JPH03134503A - Laser length measuring instrument and correcting method for air fluctuation instrument in the instrument - Google Patents
Laser length measuring instrument and correcting method for air fluctuation instrument in the instrumentInfo
- Publication number
- JPH03134503A JPH03134503A JP1271658A JP27165889A JPH03134503A JP H03134503 A JPH03134503 A JP H03134503A JP 1271658 A JP1271658 A JP 1271658A JP 27165889 A JP27165889 A JP 27165889A JP H03134503 A JPH03134503 A JP H03134503A
- Authority
- JP
- Japan
- Prior art keywords
- air
- measurement
- refractive index
- correction
- optical path
- 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
- 238000000034 method Methods 0.000 title claims description 6
- 238000012937 correction Methods 0.000 claims abstract description 44
- 238000006073 displacement reaction Methods 0.000 claims abstract description 14
- 238000005259 measurement Methods 0.000 claims description 55
- 230000003287 optical effect Effects 0.000 claims description 34
- 238000004364 calculation method Methods 0.000 claims description 5
- 230000000644 propagated effect Effects 0.000 claims 3
- 230000010287 polarization Effects 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 4
- 239000011521 glass Substances 0.000 abstract description 2
- 238000012544 monitoring process Methods 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
Landscapes
- Instruments For Measurement Of Length By Optical Means (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明はレーザ測長器及びレーザ測長器における空気の
ゆらぎ、即ち空気の屈折率変化による変位の測定誤差の
補正方法に係り、特に半導体製造装置におけるウェハの
位置決め精度を向上させるのに有効なレーザ測長器及び
レーザ測長器における空気のゆらぎの補正方法に関する
。Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a laser length measuring device and a method for correcting displacement measurement errors due to air fluctuations in the laser length measuring device, that is, changes in the refractive index of the air. The present invention relates to a laser length measuring device effective for improving wafer positioning accuracy in manufacturing equipment and a method for correcting air fluctuations in the laser length measuring device.
半導体製造装置においては、縮小投影露光装置のＸＹス
テージにより高密度にウェハを位置決めする技術が要求
されており、現状ではステージ位置決めようセンサとし
てレーザ測長器が広く利用されている。しかし、半導体
素子の高密度化に伴ないステージに要求される位置決め
精度がより高くなり、レーザビーム上の空気のゆらぎ、
即ち空気の屈折率の変化に起因する測定誤差が無視し得
なくなりつつある。In semiconductor manufacturing equipment, there is a demand for technology for positioning a wafer with high density using an XY stage of a reduction projection exposure apparatus, and currently, laser length measuring devices are widely used as sensors for stage positioning. However, as the density of semiconductor devices increases, the positioning accuracy required for the stage becomes higher, and air fluctuations on the laser beam.
That is, measurement errors caused by changes in the refractive index of air are becoming impossible to ignore.
このような空気のゆらぎによる測定誤差を減らすために
、特開昭６０−２６３８０１号公報に記載の装置によれ
ば、信号ビームの他に屈折率補正用ビームとして参照ビ
ームを信号ビームの近傍に設け、参照ビーム反射鏡と信
号ビーム反射鏡をほぼ同じ距離だけ離して設定すること
により両ビームがほぼ同程度の屈折率変化を受けるので
、両光の干渉をとることによってこれらの影響がほぼキ
ャンセルされるとしているが、近似的に補正を行うだけ
で、測定対象物がある程度長い距離を動いて両ビームの
光路長差が大きくなったときに発生する測定誤差につい
ては配慮していなかった。In order to reduce measurement errors caused by such air fluctuations, according to the device described in Japanese Patent Application Laid-Open No. 60-263801, a reference beam is provided in the vicinity of the signal beam as a refractive index correction beam in addition to the signal beam. By setting the reference beam reflector and the signal beam reflector at approximately the same distance apart, both beams undergo approximately the same degree of refractive index change, so these effects are almost canceled by interference between the two beams. However, it only makes approximate corrections and does not take into account measurement errors that occur when the object to be measured moves a certain long distance and the difference in optical path length between the two beams becomes large.
また現在のところ広く行われている従来技術としては、
環境センサを使って信号ビームの近傍における空気の温
度、圧力、湿度等を測定し、数式によって空気の屈折率
を算出して数値補正を行っていたが、環境の測定点数が
限られるためその測定点数における屈折率の平均値的な
ものでしか補正が行えず、レーザビームパス全体につい
ての補正としては完全なものとは言えなかった。In addition, the conventional techniques that are currently widely used include:
Environmental sensors were used to measure the temperature, pressure, humidity, etc. of the air in the vicinity of the signal beam, and numerical corrections were made by calculating the refractive index of the air using mathematical formulas. However, due to the limited number of environmental measurement points, the measurement Correction can only be made based on the average value of the refractive index at a number of points, and it cannot be said to be a complete correction for the entire laser beam path.
上記従来技術では、測定対象物が変位して参照ビームと
測定ビームの光路長差が大きくなったときには両ビーム
に与える空気の屈折率変化の影響の度合いが異なるため
に補正が不完全になり測定誤差が大きくなる点が課題と
なっていた。In the above conventional technology, when the object to be measured is displaced and the difference in optical path length between the reference beam and the measurement beam becomes large, the degree of influence of the change in the refractive index of air on both beams is different, resulting in incomplete correction and measurement. The problem was that the error was large.
本発明は上記の課題を解決し、測定対象物が長い距離動
いても、測定誤差の補正が完全になされるようにレーザ
測長器及びレーザ測長器における空気のゆらぎの補正方
法を備えることを目的とする。The present invention solves the above problems and provides a laser length measuring device and a method for correcting air fluctuations in the laser length measuring device so that measurement errors are completely corrected even if the object to be measured moves over a long distance. With the goal.
上記目的は、レーザ光の干渉を利用したレーザ測長器に
おいて、レーザビームを二分割し、分割した一方のビー
ムを空気中を経由する測定用ビームとして、これにより
測定用出力を生ずる測定用干渉計手段を構成すると共に
、他方のビームを前記測定用ビームの過分の空気中を経
由して、屈折率変化補正用ビームとし、前記測定用ビー
ムと異なる影響下で空気の屈折率変化の影響を受けた測
定出力を生じる補正用干渉計を構成し、リセット時の前
記両ビームの光路長の情報および空気の屈折率値を定数
入力として且つ前記再測定出力を随時入力として取り込
み、リセット時以降の空気の空気の屈折率変化の影響を
補正した測定対象物の変位量を示す測定結果を出力する
演算装置を備えることにより達成される。The above purpose is to use a laser length measuring device that uses laser beam interference to split the laser beam into two, use one of the split beams as a measurement beam that passes through the air, and thereby generate a measurement output. The other beam is used as a refractive index change correction beam by passing through the air in excess of the measuring beam, and the effect of the refractive index change of the air is corrected under a different influence from the measuring beam. A correction interferometer that generates the received measurement output is constructed, and the information on the optical path lengths of the two beams and the refractive index value of air at the time of reset are taken as constant inputs, and the re-measurement output is taken as input at any time. This is achieved by providing an arithmetic device that outputs a measurement result indicating the amount of displacement of the object to be measured after correcting the influence of the change in the refractive index of the air.
また補正用干渉計において、補正用ビームを参照光と信
号光に分割し、前者を屈折率が一定な光路に、後者を空
気中に伝播させることにより空気の屈折率の変動分だけ
を測定できる。In addition, in a correction interferometer, by splitting the correction beam into a reference beam and a signal beam, and propagating the former through an optical path with a constant refractive index and the latter into the air, it is possible to measure only the variation in the refractive index of the air. .
〔作用〕
レーザビームを２分割して、その一方を屈折率変化に伴
なう測定誤差補正用ビームとして、変位測定用ビームと
は別に全く独立した補正用干渉計を構成する。この補正
用ビームにより空気の屈折率変化をモニタし、このモニ
タの結果を演算装置に取入れて、空気の屈折率変化に起
因する成分を消去して、その影響を全く受けない測定結
果を出力する。[Operation] The laser beam is divided into two parts, one of which is used as a beam for correcting measurement errors due to changes in refractive index, thereby constructing a completely independent correction interferometer separate from the displacement measuring beam. This correction beam monitors the change in the refractive index of the air, and the results of this monitoring are taken into a calculation device to eliminate components caused by the change in the refractive index of the air, and output measurement results that are completely unaffected by the change in the refractive index of the air. .
補正用干渉計においては、その参照光と信号光の光路長
を等しくとり、前者の光路は屈折率が変動しない媒質中
とし、後者の光路は空気中として空気のゆらぎを受ける
ようにすることで、空気の屈折率の変動分だけを測定で
きる。このとき支持部材等の熱伸縮による両光路長の変
動はキャンセルされるので問題とならない、このような
補正用ビームを、変位測定用干渉計の信号光に近いとこ
ろに設置すれば、かなり高い精度でその空気のゆらぎを
モニタし、出力を補正することができる。In a correction interferometer, the optical path lengths of the reference light and signal light are made equal, the former optical path is in a medium whose refractive index does not fluctuate, and the latter optical path is in the air and is subjected to air fluctuations. , only the fluctuations in the refractive index of air can be measured. At this time, fluctuations in both optical path lengths due to thermal expansion and contraction of the support member, etc. are canceled out, so there is no problem.If such a correction beam is installed close to the signal light of the displacement measurement interferometer, it will be possible to achieve considerably high accuracy. This allows you to monitor the air fluctuations and correct the output.
以下５本発明のレーザ測長器の一実施例を第１図及び第
２図により説明する。An embodiment of the laser length measuring device of the present invention will be described below with reference to FIGS. 1 and 2.
レーザ測長器は直線偏光を発振する波長安定化レーザ発
振器１と、発振したレーザ光を二分割するビーム分割器
２とを備え、一方で偏光ビームスプリッタ１５．１／４
波長板１７．偏光板２７及び三角プリズム１６よりなる
補正用干渉計４と、ミラー６及び例えば石英ガラス等で
できた補正用参照光路７により補正用光学系を構成する
と共に、他方で１７４波長板２０，２１、偏光板２８お
よび偏光ビームスプリッタ２７よりなる測定用干渉計５
と、測定対象物であるＸＹステージ１４上に設置された
捧ミラー８により測定用光学系を構成している。The laser length measuring device includes a wavelength stabilized laser oscillator 1 that oscillates linearly polarized light, a beam splitter 2 that splits the oscillated laser light into two, and a polarizing beam splitter 15.1/4.
Wave plate 17. A correction optical system is constituted by a correction interferometer 4 consisting of a polarizing plate 27 and a triangular prism 16, a mirror 6 and a correction reference optical path 7 made of, for example, quartz glass, and on the other hand, 174 wavelength plates 20, 21, Measurement interferometer 5 consisting of a polarizing plate 28 and a polarizing beam splitter 27
A measurement optical system is constituted by a dedicated mirror 8 installed on the XY stage 14 which is the object to be measured.
９．１０はそれぞれ干渉計４，５からの干渉光を光電変
換してこれにより位相変化を測定する光路差測定装置で
、これらの出力Ａ、Ｂを演算装置１１に取り込んで演算
処理し、空気のゆらぎを補正した変位測定出力Ｘを出力
する。9.10 is an optical path difference measuring device that photoelectrically converts the interference light from the interferometers 4 and 5 and thereby measures the phase change.These outputs A and B are taken into the calculation device 11 and processed, and A displacement measurement output X with the fluctuations corrected is output.
以下に、各部の動作を詳細に説明する。波長を安定化し
たレーザ発振器１を発した紙面に対して４５°方向に偏
光面をもつ直線偏光のレーザ光は、ビーム分割器２によ
り補正用ビーム２３と測定用ビーム２４に２分割される
。補正用ビーム２３は補正用干渉計４の偏光ビームスプ
リッタ１５に入射し、紙面に垂直な直線偏光成分である
補正用参照光２５と５紙面に平行な直線偏光成分である
補正用信号光２６に２分割される。補正用参照光２５は
１／４波長板１７を経て円偏光となり、例えば石英ガラ
スなどでできているロンド状の補正用参照光路７中を伝
播し、その先端に位置する反射鏡６で反射され、再び同
一光路を戻って偏光ビームスプリッタ１５に至るが、１
／４波長板１７を一往復したこの光は偏光面が９０°回
転しているので今度は偏光ビームスプリッタ１５を透過
して偏光板２７に至る。一方、はじめに偏光ビームスプ
リッタ１５を透過した補正用信号光２６は三角プリズム
１６で反射し１／４波長板を経て同じく円偏光となるが
、こちらは空気中を伝播して反射鏡６に至り、ここで反
射されてやはり同一光路を戻って偏光ビームスプリッタ
１５に再入射する。The operation of each part will be explained in detail below. Linearly polarized laser light having a polarization plane at 45 degrees with respect to the plane of the paper, which is emitted by a wavelength-stabilized laser oscillator 1, is split into two by a beam splitter 2 into a correction beam 23 and a measurement beam 24. The correction beam 23 enters the polarization beam splitter 15 of the correction interferometer 4, and is divided into a correction reference beam 25, which is a linearly polarized component perpendicular to the plane of the paper, and a correction signal beam 26, which is a linearly polarized component parallel to the plane of the paper. It is divided into two parts. The correction reference light 25 becomes circularly polarized light after passing through a quarter-wave plate 17, propagates through a Rondo-shaped correction reference optical path 7 made of, for example, quartz glass, and is reflected by a reflecting mirror 6 located at the tip thereof. , returns along the same optical path again to reach the polarizing beam splitter 15, but 1
Since the plane of polarization of this light that has made one round trip through the /4 wavelength plate 17 has been rotated by 90 degrees, it passes through the polarizing beam splitter 15 and reaches the polarizing plate 27. On the other hand, the correction signal light 26 that first passes through the polarizing beam splitter 15 is reflected by the triangular prism 16 and becomes circularly polarized light after passing through a quarter-wave plate, but this propagates through the air and reaches the reflecting mirror 6. It is reflected here, returns along the same optical path, and enters the polarizing beam splitter 15 again.
この場合も先と同様１／４波長板を一往復したこの光は
偏光面が９０’回転しているので今度は偏光ビームスプ
リッタ１５で反射して先の補正用参照光と共に偏光板２
７に至る。ここで偏光板２７はその透過軸を紙面に対し
て４５°に設置しであるので１両光の共通な偏光成分同
志が干渉を起こす。補正用参照光路はすべてガラス中な
ので空気のゆらぎの影響を受けることはなくその光路長
は安定しているのに対し、補正用信号光路上の空気の屈
折率がゆらぎにより変化すると、反射光の位相が変化し
、干渉光の強度が変化するので、光路差測定装置９にお
いてその強度変化から、空気のゆらぎによる位相の変化
分を出力Ａとして得られる。つまり、この出力Ａは、補
正用信号光路上の空気のゆらぎの度合いを示しているこ
とになり、これが空気の屈折率変化のモニタとなる。In this case, as before, this light that has made one round trip through the 1/4 wavelength plate has its polarization plane rotated by 90', so it is reflected by the polarizing beam splitter 15 and sent to the polarizing plate 2 along with the previous correction reference light.
It reaches 7. Here, since the polarizing plate 27 has its transmission axis set at 45 degrees with respect to the plane of the paper, the common polarized components of both lights cause interference. Since the correction reference optical path is entirely inside glass, it is not affected by air fluctuations and its optical path length is stable. However, if the refractive index of the air on the correction signal optical path changes due to fluctuations, the reflected light will change. Since the phase changes and the intensity of the interference light changes, the optical path difference measuring device 9 obtains the change in phase due to air fluctuations as an output A from the change in intensity. In other words, this output A indicates the degree of fluctuation of the air on the correction signal optical path, and serves as a monitor for the change in the refractive index of the air.
次にビーム分割器２で分けられた一方の光、測定用ビー
ム２４は１反射鏡３を経て測定用干渉計５の偏光ビーム
スプリッタ２２に入射する。ここでも先の補正用ビーム
の場合と同様に偏光ビームスプリッタ２２で測定用参照
光と測定用信号光に２分割される。測定用参照光ははじ
め偏光ビームスプリッタ２２を透過して１／４波長板２
１へ入射し、その裏面に付けた反射膜２９で反射して再
び偏光ビームスプリッタ２２を経て偏光板２８に至る。Next, one of the lights separated by the beam splitter 2, the measuring beam 24, passes through one reflecting mirror 3 and enters the polarizing beam splitter 22 of the measuring interferometer 5. Here, as in the case of the correction beam, the beam is split into two by the polarization beam splitter 22 into a measurement reference beam and a measurement signal beam. The reference light for measurement first passes through the polarizing beam splitter 22 and passes through the 1/4 wavelength plate 2.
1, is reflected by a reflective film 29 attached to the back surface, passes through the polarizing beam splitter 22 again, and reaches the polarizing plate 28.
−力測定用信号光ははじめ偏光ビームスプリッタ２２で
反射し、１７４波長板２０を経てＸＹステージ１４上の
捧ミラー８に至り、ここで反射して再び１７４波長板２
−Ｏ２偏光ビームスプリッタ２２を経て偏光板２８に至
る。ここで両光の共通成分同志が干渉し、ステージ１４
が変位して測定用信号光路長が変化することに応じてそ
の干渉光張渡が変化するので、これを光路差測定装置１
０において処理し、ｘＹステージの変位量として出力Ｂ
を得ている。- The signal light for force measurement is first reflected by the polarizing beam splitter 22, passes through the 174-wave plate 20, reaches the dedicated mirror 8 on the XY stage 14, and is reflected there again to the 174-wave plate 20.
-O2 The light passes through the polarizing beam splitter 22 and reaches the polarizing plate 28. Here, the common components of both lights interfere, and the stage 14
As the measurement signal optical path length changes due to the displacement, the interference light distribution changes.
0, and output B as the displacement amount of the xY stage.
I am getting .
続いて出力Ａ、Ｂについて説明する。ここでは測定の原
点（リセット時）、つまり測定対象物のＸＹステージ１
４の変位が零の時の測定用干渉計５とＸＹステージ上の
棒ミラー８との距離をＱｌ。Next, outputs A and B will be explained. Here, the origin of measurement (at reset), that is, the XY stage 1 of the measurement target
Ql is the distance between the measuring interferometer 5 and the rod mirror 8 on the XY stage when the displacement of 4 is zero.
補正用干渉計４と反射鏡６との距離、つまり補正用参照
光路長をｆｉｘ、補正用参照光路７を構成する部材の屈
折率をｎｇ、またＱｌ及びＱＺの領域では空気の屈折率
は一様でｎであると考える。この状態から測定対象物で
あるＸＹステージ１４がＸだけ変化したとし、この間に
空気の屈折率が全光路上において一様にΔｎだけ変化し
て（ｎ＋Δｎ）になったとすると光路差測定装置！９．
１０の出力Ａ、Ｂはそれぞれ次のようになる。The distance between the correction interferometer 4 and the reflecting mirror 6, that is, the correction reference optical path length, is fixed, the refractive index of the member constituting the correction reference optical path 7 is ng, and the refractive index of air is the same in the regions Ql and QZ. and n. Suppose that the XY stage 14, which is the object to be measured, changes by an amount of X from this state, and during this time, the refractive index of the air uniformly changes by Δn on the entire optical path to become (n+Δn), then the optical path difference measuring device! 9.
The outputs A and B of 10 are as follows.
Ａ＝（ｎｇ−ｒｌ＋Δｎ）Ｑｔ−（ｎｇ−ｎ）Ｑｚ＝Δ
ｎＱ１ ・・・（１）Ｂ＝（ｕ
ｚ＋ｘ）（ｎ＋Δｎ）−Ｑｚｎ＝＝ｎｘ＋（１ｔ＋ｘ）
Δｎ −（２）（１）よりΔｎ ＝ Ａ
／ Ｑ １ を（２）に代入してＸについて整理すると
次のようになる。A=(ng-rl+Δn)Qt-(ng-n)Qz=Δ
nQ1...(1)B=(u
z+x)(n+Δn)-Qzn==nx+(1t+x)
Δn - (2) From (1), Δn = A
/ Q 1 is substituted into (2) and rearranged regarding X, the result is as follows.
Ｊｌ ｔ ｎ ＋ Ａ
従ってリセット時のＭｔ、Ｑｚ、ｎの値を初期値として
演算装置１１に入力しておき、光路差測定装置９，１０
の出力Ａ、Ｂを随時演算装置１１に取り込んで（３）式
の演算を実行し、その解Ｘを随時出力又として出力すれ
ば、この出力Ｘは空気の屈折率変化Δｎ、つまり空気の
ゆらぎの影響を受けない安定な変位Ｘの測定結果となる
。Jl t n + A Therefore, the values of Mt, Qz, and n at the time of reset are input to the arithmetic unit 11 as initial values, and the optical path difference measuring devices 9 and 10
If the outputs A and B of are taken into the arithmetic unit 11 at any time and the calculation of equation (3) is executed, and the solution X is output as an output at any time, this output This results in a stable measurement result of displacement X that is not affected by.
２二で初期値として用いるリセット時のＱｌの測定誤差
あるいは測定中の温度変動によるａｌの変動による測定
誤差を検討する。Ｑｌに誤差δＱｌが含まれるときに発
生する測定誤差δＸはっぎのようになる。In step 22, a measurement error due to a measurement error of Ql at the time of reset used as an initial value or a measurement error due to a variation in al due to a temperature variation during measurement is examined. The measurement error δX that occurs when Ql includes an error δQl is as follows.
一δＱ ｚＢ （ｆｆ ｔｎ ＋Ａ）＋δＱ１ｎ（ＱＩ
Ｂ−ＱｚＡ）（（ａｌ−δＩｘ）ｎ＋Ａ）（１２ｔｎ＋
Ａ）−δＱ１・Ａ（Ｂ＋Ｑ２ｎ）
Ｑｘ”
ここで実際的な値としてＱｚ＝Ｑｚ＝Ｂ＝０．２（ｍ）
、ｎ＝１．またこの程度の長さの光路上で気温が仮に１
℃変化するとΔｎは１０−６程度変化するので、これら
の値を代入すると
δｘ＝２６ＱｚＸ１０−’
よって、測定値Ｘを誤差ｉｎｎ以下で測定するためには
２δｊｌｚＸ１０″″Ｂ＜１０−”
δｎｔ＜５Ｘ１０″″４（ｍ）
という条件から、初期値としてのａＸの精度は０．５（
■）程度でよく、また測定中にΩ！が０．５（■）程度
は変動しても支障はない。- δQ zB (ff tn +A) + δQ1n (QI
B-QzA) ((al-δIx)n+A)(12tn+
A)-δQ1・A(B+Q2n) Qx” Here, as a practical value, Qz=Qz=B=0.2(m)
, n=1. Also, if the temperature is 1 on an optical path of this length,
When ℃ changes, Δn changes by about 10-6, so by substituting these values, δx=26QzX10-' Therefore, in order to measure the measured value Based on the condition ``''4 (m), the accuracy of aX as an initial value is 0.5 (
■) is sufficient, and during measurement, Ω! There is no problem even if it fluctuates by about 0.5 (■).
本発明によれば、レーザ干渉を利用した測長器において
、ビームを二分割して、一方を変位測定用ビームとし、
他方を補正用ビームとして空気の屈折率をモニタし、両
ビームによる測定結果を演算する装置に取り込み、Ｈｉ
折率変化分を消去する演算を行うことにより、測定対象
物がどのような位置にあるときにでも、また空気の屈折
率がビーム上でどのように分布し、さらにそれが不均一
に変化するときにでも空気の屈折率変化による変位の測
定誤差を補正し、高精度で再現性の高い安定な出力が得
られる。According to the present invention, in a length measuring device using laser interference, a beam is divided into two, one of which is used as a beam for measuring displacement,
The other beam is used as a correction beam to monitor the refractive index of the air, and the measurement results from both beams are taken into a device that calculates the Hi.
By performing calculations to eliminate changes in the refractive index, it is possible to determine how the refractive index of air is distributed on the beam, regardless of the position of the object to be measured, and how it changes non-uniformly. It corrects displacement measurement errors caused by changes in the refractive index of air, and provides stable output with high precision and high reproducibility.
現状では空気の流れによる屈折率の変化によって、０．
０１〜０．１μｍ程度の測定誤差が発生するが本発明に
よれば、この誤差を１／１０〜１／１００に低（できる
。Currently, due to changes in the refractive index due to air flow, the 0.
Although a measurement error of about 0.01 to 0.1 μm occurs, according to the present invention, this error can be reduced to 1/10 to 1/100.
第１図は本発明のレーザ測長器の構成図、第２図は第１
図に示した補正用光学系部分の拡大図である。
１・・・レーザ発振器、２・・・ビーム分割器、４・・
・補正用干渉計、５・・・測定用干渉計、７・・・補正
用参照光ｊ１算栗ＩFig. 1 is a configuration diagram of the laser length measuring device of the present invention, and Fig. 2 is a configuration diagram of the laser length measuring device of the present invention.
FIG. 3 is an enlarged view of the correcting optical system portion shown in the figure. 1... Laser oscillator, 2... Beam splitter, 4...
- Interferometer for correction, 5... Interferometer for measurement, 7... Reference light j1 for correction I
Claims (1)
レーザビームを二分割する手段と、分割した一方のビー
ムを空気中を経由する測定用ビームとして、これにより
測定対象物の変位量を示す測定出力を生ずる測定用干渉
計手段と、他方のビームを前記測定用ビームの近傍の空
気中を経由して屈折率変化補正用ビームとし、前記測定
用ビームと異なる影響下で空気の屈折率変化の影響を受
けた測定出力を生ずる補正用干渉計手段と、リセット時
の前記両ビームの光路長の情報および空気の屈折率値を
定数入力として且つ前記両干渉計手段の測定出力を随時
入力として取り込み、リセット時以降の空気の屈折率変
化の影響を補正した測定対象物変位量を示す測定結果を
出力する演算手段とからなるレーザ測長器。２、前記補
正用干渉計手段が前記補正用ビームを参照光と信号光に
分割する手段を含み、更に屈折率が一定な光路を設けて
、前記参照光を前記光路に、前記信号光を空気中に伝播
させるようにした請求項１記載のレーザ測長器。 ３、レーザ光の干渉を利用したレーザ測長器において、
レーザビームを二つに分割し、一方のビームを空気中を
経由する測定用ビームとして、これにより測定対象物の
変化量を示す測定出力を生じる測定用干渉計を構成する
と共に、他方のビームを前記測定用ビームの近傍の空気
中を経由して屈折率変化補正用ビームとし、前記測定用
ビームと異なる影響下で空気の屈折率変化の影響を受け
た測定出力を生じる補正用干渉計を構成し、リセット時
の前記両ビームの光路長の情報および空気の屈折率値を
定数入力として且つ前記両測定出力を随時入力として取
り込み、リセット時以降の空気の屈折率変化の影響を補
正した測定対象物の変化量を示す測定結果を出力するよ
うにしたことを特徴とするレーザ測長器における空気の
ゆらぎに伴なう測定誤差の補正方法。 ４、前記補正用ビームを参照光と信号光に分割し、更に
屈折率が一定な光路を設けて、前記参照光を前記光路に
、前記信号光を空気中に伝播させることを特徴とする請
求項３記載の方法。[Claims] 1. In a laser length measuring device using interference of laser light,
A means for splitting a laser beam into two; a measuring interferometer means for using one of the split beams as a measurement beam passing through the air to thereby generate a measurement output indicating the amount of displacement of an object to be measured; a correction interferometer means for generating a refractive index change correction beam through the air near the measurement beam, and producing a measurement output affected by the refractive index change of the air under a different influence from the measurement beam; , the information on the optical path lengths of the two beams and the refractive index value of air at the time of reset are taken as constant inputs, and the measurement outputs of both of the interferometer means are taken in as inputs at any time, and the influence of the change in the refractive index of air after the time of reset is corrected. A laser length measuring device comprising calculation means for outputting a measurement result indicating the amount of displacement of an object to be measured. 2. The correction interferometer means includes means for splitting the correction beam into a reference beam and a signal beam, and further includes an optical path with a constant refractive index, so that the reference beam is placed in the optical path and the signal beam is placed in the air. 2. The laser length measuring device according to claim 1, wherein the laser beam is propagated inside. 3. In a laser length measuring device that uses laser light interference,
The laser beam is split into two, and one beam is used as a measurement beam that passes through the air, thereby constructing a measurement interferometer that generates a measurement output that indicates the amount of change in the object to be measured. A correction interferometer is configured to generate a refractive index change correction beam through the air near the measurement beam, and generate a measurement output affected by the refractive index change of the air under a different influence from the measurement beam. The information on the optical path lengths of the two beams at the time of reset and the refractive index value of the air are taken as constant inputs, and both of the measurement outputs are taken in as inputs at any time, and the influence of the change in the refractive index of the air after the time of reset is corrected. A method for correcting measurement errors caused by air fluctuations in a laser length measuring device, characterized in that a measurement result indicating the amount of change in an object is output. 4. A claim characterized in that the correction beam is divided into a reference beam and a signal beam, further an optical path having a constant refractive index is provided, and the reference beam is propagated through the optical path and the signal beam is propagated in the air. The method described in Section 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1271658A JPH03134503A (en) | 1989-10-20 | 1989-10-20 | Laser length measuring instrument and correcting method for air fluctuation instrument in the instrument |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1271658A JPH03134503A (en) | 1989-10-20 | 1989-10-20 | Laser length measuring instrument and correcting method for air fluctuation instrument in the instrument |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03134503A true JPH03134503A (en) | 1991-06-07 |
Family
ID=17503098
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1271658A Pending JPH03134503A (en) | 1989-10-20 | 1989-10-20 | Laser length measuring instrument and correcting method for air fluctuation instrument in the instrument |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03134503A (en) |
-
1989
- 1989-10-20 JP JP1271658A patent/JPH03134503A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6541759B1 (en) | Interferometry system having a dynamic beam-steering assembly for measuring angle and distance and employing optical fibers for remote photoelectric detection | |
| US5991033A (en) | Interferometer with air turbulence compensation | |
| US6839141B2 (en) | Method and apparatus for compensation of time-varying optical properties of gas in interferometry | |
| US6888638B1 (en) | Interferometry system having a dynamic beam steering assembly for measuring angle and distance | |
| US5847828A (en) | Michelson interferometer using matched wedge-shaped beam splitter and compensator | |
| JPH021501A (en) | Laser interference length measuring machine and positioning method using the same machine | |
| KR20010041209A (en) | Interferometer and method for measuring the refractive index and optical path length effects of air | |
| JPH08240792A (en) | Beam outputting device and beam outputting method | |
| JPH0198902A (en) | Light wave interference length measuring instrument | |
| US20180045500A1 (en) | Method of air refractive index correction for absolute long distance measurement | |
| US5493395A (en) | Wavelength variation measuring apparatus | |
| KR101429532B1 (en) | Wavelength shift measuring apparatus, optical source apparatus, interference measuring apparatus, exposure apparatus, and device manufacturing method | |
| KR100588128B1 (en) | Lithographic Apparatus and Device Manufacturing Method | |
| US6563593B2 (en) | Dynamic angle measuring interferometer | |
| JPH09178415A (en) | Light wave interference measuring device | |
| KR20200143482A (en) | Measurement assembly for frequency-based determination of component location | |
| US20200240770A1 (en) | Device and Method for Calibrating a Measuring Apparatus Using Projected Patterns and a Virtual Plane | |
| JPH03134503A (en) | Laser length measuring instrument and correcting method for air fluctuation instrument in the instrument | |
| US11353315B2 (en) | Laser interference device | |
| JP2000314609A (en) | Laser interferometric measuring device | |
| JP3508988B2 (en) | Measurement method of phase shift amount for processing phase shift mask | |
| JPH0543058U (en) | Air refractive index measuring device | |
| JPH06123607A (en) | Length measuring device | |
| WO2024037799A1 (en) | Method to stabilize a wavelength of a tunable laser device, tunable laser device, and position measurement system provided with the tunable laser device | |
| JPH0373825A (en) | Instrument for measuring refractive index of fluid |