ぞれいくつかのビームスプリッタを介して90°ずっ位
相のずれた3又は4種の光信号とし、これらの光信号に
対応した信号を演算することによって、ターゲットの変
位を知るようにしたものである。The device according to the present invention is a micleson interference needle.
By converting the reflected light from the target and the reflected light from the mirror into three or four types of optical signals with a phase shift of 90 degrees through several beam splitters, and calculating signals corresponding to these optical signals. , the displacement of the target is known.
第2図は本発明に係る装置の一例を示す構成説明図であ
る。図において、lは光源で、例えば、HeNe レ
ーザ光源が使用され、ここがら可干渉な光が出射する。FIG. 2 is a configuration explanatory diagram showing an example of the apparatus according to the present invention. In the figure, l is a light source, for example, a HeNe laser light source is used, and from this, coherent light is emitted.
21.22.23.24 Fi、、それぞれ偏光ビーム
スプリッタ(以下PBSと略す)で、第1のPB821
は、光源1からのレーザビームが入射し、これを2方向
に分割する。第2のPBS22ij、第1+7)PBS
211C対してその光軸が45゜回転させて配置され、
また、第3及び第4のPBS23及び24IIi、第2
(7)PB822に対してその光軸が4ぎ回転させて配
置されている。3は反射面30を有するターゲットで、
これには矢印2(光軸)方向の被測定変位が与えられる
。41.42は光経路変更用の固定ミラーで、第1のP
BS 21で分割された光ビームを第2のPBS22に
入射させる。なお、この固定ミラーに代えてプリズム等
を使用するようにしてもよい。51.52.53゜54
はそれぞれ光検出器で、例えばホトトランジスタ、ホ)
ダイオード、光電池等が使用される。21.22.23.24 Fi, the first PB821 is a polarizing beam splitter (hereinafter abbreviated as PBS), respectively.
A laser beam from a light source 1 enters and is split into two directions. 2nd PBS22ij, 1st+7) PBS
The optical axis is arranged with its optical axis rotated by 45 degrees with respect to 211C,
In addition, the third and fourth PBS23 and 24IIi, the second
(7) The optical axis is rotated by four degrees with respect to the PB822. 3 is a target having a reflective surface 30;
The displacement to be measured in the direction of arrow 2 (optical axis) is given to this. 41 and 42 are fixed mirrors for changing the optical path, and the first P
The light beam split by the BS 21 is made incident on the second PBS 22. Note that a prism or the like may be used instead of this fixed mirror. 51.52.53゜54
are each a photodetector, e.g. a phototransistor, e)
Diodes, photovoltaic cells, etc. are used.
光検出器51.52tj:、第30PBS23−t’分
割さ。Photodetector 51.52tj: 30th PBS23-t' divided.
れた光、をそれぞれ受光し、また、光検出器53゜54
は、第4のPB824で分割された光を受光する。61
は第1のPB821とターゲット3との間に設置したλ
/4板、62は第1のPBS21とiジー41との間に
設置したλ/4板である。The photodetectors 53 and 54 receive the received light, respectively.
receives the divided light at the fourth PB824. 61
is the λ installed between the first PB821 and target 3.
A /4 board 62 is a λ/4 board installed between the first PBS 21 and the iG 41.
第3図は第1図装置において、電気的な回路を示す構成
ブロック図である。この図において、71は光検出器5
1と光検出器52との出方信号の差を得る差動増巾器、
72は光検出器53と光検出器54との出力信号の差を
得る差動増巾器、81゜82はそれぞれミキサ、80は
ミキサ81,82を介して印加される各差動増巾器71
.72からの信号を加算する加算増巾器、91は加算増
巾器80の出力周波数信号を計数するカウンタ、92は
ミキサ82に印加している周波数信号(COS・wtc
t)を計数するカラ/り、90fiカウンタ91の計数
値とカウンタ92の計数値とを入力し、加算演算する演
算器である。FIG. 3 is a block diagram showing an electrical circuit in the apparatus shown in FIG. In this figure, 71 is the photodetector 5
a differential amplifier that obtains the difference between the output signals of 1 and the photodetector 52;
72 is a differential amplifier that obtains the difference between the output signals of the photodetector 53 and the photodetector 54, 81 and 82 are mixers, respectively, and 80 is each differential amplifier to which the signal is applied via the mixers 81 and 82. 71
.. 91 is a counter that counts the output frequency signal of the summing amplifier 80; 92 is a frequency signal (COS/wtc) applied to the mixer 82;
This is an arithmetic unit which inputs the count value of the 90fi counter 91 and the count value of the counter 92 and performs an addition operation.
このように構成した装置の動作は次の通りである。光源
lから出射された光は、第1のPR821で2方向に分
割され、一方はλ/4 側光板62を通って円偏光とな
9、ミラー41.42を通って第2のPBB22に入射
し参照光となる。第1のPBS21で分割された他方の
光は、λ/4板6板金1って円偏光となった後、ターゲ
ット3の反射面30で反射され、再びλ/4 板を通り
、直線偏光に戻され、第1のPBS21を経て第2のP
B822に入射する。The operation of the device configured as described above is as follows. The light emitted from the light source 1 is split into two directions by the first PR 821, one passes through the λ/4 side light plate 62 and becomes circularly polarized light 9, and the other passes through the mirror 41.42 and enters the second PBB 22. and serves as a reference light. The other light split by the first PBS 21 becomes circularly polarized light through the λ/4 plate 6 sheet metal 1, is reflected by the reflective surface 30 of the target 3, passes through the λ/4 plate again, and becomes linearly polarized light. is returned to the second PBS via the first PBS 21.
It enters B822.
ここで、参照光の電界をER(EH@1nst+ ER
e08ωt)、ターゲット3の反射面3oがらの戻シ光
をE75in(a+t+ψ)とすれば、第3のPB82
3に入射する光の電界のベクトル図は、!jg4図(イ
)の実線に示す通シとなり、また、第4のPBS24に
入射する光の電界のベクトル図は、第4図(ロ)の実線
に示す通りとなる。ただし、ωは光の角周波数、ψは2
π/λ・2で、λは波長、2はターゲット3の光軸方向
変位量である。Here, the electric field of the reference light is ER (EH@1nst+ER
e08ωt), and if the return light from the reflective surface 3o of the target 3 is E75in (a+t+ψ), then the third PB82
The vector diagram of the electric field of light incident on 3 is ! The vector diagram of the electric field of the light incident on the fourth PBS 24 is as shown by the solid line in FIG. 4(b). However, ω is the angular frequency of light, and ψ is 2
π/λ·2, where λ is the wavelength and 2 is the amount of displacement of the target 3 in the optical axis direction.
ターゲット3からの戻り光は、第2のPB822が、第
1のPB821に対して45°回転して設置しであるの
で、電界は、」1−・sin (ωt+ψ) とな[
る。更に、第2のPB822に対してそれぞれ45°回
転する第3.第4のPBS23.24 を通って、各
光検出器51.52.53.54 に入射する光の電
界は、それぞれ第4図(イ)、(ロ)の破線に示す通り
となる。Since the second PB 822 is rotated by 45 degrees with respect to the first PB 821, the electric field of the return light from the target 3 is 1-sin (ωt+ψ). Further, the third PB 822 is rotated by 45 degrees with respect to the second PB822. The electric field of the light passing through the fourth PBS 23.24 and entering each photodetector 51.52.53.54 is as shown by the broken lines in FIGS. 4(a) and 4(b), respectively.
したがって、各光検出器51〜54で検出される光パワ
ーをPD、〜PD4とすれば、これらはT1)〜(4)
式でそれぞれ表わすことができる。Therefore, if the optical power detected by each photodetector 51 to 54 is PD, to PD4, these are T1) to (4).
Each can be expressed by the formula.
1 1 ET
PD、 =< qERsinωt+r7−77 esi
nC#t+9’))2>1 1
ET
PD・=〈ヴ゛珈°1”を−汀°W−°“ml“訝ψ)
)′〉PD4=<−−−EReosωt−−!= −!
”−5in(1+p))2>四 ■「 ゾ
とおくと、(1)〜(4)式祉それぞれ90°ずつ位相
のずれ念(5)〜(8)式で表わされる信号となる。1 1 ET PD, =< qERsinωt+r7-77 esi
nC#t+9'))2>1 1
ET PD.
)'〉PD4=<---EReosωt--! = −!
``-5in(1+p))2>4 ■'' If we set the equations (1) to (4) to have a phase shift of 90 degrees, the signals will be expressed by the equations (5) to (8).
PD、 = A + B cot tp =
(51P D2 = A B cart v
・・・曲・・16)PD、”=A −B sin
tp ・−” (7)P D4 = A
十B s ln 9’ ・・”・□・” 1
8)第3図に示す回路において、差動増幅器71は光検
出器51.52からの(5)式、(6)式で表わされる
各信号を入力し、両信号の差を演算することによってそ
の出力端に、2Bcosψ なる信号を出力する。同じ
よ51C,差動増幅器7211t、(7)式、(8)式
で表わされる各信号を入力し、両信号の差を演算するこ
とによってその出力端に、−2Bs1nψなる信号を出
力する。加算増巾器8oは、それぞれミキサ81.82
を通って印加される各信号を加算することによって、そ
の出力端に、2B 5in(ωct−ψ)なる周波数信
号余得る。ここでωCは、ミキサ81.82に印加する
キャリア信号のキャリア周波数を示す。カウンタ91は
、加算増幅器8oがらの周波数信号を計数し、塘た、カ
ウンタ92はキ 11ヤリア信号の周波数を計数す
る。演算回路9oは、各カウンタ91.92からの計数
値の差を演算することによって、位相量ψ=二「・2
を求めルコとができる。PD, = A + B cot tp =
(51P D2 = A B cart v
...Song...16) PD, ”=A −B sin
tp ・-” (7) P D4 = A
10 B s ln 9'...”・□・” 1
8) In the circuit shown in FIG. 3, the differential amplifier 71 inputs the signals expressed by equations (5) and (6) from the photodetectors 51 and 52, and calculates the difference between the two signals. A signal of 2Bcosψ is outputted to its output terminal. Similarly, 51C and differential amplifier 7211t are inputted with the signals expressed by equations (7) and (8), and by calculating the difference between the two signals, a signal of -2Bs1nψ is outputted at its output terminal. The summing amplifier 8o is a mixer 81.82, respectively.
By summing each signal applied through the circuit, a frequency signal of 2B 5in(ωct-ψ) is obtained at its output. Here, ωC indicates the carrier frequency of the carrier signal applied to the mixers 81 and 82. A counter 91 counts the frequency signal from the summing amplifier 8o, and a counter 92 counts the frequency of the carrier signal. The arithmetic circuit 9o calculates the phase amount ψ=2"・2 by calculating the difference between the count values from each counter 91.92.
You can ask Ruco.
なお、各光検出器からの出力信号の演算処理回路として
h、ia図のブロック図以外の他の回路を用いてもよい
。ま゛た、ターゲットとしては反射のある拡散面を用い
てもよい。Note that circuits other than those shown in the block diagrams in FIGS. h and ia may be used as arithmetic processing circuits for output signals from each photodetector. Alternatively, a reflective diffusing surface may be used as the target.
また、第2図において、光検出器52を省略して3個の
光検出器とし、第5図に示すような演算処理回路を用い
るようにしてもよい。In addition, in FIG. 2, the photodetector 52 may be omitted to provide three photodetectors, and an arithmetic processing circuit as shown in FIG. 5 may be used.
すなわち、第5図において第3図と異なる点は、光検出
器51.53からの(5)式、(7)式で表わされる信
号の差を演算することによって 2Bs+in(ψ+π
/4)なる信号を得、また、光検出器51.54からの
(5)式、(8)式で表わされる信号の差を演算するこ
とによって−2Ba1n(ψ−π/4)なる信号を得る
ようにし、位相差量ψを演算するようにしたものである
。That is, the difference between FIG. 5 and FIG. 3 is that 2Bs+in(ψ+π
/4), and by calculating the difference between the signals expressed by equations (5) and (8) from the photodetector 51.54, a signal -2Ba1n(ψ-π/4) is obtained. The phase difference amount ψ is calculated.
このように構成した装置によれば、各光検出器から得ら
れる(5)〜(8)式で示されるような信号の差を演算
し、これを更に演算することによって、ターゲット3の
変位量2を知るようにし友ものであるから、例えばiラ
ーが曇ったりして、干渉のビジビリティ−(B/A)が
小さくなっても、これらの影響を受けず、変位測定を行
なうことができる。tた、ターゲットの変位方向は、位
相量9の極性変化となって表われるので、変位方向の判
別も行なうことができる。また、λ/2以上の変位変化
も知る仁とができる。According to the device configured in this way, the displacement amount of the target 3 is calculated by calculating the difference between the signals as shown in equations (5) to (8) obtained from each photodetector, and further calculating this. Therefore, even if the visibility (B/A) of interference becomes small due to fogging of the i-lar, for example, displacement measurement can be performed without being affected by this. Furthermore, since the direction of displacement of the target is expressed as a change in polarity of the phase amount 9, the direction of displacement can also be determined. Furthermore, it is possible to detect displacement changes of λ/2 or more.
第1図は公知のマイケルソン変位計の構成説明図、第2
図は本発明に係る装置の一例を示す構成説明図、第3図
はその電気的な回路を示す構成ブロック図、第4図は動
作説明図、第5図は電気回路の他の例を示す構成ブロッ
ク図である。
1・・・光源、21〜24・・・偏光ビームスプリッタ
、3・・・ターゲット、30・・・反射面、41.42
・・・きラー、51〜54・・・光検出器、61.62
・・・λ/4板代理人 弁理士 小 沢 信 助Figure 1 is an explanatory diagram of the configuration of a known Michelson displacement meter;
The figure is a configuration explanatory diagram showing an example of the device according to the present invention, FIG. 3 is a configuration block diagram showing its electric circuit, FIG. 4 is an operation explanatory diagram, and FIG. 5 is a diagram showing another example of the electric circuit. It is a configuration block diagram. DESCRIPTION OF SYMBOLS 1... Light source, 21-24... Polarization beam splitter, 3... Target, 30... Reflection surface, 41.42
... Killer, 51-54 ... Photodetector, 61.62
...λ/4 Board Agent Patent Attorney Shinsuke Ozawa
Claims (1)
プリッタ及びλ/4(λは波長)板を介して被測定変位
が与えられるターゲットの反射面に照射させ、ここから
の戻り光と的記第1の偏光ビームスプリッタで分割され
次光源からの参照光とをそれぞれ2以上の偏光ビームス
グリツタを介して互いに90”ずつ位相のずれた3又は
4種の光信号とし、これらの光信号に関連し次信号を差
演算を含む所定の演算を行なうことによって位相差量(
ψ)を求め、これから前記ターゲットの変位量を知るよ
うにした光学式変位測定装置。(1) Coherent light from a light source is irradiated via the first polarizing beam splitter and a λ/4 (λ is wavelength) plate to the reflective surface of the target to which the displacement to be measured is applied, and the return light and Note: The first polarizing beam splitter splits the reference light from the next light source into three or four types of optical signals with a phase shift of 90'' from each other through two or more polarizing beam splitters, and these lights are The amount of phase difference (
ψ), and the amount of displacement of the target can be determined from this.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP57108725A JPS58225301A (en) | 1982-06-24 | 1982-06-24 | Optical type displacement measuring apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP57108725A JPS58225301A (en) | 1982-06-24 | 1982-06-24 | Optical type displacement measuring apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS58225301A true JPS58225301A (en) | 1983-12-27 |
Family
ID=14491965
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP57108725A Pending JPS58225301A (en) | 1982-06-24 | 1982-06-24 | Optical type displacement measuring apparatus |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS58225301A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6484101A (en) * | 1987-09-28 | 1989-03-29 | Idec Izumi Corp | Laser interference device |
JPS6484102A (en) * | 1987-09-28 | 1989-03-29 | Idec Izumi Corp | Laser interference device |
JP2010151572A (en) * | 2008-12-25 | 2010-07-08 | Ojima Shisaku Kenkyusho:Kk | Polarization splitting section of polarization-split interferometer, the polarization-split interferometer, and polarization-split interferometer type length measuring device |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS4854950A (en) * | 1971-11-08 | 1973-08-02 | ||
JPS56138202A (en) * | 1980-02-21 | 1981-10-28 | Rank Organisation Ltd | Optical apparatus |
-
1982
- 1982-06-24 JP JP57108725A patent/JPS58225301A/en active Pending
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS4854950A (en) * | 1971-11-08 | 1973-08-02 | ||
JPS56138202A (en) * | 1980-02-21 | 1981-10-28 | Rank Organisation Ltd | Optical apparatus |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6484101A (en) * | 1987-09-28 | 1989-03-29 | Idec Izumi Corp | Laser interference device |
JPS6484102A (en) * | 1987-09-28 | 1989-03-29 | Idec Izumi Corp | Laser interference device |
JP2010151572A (en) * | 2008-12-25 | 2010-07-08 | Ojima Shisaku Kenkyusho:Kk | Polarization splitting section of polarization-split interferometer, the polarization-split interferometer, and polarization-split interferometer type length measuring device |
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