JPH02259505A - Fringe scanning type interference measuring instrument - Google Patents
Fringe scanning type interference measuring instrumentInfo
- Publication number
- JPH02259505A JPH02259505A JP8234189A JP8234189A JPH02259505A JP H02259505 A JPH02259505 A JP H02259505A JP 8234189 A JP8234189 A JP 8234189A JP 8234189 A JP8234189 A JP 8234189A JP H02259505 A JPH02259505 A JP H02259505A
- Authority
- JP
- Japan
- Prior art keywords
- light
- phase difference
- measured
- beam splitter
- electro
- Prior art date
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Links
- 230000004907 flux Effects 0.000 claims abstract description 10
- 230000003287 optical effect Effects 0.000 claims description 24
- 230000005684 electric field Effects 0.000 claims description 5
- 238000005305 interferometry Methods 0.000 claims 1
- 230000010287 polarization Effects 0.000 abstract description 13
- 230000002159 abnormal effect Effects 0.000 abstract 1
- 238000005259 measurement Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000003384 imaging method Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
Landscapes
- Instruments For Measurement Of Length By Optical Means (AREA)
- Length Measuring Devices 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、参照光と被測定物体からの光との位相差を時
間的に変化させることにより縞走査を行なわせ被測定物
体の形状などを測定する縞走査型測定装置にかんする。Detailed Description of the Invention [Industrial Field of Application] The present invention performs fringe scanning by temporally changing the phase difference between a reference beam and light from an object to be measured. This article relates to a stripe scanning measuring device that measures .
〔従来の技術J
従来、第3図に示すごとき縞走査型干渉測定装置が知ら
れている。[Prior Art J] Conventionally, a fringe scanning type interference measuring device as shown in FIG. 3 has been known.
同図において、1はレーザ光源、2はビームエキスパン
ダー光学系、3は偏光ビームスプリッタ−14a、4b
は1/4波長板、5は電気光学素子、6は電気光学素子
5に変化する電圧を印加して電気光学素子5の光学異方
性の大きさを変化させる為の電源、7は被測定物体、8
は参照ミラー、9は結像レンズ10は光検出器、11は
偏光板である。In the figure, 1 is a laser light source, 2 is a beam expander optical system, and 3 is a polarizing beam splitter 14a, 4b.
5 is a quarter-wave plate, 5 is an electro-optical element, 6 is a power source for applying a changing voltage to the electro-optical element 5 to change the magnitude of optical anisotropy of the electro-optical element 5, and 7 is a device to be measured. object, 8
9 is a reference mirror, 9 is an imaging lens 10 is a photodetector, and 11 is a polarizing plate.
ここにおいて、レーザ光源lからの光束はビームエキス
パンダー光学系2でその径を広げられて偏光ビームスプ
リッタ−3に入射し、偏光方向の違いに従って透過成分
は図波長板4aに入射し反射成分は電気光学素子5及び
図波長板4bに入射する。透過成分は図波長板4aで円
偏光とされて被測定物体7で反射され、再び図波長板4
aを通ることでこれへの入射時と比べて偏光面が90度
回転された状態で偏光ビームスプリッタ−3に戻る。Here, the beam from the laser light source 1 is expanded in diameter by the beam expander optical system 2 and then enters the polarizing beam splitter 3. According to the difference in polarization direction, the transmitted component enters the wave plate 4a, and the reflected component is electrical. The light is incident on the optical element 5 and the wavelength plate 4b. The transmitted component is converted into circularly polarized light by the wavelength plate 4a, reflected by the object to be measured 7, and then returned to the wavelength plate 4a.
By passing through a, the beam returns to the polarizing beam splitter 3 with the plane of polarization rotated by 90 degrees compared to when it was incident thereon.
従って、今度はこの被測定物体7からの光束は偏光ビー
ムスプリッタ−3で第3図下方に反射される。Therefore, this time, the light beam from the object to be measured 7 is reflected downward in FIG. 3 by the polarizing beam splitter 3.
一方、例えば、紙面垂直方向の偏光面を持つ反射成分は
、光学軸が適宜に配向された電気光学素子5において異
常光線に対する屈折率の作用を受けてこれを透過し、図
波長板4bを経て参照ミラー8により反射される。そし
て、図波長板4bを再び透過して偏向面が最初の入射時
と比して90度回転された状態で再度電気光学素子5に
入射する。従って、今度は反射成分は電気光学素子5に
おいて常光線に対する屈折率の作用を受けてこれを透過
し、偏向ビームスプリッタ−3に入射しここをそのまま
透過して第3図下方に向かう。On the other hand, for example, a reflected component having a polarization plane perpendicular to the plane of the paper is transmitted through the electro-optical element 5 whose optical axis is appropriately oriented under the effect of the refractive index with respect to the extraordinary ray, and passes through the wavelength plate 4b in the figure. It is reflected by the reference mirror 8. Then, the light passes through the wavelength plate 4b again and enters the electro-optical element 5 again with the deflection plane rotated by 90 degrees compared to the initial incidence. Therefore, this time, the reflected component is transmitted through the electro-optical element 5 under the effect of the refractive index with respect to the ordinary ray, and then enters the deflection beam splitter 3, where it is transmitted as it is, and heads downward in FIG.
こうして、参照ミラー8からの参照光と被測定物体7か
らの光束は重ね合わされて、適宜に配向された偏光板1
1及び結像レンズ9を通って光検出器10に到達する。In this way, the reference light from the reference mirror 8 and the light flux from the object to be measured 7 are superimposed, and the polarizing plate 1 is properly oriented.
1 and an imaging lens 9 to reach a photodetector 10.
このとき、偏光ビームスプリッタ−3の境界面上で干渉
させられた上記両光束は、偏光板11を通過することで
光検出器lOでは干渉縞強度として検出される。At this time, the two light beams interfered on the boundary surface of the polarizing beam splitter 3 pass through the polarizing plate 11 and are detected by the photodetector lO as interference fringe intensity.
この際、電気光学素子の光学異方性は変化する印加電圧
によってその大きさが変化し、常屈折率と異常屈折率が
変化するので(一方が増加する場合、他方は減少する)
、電気光学素子5を2度通過する反射成分の位相は変化
させられる。従って、この参照光と被測定物体7からの
光との位相差は変化し、光検出器10上の干渉縞は移動
させられる。そして、電気光学素子5の光学異方性を変
化させる電源6の動作に同期して、上記移動する干渉縞
データの取り込みが行なわれ、コンビ二一夕で解析され
て被測定物体7の形状等が測定される。これは縞走査と
呼ばれる測定法であり、これによれば大気のゆらぎやノ
イズ等に起因する誤差が最小化されて測定がより正確に
行なわれる(例えばS、Yokozeki、に、Pat
orski and K、0hnishi:0pt
ics Commun。At this time, the optical anisotropy of the electro-optical element changes in magnitude depending on the applied voltage, and the ordinary refractive index and extraordinary refractive index change (if one increases, the other decreases).
, the phase of the reflected component that passes through the electro-optical element 5 twice is changed. Therefore, the phase difference between this reference light and the light from the object to be measured 7 changes, and the interference fringes on the photodetector 10 are moved. Then, in synchronization with the operation of the power supply 6 that changes the optical anisotropy of the electro-optical element 5, the above-mentioned moving interference fringe data is captured and analyzed by the combination machine to determine the shape of the object to be measured 7. is measured. This is a measurement method called fringe scanning, which minimizes errors caused by atmospheric fluctuations and noise, resulting in more accurate measurements (e.g., S., Yokozeki, Pat.
orski and K, 0hnishi: 0pt
ics Commun.
14 (1975)401やDigitalWavef
ront MeasuringInterferom
eter for Testing 0ptic
al 5urfaces and Lenses
:Applfed 0ptics/Vo1.13
.N。14 (1975) 401 and DigitalWavef
rontMeasuringInterferom
eter for Testing 0ptic
al 5 surfaces and lenses
:Applfed 0ptics/Vo1.13
.. N.
11/Novemher 19749照)また、電気
光学素子5をなくし、参照ミラー8を電圧素子などで振
動させて参照光と被測定物体7からの光との位相差を変
化させる構成も知られている。11/Novemher 19749) Furthermore, a configuration is also known in which the electro-optical element 5 is eliminated and the reference mirror 8 is vibrated by a voltage element or the like to change the phase difference between the reference light and the light from the object to be measured 7.
[発明が解決しようとする課題]
しかし乍ら、上記従来例では、面積が成る程度大きな被
測定物体の形状等を測定する場合、それに応じて光束の
径も成る程度大きくなり、従って参照光を作る電気光学
素子や振動ミラーも成る程度の面積を有する必要がある
。このことは、電気光学素子が成る程度の面積に亙って
均一の特性を持つことや、振動ミラーが成る程度の面積
において傾かずに精確に光軸方向に振動する必要が成る
ことを意味する。従って、電気光学素子の作成や圧電素
子、参照ミラーなどの作成、位置決めに高度で煩わしい
技術が要求され、コストが高くなるという欠点があった
。[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, when measuring the shape of an object to be measured whose area is large enough, the diameter of the light beam becomes correspondingly large, and therefore it is difficult to use the reference light. The electro-optical elements and vibrating mirrors also need to have a sufficient area. This means that the electro-optical element must have uniform characteristics over an area that is large enough, and that it must vibrate precisely in the optical axis direction without tilting over an area that is large enough for a vibrating mirror. . Therefore, sophisticated and troublesome techniques are required for the production and positioning of electro-optical elements, piezoelectric elements, reference mirrors, etc., resulting in high costs.
特に、電気光学素子を参照光路内に設ける従来例では、
参照光路の往復で光束に位相変化を与える構成であるの
で、往路で電気光学素子の異常屈折率の作用を受けた場
合、復路では偏光面が90度回転している為に常屈折率
の作用を受けることになり、(逆も同様)、常及び異常
屈折率は互いに逆の方向に変化するので往復での位相変
化量が打ち消し合うことになる。従って、大きな位相変
化を得る為には電気光学素子に大電界を印加する必要が
ある。In particular, in the conventional example in which an electro-optical element is provided in the reference optical path,
Since the configuration is such that a phase change is given to the light beam on the round trip of the reference optical path, if it is affected by the extraordinary refractive index of the electro-optical element on the outgoing path, the polarization plane is rotated by 90 degrees on the return path, so that it is affected by the ordinary refractive index. Since the ordinary and extraordinary refractive indices change in opposite directions (and vice versa), the amount of phase change in the round trip cancels out. Therefore, in order to obtain a large phase change, it is necessary to apply a large electric field to the electro-optical element.
従って、本発明の目的は、上記欠点を解決すべく、電気
光学素子や振動する参照ミラーを使用しても参照光と被
測定物体からの光との位相差が充分な精度と大きさを持
って容易に得られる様に構成された縞走査型干渉測定装
置を提供することにある。Therefore, an object of the present invention is to solve the above-mentioned drawbacks by ensuring that the phase difference between the reference light and the light from the object to be measured has sufficient precision and magnitude even when an electro-optical element or a vibrating reference mirror is used. It is an object of the present invention to provide a fringe scanning type interference measuring device configured so that it can be easily obtained.
[課題を解決するための手段〕
上記目的を達成する本発明の縞走査型干渉測定装置にお
いては、レーザ光源などの光源からの光を処理して時間
的に位相差の変化する2光波成分を含む光束を作り出す
位相差変化手段が設けられ、偏光ビームスプリッタ−な
どのビームスプリッタ−により位相差変化手段からの光
束の2光波成分が被測定物体へ向かう光と9111i面
へ向かう光とに分割される位相差変化手段は、具体的に
は、電気光学素子或は圧電素子で振動される反射ミラー
などから構成され、これら電気光学素子や圧電素子など
に印加される電圧を制御することにより位相差の変化が
制御される。[Means for Solving the Problems] In the fringe scanning interference measurement device of the present invention that achieves the above object, light from a light source such as a laser light source is processed to generate two light wave components whose phase difference changes over time. A phase difference changing means is provided, and a beam splitter such as a polarizing beam splitter splits two light wave components of the light beam from the phase difference changing means into light directed toward the object to be measured and light directed toward the 9111i plane. Specifically, the phase difference changing means is composed of a reflection mirror vibrated by an electro-optical element or a piezoelectric element, and the phase difference is changed by controlling the voltage applied to these electro-optical elements or piezoelectric elements. changes are controlled.
位相差変化手段からの2光波成分を、どの様に被測定物
体及び参照面へ向かう光に振り分けるかは設計に応じて
適宜法めれば良い。How to distribute the two light wave components from the phase difference changing means into light directed toward the object to be measured and the reference surface may be determined as appropriate depending on the design.
[作用]
本発明においては、被測定物体からの反射光束或は透過
光束と参照面からの光束が干渉させられ、且つこれら2
光束の位相差が制御され乍ら時間的に変化させられ、こ
れに伴って変化する干渉縞強度の位相差から被測定物体
の形状或は透過波面形状などが測定されるそして、被測
定物体への入射光束と参照面への参照光束とにビームス
プリッタ−で分割される前の段階に、時間的に位相差の
変化する2光波成分を含む光束を作り出して上記ビーム
スプリッタ−に入射させる位相差変化手段が設けられて
いるので、この位相差変化手段は比較的細い光束を処理
できることになって、位相差変化動作に伴う精度への悪
影響が最小化され且つ位相差変化の程度に関して柔軟性
に富んだ装置が比較的安価に構成される[実施例]
第1図は本発明の第1実施例を示す。同図の構成におい
ては、第3図の従来例と比較して、電気光学素子15が
レーザ光源1とビームエキスパンダー光学系2との間の
光路中に配置されている。[Function] In the present invention, the reflected or transmitted light flux from the object to be measured and the light flux from the reference surface are caused to interfere with each other, and these two
The phase difference of the light flux is controlled and temporally changed, and the shape of the object to be measured or the shape of the transmitted wavefront is measured from the phase difference of the interference fringe intensity that changes accordingly. Before being split by a beam splitter into an incident light beam and a reference light beam to a reference surface, a light beam containing two light wave components whose phase difference changes over time is created and made to enter the beam splitter. Since the phase difference changing means is provided, the phase difference changing means can process a relatively narrow beam of light, minimizing the negative impact on accuracy associated with the phase difference changing operation and providing flexibility regarding the degree of phase difference changing. EMBODIMENT OF THE INVENTION FIG. 1 shows a first embodiment of the present invention. In the configuration shown in the figure, an electro-optical element 15 is arranged in the optical path between the laser light source 1 and the beam expander optical system 2, compared to the conventional example shown in FIG.
レーザー光源1から出射した光束は先ず電気光学素子1
5に入射する。電気光学素子15は、例えば、PLZT
板より成り、その端面に電極を設けて光束の方向に電界
を印加すると入射光束に垂直な面内で互いに直交する2
つの方向に関して光学異方性を発生する様lトなってい
る。従って、電源6より、変化する電圧が電気光学素子
15に印加されると、上記互いに直交する2つの方向に
偏光面を有する偏光成分は、夫々、常光線及び異常光線
として、時間的に変化する常屈折率及び異常屈折率を経
験するので、電気光学素子15からの出射光はその偏光
方向の違いにより、時間的に変化する異なった2つの位
相を有することになる。The light beam emitted from the laser light source 1 first passes through the electro-optical element 1
5. The electro-optical element 15 is made of, for example, PLZT.
It consists of a plate, and when an electrode is provided on the end face and an electric field is applied in the direction of the luminous flux, two
It is designed to generate optical anisotropy in two directions. Therefore, when a changing voltage is applied to the electro-optical element 15 from the power source 6, the polarized light components having polarization planes in the two mutually orthogonal directions change over time as ordinary rays and extraordinary rays, respectively. Since the light experiences an ordinary refractive index and an extraordinary refractive index, the light emitted from the electro-optical element 15 has two different phases that change over time due to the difference in its polarization direction.
このとき、入射光束はその径がまだ比較的小さいので、
電気光学素子15の均一特性部分の面積は小さくて済み
、また出射光束に含まれる常光線成分と異常光線成分は
、夫々、互いに反対方向に変化する常屈折率と異常屈折
率を、電気光学素子15を一度通過して経験するのであ
るから、両成分の位相差ないし変化量を大きくできる。At this time, the diameter of the incident luminous flux is still relatively small, so
The area of the uniform characteristic portion of the electro-optical element 15 is small, and the ordinary ray component and the extraordinary ray component included in the emitted light beam have an ordinary refractive index and an extraordinary refractive index that change in opposite directions, respectively. 15, the phase difference or amount of change between the two components can be increased.
電気光学素子15から出射した上記常光線成分と異常光
線成分とを含む光束は、ビームエキスパンダー光学系2
で、その径が被測定物体7の大きさに応じた適当な大き
さに広げられ、偏光ビームスプリッタ−3に入射する、
偏光ビームスプリッタ−3は、例えば、その透過成分の
偏光方向を上記常光線成分の偏光方向と一致させて配置
され、従ってその反射成分の偏光方向は上記異常光線成
分のそれと一致している。The light beam including the ordinary ray component and the extraordinary ray component emitted from the electro-optical element 15 is transmitted to the beam expander optical system 2.
Then, its diameter is expanded to an appropriate size according to the size of the object to be measured 7, and the beam is incident on the polarizing beam splitter 3.
The polarizing beam splitter 3 is arranged, for example, so that the polarization direction of its transmitted component matches that of the ordinary ray component, and therefore the polarization direction of its reflected component matches that of the extraordinary ray component.
よって、常光線成分はそのまま偏光ビームスプリッタ−
3を透過し電波長板4aを通過した後、被測定物体7で
反射され、再び電波長板4aを通って偏光ビームスプリ
ッタ−3に戻ってくる。戻ってきた常光線成分が偏光ビ
ームスプリッタ−3で反射され第1図下方に向かうこと
は、第3図の説明で述べたと同じ理由による。Therefore, the ordinary ray component is directly transmitted to the polarizing beam splitter.
After passing through the electromagnetic wave plate 4a, it is reflected by the object to be measured 7, passes through the electromagnetic wave plate 4a again, and returns to the polarizing beam splitter 3. The reason why the returning ordinary ray component is reflected by the polarizing beam splitter 3 and directed downward in FIG. 1 is due to the same reason as stated in the explanation of FIG. 3.
一方、異常光線成分は偏光ビームスプリッタ−3で反射
され、電波長板4bを通過した後、参照面である参照ミ
ラー8で反射され、再び域波長板4bを通って偏光ビー
ムスプリッタ−3に戻って(る、この戻ってきた異常光
線成分が偏光ビームスプリッタ−3をそのまま透過して
第1図下方に向かうことも、第3図の説明で述べたと同
じ理由による。On the other hand, the extraordinary ray component is reflected by the polarizing beam splitter 3, passes through the radio wave plate 4b, is reflected by the reference mirror 8, which is a reference surface, and returns to the polarizing beam splitter 3 through the wavelength plate 4b again. The reason why this returned extraordinary ray component passes through the polarizing beam splitter 3 as it is and goes downward in FIG. 1 is due to the same reason as stated in the explanation of FIG. 3.
こうして、常及び異常光線成分は偏光ビームスプリッタ
−3の境界面上で干渉し、偏光板11、結像レンズ9を
通過することで光検出器lOで干渉縞強度として検出さ
れる。In this way, the ordinary and extraordinary ray components interfere on the boundary surface of the polarizing beam splitter 3, pass through the polarizing plate 11 and the imaging lens 9, and are detected as interference fringe intensity by the photodetector IO.
ここにおいて、電気光学素子15への印加電界の大きさ
が変化させられるので上記両光束成分の位相差が変化し
、縞走査による測定が行なわれるのは第3図の従来例で
述べたのと同じである。Here, since the magnitude of the electric field applied to the electro-optical element 15 is changed, the phase difference between the two luminous flux components is changed, and measurement by fringe scanning is performed, which is different from the conventional example shown in FIG. It's the same.
この様に、第1実施例では、電気光学素子15などから
成る位相差変化手段で1時間的に位相差の変化する2光
波酸分を含む光束を作り出し、偏光ビームスプリッタ−
3等を有する干渉計側にこの光束を入射させる構成であ
るので、位相差変化手段は比較的細い光束を処理すれば
良く侍相差制御の精度、柔軟性及びコストの点で有利に
なる。In this manner, in the first embodiment, a light beam containing two light wave components whose phase difference changes over an hour is created by the phase difference changing means consisting of the electro-optical element 15, etc., and the polarizing beam splitter
Since the configuration is such that this light beam is incident on the interferometer side having a 3.5-meter beam, the phase difference changing means only needs to process a relatively narrow light beam, which is advantageous in terms of accuracy, flexibility, and cost of phase difference control.
次に第2図の第2実施例を説明する。Next, a second embodiment shown in FIG. 2 will be explained.
同図において、偏光ビームスプリッタ−3などから成る
干渉計測は第1図の第1実施例と同じであり1時間的に
位相差の変化する2光波酸分を含む光束を出射する位相
差変化手段のみが第1実施例と異なる。In the same figure, the interferometric measurement consisting of the polarizing beam splitter 3 and the like is the same as the first embodiment in FIG. Only this differs from the first embodiment.
第2実施例において、21は電源6により光軸方向に伸
縮させられる圧電素子、22は圧電素子21に固着され
た反射ミラー、23は固定された反射ミラー 24a、
24bは残液長板、25は偏光ビームスプリッタ−3と
は別設の偏光ビームスプリッタ−116はビームエキス
パンダー光学系2内に設けられた光束の形状等を整える
為のピンホールである。In the second embodiment, 21 is a piezoelectric element that is expanded and contracted in the optical axis direction by a power source 6, 22 is a reflection mirror fixed to the piezoelectric element 21, 23 is a fixed reflection mirror 24a,
24b is a residual liquid long plate, and 25 is a polarizing beam splitter 116 provided separately from the polarizing beam splitter 3, which is a pinhole provided in the beam expander optical system 2 for adjusting the shape of the light beam.
レーザ光源1から出射した光束は偏光ビームスプリッタ
−25に入射し、偏光方向の違いにより透過成分は振動
するミラー22の方向へ、反射成分は固定のミラー23
の方向へ分割される。偏光ビームスプリッタ−25を透
過した光束は電波長板24aを通過しミラ−22で反射
されて、再び図波長板24aを通過して偏光ビームスプ
リッタ−25へ戻るが、ス波長板24aを2度通過する
ので往路と復路とでその偏光方向は直交している。従っ
て、偏光ビームスプリッタ−25で反射されてビームエ
キスパンダー光学系2へ入射する。The light beam emitted from the laser light source 1 enters the polarizing beam splitter 25, and due to the difference in polarization direction, the transmitted component is directed toward the vibrating mirror 22, and the reflected component is directed toward the fixed mirror 23.
It is divided in the direction of The light beam that has passed through the polarizing beam splitter 25 passes through the wave plate 24a, is reflected by the mirror 22, passes through the wave plate 24a again, and returns to the polarizing beam splitter 25, but it passes through the wave plate 24a twice. Since the light passes through the light, its polarization directions are orthogonal on the outbound and return trips. Therefore, it is reflected by the polarizing beam splitter 25 and enters the beam expander optical system 2.
一方、偏光ビームスプリッタ−25での反射成分は図波
長板24bを通過し固定ミラー23で反射されて、再び
属波長@24bを通って偏光ビームスプリッタ−25へ
戻るが、上記透過成分の説明における理由と原理的に同
理由により偏光ビームスプリッタ−25を透過してビー
ムエキスパンダー光学系2へ入射する。こうして透過及
び反射成分の両光束は再び同一光路を辿ってビームエキ
スパンダー光学系2に入射する。On the other hand, the reflected component at the polarizing beam splitter 25 passes through the wavelength plate 24b, is reflected by the fixed mirror 23, and returns to the polarizing beam splitter 25 through the wavelength plate 24b again. For essentially the same reason, the light passes through the polarizing beam splitter 25 and enters the beam expander optical system 2. In this way, both the transmitted and reflected light beams follow the same optical path again and enter the beam expander optical system 2.
この際、偏光方向が相互に直交している両光束の位相差
は振動ミラー22の位置に依存するので、電源6の電圧
によりこの位相差は時間的に変化させられる。At this time, since the phase difference between the two light beams whose polarization directions are orthogonal to each other depends on the position of the vibrating mirror 22, this phase difference is temporally changed by the voltage of the power source 6.
次に、両光束は径を広げられて偏光ビームスプリッタ−
3に入射し、偏光方向の違いに従ってここで分割される
のであるが、この干渉計側の振舞は第1実施例と本質的
に同じであるので説明を省略する。Next, both beams are expanded in diameter and passed through a polarizing beam splitter.
3 and is split here according to the difference in polarization direction, but since the behavior on the interferometer side is essentially the same as in the first embodiment, the explanation will be omitted.
上記第2実施例でも、第1実施例と同様に、振動ミラー
22などの位相差変化手段を干渉計から分離し、光源か
ら出射直後の比較的細い光束を処理して位相差の時間的
に変化する2光波酸分を含む光束を作り出しているので
、振動ミラー22などの傾きなどが位相差変化の精度を
劣化させることが最小化されるまた、第1実施例では両
光波成分の位相が時間的に変化させられて時間的に変化
する位相差が実現されているが、第2実施例では一方の
光波成分の位相のみを時間的に変化させている。In the second embodiment, as in the first embodiment, the phase difference changing means such as the vibrating mirror 22 is separated from the interferometer, and the relatively thin beam immediately after being emitted from the light source is processed to change the phase difference over time. Since a light beam containing a changing two-wavelength acid component is generated, it is possible to minimize the possibility that the tilt of the vibrating mirror 22 etc. degrades the accuracy of the phase difference change. Although a phase difference that changes over time is realized by changing the phase difference over time, in the second embodiment, only the phase of one light wave component is changed over time.
[発明の効果]
以上の様に、本発明の構成によれば、被測定物体への入
射光束と参照光束とに分割する前の段階で、電気光学素
子や振動ミラーなどを用いて位相差の時間的に変化する
2光波酸分を含む光束を作り出し、この光束を分割して
被測定物体への入射光束と参照光束を作り出しているの
で、位相差変化手段が充分な精度で比較的安価に実現で
きる。[Effects of the Invention] As described above, according to the configuration of the present invention, the phase difference is calculated using an electro-optical element, a vibrating mirror, etc. before dividing the light beam incident on the object to be measured and the reference light beam. Since a light beam containing a temporally varying two-wavelength acid component is created, and this light beam is divided to create a light beam incident on the object to be measured and a reference light beam, the phase difference changing means can be used with sufficient accuracy and at a relatively low cost. realizable.
第1図は本発明の第1実施例の構成°図、第2図は本発
明の第2実施例の構成図、第3図は従来例の構成図であ
る。
l・・・・・レーザ光源、2・・・・・ビームエキスパ
ンダー光学系、3.25・・・・・偏光ビームスプリッ
タ−14a、4b、24a、24b・・・・・4波長扱
、6・・・・・電源、7・・・・・被測定物体、8・・
・・・参照ミラー lO・・・・・光検出器11・・・
・・偏光板、15・・・・・電気光学素子、21・・・
・・圧電素子、22.23・・・・・反射ミラー、26
・・・・・ピンホールFIG. 1 is a block diagram of a first embodiment of the present invention, FIG. 2 is a block diagram of a second embodiment of the present invention, and FIG. 3 is a block diagram of a conventional example. l...Laser light source, 2...Beam expander optical system, 3.25...Polarizing beam splitter-14a, 4b, 24a, 24b...4 wavelength handling, 6. ...Power source, 7...Object to be measured, 8...
...Reference mirror 1O...Photodetector 11...
...Polarizing plate, 15...Electro-optical element, 21...
...Piezoelectric element, 22.23...Reflection mirror, 26
·····Pinhole
Claims (1)
且つこれら2つの光の位相差を時間的に変化させること
によって、これに伴って変化する干渉縞強度の位相差か
ら被測定物体の形状等を測定する縞走査型干渉測定装置
に於て、 光源からの光を処理して時間的に位相差の 変化する2光波成分を含む光束を作り出す位相差変化手
段が設けられ、該位相差変化手段からの上記光束の2光
波成分がビームスプリッターにより被測定物体へ向かう
光と参照面へ向かう光とに分割されることを特徴とする
縞走査型干渉測定装置。 2、前記位相差変化手段とビームスプリッターとの間の
光路内にビームエキスパンダー光学系が設けられている
請求項1記載の測定装置3、前記位相差変化手段は、光
源からの光束が入射し印加電界強度に依存して光学異方
性が変化する電気光学素子を有し、前記ビームスプリッ
ターにより、該電気光学素子より出射される光束の常光
線成分と異常光線成分のうちのいずれか一方が被測定物
体に入射させられ、他方が参照面に入射させられ、且つ
上記電界強度を制御することにより、被測定物体と参照
面への上記2つの入射光束の位相差が制御される請求項
1記載の測定装置。 4、前記位相差変化手段は、光源からの光束を分割する
別のビームスプリッターと該別のビームスプリッターに
より分割された2光束の一方を受ける固定された反射ミ
ラーとこの分割された2光束の他方を受ける移動する反
射ミラーとを有し、該移動する反射ミラーの動きを制御
することによりこれら2光束の位相差が制御される請求
項1記載の測定装置。[Claims] 1. By causing light from the object to be measured and light from the reference surface to interfere with each other and by temporally changing the phase difference between these two lights, the interference fringe intensity changes accordingly. In a fringe scanning interferometry device that measures the shape of an object to be measured from the phase difference of A fringe scanning interference measuring device, characterized in that the two light wave components of the light beam from the phase difference changing means are split by a beam splitter into light directed toward the object to be measured and light directed toward the reference surface. . 2. A measuring device according to claim 1, wherein a beam expander optical system is provided in the optical path between the phase difference changing means and the beam splitter. It has an electro-optic element whose optical anisotropy changes depending on the electric field strength, and either one of the ordinary ray component and the extraordinary ray component of the luminous flux emitted from the electro-optic element is covered by the beam splitter. 2. A phase difference between the two incident light beams on the object to be measured and the reference surface is controlled by controlling the intensity of the electric field. measuring device. 4. The phase difference changing means includes another beam splitter that splits the light beam from the light source, a fixed reflection mirror that receives one of the two light beams split by the another beam splitter, and the other of the two split light beams. 2. The measuring device according to claim 1, further comprising a moving reflecting mirror that receives the light, and a phase difference between these two beams is controlled by controlling the movement of the moving reflecting mirror.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8234189A JPH02259505A (en) | 1989-03-31 | 1989-03-31 | Fringe scanning type interference measuring instrument |
US07/875,592 US5170217A (en) | 1989-03-31 | 1992-04-28 | Object measuring apparatus using lightwave interference |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8234189A JPH02259505A (en) | 1989-03-31 | 1989-03-31 | Fringe scanning type interference measuring instrument |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH02259505A true JPH02259505A (en) | 1990-10-22 |
Family
ID=13771864
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP8234189A Pending JPH02259505A (en) | 1989-03-31 | 1989-03-31 | Fringe scanning type interference measuring instrument |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH02259505A (en) |
-
1989
- 1989-03-31 JP JP8234189A patent/JPH02259505A/en active Pending
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