JPH0484704A - Multiple-wavelength type interferometer - Google Patents
Multiple-wavelength type interferometerInfo
- Publication number
- JPH0484704A JPH0484704A JP2197675A JP19767590A JPH0484704A JP H0484704 A JPH0484704 A JP H0484704A JP 2197675 A JP2197675 A JP 2197675A JP 19767590 A JP19767590 A JP 19767590A JP H0484704 A JPH0484704 A JP H0484704A
- Authority
- JP
- Japan
- Prior art keywords
- interference fringes
- wavelength
- measurement surface
- fringes
- fringe
- Prior art date
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- Pending
Links
- 230000003287 optical effect Effects 0.000 claims abstract description 55
- 238000009826 distribution Methods 0.000 claims abstract description 28
- 230000004907 flux Effects 0.000 claims abstract description 8
- 238000005259 measurement Methods 0.000 claims description 62
- 238000003384 imaging method Methods 0.000 claims description 20
- 238000010586 diagram Methods 0.000 description 13
- 238000000034 method Methods 0.000 description 11
- 239000004065 semiconductor Substances 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005352 clarification Methods 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000000203 mixture Substances 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、波長の異なる複数個の光源を漏え、測定面、
特に球面、非球面等の形状、面精度を測定する多波長型
干渉計に関するものである。[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for emitting a plurality of light sources with different wavelengths,
In particular, it relates to a multi-wavelength interferometer that measures the shape and surface accuracy of spherical, aspherical, etc. surfaces.
［従来の技術］
レーザー干渉計は、測定面の面形状を非接触、非破壊に
測定できる装置として知られている。この装置は０．０
１μｍにも達する高い測定精度を実現しながらその反面
、測定範囲が数μｍ程度で限界に達する。したがって、
面精度が数１０μｍに達するような少し精度の悪いもの
の測定には使用できない。[Prior Art] A laser interferometer is known as a device that can measure the shape of a measurement surface in a non-contact and non-destructive manner. This device is 0.0
While achieving high measurement accuracy of up to 1 μm, the measurement range reaches its limit at around several μm. therefore,
It cannot be used for measurements with slightly poor surface accuracy, such as a surface accuracy of several tens of micrometers.
別な測定方法として、モアレを利用した測定装置がある
が、これらの到達精度は５０μｍ程度であり、数１０μ
ｍ〜１００μｍの領域での形状測定にはやはり使用でき
ないと云う難点があった。As another measurement method, there is a measuring device that uses moiré, but the accuracy achieved by these is about 50 μm, which is several tens of μm.
There was a drawback that it could not be used for shape measurement in the region of m to 100 μm.
そこで、本発明者等はこの領域での測定を可能にするも
のとして２種類以上の波長を持つレーザー光源を使用し
た多波長型干渉計を先に提案した。Therefore, the present inventors previously proposed a multi-wavelength interferometer that uses a laser light source with two or more types of wavelengths to enable measurements in this region.
このような干渉計においては、それぞれの波長による干
渉縞が重なり合って和のモアレ縞が生じる。In such an interferometer, interference fringes of each wavelength overlap to produce a sum of moiré fringes.
例えば、λ１とλ２の２波長の場合、生じる和のモアレ
縞の間隔は、λ１とλ２の等価波長λｅ （λ、・λ２
／！λ□−＾２１）による干渉縞と一致する。しかし、
このモアレ縞は大変不鮮明で視認でも観察しずらく、通
常の干渉縞の処理に用いられる方法は使用できない０例
えば、λ１−６３２．８ｎｍ、λｚ ＝６７０ｎｍとす
ると、λ８≠１１．４μｍとなり干渉縞間隔は約５μｍ
となる。For example, in the case of two wavelengths λ1 and λ2, the interval of the resulting sum of moiré fringes is the equivalent wavelength λe (λ,・λ2
/! This coincides with the interference fringes due to λ□−＾21). but,
These moiré fringes are very unclear and difficult to visually observe, and the methods used to process normal interference fringes cannot be used. The interval is approximately 5μm
becomes.
この不鮮明な干渉縞を鮮明にし、通常の干渉縞処理が可
能になると、２つの波長の光を混合して生じる等価波長
での計測が可能となる。If these blurred interference fringes are made clearer and normal interference fringe processing becomes possible, measurement using the equivalent wavelength generated by mixing two wavelengths of light becomes possible.
［発明が解決しようとする課題］
ところで、多波長型干渉計の光源として使用するレーザ
ー光源は、波長安定化されたＨｅ−Ｎｅレーザー等の可
干渉距離の長いものが理想であるが、これらの波長安定
化されたレーザーは高価であり、波長の異なったレーザ
ーを数種類用意し、干渉計に組込むことは実用的でない
。[Problems to be Solved by the Invention] By the way, the ideal laser light source used as a light source for a multiwavelength interferometer is one with a long coherence length, such as a wavelength-stabilized He-Ne laser. Wavelength-stabilized lasers are expensive, and it is not practical to prepare several types of lasers with different wavelengths and incorporate them into an interferometer.
一方、半導体レーザーは小型で安価なため入手し易いが
、可干渉距離が数■と短いために、レーザー干渉計の光
源に使用しようとすると、この可干渉距離の長さによっ
て干渉計の装置構成が制約されてしまう、このため、先
に提案された多波長型干渉計では光源にＨｅ−Ｎｅレー
ザーと半導体レーザーを搭載し、測定面の平面度測定を
可能にしたが、球面や非球面等の形状測定を行う場合は
、曲率半径が異なると、光路長が変化するため、平面度
測定の装Ｗ楕或をそのまま使用しても測定することがで
きず、何等かの対策が必要であった。On the other hand, semiconductor lasers are small and inexpensive, so they are easy to obtain, but their coherence length is as short as a few square meters, so when they are used as a light source for a laser interferometer, it is difficult to configure the interferometer's equipment depending on the length of the coherence length. For this reason, the previously proposed multi-wavelength interferometer was equipped with a He-Ne laser and a semiconductor laser as a light source, making it possible to measure the flatness of the measurement surface. When measuring the shape of an object, if the radius of curvature differs, the optical path length changes, so it is impossible to measure even if the flatness measurement device W ellipse is used as is, and some countermeasure is required. Ta.
なお、等価波長λ、４１１．４μｍは炭酸ガスレーザー
の波長と略等しく、したがって２つの光源の代わりに１
つの炭酸ガスレーザーを使用することも考えられるが、
その場合は通常の光学素子を使用することができず、高
価なものになると云う問題を含んでいる。Note that the equivalent wavelength λ, 411.4 μm, is approximately equal to the wavelength of the carbon dioxide laser, so one light source is used instead of two light sources.
It is also possible to use two carbon dioxide lasers,
In that case, there is a problem in that ordinary optical elements cannot be used and are expensive.
したがって、本発明は上記したような従来の問題点に鑑
みてなされたもので、その目的とするところは波長の異
なった複数の光源を使用して球面、非球面等の形状測定
を、通常の干渉計では測定困難だった数１０μｍから１
００μｍの領域で行塾１得るようにした多波長型干渉計
を提供することにある。Therefore, the present invention has been made in view of the above-mentioned conventional problems, and its purpose is to measure shapes of spherical, aspherical, etc. surfaces using a plurality of light sources with different wavelengths. From several tens of micrometers, which was difficult to measure with an interferometer, to 1
It is an object of the present invention to provide a multi-wavelength interferometer capable of obtaining data in the 00 μm region.
［課題を解決するための手段］
本発明は上記目的を達成するためになされたもので、そ
の第１の発明は、異なった波長を有する少なくとも２つ
の光源と、前記各光源からの光束を２分割し参照面と球
面もしくは非球面からなる測定面に導く光学素子と、前
記光学素子と測定面間に配設された対物レンズと、前記
各光源による測定面と参照面の干渉縞が重なり合って結
像される撮像装置と、前記参照面もしくは測定面の少な
くともいずれか一方を光軸に沿って移動調整し干渉計の
光路長差を実質的に零にする調整手段とを備え、前記干
渉縞の重ね合わせにより生じる不鮮明な和のモアレ縞を
縞走査して鮮明化し、等価波長による干渉縞の強度分布
を得るようにしたものである。[Means for Solving the Problems] The present invention has been made to achieve the above object, and a first aspect of the present invention is to provide at least two light sources having different wavelengths, and to divide the luminous flux from each of the light sources into two. An optical element that divides and guides the measurement surface to a reference surface and a spherical or aspherical surface, an objective lens disposed between the optical element and the measurement surface, and interference fringes of the measurement surface and the reference surface caused by each of the light sources overlap each other. an imaging device that forms an image; and an adjusting means that moves and adjusts at least one of the reference surface and the measurement surface along the optical axis to substantially zero the optical path length difference of the interferometer; This method uses fringe scanning to sharpen the blurred sum moiré fringes caused by the superposition of the two, and obtains the intensity distribution of the interference fringes according to the equivalent wavelength.
また、第２の発明は、異なった波長を有する少なくとも
２つの光源と、前記各光源からの光束を２分割し参照面
と球面もしくは非球面からなる測定面に導く光学素子と
、前記光学素子と測定面間に配設された対物レンズと、
前記対物レンズの焦光点と前記測定面の曲率の中心とが
一致するように前記対物レンズを光軸に沿って移動調整
する手段と、前記各光源による測定面と参照面の干渉縞
が互いに重なり合って結像される撮像装置とを備え、前
記参照面と測定面は、干渉計の光路長差が実質的に零に
なる位置に固定配置され、前記干渉縞の重ね合わせによ
り生じる不鮮明な和のモアレ縞を縞走査して鮮明化し、
等価波長による干渉縞の強度分布を得るようにしたもの
である。Further, a second invention includes at least two light sources having different wavelengths, an optical element that divides the light flux from each of the light sources into two and guides it to a reference surface and a measurement surface that is a spherical or aspherical surface, and the optical element. an objective lens placed between the measurement surfaces;
means for moving and adjusting the objective lens along the optical axis so that the focal point of the objective lens coincides with the center of curvature of the measurement surface, and interference fringes on the measurement surface and the reference surface caused by each of the light sources are mutually an imaging device that forms images in an overlapping manner, and the reference surface and the measurement surface are fixedly arranged at a position where the difference in optical path length of the interferometer becomes substantially zero, and the blurring sum caused by the superposition of the interference fringes is eliminated. The moiré fringes of the image are scanned to make them clearer.
This is to obtain the intensity distribution of interference fringes according to equivalent wavelengths.
さらに、第３の発明は、上記第１または第２の発明にお
いて、和のモアレ縞の縞走査により得られた等価波長干
渉縞に対してさらに縞走査を行い位相検出することによ
り、測定面の面精度または形状を測定するようにしたも
のである。Furthermore, a third invention is a method according to the first or second invention, by further performing fringe scanning on the equivalent wavelength interference fringes obtained by fringe scanning of the sum of moiré fringes and detecting the phase. It is designed to measure surface accuracy or shape.
［作用］
本発明において、測定面の曲率半径によって光学素子か
ら測定面までの光路長が変化し、調整手段によって参照
面、測定面もしくは対物レンズを光軸に沿って移動調整
すると、測定光と参照光の光路長を等しくすることがで
きる。[Function] In the present invention, the optical path length from the optical element to the measurement surface changes depending on the radius of curvature of the measurement surface, and when the adjustment means moves and adjusts the reference surface, measurement surface, or objective lens along the optical axis, the measurement light and The optical path lengths of the reference lights can be made equal.
異なった２波長λ１、λ２による干渉縞が重なり合うと
、和のモアレ縞が観測され、その縞間隔は、λｌ、λ２
による等価波長（λｅ）による干渉縞と一致する。この
和のモアレ縞のことを等価波長干渉縞と云う、そして、
和のモアレ縞は大きなうねりの中に細かな強度変化のあ
るビート信号のような強度分布をもつ、その大きなうね
りが等価波長での干渉縞である。これはきわめて不鮮明
で、通常の干渉縞処理では不可能とされる。When the interference fringes of two different wavelengths λ1 and λ2 overlap, a sum of moiré fringes is observed, and the fringe spacing is λl, λ2.
It matches the interference fringe due to the equivalent wavelength (λe). This sum of moire fringes is called equivalent wavelength interference fringes, and
The sum moiré fringes have an intensity distribution like a beat signal with small intensity changes within large undulations, and the large undulations are interference fringes at the equivalent wavelength. This is extremely unclear and is considered impossible with normal interference fringe processing.
そこで、不鮮明な等価波長干渉縞を縞走査により鮮明に
する。すなわち、参照面を光軸に沿って動かすと、干渉
縞の強度分布は参照面の移動量に応じて変化する０例え
ばλ／８の間隔で参照面を光軸に沿って平行に動かす時
の撮像装置上での一点での強度変化をＡＩ 、Ｂｌ 、
ＣＩ 、ＤＩとすると、各点での一波長における干渉縞
の位相ωは、・ ・ −・ （１）
２π
に−−・・・・ （２）
λ
で表される。Therefore, the blurred equivalent wavelength interference fringes are made clearer by fringe scanning. In other words, when the reference plane is moved along the optical axis, the intensity distribution of the interference fringes changes depending on the amount of movement of the reference plane. For example, when the reference plane is moved parallel to the optical axis at intervals of λ/8. The intensity change at one point on the imaging device is expressed as AI, Bl,
Assuming CI and DI, the phase ω of the interference fringe at one wavelength at each point is expressed as... (1) 2π and (2) λ.
ここで、その振幅の２乗は、
ＴＨ２＝ （Ａ□−Ｃ，）２＋ （Ｂ、−Ｄ、） ２・
（３）
で表される。Here, the square of the amplitude is TH2= (A□-C,)2+ (B,-D,) 2・
(3) It is expressed as
そこで、式（３）に着目し、２つの干渉縞の重なり合っ
た状態でλ、もしくはλ２について１周期分の縞走査を
行い、式（３）のＴＨ２の値を求める。２波長における
ＴＨ２の値は、和のモアレ縞の各点における振幅の２乗
に比例する。つまり、ＴＨ” Ｑ値は、等価波長干渉縞
の強度変化に比例していることになる。この動作を２次
元の干渉縞図形において行うと、鮮明な等価波長干渉縞
が得られる。Therefore, focusing on equation (3), one cycle of fringe scanning is performed for λ or λ2 in a state where the two interference fringes overlap, and the value of TH2 in equation (3) is determined. The value of TH2 at two wavelengths is proportional to the square of the amplitude at each point of the sum of moiré fringes. In other words, the TH"Q value is proportional to the change in the intensity of the equivalent wavelength interference fringe. If this operation is performed on a two-dimensional interference fringe pattern, a clear equivalent wavelength interference fringe can be obtained.
また、等価波長干渉縞が得られると、この等価波長の１
周期分を何分割かし、縞走査することにより、等価波長
での位相分布が式（１）がら求めることができる。Moreover, when an equivalent wavelength interference fringe is obtained, 1 of this equivalent wavelength is
By dividing the period and performing fringe scanning, the phase distribution at the equivalent wavelength can be determined using equation (1).
［実施例］
以下、本発明を図面に示す実施例に基づいて詳細に説明
する。[Example] Hereinafter, the present invention will be described in detail based on an example shown in the drawings.
第１図は本発明に係る多波長型干渉計の一実施例を示す
光学系の図である。同図において、多波長型干渉計は、
波長の異なった２つの光源１．２を備えている。第１の
光源１としては、可視、赤外または紫外の光束を発する
ものとして、例えばＨｅ−Ｎｅレーザー（波長λ、＝＝
６３２．８ｎｍ）が、第２の光源２としては可干渉距離
の短い半導体レーザー（波長λ２ ＝６７０ｎｍ）がそ
れぞれ使用される。第２の光源２から出た光束は、コリ
メータレンズ３と、アナモルフィックプリズム４により
平行光線に調整された後、ビームミキサー５により第１
の光源１の光束と重ね合わされる。FIG. 1 is a diagram of an optical system showing an embodiment of a multiwavelength interferometer according to the present invention. In the figure, the multiwavelength interferometer is
It is equipped with two light sources 1.2 with different wavelengths. The first light source 1 is one that emits visible, infrared, or ultraviolet light, for example, a He-Ne laser (wavelength λ, ==
632.8 nm), and a semiconductor laser with a short coherence length (wavelength λ2 = 670 nm) is used as the second light source 2. The light flux emitted from the second light source 2 is adjusted to parallel light beams by a collimator lens 3 and an anamorphic prism 4, and then is passed through a beam mixer 5 to a first parallel light beam.
The light beam from the light source 1 is superimposed with the light beam from the light source 1.
なお、第１の光源１、第２の光源２の光量は、ビームミ
キサー５以後等しくなるように調整されている。Note that the light quantities of the first light source 1 and the second light source 2 are adjusted to be equal after the beam mixer 5.
６は発散レンズ、７はハーフミラ−１８はコリメータレ
ンズ、９はハーフミラ−からなるメインミラー、１０は
球面あるいは非球面からなる測定面、１１は光学素子９
と測定面１０の間の光路中に配置された対物レンズ、１
２は測定面１０の試料台、１３は試料台１２を光軸に沿
って移動調整する調整手段、１４は参照面、１５は参照
面１４のホルダー１６を光軸方向に移動調整する調整手
段、１７は参照面１４を光軸方向に移動させる装置（例
えばピエゾ素子）、１８は観測する干渉縞のノイズ除去
と装置のダイナミックレンジを決めるスペーシャルフィ
ルタ、１９は結像レンズ、２０はＣＣＤカメラ等の撮像
装置、２１は画像入力装置、２２は画像処理するコンピ
ュータである。6 is a diverging lens, 7 is a half mirror, 18 is a collimator lens, 9 is a main mirror consisting of a half mirror, 10 is a measurement surface consisting of a spherical or aspherical surface, 11 is an optical element 9
an objective lens arranged in the optical path between the measurement surface 10 and the measuring surface 10;
Reference numeral 2 denotes a sample stand for the measurement surface 10, 13 an adjusting means for moving and adjusting the sample stand 12 along the optical axis, 14 a reference plane, and 15 an adjusting means for moving and adjusting the holder 16 of the reference plane 14 in the optical axis direction. 17 is a device (for example, a piezo element) that moves the reference plane 14 in the optical axis direction, 18 is a spatial filter that removes noise from the observed interference fringes and determines the dynamic range of the device, 19 is an imaging lens, and 20 is a CCD camera, etc. 21 is an image input device, and 22 is a computer for image processing.
このような構成において、第１の光源１から発射された
波長λｌのレーザー光は、ビームミキサー５を透過して
発散レンズ６により発散光となり、ハーフミラ−７で反
射され、コリメータレンズ８によって再び平行光とされ
た後、その一部がメインミラー９に当たって反射し、対
物レンズ１１によってその焦光点Ｐに集光された後測定
面１０を照射する一方、他の一部がメインミラー９を透
過して参照面１４を照射する。測定面１０と参照面１４
に当たってそれぞれ反射した反射光は同一光路を戻るこ
とにより互いに重ね合わされ、コリメータレンズ８、ハ
ーフミラ−７、スペーシャルフィルタ１８を通過し、結
像レンズ１９によって撮像装置２０の撮像面に結像され
ることにより、再反射光の相互干渉に基づく干渉縞を形
成し、これを画像入力装置２１によって画像化する。In such a configuration, a laser beam of wavelength λl emitted from the first light source 1 passes through the beam mixer 5, becomes a diverging beam by the diverging lens 6, is reflected by the half mirror 7, and is made parallel again by the collimator lens 8. After being turned into light, a part of it hits the main mirror 9 and is reflected, and after being focused at a focal point P by the objective lens 11, it irradiates the measurement surface 10, while the other part passes through the main mirror 9. Then, the reference surface 14 is irradiated. Measuring surface 10 and reference surface 14
The reflected lights that hit the target and are respectively reflected are superimposed on each other by returning along the same optical path, pass through the collimator lens 8, the half mirror 7, and the spatial filter 18, and are imaged by the imaging lens 19 on the imaging surface of the imaging device 20. As a result, interference fringes are formed based on the mutual interference of the re-reflected lights, and this is converted into an image by the image input device 21.
第２の光源２から発射された波長λ２のレーザー光は、
コリメーターレンズ３およびアナモルフィックプリズム
４を通過してビームミキサー５により反射された後、上
記した第１の光源１の光束と同一の光路を通って測定面
ｌＯと、参照面１４を照射し、その反射光が結像レンズ
１９により撮像装置２０の撮像面上に結像されることに
より干渉縞を形成する。The laser beam of wavelength λ2 emitted from the second light source 2 is
After passing through the collimator lens 3 and the anamorphic prism 4 and being reflected by the beam mixer 5, the light passes through the same optical path as the light beam of the first light source 1 described above and irradiates the measurement surface 10 and the reference surface 14. , the reflected light is imaged by the imaging lens 19 onto the imaging surface of the imaging device 20, thereby forming interference fringes.
今、光学素子９から測定面１０までの光路長ｊ１と光学
素子９から参照面１４までの光路長ｊｒが等しいとき（
Ｊ、＝１．、） 、第２の光源２により生じる干渉縞は
、最も鮮明になる。１ｒとｌ。Now, when the optical path length j1 from the optical element 9 to the measurement surface 10 and the optical path length jr from the optical element 9 to the reference surface 14 are equal (
J,=1. , ), the interference fringes produced by the second light source 2 will be the clearest. 1r and l.
の差をδ（＝Ｊ、−ｆ、）とすると、δ＝０のとき、光
路長が等しいことを示す。Letting the difference between them be δ (=J, −f,), when δ=0, it means that the optical path lengths are equal.
球面形状の測定に際して、測定面１０と参照面１４は調
整手段１３．１５によって光軸に沿って移動調整され、
δ＝０となる位置に設定される。When measuring the spherical shape, the measuring surface 10 and the reference surface 14 are adjusted in movement along the optical axis by adjusting means 13.15,
It is set at a position where δ=0.
この時、対物レンズ１１の焦光点Ｐと、測定面１０の曲
率半径の中心とが一致するように調整する。At this time, adjustment is made so that the focal point P of the objective lens 11 and the center of the radius of curvature of the measurement surface 10 coincide.
調整に際しては干渉計の光源を可干渉距離の短い半導体
レーザー２の単波長のみにし、可干渉距離の長いＨｅ−
Ｎｅレーザー１は遮光する。この状態で干渉縞を撮像装
置２０でＷ１測し、−点での干渉縞の光量変化を測定し
ながら参照面１４を光軸に沿って移動させると、その光
景変化は第２図のようになる。During adjustment, the light source of the interferometer is set to only the single wavelength of the semiconductor laser 2, which has a short coherence length, and He-
The Ne laser 1 is blocked. In this state, the interference fringes are measured W1 by the imaging device 20, and when the reference plane 14 is moved along the optical axis while measuring the change in the light intensity of the interference fringes at the - point, the scene changes as shown in Figure 2. Become.
第２図において、縦軸は光景変化、横軸は参照面１４の
移動量、２６は干渉縞の強度、２７は干渉縞のピークを
結んだ放絡線を示す。In FIG. 2, the vertical axis shows the change in the scene, the horizontal axis shows the amount of movement of the reference plane 14, 26 shows the intensity of the interference fringes, and 27 shows the radial line connecting the peaks of the interference fringes.
δ＝０の条件を満たず参照面１４の位置は第２図のグラ
フで放Ｍｉ１１２７の振幅が最大になる点Ｑになる。し
たがって、Ｑの位置に参照面１４を移動させれば、調整
は終了する。If the condition of δ=0 is not satisfied, the position of the reference plane 14 is a point Q in the graph of FIG. 2 where the amplitude of the radiated Mi 1127 is maximum. Therefore, if the reference plane 14 is moved to the position Q, the adjustment is completed.
光路長の調整方法としては、本実Ｉ＃、例の場合対物レ
ンズ１１を固定配置し、測定面１０と参照面１４を光軸
に沿って移動調整するようにした例を示したが、これに
限らず第３図に示すように測定面１０と参照面１４をＪ
、 −ｉＩ、となる位置に予め固定配置しておき、対物
レンズ１１を調整手段２８によって光軸に沿って移動調
整し、該レンズの焦光点Ｐと測定面１０の曲率半径の中
心が一致するように調整してもよい。As a method for adjusting the optical path length, an example was shown in which the objective lens 11 was fixedly arranged and the measuring surface 10 and the reference surface 14 were adjusted by moving along the optical axis. However, as shown in FIG.
, -iI, and move and adjust the objective lens 11 along the optical axis by the adjusting means 28, so that the focal point P of the lens coincides with the center of the radius of curvature of the measurement surface 10. You may adjust it so that
この場合も干渉縞を撮像装Ｗ２０で観察し、測定面１０
が全面ＦＡ察できる位置に調整すればよい。In this case as well, the interference fringes are observed with the imaging device W20, and the measurement surface 10 is
All you have to do is adjust it to a position where you can see the entire FA.
対物レンズ１１の焦光点Ｐと測定面１０の曲率半径の中
心が一致すると、測定面１０には光が略垂直に入射する
ので、略全面の光が対物レンズ１１に戻る。したがって
、対物レンズ１１を光軸に沿って移動させながら干渉縞
を観察すると、第４図（ａ＞、（ｂ）、（Ｃ）に示すよ
うな干渉縞となる、すなわち、同図（ａ）は、対物レン
ズ１１の焦光点Ｐが測定面１０の曲率半径の中心より下
方に位置する場合、同図（ｂ）は焦光点Ｐと測定面１０
の曲率半径の中心が一致した場合、同図（ｃ）の写真は
焦光点Ｐが測定面ｌＯの曲率半径の中心より上方に位置
する場合の干渉縞をそれぞれ示す。When the focal point P of the objective lens 11 and the center of the radius of curvature of the measurement surface 10 coincide, the light enters the measurement surface 10 substantially perpendicularly, so that substantially the entire surface of the light returns to the objective lens 11. Therefore, if the interference fringes are observed while moving the objective lens 11 along the optical axis, the interference fringes will be as shown in FIG. When the focal point P of the objective lens 11 is located below the center of the radius of curvature of the measurement surface 10, FIG.
When the centers of the radii of curvature coincide, the photograph in FIG. 3(c) shows interference fringes when the focal point P is located above the center of the radius of curvature of the measurement surface IO.
波長λ１による干渉縞の強度分布と、波長λ２による干
渉縞の強度分布が撮像装置２０の撮像面上に重なり合う
と、その強度分布は丙子渉縞による和のモアレ縞となる
。When the intensity distribution of interference fringes with the wavelength λ1 and the intensity distribution of the interference fringes with the wavelength λ2 overlap on the imaging surface of the imaging device 20, the intensity distribution becomes a sum of Moiré fringes due to the Heiko interference fringes.
つまり、２つの光源ｌ、２の光束を混合した状態で測定
面１０を照射すると、観測される干渉縞は和のモアレ縞
である。このモアレ縞の間隔は、λ１、λ２による等僅
波長（λ８）による干渉縞と一致することが原理的に明
らかで、以後このモアレ縞のことを等価波長干渉縞とい
う。That is, when the measurement surface 10 is irradiated with a mixture of the light beams from the two light sources 1 and 2, the observed interference fringes are the sum of moiré fringes. It is clear in principle that the interval between these moire fringes coincides with the interference fringes of equal wavelengths (λ8) due to λ1 and λ2, and hereinafter, these moire fringes will be referred to as equivalent wavelength interference fringes.
第５図（ａ＞は波長λ１による干渉縞の写真である。干
渉縞の間隔はλ１／２≠０．３μｍである。同図（ｂ）
は波長λ１の干渉縞と波長λ２の干渉縞の重ね合わせに
よる和のモアレ縞の写真である。Fig. 5 (a> is a photograph of interference fringes at wavelength λ1. The interval of interference fringes is λ1/2≠0.3 μm. Fig. 5 (b)
is a photograph of the sum of moire fringes resulting from the superposition of interference fringes with wavelength λ1 and interference fringes with wavelength λ2.
第６図（ａ＞は２つの波長λｌ、＾２の干渉績を示す図
で、波の低い部分が暗、高い部分が明を表している。同
図（ｂ）は同図（ａ）の２つの干渉縞の重ね合わせによ
る波の「うねりＪを示す図であり、この図から明らかな
ように２つの干渉縞が重なり合うと、明暗が激しく入れ
替わる部分と明暗の変化のない部分が生じ、例えばこの
明暗変化がなく中間の明るさのところをつないだものが
モアレ縞Ｍｏ（第５図（ｂ）の白い部分に対応）だと云
える。このモアレ縞Ｍ。は第６図（ｂ）から明らかなよ
うに大きなうねりの中に細かな強度変化のあるビート信
号のような強度分布をもつため、コントラストが著しく
悪く、目視でも観察しずらく、通常の干渉縞処理は不可
能である。Figure 6 (a) is a diagram showing the interference results of two wavelengths λl and ^2, where the lower part of the wave is dark and the higher part is bright. This is a diagram showing the undulation J of a wave caused by the superposition of two interference fringes.As is clear from this diagram, when two interference fringes overlap, there are parts where the brightness changes drastically and parts where there is no change in brightness, for example. It can be said that the moiré fringe Mo (corresponding to the white part in Fig. 5(b)) is the one that connects the areas of intermediate brightness without this change in brightness and darkness.This moiré fringe M. can be seen from Fig. 6(b). As is clear, the intensity distribution is like a beat signal with small intensity changes within large undulations, so the contrast is extremely poor and it is difficult to observe visually, making normal interference fringe processing impossible.
■ 不鮮明な和のモアレ縞の鮮明化
そこで、不鮮明な干渉縞から和のモアレ縞による強度分
布のみを縞走査によって取出し、鮮明な等価波長干渉縞
の強度分布を得る。すなわち、ピエゾ素子１７によって
参照面１４を光軸に沿って動かすと、ｌ、が変化し、δ
が変わる。したがって、干渉縞の強度分布は参照面１４
の移動量に応じて変化する。これを縞走査と云う。■ Clarification of blurred sum moire fringes Therefore, only the intensity distribution due to sum moiré fringes is extracted from the blurred interference fringes by fringe scanning to obtain a clear intensity distribution of equivalent wavelength interference fringes. That is, when the reference surface 14 is moved along the optical axis by the piezo element 17, l changes and δ
changes. Therefore, the intensity distribution of the interference fringes is
changes depending on the amount of movement. This is called fringe scanning.
δ＝、＆、−１１−とすると；測定面１０にて反射した
第１の光源ｌによる測定光と、参照面１４に当たって反
射した参照光とは往復２δの光路差を生じる。この２δ
の光路差から生じる干渉模様の強度は、
Ｉ ｃｃ ｃ ｏ ｓ ２（２ｙｒλ、δ＋Φ）（但し
、Φハ整数）
となる。If δ=, &, -11-; the measurement light from the first light source 1 that is reflected at the measurement surface 10 and the reference light that hits the reference surface 14 and is reflected produce a round trip optical path difference of 2δ. This 2δ
The intensity of the interference pattern resulting from the optical path difference is Icccos2(2yrλ, δ+Φ) (where Φ is an integer).
すなわち、光路差２δがλ□／２の奇数倍の時、２δ＝
λｌ／２・（２ｎ−１）（但し、ｎは整数）となり、互
いに打ち消し合って暗い縞が生じ、λｉ／２の偶数倍の
時、２δ＝λ１／２・（２ｎ）となり、互いに強め合っ
て明るい縞が生じる。That is, when the optical path difference 2δ is an odd multiple of λ□/2, 2δ=
λl/2・(2n-1) (where n is an integer), and they cancel each other out, producing dark stripes.When λi/2 is an even multiple, 2δ=λ1/2・(2n), and they strengthen each other. bright stripes occur.
なお、第２の光源２による干渉縞も同様である。Note that the same applies to the interference fringes produced by the second light source 2.
第７図は波長λ１ （もしくはλ２）のみの光により生
じた干渉縞の撮像面上の１点での強度変化をプロットし
たものであり、縦軸は光量、横軸はピエゾ素子１７への
加電圧である。第７図のようにピエゾ素子１７を用いて
参照面１４を光軸方向にλ！／８ずつ（光路長に対して
λｌ／４ずつ）変化させた時の撮像面上の一点での強度
変化をＡ□、Ｂ、 、Ｃ□、Ｄ８とすると、各点での一
波長における干渉縞の位相ωは、
・ ・ ・ ・ （１）
λ１
で表される。FIG. 7 is a plot of the intensity change at one point on the imaging plane of interference fringes caused by light with only wavelength λ1 (or λ2), where the vertical axis represents the light amount and the horizontal axis represents the addition to the piezo element 17. It is voltage. As shown in FIG. 7, a piezo element 17 is used to move the reference surface 14 in the optical axis direction λ! If the intensity changes at one point on the imaging plane when changed by /8 (by λl/4 with respect to the optical path length) are A□, B, , C□, and D8, then the interference at one wavelength at each point is The phase ω of the fringe is expressed as ・ ・ ・ ・ (1) λ1.
ここで、その振幅の２乗は
ＴＨ２＝ （Ａｔ −ＣＸ）” （−＜８１ ＤＩ
） ２− ・ −（３）
で表される。Here, the square of the amplitude is TH2= (At −CX)” (−<81 DI
) 2- ・-(3)
式（３）に着目し、第５図（ｂ）のように２つの干渉縞
の重なり合った状態で波長λ１について１周期分の縞走
査を行い、式（３）のＴＨ”の値を求める。Focusing on equation (3), one cycle of fringe scanning is performed for wavelength λ1 in a state where two interference fringes overlap as shown in FIG. 5(b), and the value of TH'' in equation (3) is determined.
つまり、ＴＨ２の値は等価波長干渉縞の強度変化に比例
していることになる。この動作を２次元の干渉縞図形に
おいて行なうと、第５図（ｃ）に示すような２つの干渉
縞の重ね合わせから鮮明な等値干渉縞が得られる。In other words, the value of TH2 is proportional to the change in intensity of the equivalent wavelength interference fringe. When this operation is performed on a two-dimensional interference fringe pattern, clear equivalued interference fringes can be obtained from the superposition of two interference fringes as shown in FIG. 5(c).
第６図（ｃ）はこの時の等価波長干渉縞の強度分布を示
す図であり、こまかな縞が消えモアレ縞が鮮明化したこ
とを示している。FIG. 6(c) is a diagram showing the intensity distribution of the equivalent wavelength interference fringes at this time, and shows that the fine fringes have disappeared and the moiré fringes have become clearer.
■ 等価波長干渉縞による測定面の形状測定第６図（ｃ
）に示すように等債波長干渉縞の強度分布が得られると
、この等価波長の１周期を何分割かし、縞走査すること
により等価波長での位相分布を式（１）から求めること
ができる。■ Measurement of the shape of the measurement surface using equivalent wavelength interference fringes Figure 6 (c
) Once the intensity distribution of the equivalent wavelength interference fringes is obtained, the phase distribution at the equivalent wavelength can be obtained from equation (1) by dividing one cycle of this equivalent wavelength into several parts and scanning the fringes. can.
ここでは第７図の等価波長干渉縞の強度分布の１周期を
等分割し、位相を求める方法を、４分割を例に説明する
。Here, a method of equally dividing one cycle of the intensity distribution of the equivalent wavelength interference fringes in FIG. 7 and determining the phase will be explained using an example of dividing into four.
第７図において、点Ａ１ 、Ｂ１、Ｃ□、Ｄｌの強度変
化から式（１）を用いて等価波長干渉縞の強度分布が求
まることは先に述べた。As mentioned above, in FIG. 7, the intensity distribution of the equivalent wavelength interference fringes can be determined from the intensity changes at points A1, B1, C□, and Dl using equation (1).
次に、この等価波長を４分割し、点Ａ！、Ａ２、Ａ３
＋ Ａ４の強度変化から式（２ンを用いて位相量の計算
ができる。Next, divide this equivalent wavelength into four, and point A! , A2, A3
+ From the intensity change of A4, the phase amount can be calculated using the formula (2).
（Ａ□、Ｂ８、Ｃ，、Ｄｌｌから式（１）を用いて求ま
る等価波長干渉縞と、（Ａｚ 、Ｂ２ 、Ｃｚ ＋ Ｂ
２１から、そして＋Ａｓ 、Ｂ、、Ｃ，−Ｄ、）、（Ａ
４．Ｂａ、Ｃ４、Ｄａｌから求まる計４枚の等価波長干
渉縞から、（Ａ□、Ａ２ 、Ａ３、Ａ４）が得られる。Equivalent wavelength interference fringes found from (A□, B8, C, , Dll using equation (1) and (Az , B2 , Cz + B
21, and +As,B,,C,-D,),(A
4. (A□, A2, A3, A4) are obtained from a total of four equivalent wavelength interference fringes determined from Ba, C4, and Dal.
つまり、４枚の干渉縞図形から１枚の等価波長干渉縞を
得ることができ、この動作を計４回繰り返すと、４枚の
等価波長干渉縞が得られる。そしてこの４枚の等価波長
干渉縞から等価波長での位相分布が式（２）から計算で
き、形状を測定できることになる。In other words, one equivalent wavelength interference fringe can be obtained from four interference fringe patterns, and by repeating this operation four times in total, four equivalent wavelength interference fringes can be obtained. From these four equivalent wavelength interference fringes, the phase distribution at the equivalent wavelength can be calculated from equation (2), and the shape can be measured.
しかし、この動作を実現するためには（Ａ□、Ｂｌ、Ｃ
Ｌ、Ｄｌ）、（Ａ２ 、Ｂ２ 、Ｃｚ 、Ｂ２ ）（Ａ
３ 、ＢＳ 、ＣＳ、Ｂ３１、（Ａ４、Ｂ、、Ｃ４、Ｂ
４ ）がそれぞれＡ１もしくはＡ２の１周期を４分割し
ており、さらに（Ａ Ｉ 、Ａｚ 、Ａ３、Ａ４）はＡ
ｌ、Ａ２による等価波長λ、の１周期を４分割していな
ければならない。However, in order to realize this operation (A□, Bl, C
L, Dl), (A2, B2, Cz, B2) (A
3, BS, CS, B31, (A4, B,, C4, B
4) divides one cycle of A1 or A2 into four, and (A I , Az , A3, A4) divides A
One period of the equivalent wavelength λ due to l and A2 must be divided into four.
■ 「干渉縞の鮮明化」および「形状測定」を行なうた
めの縞走査の方法
上記■で説明した縞走査を繰り返し行い、形状測定のた
めの位相検出をするための方法を次に説明する。(2) Method of fringe scanning for "clarifying interference fringes" and "measuring shape" Next, a method for repeatedly performing the fringe scanning described in (2) above and detecting a phase for shape measurement will be described.
第７図は上述した通り波長λ１による干渉縞の強度変化
を示したグラフで、参照面１４を光軸方向に動かした時
の撮像面上の１点での強度変化である。グラフ上の点（
Ａｔ、Ｂ１、Ｃ１、Ｄ工）は、−波長における干渉縞の
強度変化の１周期分を４分割した位置である０点＋Ａ２
、Ｂ２ 、Ｃ２、Ｄｚ ）、（Ａ３．Ｂ３ 、Ｃ５、
Ｂ３ ）、（Ａ４、Ｂ４ 、Ｃ４、Ｂ４ ＞は１周期の
初期位置が異なるだけで、同様に１周期を４分割した位
置である。As described above, FIG. 7 is a graph showing the intensity change of the interference fringes depending on the wavelength λ1, and shows the intensity change at one point on the imaging plane when the reference plane 14 is moved in the optical axis direction. A point on the graph (
At, B1, C1, D) is the 0 point + A2, which is the position where one cycle of the intensity change of the interference fringe at the − wavelength is divided into four.
, B2 , C2, Dz ), (A3.B3 , C5,
B3), (A4, B4, C4, B4> differ only in the initial position of one period, and are similarly the positions obtained by dividing one period into four.
この（ＡＩ 、Ｂｌ −Ｃ１，Ｄｔ ｌらの位置に参照
面１４を動かすことにより、干渉縞は１７４周期ずつ変
化する。初期位置（ＡＨ、Ａ２ 、Ａｓ 、Ａ４）は、
等価波長干渉縞の１周期を４等分した位置になる。By moving the reference plane 14 to the positions of (AI, Bl - C1, Dt l, etc.), the interference fringes change by 174 periods. The initial positions (AH, A2, As, A4) are
This is the position where one period of the equivalent wavelength interference fringe is equally divided into four.
第８図は横軸に第７図の強度変化のピーク位置（最大値
、最小値の位置）、縦軸にピエゾ素子１７への駆動電圧
をプロットしたものである。In FIG. 8, the horizontal axis is the peak position (maximum value, minimum value position) of the intensity change in FIG. 7, and the vertical axis is the drive voltage to the piezo element 17.
λｌ＝０．６３２８μｍ、Ａ２ ＝０．６７０μｍの時
、等価波長λ８は１１．３９７μｍになる。When λl = 0.6328 μm and A2 = 0.670 μm, the equivalent wavelength λ8 is 11.397 μm.
λ、による干渉縞の強度変化１周期分のうちに、Ａ１に
よる干渉縞は第７図から明らかなように約１８本台まれ
る。つまり、Ａ１の波長による干渉縞を基準に考えると
、（Ａｌ、Ａ２ 、Ａ３ 、Ａ４ ）の位置は、λ、の
波長による干渉縞の本数で（０，４，５，９，１３，５
）となる。As is clear from FIG. 7, about 18 interference fringes due to A1 are formed within one cycle of the intensity change of the interference fringes due to λ. In other words, considering the interference fringes due to the wavelength of A1 as a reference, the positions of (Al, A2, A3, A4) are (0, 4, 5, 9, 13, 5) with the number of interference fringes due to the wavelength of λ.
).
なお、第７図にプロットした点（ＡＩ、Ａ２、Ａ３ 、
Ａ４ ）の位置は、Ａ１の干渉縞の位置を基準に本数で
決められている。Note that the points plotted in Figure 7 (AI, A2, A3,
The position of A4) is determined by the number of interference fringes based on the position of the interference fringes of A1.
点ｆＡ４、Ｂｌ、Ｃｔ、Ｄｘ ）、（Ａ２ 、Ｂ ２、
Ｃ２−Ｂ２１ ・・・・などの位置を決める別の方法と
して、Ａｌ、Ａ２の両方の光を混合したままの状態で縞
走査し、和のモアレ縞の強度変化を直接検出することに
より、その強度変化から点（Ａ、−８１、Ｃ□、Ｄｌ
）、（Ａ２ 、Ｂ２ 、Ｃ２、Ｄ２１ ・・・・などの
位置を決めることができる。Point fA4, Bl, Ct, Dx), (A2, B2,
Another method for determining the position of C2-B21..., etc. is to perform fringe scanning with both Al and A2 light mixed together and directly detect the intensity change of the sum of moiré fringes. From the intensity change, the point (A, -81, C□, Dl
), (A2, B2, C2, D21, etc.) can be determined.
かくしてこのような多波長型干渉計においては、従来、
波長λ１、Ａ２の干渉縞の重ね合わせによって生じる和
のモアレ縞の強度分布は鮮明度が悪く、形状測定には用
いることが困難とされていたが、式（３）の値をコンピ
ュータ２２によって計算することにより、和のモアレ縞
から鮮明な等価波長干渉縞の強度分布が得られるように
なった。Thus, in such a multi-wavelength interferometer, conventionally,
The intensity distribution of the sum of moiré fringes produced by the superposition of interference fringes of wavelengths λ1 and A2 has poor clarity and is difficult to use for shape measurement, but the value of equation (3) was calculated by computer 22. By doing this, it became possible to obtain a clear intensity distribution of equivalent wavelength interference fringes from the sum of moiré fringes.
また、得られた等価波長干渉縞の強度変化の１周期を４
分割するように再び縞走査法を重ねて用いることにより
、今度は式（２）の値まで計算すると、等価波長での位
相検出ができる。したがって、この位相分布をつなぎ合
わせると、測定面１０の形状が求まる。In addition, one period of the intensity change of the obtained equivalent wavelength interference fringe is 4
By using the fringe scanning method again in a divided manner and calculating the value of equation (2), phase detection at the equivalent wavelength can be performed. Therefore, by connecting these phase distributions, the shape of the measurement surface 10 can be determined.
λ□の波長による干渉縞を基準に考えるとき、強度変化
の１周期分を仮に４等分すると、４×４回、計１６回参
照面１４の位置を変えて干渉縞図形の強度分布および位
相分布を高精度に求めることができる。When considering the interference fringe due to the wavelength of λ□, if one period of intensity change is divided into four equal parts, the position of the reference plane 14 is changed 4×4 times, a total of 16 times, and the intensity distribution and phase of the interference fringe pattern are calculated. Distribution can be determined with high precision.
第５図（ｄ）は位相計算の結果得られた和のモアレ縞を
示す図である。FIG. 5(d) is a diagram showing the sum of moiré fringes obtained as a result of phase calculation.
＾１＝６３２．８ｎｍ、Ａ２ ＝６７０ｎｍの時、λｅ
−１１，３９７μｍとなり、Ａ８による干渉縞は間隔が
λ、／２＝５．６９９μｍとなる。これは、λｌによる
干渉縞間隔λ１／２＃０．３μｍの約１８倍である。単
純に考えてもＡ１による単波長干渉計の約１８倍のダイ
ナミックレンジをもつことが分かる。When ^1 = 632.8 nm, A2 = 670 nm, λe
-11,397 μm, and the interference fringes due to A8 have an interval of λ,/2=5.699 μm. This is about 18 times the interference fringe spacing λ1/2#0.3 μm due to λl. Even when considered simply, it can be seen that the dynamic range is about 18 times that of the single wavelength interferometer using A1.
なお、本発明者等によって製作された装置では、波長λ
□＝６３２．８ｎｍ、λ２＝６７０ｎｍにおいて、有効
径６０ｍｍの光束において、約２００μｍのダイナミッ
クレンジを確認した。Note that in the device manufactured by the present inventors, the wavelength λ
At □ = 632.8 nm and λ2 = 670 nm, a dynamic range of about 200 μm was confirmed for a luminous flux with an effective diameter of 60 mm.
また、上記実施例は測定面１０が球面の場合について説
明したが、非球面であっても全く同様に測定することが
できるものである。Furthermore, although the above embodiments have been described with reference to the case where the measurement surface 10 is a spherical surface, even if the measurement surface 10 is an aspheric surface, the measurement can be performed in exactly the same way.
［発明の効果］
以上説明したように本発明に係る多波長型干渉計は、測
定面の手前に対物レンズを配置し、測定面、参照面もし
くは対物レンズを調整手段によって光軸に沿って移動調
整し、測定面と参照面の光路長を一致させ、波長の異な
る干渉縞の重ね合わせにより生じる不鮮明な和のモアレ
縞を縞走査するようにしたので、鮮明な等価波長干渉縞
の強度分布を得ることができ、またこの得られた等僅波
長干渉縞に対して再び縞走査を重ねて行なうことにより
、位相検出を行うようにしたので、可干渉距離の短い半
導体レーザーを光源として使用しても、球面、非球面等
の形状測定を数１０μｍ〜１００μｍの領域で良好に行
うことができ、その効果は非常に大である。[Effects of the Invention] As explained above, in the multiwavelength interferometer according to the present invention, the objective lens is arranged in front of the measurement surface, and the measurement surface, the reference surface, or the objective lens is moved along the optical axis by the adjustment means. By adjusting the optical path lengths of the measurement surface and the reference surface to match, we scanned the moiré fringes, which are the blurred sum of interference fringes caused by the superposition of interference fringes with different wavelengths, so that the intensity distribution of clear equivalent wavelength interference fringes can be obtained. We also performed phase detection by repeating fringe scanning on the obtained equislight wavelength interference fringes, so we used a semiconductor laser with a short coherence length as the light source. Also, the shape measurement of spherical surfaces, aspherical surfaces, etc. can be performed well in the range of several tens of micrometers to 100 micrometers, and the effect is very large.
第１図は本発明に係る多波長型干渉計の一実施例を示す
光学系の構成図、第２図はホルダーを移動させた時の光
量変化を示す図、第３図は本発明の他の実施例を示す光
学系の要部構成図、第４図（ａ）、（ｂ）、（Ｃ）はそ
れぞれ対物レンズを移動調整した場合の干渉縞、第５図
（ａ）は波長１による干渉縞、（ｂ）は波長λ□による
干渉縞と波長λ２による干渉縞の重ね合わせによる和の
モアレ縞、（Ｃ）は鮮明化された和のモアレ縞、（ｄ）
は位相計算の結果を示す図、第６図（ａ）はＡ１とＡ２
による干渉縞、（ｂ）は干渉縞の重ね合わせによる波の
「うねり」を示す図、（Ｃ）は等価波長干渉縞の強度分
布を示す図、第７図はＨｅ−Ｎｅレーザーの波長λ□に
よる干渉縞の強度変化を示すグラフ、第８図は横軸に第
７図の強度変化のピーク位Ｗ（最大値、最小値の位置）
、縦軸にピエゾ素子１２への駆動電圧をプロットした図
である。
１．２・・・光源、３・・・コリメーターレンズ、４・
・・アナモルフィックプリズム、５・・・ビームミキサ
ー、６・・・発散レンズ、７・・・ハーフミラ−１８・
・・コリメータレンズ、９・・・メインミラー、１０・
・・測定面、１１・・・対物レンズ、１°２・・・試料
台、１３・・・調整手段、１４・・・参照面、１５・・
−調整手段、１６・・・ホルダ、１７・・−ピエゾ素子
、２０・・・撮像装置、２１−・・画像入力装置、２２
・・・コンピュータ、２８・
・調整手段。FIG. 1 is a configuration diagram of an optical system showing one embodiment of a multiwavelength interferometer according to the present invention, FIG. 2 is a diagram showing changes in light amount when the holder is moved, and FIG. 3 is a diagram showing an example of a multiwavelength interferometer according to the present invention. 4(a), (b), and (C) are the interference fringes when the objective lens is moved and adjusted, and FIG. 5(a) is the interference pattern at wavelength 1. Interference fringes, (b) is the sum of moiré fringes resulting from the superposition of interference fringes with wavelength λ□ and interference fringes with wavelength λ2, (c) is the sharpened sum of moiré fringes, (d)
is a diagram showing the result of phase calculation, and Fig. 6(a) shows A1 and A2.
(b) is a diagram showing the "undulation" of the wave due to the superposition of interference fringes, (C) is a diagram showing the intensity distribution of the equivalent wavelength interference fringe, and Figure 7 is a diagram showing the wavelength λ□ of the He-Ne laser. Figure 8 is a graph showing the intensity change of interference fringes due to
, in which the driving voltage to the piezo element 12 is plotted on the vertical axis. 1.2... Light source, 3... Collimator lens, 4...
... Anamorphic prism, 5... Beam mixer, 6... Diverging lens, 7... Half mirror 18.
... Collimator lens, 9... Main mirror, 10.
...Measurement plane, 11...Objective lens, 1°2...Sample stage, 13...Adjustment means, 14...Reference plane, 15...
- Adjustment means, 16... Holder, 17... - Piezo element, 20... Imaging device, 21-... Image input device, 22
...Computer, 28. -Adjustment means.
Claims (3)
前記各光源からの光束を２分割し参照面と球面もしくは
非球面からなる測定面に導く光学素子と、前記光学素子
と測定面間に配設された対物レンズと、前記各光源によ
る測定面と参照面の干渉縞が重なり合って結像される撮
像装置と、前記参照面もしくは測定面の少なくともいず
れか一方を光軸に沿つて移動調整し干渉計の光路長差を
実質的に零にする調整手段とを備え、前記干渉縞の重ね
合わせにより生じる不鮮明な和のモアレ縞を縞走査して
鮮明化し、等価波長による干渉縞の強度分布を得るよう
にしたことを特徴とする多波長型干渉計。(1) at least two light sources having different wavelengths;
an optical element that divides the light flux from each of the light sources into two and guides it to a reference surface and a measurement surface made of a spherical or aspherical surface; an objective lens disposed between the optical element and the measurement surface; and a measurement surface by each of the light sources. An imaging device in which interference fringes on a reference surface are imaged by overlapping, and adjustment by moving at least one of the reference surface or the measurement surface along an optical axis to substantially zero the difference in optical path length of the interferometer. A multi-wavelength interferometer, characterized in that the moiré fringes of the blurred sum caused by the superposition of the interference fringes are scanned to make them clearer, and the intensity distribution of the interference fringes according to equivalent wavelengths is obtained. .
前記各光源からの光束を２分割し参照面と球面もしくは
非球面からなる測定面に導く光学素子と、前記光学素子
と測定面間に配設された対物レンズと、前記対物レンズ
の焦光点と前記測定面の曲率の中心とが一致するように
前記対物レンズを光軸に沿って移動調整する手段と、前
記各光源による測定面と参照面の干渉縞が互いに重なり
合って結像される撮像装置とを備え、前記参照面と測定
面は、干渉計の光路長差が実質的に零になる位置に固定
配置され、前記干渉縞の重ね合わせにより生じる不鮮明
な和のモアレ縞を縞走査して鮮明化し、等価波長による
干渉縞の強度分布を得るようにしたことを特徴とする多
波長型干渉計。(2) at least two light sources having different wavelengths;
an optical element that divides the light flux from each of the light sources into two and guides it to a reference surface and a measurement surface made of a spherical or aspherical surface; an objective lens disposed between the optical element and the measurement surface; and a focal point of the objective lens. means for moving and adjusting the objective lens along the optical axis so that the center of curvature of the measurement surface coincides with the center of curvature of the measurement surface; and imaging in which interference fringes of the measurement surface and the reference surface formed by each of the light sources overlap each other and are formed. The reference surface and the measurement surface are fixedly arranged at a position where the difference in optical path length of the interferometer becomes substantially zero, and the device scans the blurred sum of Moiré fringes caused by the superposition of the interference fringes. A multi-wavelength interferometer characterized by sharpening the intensity distribution of interference fringes at equivalent wavelengths.
において、和のモアレ縞の縞走査により得られた等価波
長干渉縞に対してさらに縞走査を行い位相検出すること
により、測定面の面精度または形状を測定するようにし
たことを特徴とする多波長型干渉計。(3) In the multi-wavelength interferometer according to claim (1) or (2), by further performing fringe scanning on the equivalent wavelength interference fringe obtained by fringe scanning of the sum moiré fringe and detecting the phase, A multi-wavelength interferometer characterized by measuring the surface accuracy or shape of a measurement surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2197675A JPH0484704A (en) | 1990-07-27 | 1990-07-27 | Multiple-wavelength type interferometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2197675A JPH0484704A (en) | 1990-07-27 | 1990-07-27 | Multiple-wavelength type interferometer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0484704A true JPH0484704A (en) | 1992-03-18 |
Family
ID=16378472
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2197675A Pending JPH0484704A (en) | 1990-07-27 | 1990-07-27 | Multiple-wavelength type interferometer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0484704A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001304837A (en) * | 2000-04-19 | 2001-10-31 | Nok Corp | Plane inspection apparatus and plane inspection method |
| JP2008025568A (en) * | 2006-07-07 | 2008-02-07 | Snecma | Oil waste processing method of gas turbine engine |
| JP2010169002A (en) * | 2009-01-23 | 2010-08-05 | Kubota Corp | Method for manufacturing engine |
| JP2013061255A (en) * | 2011-09-14 | 2013-04-04 | Canon Inc | Measuring apparatus |
| JP2016057224A (en) * | 2014-09-11 | 2016-04-21 | 国立大学法人大阪大学 | Spectrometer and spectrum measuring method |
| CN107388963A (en) * | 2017-07-13 | 2017-11-24 | 北京理工大学 | The digital Moiré patterns phase extraction method that wavelet analysis and LPF are combined |
-
1990
- 1990-07-27 JP JP2197675A patent/JPH0484704A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001304837A (en) * | 2000-04-19 | 2001-10-31 | Nok Corp | Plane inspection apparatus and plane inspection method |
| JP4529227B2 (en) * | 2000-04-19 | 2010-08-25 | Ｎｏｋ株式会社 | Plane inspection apparatus and plane inspection method |
| JP2008025568A (en) * | 2006-07-07 | 2008-02-07 | Snecma | Oil waste processing method of gas turbine engine |
| JP2010169002A (en) * | 2009-01-23 | 2010-08-05 | Kubota Corp | Method for manufacturing engine |
| JP2013061255A (en) * | 2011-09-14 | 2013-04-04 | Canon Inc | Measuring apparatus |
| US9115971B2 (en) | 2011-09-14 | 2015-08-25 | Canon Kabushiki Kaisha | Measuring apparatus |
| JP2016057224A (en) * | 2014-09-11 | 2016-04-21 | 国立大学法人大阪大学 | Spectrometer and spectrum measuring method |
| CN107388963A (en) * | 2017-07-13 | 2017-11-24 | 北京理工大学 | The digital Moiré patterns phase extraction method that wavelet analysis and LPF are combined |
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