JP2990309B2 - Optical member for measuring correction coefficient of differential interferometer - Google Patents
Optical member for measuring correction coefficient of differential interferometerInfo
- Publication number
- JP2990309B2 JP2990309B2 JP3137826A JP13782691A JP2990309B2 JP 2990309 B2 JP2990309 B2 JP 2990309B2 JP 3137826 A JP3137826 A JP 3137826A JP 13782691 A JP13782691 A JP 13782691A JP 2990309 B2 JP2990309 B2 JP 2990309B2
- Authority
- JP
- Japan
- Prior art keywords
- length
- wavelength
- fixed
- measuring
- reflecting member
- 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 - Lifetime
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- Instruments For Measurement Of Length By Optical Means (AREA)
Description
【0001】[0001]
【産業上の利用分野】本発明は、レーザ光源からのレー
ザ光束を参照光束と測長光束に分岐して、平行な両光束
をそれぞれ戻し部材で来た方向に戻す往復光路に通した
後、両光束を合わせて両光束の前記戻し部材の間の距離
情報を担持した干渉光束を得る差動型干渉測長計の波長
補正に用いられる補正係数測定用光学部材(以下、単に
補正用部材と言う)に関する。BACKGROUND OF THE INVENTION The present invention relates to a method for splitting a laser beam from a laser light source into a reference beam and a length-measuring beam, and passing the two parallel beams through a reciprocating optical path for returning the beams in the direction in which they came from a returning member. An optical member for correction coefficient measurement (hereinafter simply referred to as a correction member) used for wavelength correction of a differential interferometer that obtains an interference light beam carrying distance information between the return members of the two light beams by combining the two light beams. ).
【0002】[0002]
【従来の技術】上述のような差動型干渉測長計は参照光
束と測長光束の前記戻し部材間の距離の変化をnm程度の
測長分解能の精度で求めることができる。しかし、それ
には、温湿度や大気圧等の環境条件の変化で変わる波長
が関係するから、波長変化に基づく誤差を補正する必要
があり、その補正には従来、参照光束と測長光束に予じ
め知り得る基準長の光路差を設けておいて環境条件の変
化に伴って波長が変化することによる基準長光路差の測
定波数変化を二つの環境条件間について求め、別途例え
ば同様の測長計により前記二つの環境条件のうちの一方
の環境条件を基準条件としてその条件で波数が例えば1
だけ変化する測長鏡の移動量から基準条件の波長すなわ
ち基準波長を求めて、この基準波長と基準長光路差と測
定波数変化とから基準条件に対して変化した他方の環境
条件での波長を計算し、得られた波長を別途同様の環境
条件と測長計により求めた測定波数に対して用いる第1
の方法、参照光束と測長光束をそれぞれ同じ距離の環境
条件が変化しない真空中と変化する空気中を通すことで
両光束から基準波長に対する環境条件の変化に伴う波長
変化を求め、別途第1の方法で基準波長を求めたのと同
じ方法で上述の波長変化に対応した環境条件の波長を求
めてその波長と波長変化とから基準波長を決定し、その
基準波長と環境条件に応じた波長変化から環境条件に応
じた波長を求めて、その波長を同様の環境条件と測長計
により求めた測定波数に対して用いる第2の方法、環境
条件の温度、湿度、大気圧、CO2濃度を測定し、Edl'en
らの関係式により空気の屈折率を求め、それからレーザ
光源の発振周波数によりレーザ光束の大気中での波長を
求めて、その波長を同様の環境条件で求めた測定波数に
対して用いる第3の方法、第3の方法で求めた波長を第
1の方法における基準波長や第2の方法における波長変
化に対応した環境条件の波長として用いる第3と第1ま
たは第2の方法を組合わせたような第4の方法が用いら
れている。これらの方法のうちでは第1と第2の方法、
特に第1の方法が最も直接的な測定に基づく簡便な補正
方法である。2. Description of the Related Art A differential interferometer as described above can determine a change in the distance between a return beam of a reference beam and a length measurement beam with an accuracy of a length measurement resolution of about nm. However, since this involves a wavelength that changes due to changes in environmental conditions such as temperature and humidity and atmospheric pressure, it is necessary to correct errors based on the change in wavelength. The optical path difference of the reference length that can be known in advance is provided, and the measurement wave number change of the reference length optical path difference due to the change of the wavelength with the change of the environmental condition is obtained for the two environmental conditions. As a result, one of the two environmental conditions is set as a reference condition, and the wave number is, for example, 1 under the condition.
The wavelength of the reference condition, that is, the reference wavelength, is obtained from the amount of movement of the length measuring mirror that only changes, and the wavelength under the other environmental condition that has changed with respect to the reference condition is determined from the reference wavelength, the reference length optical path difference, and the change in the measurement wave number. Calculate and use the obtained wavelength separately for the same environmental conditions and the measured wave number obtained by the length measuring device.
In the method, the reference light beam and the length measuring light beam are passed through the same distance in a vacuum where the environmental conditions do not change and in the changing air, thereby obtaining a wavelength change due to the change in the environmental conditions with respect to the reference wavelength from both the light beams. The wavelength of the environmental condition corresponding to the above-mentioned wavelength change is obtained by the same method as that for obtaining the reference wavelength by the method described above, and the reference wavelength is determined from the wavelength and the wavelength change, and the wavelength corresponding to the reference wavelength and the environmental condition is obtained. A second method of obtaining a wavelength corresponding to the environmental condition from the change, and using the wavelength for the same environmental condition and the measurement wave number obtained by the length meter, temperature, humidity, atmospheric pressure, and CO 2 concentration of the environmental condition Measure and Edl'en
The third is to determine the refractive index of air by the above relational expressions, then determine the wavelength of the laser beam in the atmosphere by the oscillation frequency of the laser light source, and use that wavelength for the measurement wave number determined under similar environmental conditions. Method, a combination of the third method and the first or second method using the wavelength obtained by the third method as the reference wavelength in the first method or the wavelength of the environmental condition corresponding to the wavelength change in the second method. A fourth method is used. Of these methods, the first and second methods,
In particular, the first method is a simple correction method based on the most direct measurement.
【0003】第1および第2の方法にはそれぞれ図3お
よび図4に示したような補正用部材1が用いられる。図
3の補正用部材1は、例えば石英等の低線膨張係数材料
から成るスペーサ11によって部分裏面鏡板12と表面鏡板
13とを環境条件の変化に対し安定して予め正確に求める
ことができる間隔で平行に対峙させた構造から成る。ま
た、図4の補正用部材1は、石英等の低線膨張係数材料
から成る筒壁14と、筒壁14の両端を閉塞して筒壁14内の
真空を保ち筒壁14の少なくとも対向壁部分の両外側に張
り出す表面積を持った一端側の透光端板15と、他端側の
前記透光端板15と対向する面に反射面16aを形成されて
いる反射鏡端板16との結合構造から成る。In the first and second methods, a correction member 1 as shown in FIGS. 3 and 4, respectively, is used. The correction member 1 shown in FIG. 3 is made up of a partial back end plate 12 and a front end plate 12
13 in parallel with each other at an interval that can be obtained stably and accurately in advance with respect to changes in environmental conditions. 4 includes a cylindrical wall 14 made of a material having a low linear expansion coefficient such as quartz and a cylindrical wall 14 which is closed at both ends to maintain a vacuum inside the cylindrical wall 14 and at least an opposing wall of the cylindrical wall 14. A light-transmitting end plate 15 on one end side having a surface area extending to both outer sides of the portion, and a reflecting mirror end plate 16 having a reflecting surface 16a formed on a surface facing the light-transmitting end plate 15 on the other end side. .
【0004】図3の測長計は、不図示のレーザ光源から
の矢印を符した実線Lで示した、ヘテロダイン方式では
互いに直交した直線偏光の2波長のレーザ光束、または
干渉縞係数方式では単一波長の円偏光のレーザ光束が、
偏光ビームスプリッタ2により矢印を符した一点鎖線で
示した参照光束Rと矢印を符した二点鎖線で示した測長
光束Mとに分岐され、参照光束Rが補正用部材1の部分
裏面鏡板12で反射される往復光路を2度通り、測長光束
Mが補正用部材1の表面鏡板13で反射される往復光路を
2度通って、その後両光束M,Rが偏光ビームスプリッ
タ2により会合させられて部分裏面鏡板12と表面鏡板13
の反射面間の距離情報を担持した矢印を符した点線で示
した干渉光束Iを与え、この干渉光束Iを図3には不図
示の検出手段に入力して環境条件の変化で波長が変化す
ることによる前記反射面間の測定長変化をヘテロダイン
方式では2波長のビート周波数の変化として、また干渉
縞係数方式では干渉縞の強度変化として求めるものであ
る。そして第1の方法は、図3の測長計で求めた測定長
変化と、スペーサ11の長さとして別に求められる基準長
と、別の同様の差動型干渉測長計を用いて図3の測長計
で測定長変化を求めたときの一方の環境条件と同じ条件
により測長鏡の1波長分の移動量として求められる基準
波長とから測定長変化を求めたときの他方の環境条件に
対応する波長を求めて、この波長を同様の環境条件と測
長計により求めた測定波数の波長として用いる方法であ
る。なお、第4の方法は、上述の基準波長の代りに前述
の第3の方法で得られる同じ環境条件に対応した波長を
用いる方法である。また図3の参照光束Rと測長光束M
は入れ換っても結果は変らない。そして、3はコーナー
キューブプリズム、4はλ/4移相板、5は反射鏡であ
る。The length measuring device shown in FIG. 3 is a laser beam of two wavelengths of linearly polarized light orthogonal to each other in the heterodyne system or a single beam in the interference fringe system, as indicated by a solid line L with an arrow from a laser light source (not shown). A circularly polarized laser beam of wavelength
The polarization beam splitter 2 splits the reference light beam R indicated by an alternate long and short dash line indicated by an arrow and the length measuring light beam M indicated by an alternate long and two short dash line indicated by an arrow. The light beam M passes through the reciprocating optical path twice, and the length-measuring light beam M passes through the reciprocating light path twice reflected by the front end plate 13 of the correcting member 1. Thereafter, the two light beams M and R are associated by the polarizing beam splitter 2. Partial back plate 12 and front plate 13
And the interference light flux I indicated by a dotted line with an arrow carrying information on the distance between the reflection surfaces is input to the detection means (not shown in FIG. 3), and the wavelength changes with environmental conditions. The change in the measurement length between the reflection surfaces is obtained as a change in the beat frequency of two wavelengths in the heterodyne method, and as a change in the intensity of the interference fringe in the interference fringe coefficient method. The first method uses the measurement length change obtained by the length measuring device shown in FIG. 3, the reference length separately obtained as the length of the spacer 11, and the other similar differential interferometers shown in FIG. It corresponds to the other environmental condition when the measurement length change is obtained from the reference wavelength obtained as the movement amount for one wavelength of the length measuring mirror under the same condition as the one environmental condition when the measurement length change is obtained by the length meter. In this method, a wavelength is determined, and this wavelength is used as a wavelength of a measurement wave number determined by a similar environmental condition and a length measuring instrument. The fourth method is a method using a wavelength corresponding to the same environmental condition obtained by the above-described third method, instead of the above-described reference wavelength. Further, the reference beam R and the measuring beam M shown in FIG.
The result does not change even if is replaced. Reference numeral 3 denotes a corner cube prism, 4 denotes a λ / 4 phase shift plate, and 5 denotes a reflecting mirror.
【0005】図4の測長計は、図3と同様のレーザ光束
Lが図3と同様の光学系または従来公知の偏光シェアリ
ング板等を用いた光学系あるいは先に本発明者により発
明されて特願平3-44890号により出願されている干渉プ
リズムを用いた光学系から成るような干渉用の分岐会合
光学系6によって参照光束Rと測長光束Mに分岐され、
参照光束Rが筒壁14の内側の真空中を通って反射鏡端板
16の反射面16aで反射される往復光路を2度通り、測長
光束Mが筒壁14の外側の空気中を通って反射鏡端板16の
反射面16aで反射される往復光路を2度通った後、参照
光束Rと測長光束Mが分岐会合光学系6によって会合さ
せられて環境条件の変化で基準波長に対し変化した波長
情報を担持している干渉光束Iとして検出手段7に入射
され、検出手段7により基準波長に対し相対的に変化し
た波長を求めるものである。この場合も基準波長を第1
の方法と同様別途測長計または第3の方法により求め、
その基準波長と上述の相対的変化の波長とから環境条件
に応じて変化した波長を求め、その波長を同様の環境条
件と測長計により求めた測定波数に乗ずることになる。In the length measuring device shown in FIG. 4, a laser beam L similar to that shown in FIG. 3 has an optical system similar to that shown in FIG. 3, an optical system using a conventionally known polarization sharing plate or the like, or has been invented by the present inventors. The reference light beam R and the length measuring light beam M are branched by a branching and associating optical system 6 for interference such as an optical system using an interference prism filed by Japanese Patent Application No. 3-44890.
The reference light beam R passes through the vacuum inside the cylindrical wall 14 and passes through the reflector end plate.
The measurement light flux M passes through the air outside the cylindrical wall 14 twice and passes through the reciprocating optical path reflected by the reflecting surface 16a of the reflecting mirror end plate 16 twice. After passing through, the reference light beam R and the measuring light beam M are associated by the branching association optical system 6 and are incident on the detection means 7 as an interference light beam I carrying wavelength information changed with respect to the reference wavelength due to a change in environmental conditions. The detection means 7 obtains a wavelength relatively changed with respect to the reference wavelength. Also in this case, the reference wavelength is set to the first.
In the same way as the method described above, it is separately obtained by a length measuring device or the third method,
A wavelength changed according to environmental conditions is obtained from the reference wavelength and the wavelength of the above-mentioned relative change, and the wavelength is multiplied by the same environmental conditions and a measurement wave number obtained by a length measuring instrument.
【0006】[0006]
【発明が解決しようとする課題】従来の図3に示した補
正用部材1は、前述のように、少なくともスペーサ部材
11と、透光板の片面中央部に反射防止コートを設け、そ
の両側に反射コートを設けたような部分裏面鏡板12と、
表面鏡板13とを接合した構造から成るため、精度よく作
るのに手間が掛ってコストが高く付くと言う問題があ
る。また図4に示した補正用部材1は、透光端板15が反
射コートを必要としないだけ図3の部分裏面鏡板12によ
り簡単であるとしても、筒壁14の内側を真空にしなけれ
ばならないから一層製作に手間が掛ってコスト高になる
と言う問題がある。As described above, the conventional correction member 1 shown in FIG. 3 has at least a spacer member.
11 and a partial back end plate 12 in which an anti-reflection coat is provided on the center of one side of the light-transmitting plate and reflection coats are provided on both sides thereof,
Since it has a structure in which it is bonded to the front end plate 13, there is a problem that it takes time and effort to make it with high accuracy and the cost is high. In addition, the correction member 1 shown in FIG. 4 requires the inside of the cylindrical wall 14 to be evacuated even if the translucent end plate 15 is simpler than the partial back end plate 12 in FIG. However, there is a problem that the production is more troublesome and the cost is increased.
【0007】本発明は、上述の問題を解消するためにな
されたものであり、構造が簡単で容易に精度よく安価に
得られて堅牢性にも優れ、機能が図3の補正用部材1と
変わらない補正用部材の提供を目的とする。The present invention has been made in order to solve the above-mentioned problems, and has a simple structure, can be obtained easily, accurately and inexpensively, has excellent robustness, and has functions similar to those of the correction member 1 shown in FIG. An object of the present invention is to provide a correction member that does not change.
【0008】[0008]
【課題を解決するための手段】本発明は、レーザ光源か
らのレーザ光束を参照光束と測長光束に分岐して、平行
な両光束をそれぞれ戻し部材で来た方向に戻す往復光路
に通した後、両光束を合わせて両光束の前記戻し部材の
間の距離情報を担持した干渉光束を得る差動型干渉測長
計の波長補正に用いられる補正用部材において、両端面
が平滑面に研摩されてそのうちの一方の端面を反射面と
された棒状の定長反射部材と、該定長反射部材の他方の
端面から横に食み出す長さの一側面を平滑面に研摩され
てその中央部を前記定長反射部材の他方の端面に合わせ
て定長反射部材とT字型に組合わされ定長反射部材から
両側に食み出た前記一側面の平滑面を反射面とされた棒
状の桁型反射部材とから成ることを特徴とする差動型干
渉測長計の補正用部材にあり、この構成によって前記目
的を達成する。According to the present invention, a laser beam from a laser light source is split into a reference beam and a length-measuring beam, and the two parallel beams are passed through a reciprocating optical path for returning the beams in the direction in which they came from a return member. After that, in a correction member used for wavelength correction of a differential interferometer that obtains an interference light beam carrying distance information between the return members of the two light beams by combining the two light beams, both end surfaces are polished to a smooth surface. And a rod-shaped fixed-length reflecting member having one end surface as a reflecting surface, and one side of the fixed-length reflecting member, the length of which protrudes laterally from the other end surface, is polished to a smooth surface and the central portion thereof is polished. A bar-shaped girder that is combined with the fixed-length reflecting member in a T-shape in accordance with the other end face of the fixed-length reflecting member, and the smooth surface of the one side that protrudes to both sides from the fixed-length reflecting member is a reflecting surface. For interferometers of differential type characterized by comprising a reflective member Located wood, to achieve the above object by this configuration.
【0009】[0009]
【作用】すなわち、本発明の補正用部材は、両端面を平
滑面に研摩されてそのうちの一端面を反射面にした棒状
の定長反射部材と、定長反射部材の端面から食み出す長
さの一側面を平滑面に研摩されてその面の定長反射部材
の端面から両側に食み出す部分を反射面にした棒状の桁
型反射部材とをT字型に組合わした簡単な構造から成る
から、容易に精度よく安価に作ることができて、堅牢性
に優れ、定長反射部材の反射面と桁型反射部材の反射面
とをそれぞれ参照光束と測長光束を往復させる反射面と
することによって、図3で述べたと同様に環境条件によ
って変化する波長の影響を補正するのに用いることがで
きる。In other words, the correcting member of the present invention has a rod-shaped constant-length reflecting member whose both end surfaces are polished to a smooth surface and one end surface of which is a reflecting surface, and a length protruding from the end surface of the constant-length reflecting member. A simple structure in which one side is polished to a smooth surface and a bar-shaped girder reflective member whose reflective surface has a portion that protrudes to both sides from the end face of the fixed-length reflective member is formed in a T-shape. , Which can be easily and accurately manufactured at low cost, has excellent robustness, and has a reflecting surface for reciprocating the reference light beam and the length measuring light beam between the reflecting surface of the fixed-length reflecting member and the reflecting surface of the girder-shaped reflecting member, respectively. By doing so, it can be used to correct the effect of the wavelength that changes depending on the environmental conditions as described with reference to FIG.
【0010】[0010]
【実施例】以下、本発明を図1、図2に示した実施例に
よって説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS.
【0011】図1は本発明の補正用部材の例を示す斜視
図、図2は本発明の補正用部材を用いた補正係数測定用
の測長計の例を示す概要構成平面図である。FIG. 1 is a perspective view showing an example of a correction member of the present invention, and FIG. 2 is a schematic plan view showing an example of a length measuring instrument for measuring a correction coefficient using the correction member of the present invention.
【0012】図1の補正用部材1は、石英等の低線膨張
係数材料、好ましくは線膨張係数が10-7以下の材料から
成っていて、両端面が平滑面に研摩され、一方の端面が
反射コートを設けられて反射面17aにされた角棒状の定
長反射部材17と、同様の材料から成っていて定長反射部
材17の端面から食み出す長さの一側面が平滑面に研摩さ
れ、その面の定長反射部材17の端面から両側に食み出す
部分が反射コートを設けられて反射面18aにされた角棒
状の桁型反射部材18とをT字型に結合した構造のもので
あり、この結合は定長反射部材17の平滑端面と桁型反射
部材18の平滑側面中央部との平滑面のリンギングによる
ものでもよいし、あるいはさらに桁型反射部材18の平滑
側面とは反対側の面側から定長反射部材17内に結合用の
ねじや摩擦ピンを通して行われたものでもよい。The correction member 1 shown in FIG. 1 is made of a material having a low linear expansion coefficient such as quartz, preferably a material having a linear expansion coefficient of 10 -7 or less. Is provided with a reflective coat, and is a rectangular rod-shaped fixed-length reflecting member 17 formed on the reflecting surface 17a, and one side of a length formed of the same material and protruding from the end surface of the fixed-length reflecting member 17 is a smooth surface. A structure in which a portion which is polished and protrudes from the end face of the fixed-length reflecting member 17 to both sides thereof is provided with a reflecting coat and a rectangular bar-shaped girder reflecting member 18 formed on a reflecting surface 18a in a T-shape. This coupling may be by ringing of the smooth end surface of the fixed-length reflecting member 17 and the center of the smooth side surface of the girder-shaped reflecting member 18, or may be further formed by the smooth side surface of the girder-shaped reflecting member 18. Through the connecting screw or friction pin into the fixed length reflective member 17 from the opposite side. It may be what was done.
【0013】図2の測長計は、レーザ光束Lを参照光束
Rと測長光束Mに分岐し、また両光束R,Mを会合させ
て干渉光束Iを検出手段7に出射する分岐会合光学系6
に特願平3-44890号の干渉プリズムを用い、図1の補正
用部材1を用いて環境条件が変化して波長が変化したこ
とによる光路長差の測定波数変化を求めるものである。
環境条件に応じた波長は以下のように求める。The length measuring instrument shown in FIG. 2 branches the laser beam L into a reference beam R and a length measuring beam M, and associates the two beams R and M to emit an interference beam I to the detecting means 7. 6
The method uses the interference prism disclosed in Japanese Patent Application No. 3-44890 and uses the correction member 1 shown in FIG. 1 to determine the change in the measured wavenumber of the optical path difference due to the change in the wavelength due to the change in the environmental conditions.
The wavelength according to the environmental conditions is obtained as follows.
【0014】参照光束Rと測長光束Mの幾何学的な光路
長差Dは、両光束RとMが補正用部材1で反射される往
復光路を共に2回取るから、定長反射部材17の長さの基
準長Lの4倍である。この光路長差Dをある環境条件の
波長λ0で波数M0として求めてD=4L=M0λ0の関係
が得られ、また光路長差Dを異なる環境条件の波長λ1
で波数M1として求めてD=4L=M1λ1の関係が得ら
れる。しかし、図2の測長計で求められるのは環境条件
の変化による波数変化のM1−M0=ΔMである。そこ
で、λ0を基準波長としてλ1を前述の両関係式からλ0,
L,ΔMの関数として求めると、λ1=λ0/(1+λ0・Δ
M/4L)となる。The geometrical optical path length difference D between the reference light beam R and the length measuring light beam M is determined by the fact that both light beams R and M take twice the reciprocating light path on which the correction member 1 reflects. Is four times the reference length L. The optical path length difference D at the wavelength lambda 0 of the environmental conditions that are determined as wavenumber M 0 is the relationship D = 4L = M 0 λ 0 obtained, the wavelength of different environmental conditions the optical path length difference D lambda 1
In relation D = 4L = M 1 λ 1 obtained as wavenumber M 1 is obtained. However, what is obtained by the length measuring device of FIG. 2 is M 1 −M 0 = ΔM of a change in wave number due to a change in environmental conditions. Therefore, lambda 0 0 a a lambda 1 as a reference wavelength from both relational expression described above lambda,
When calculated as a function of L, ΔM, λ 1 = λ 0 / (1 + λ 0 · Δ
M / 4L).
【0015】λ0は、前述のある環境条件で同様の差動
型干渉測長計により参照光束と測長光束の光路長差が4
波長分変化する測長鏡の移動距離を求める方法や、先の
述べた第3の方法の関係式を用いる方法によって求める
ことができる。したがって、環境条件に応じた波長λ1
はλ0,L,ΔMから得られる。この波長λ1を同様の環境
条件と測長計により求めた測定波数に乗じて環境条件の
変化による波長変化の影響を補正した測定長を得ること
ができる。At λ 0 , the optical path length difference between the reference light beam and the measured light beam is 4 by the same differential interferometer under a certain environmental condition described above.
It can be obtained by a method of obtaining the moving distance of the length measuring mirror that changes by the wavelength or a method using the above-described relational expression of the third method. Therefore, the wavelength λ 1 according to the environmental conditions
Is obtained from λ 0 , L, ΔM. By multiplying the wavelength λ 1 by the same environmental condition and the measurement wave number obtained by the length measuring instrument, it is possible to obtain a measurement length in which the influence of the wavelength change due to the change of the environmental condition is corrected.
【0016】なお、定長反射部材17の長さを基準長Lと
するためには、定長反射部材17の反射面17aと桁型反射
部材18の反射面18aの反射コート厚を等しいとして、定
長反射部材17の平滑端面が接する桁型反射部材18の平滑
側面中央部分は反射コートを設けないことが好ましい。
それは接合を平滑面のリンギングによるものとする場合
に強い接着力を得るためにも好ましいことである。接合
面間に反射コートを設けたり接着剤を用いたりすると、
接合後に反射面17aと反射面18a間の距離を測定するこ
とや接着剤の熱膨縮を考慮することが必要になる。In order to set the length of the fixed length reflecting member 17 to the reference length L, it is assumed that the reflecting surface 17a of the fixed length reflecting member 17 and the reflecting surface 18a of the girder shaped reflecting member 18 have the same thickness. It is preferable that a reflection coating is not provided on the central portion of the smooth side surface of the girder-shaped reflection member 18 with which the smooth end surface of the fixed-length reflection member 17 contacts.
It is also preferable to obtain a strong adhesive force when the joint is made by ringing of a smooth surface. If a reflective coat is provided between the joining surfaces or an adhesive is used,
After joining, it is necessary to measure the distance between the reflecting surfaces 17a and 18a and to consider the thermal expansion and contraction of the adhesive.
【0017】また、定長反射部材17の線膨張係数をαと
すれば、定長反射部材17の0℃の長さをL0としてt℃
の基準長LがL0(1+αt)で変化するから、光路長差
を求めた波長と波数をλ、Mとして、λ=4L0(1+α
t)/Mが得られるから、このλを波長とすればよい。し
かし、定長反射部材17にαが10-7以下の材料を用いた場
合は、一般的なレーザ干渉測長計の測長精度が10-7〜10
-8程度であるから、定長反射部材17の長さを一定として
十分である。If the linear expansion coefficient of the fixed-length reflecting member 17 is α, the length of 0 ° C. of the fixed-length reflecting member 17 is defined as L 0 and t ° C.
Is changed by L 0 (1 + αt), λ = 4L 0 (1 + α) where λ and M are the wavelength and wave number for which the optical path length difference is obtained.
Since t) / M is obtained, this λ may be used as the wavelength. However, when a material having α of 10 −7 or less is used for the constant-length reflecting member 17, the measurement accuracy of a general laser interferometer is 10 −7 to 10 −7.
Since it is about −8, it is sufficient to make the length of the fixed-length reflecting member 17 constant.
【0018】桁型反射部材18の線膨張係数は定長反射部
材17におけるほど重要ではないが、両者の結合部に熱応
力や歪が生じないように、桁型反射部材18にも定長反射
部材17と同様の線膨張係数の材料さらには10-7以下の線
膨張係数の材料を用いるのが好ましい。また、定長反射
部材17と桁型反射部材18は、図示例のように角棒状とす
るのが生産性等から好ましいが、それに限られるもので
はない。Although the linear expansion coefficient of the girder-shaped reflecting member 18 is not as important as that of the fixed-length reflecting member 17, the girder-shaped reflecting member 18 is also fixed-length reflecting member 18 so that thermal stress and distortion do not occur at the joint between them. It is preferable to use a material having a linear expansion coefficient similar to that of the member 17, and more preferably a material having a linear expansion coefficient of 10 −7 or less. The fixed-length reflecting member 17 and the girder-shaped reflecting member 18 are preferably formed in the shape of a square bar as shown in the drawing, from the viewpoint of productivity and the like, but are not limited thereto.
【0019】[0019]
【発明の効果】本発明の補正用部材は、構造が簡単で、
容易に精度よく安価に作ることができ、堅牢性にも優れ
る。The correcting member of the present invention has a simple structure,
It can be made easily, accurately and inexpensively, and has excellent robustness.
【図1】本発明の補正用部材の例を示す斜視図。FIG. 1 is a perspective view showing an example of a correction member according to the present invention.
【図2】本発明の補正用部材を用いた補正係数測定用の
測長計の例を示す概要構成平面図。FIG. 2 is a schematic plan view showing an example of a length measuring instrument for measuring a correction coefficient using the correction member of the present invention.
【図3】波長変化の影響の補正係数を求めるための測長
計の例を示す構成概要図。FIG. 3 is a schematic configuration diagram showing an example of a length measurement device for obtaining a correction coefficient for the influence of a wavelength change.
【図4】波長変化の影響の補正係数を求めるための測長
計の例を示す構成概要図。FIG. 4 is a schematic configuration diagram showing an example of a length measurement device for obtaining a correction coefficient for the influence of a wavelength change.
1 補正用部材 17 定長反射部材 18 桁型反射部材 17a 反射面 18a 反射面 6 分岐会合光学系 7 検出手段 L レーザ光束 R 参照光束 M 測長光束 I 干渉光束 DESCRIPTION OF SYMBOLS 1 Correction member 17 Constant-length reflective member 18 Digit-type reflective member 17a Reflective surface 18a Reflective surface 6 Branching association optical system 7 Detecting means L Laser beam R Reference beam M Measuring beam I Interference beam
Claims (3)
と測長光束に分岐して、平行な両光束をそれぞれ戻し部
材で来た方向に戻す往復光路に通した後、両光束を合わ
せて両光束の前記戻し部材の間の距離情報を担持した干
渉光束を得る差動型干渉測長計の波長補正に用いられる
補正係数測定用光学部材において、両端面が平滑面に研
摩されてそのうちの一方の端面を反射面とされた棒状の
定長反射部材と、該定長反射部材の他方の端面から横に
食み出す長さの一側面を平滑面に研摩されてその中央部
を前記定長反射部材の他方の端面に合わせて定長反射部
材とT字型に組合わされ定長反射部材から両側に食み出
た前記一側面の平滑面を反射面とされた棒状の桁型反射
部材とから成ることを特徴とする差動型干渉測長計の補
正係数測定用光学部材。1. A laser beam from a laser light source is split into a reference beam and a length-measuring beam, and the two parallel beams are passed through a reciprocating optical path for returning in a direction coming from a return member. In a correction coefficient measuring optical member used for wavelength correction of a differential interferometer that obtains an interference light beam carrying distance information between the return members of the light beam, both end surfaces are polished to a smooth surface and one of them is polished. A rod-shaped fixed-length reflecting member having an end surface as a reflecting surface, and one side of a length protruding laterally from the other end surface of the fixed-length reflecting member is polished to a smooth surface, and the central portion thereof is fixed-length reflecting member. From a rod-shaped girder reflector having a smooth surface on one side which is combined with the fixed length reflection member in a T-shape in accordance with the other end surface of the member and which protrudes to both sides from the fixed length reflection member and is a reflection surface. Optical section for measuring correction coefficient of differential interferometer Wood.
数が10-7以下の材料が用いられている請求項1の差動型
干渉測長計の補正係数測定用光学部材。2. An optical member for measuring a correction coefficient of a differential interferometer according to claim 1, wherein a material having a linear expansion coefficient of 10 −7 or less is used for at least the constant-length reflecting member.
滑面のリンギングでT字型に組合わされている請求項1
の差動型干渉測長計の補正係数測定用光学部材。3. The fixed-length reflecting member and the girder-shaped reflecting member are combined in a T-shape by ringing on a smooth surface.
Optical member for measuring the correction coefficient of the differential interferometer.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3137826A JP2990309B2 (en) | 1991-06-10 | 1991-06-10 | Optical member for measuring correction coefficient of differential interferometer |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3137826A JP2990309B2 (en) | 1991-06-10 | 1991-06-10 | Optical member for measuring correction coefficient of differential interferometer |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH04363606A JPH04363606A (en) | 1992-12-16 |
JP2990309B2 true JP2990309B2 (en) | 1999-12-13 |
Family
ID=15207755
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP3137826A Expired - Lifetime JP2990309B2 (en) | 1991-06-10 | 1991-06-10 | Optical member for measuring correction coefficient of differential interferometer |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2990309B2 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008102051A (en) * | 2006-10-20 | 2008-05-01 | Fujinon Corp | Interferometer angle sensitivity calibration method |
-
1991
- 1991-06-10 JP JP3137826A patent/JP2990309B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JPH04363606A (en) | 1992-12-16 |
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