JPH07190738A - Interference measuring method - Google Patents
Interference measuring methodInfo
- Publication number
- JPH07190738A JPH07190738A JP5348014A JP34801493A JPH07190738A JP H07190738 A JPH07190738 A JP H07190738A JP 5348014 A JP5348014 A JP 5348014A JP 34801493 A JP34801493 A JP 34801493A JP H07190738 A JPH07190738 A JP H07190738A
- Authority
- JP
- Japan
- Prior art keywords
- image receiving
- image
- receiving surface
- interferometer
- lens
- 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.)
- Granted
Links
Landscapes
- Instruments For Measurement Of Length By Optical Means (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Testing Of Optical Devices Or Fibers (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、光学素子の面形状を高
精度に測定する干渉測定方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interference measuring method for measuring the surface shape of an optical element with high accuracy.
【０００２】[0002]
【従来の技術】従来、被検面の形状を測定する手段とし
て干渉計を用いた方法が知られている。その方法とし
て、例えば特開平４−４８２０１号公報に記載される干
渉測定装置がある。上記発明は、干渉計により精度の良
い（設計形状に近く、鏡面である）被検面と参照面との
干渉縞を出し、被検面を傾けて平行直線上の干渉縞にす
る。ディストーションが無いときは、干渉縞は平行で等
間隔になるが、ディストーションがあるときは干渉縞に
歪みがでる。この時、被検面の傾きと、この干渉縞の歪
みとからディストーション量を求め、求められたディス
トーション量を補正値として被検面測定データの補正を
行うものである。2. Description of the Related Art Conventionally, a method using an interferometer is known as a means for measuring the shape of a surface to be inspected. As the method, for example, there is an interference measuring device described in JP-A-4-48201. In the above invention, an interferometer produces an interference fringe between a surface to be inspected and a reference surface with high accuracy (which is close to the designed shape and is a mirror surface) and tilts the surface to be inspected to form an interference fringe on parallel straight lines. When there is no distortion, the interference fringes are parallel and evenly spaced, but when there is distortion, the interference fringes are distorted. At this time, the distortion amount is obtained from the inclination of the surface to be inspected and the distortion of this interference fringe, and the measured surface measurement data is corrected using the obtained distortion amount as a correction value.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、前記従
来技術においては以下のような問題点があり、被検面の
測定手段としては満足できるものではなかった。すなわ
ち、被検面が非球面の場合、被検面を傾けるとコマ収差
を発生するため、縞の歪みにディストーション以外の干
渉縞の変化が生じる。このため、被検面の測定データに
おいて、歪みを補正できなくなるという問題点があっ
た。However, the above-mentioned conventional techniques have the following problems and are not satisfactory as the measuring means of the surface to be inspected. That is, when the surface to be inspected is an aspherical surface, coma aberration is generated when the surface to be inspected is tilted, so that the distortion of the fringes changes interference fringes other than distortion. Therefore, there is a problem that the distortion cannot be corrected in the measurement data of the surface to be inspected.
【０００４】因って、本発明は上記従来技術の問題点に
鑑みてなされたもので、上記の影響を無くし、被検面の
測定データの歪みを補正することができる干渉測定方法
の提供を目的とする。Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and provides an interferometric measuring method capable of eliminating the above influence and correcting the distortion of the measured data of the surface to be inspected. To aim.
【０００５】[0005]
【課題を解決するための手段および作用】本発明は、光
源から射出された光束を２分し、一方の分割光束を参照
面に、他方の分割光束を被検面にそれぞれ入射させ、各
々の反射光を干渉させて得られた干渉縞から被検面の形
状を測定する干渉計を用い、マーキングされた被検面を
前記干渉計の受像面に投影し、その投影されたマーキン
グポイント像と干渉計の光学系の投影倍率により線型変
換された受像面上の理想結像点との写像関係から、前記
干渉縞の歪みを補正する方法である。According to the present invention, a light beam emitted from a light source is divided into two, one divided light beam is made incident on a reference surface, and the other divided light beam is made incident on a surface to be inspected. Using an interferometer that measures the shape of the surface to be inspected from the interference fringes obtained by interfering the reflected light, project the marked surface to be inspected on the image receiving surface of the interferometer, and the projected marking point image This is a method of correcting the distortion of the interference fringes from the mapping relationship with the ideal image forming point on the image receiving surface which is linearly converted by the projection magnification of the optical system of the interferometer.
【０００６】図１〜図３は本発明の干渉測定方法の概略
を示し、図１ａ，ｂ，ｃは使用されるマスターレンズを
説明するもので、ａは斜視図、ｂは平面図、ｃはＸ軸上
での断面図、図２は干渉計の受像面の正面図、図３はマ
スターレンズと受像面との関係の説明図である。FIGS. 1 to 3 show the outline of the interference measuring method according to the present invention, and FIGS. 1a, 1b, 1c show the master lens used, in which a is a perspective view, b is a plan view, and c is a plan view. FIG. 2 is a front view of the image receiving surface of the interferometer, and FIG. 3 is an explanatory view of the relationship between the master lens and the image receiving surface.
【０００７】本発明の干渉測定方法は一般的な干渉計に
適用される。図１ａ〜ｃに示す様に、マスターレンズの
基準面は被検面の中心を原点とした被検面上の座標に対
して同一となるものであり、予め座標位置の知られたマ
ーキングが多数の点および線として付与されている（図
１ｂでは同一円周上に点ａとして、および円として図
示）。ここでは、被検面と同様な設計形状を持つマスタ
ーレンズの座標関係（ｘ軸，ｙ軸は被検面の周長上であ
り、ｚ軸は被検面の原点の接平面に垂直である）とマー
キングポイントａを示している。図２には、干渉計の受
像面における座標上のマスターレンズのマーキングポイ
ントａのマーキングポイント像ａ′を点として、マーキ
ングポイントａに対する計算上の理想結像点ｂを×で示
している。The interferometric method of the present invention is applied to a general interferometer. As shown in FIGS. 1a to 1c, the reference surface of the master lens is the same with respect to the coordinates on the surface to be measured with the center of the surface to be the origin, and there are many markings whose coordinate positions are known in advance. Are given as points and lines (in FIG. 1b, they are shown as points a and circles on the same circumference). Here, the coordinate relationship of the master lens having the same design shape as the test surface (x axis and y axis are on the circumference of the test surface, and z axis is perpendicular to the tangent plane of the origin of the test surface). ) And marking point a. In FIG. 2, the calculated ideal image formation point b with respect to the marking point a is shown by x, with the marking point image a ′ of the marking point a of the master lens on the coordinates on the image receiving surface of the interferometer as a point.
【０００８】以下、本発明の作用を説明する。干渉計を
用いて被検面の形状を測定する際、被検面の代わりに図
１ｂに示す様なマーキングされたマスターレンズを取り
付ける。マスターレンズのマーキングポイントａは、干
渉計の光学系により干渉計の受像面に投影される。この
時、マスターレンズのマーキングポイントａは、図２に
示す様に、干渉計の受像面においてマーキングポイント
像ａ′の位置に写り、受像面においての座標位置がＸ，
Ｙで求められる。この時、マスターレンズのマーキング
ポイントａの原点Ｏの投影像を受像面の座標の原点Ｏ′
とする。また、マスターレンズのマーキングポイントａ
の受像面における理想結像は、干渉計の光学系の倍率β
により、以下のThe operation of the present invention will be described below. When measuring the shape of the surface to be inspected using an interferometer, a marked master lens as shown in FIG. 1b is attached instead of the surface to be inspected. The marking point a of the master lens is projected on the image receiving surface of the interferometer by the optical system of the interferometer. At this time, as shown in FIG. 2, the marking point a of the master lens appears at the position of the marking point image a'on the image receiving surface of the interferometer, and the coordinate position on the image receiving surface is X,
Required by Y. At this time, the projection image of the origin O of the marking point a of the master lens is set to the origin O ′ of the coordinates of the image receiving surface.
And In addition, the marking point a of the master lens
The ideal image formation on the image receiving surface of is the magnification β of the optical system of the interferometer.
The following
【数１】 に線型変換される。[Equation 1] Is linearly converted to.
【０００９】[0009]
【数１】[Equation 1]
【００１０】また、ａ′は極座標で、ａ′（ρ′，
θ′）と表わされる。この時、マスターレンズのマーキ
ングポイントをａ（ρｉ，θｉ）としてそれに対する受
像面のマーキングポイント像をａ′（ρ′ｉ，θ′ｉ）
とする。また、ａ（ρｉ，θｉ）に対する受像面におけ
る計算上の理想結像点をｂ（ρ″ｉ，θ″ｉ）とする。
ここで、ａ′（ρ′ｉ，θ′ｉ）から（ρ″ｉ，θ″
ｉ）への写像関係を求めると、干渉計の光学系による歪
を受けたマーキングポイント位置から、歪を受けない計
算上の理想的な結像位置を求めることができる。このた
め、被検面を測定するとき、干渉計の光学系により得ら
れた受像面上の干渉縞の位置を、この写像関係、すなわ
ちａ′（ρ′，θ′）からｂ（ρ″，θ″）に補正する
ことにより、干渉縞の歪みを補正することになる。Further, a'is polar coordinates, and a '(ρ',
θ ′). At this time, the marking point of the master lens is a (ρi, θi), and the marking point image on the image receiving surface is a ′ (ρ′i, θ′i).
And Further, the calculated ideal image forming point on the image receiving surface for a (ρi, θi) is b (ρ ″ i, θ ″ i).
Here, from a '(ρ'i, θ'i) to (ρ ″ i, θ ″
When the mapping relationship to i) is obtained, it is possible to obtain a calculated ideal imaging position that is not distorted from the marking point position that is distorted by the optical system of the interferometer. Therefore, when the surface to be inspected is measured, the position of the interference fringes on the image receiving surface obtained by the optical system of the interferometer is determined by this mapping relationship, that is, from a '(ρ', θ ') to b (ρ ", By correcting to θ ″), the distortion of the interference fringes is corrected.
【００１１】[0011]
【実施例１】図４〜図６は本実施例を示し、図４は本実
施例で用いる干渉測定計の概略構成図、図５ａ，ｂ，ｃ
は使用されるマスターレンズを説明するもので、ａは断
面図、ｂは平面図、ｃは斜視図、図６は受像面の正面図
である。Embodiment 1 FIGS. 4 to 6 show this embodiment, and FIG. 4 is a schematic configuration diagram of an interferometer used in this embodiment, FIGS.
Is a cross-sectional view, b is a plan view, c is a perspective view, and FIG. 6 is a front view of an image receiving surface.
【００１２】図４において、１は非球面形状をもつ被検
面１４（以下、被検面を有するレンズを被検面という）
を測定する干渉計で、被検面１４の中心を原点とした被
検面１４上の座標に対して、図５ａ〜ｃに示す様に、極
座標ρ1 ，ρ2 ，ρ3 上で多数の点ａおよびρ2 上に線
となるように予め座標位置の知られたマーキングがされ
た被検面１４と設計上同一な形状を有するマスターレン
ズ２と、被検面１４と同様な設計形状を持つ参照面１２
と、光源５と、照明用光学系６と、照明用光学系６によ
り被検面１４および参照面１２への照射された光の反射
光を受像面４に投影するための測定光学系３と、参照面
１２と被検面１４より形成された干渉縞を画像として取
り込む測定用カメラ１０と、測定用カメラ１０の受像面
４と、参照面１２を微小量移動させるためのピエゾ１３
と、ピエゾ１３の移動を制御し、測定用カメラ１０によ
りとらえられた干渉縞のデータを解析するためのコンピ
ュータ１１とよりなる。In FIG. 4, reference numeral 1 denotes an aspherical surface to be inspected 14 (hereinafter, a lens having an inspected surface is referred to as an inspected surface).
With an interferometer for measuring, as shown in FIGS. 5a to 5c, a large number of polar coordinates ρ 1 , ρ 2 , and ρ 3 are plotted with respect to the coordinates on the test surface 14 with the center of the test surface 14 as the origin. A master lens 2 having the same design as the test surface 14 in which the coordinate position is marked in advance so as to form a line on the points a and ρ 2 and a design shape similar to the test surface 14 are formed. Reference plane 12 to have
A light source 5, an illuminating optical system 6, and a measuring optical system 3 for projecting reflected light of the light irradiated onto the test surface 14 and the reference surface 12 by the illuminating optical system 6 onto the image receiving surface 4. , A measurement camera 10 that captures the interference fringes formed by the reference surface 12 and the test surface 14 as an image, an image receiving surface 4 of the measurement camera 10, and a piezo 13 for moving the reference surface 12 by a small amount.
And a computer 11 for controlling the movement of the piezo 13 and analyzing the data of the interference fringes captured by the measuring camera 10.
【００１３】測定用光学系３は照明光を被検面１４側と
参照面１２側とに分け、それぞれの反射光を合わせるた
めのビームスプリッタ８と、被検面１４と参照面１２と
に対して照明および投影するための対物レンズ７と、ビ
ームスプリッタ８により合わされた照明光を受像面４に
投影するとともに参照面１２および被検面１４と結像関
係にするためのフォーカスレンズ系９とよりなる。The measuring optical system 3 divides the illumination light into the test surface 14 side and the reference surface 12 side, and a beam splitter 8 for combining the respective reflected lights, and the test surface 14 and the reference surface 12 are provided. The objective lens 7 for illuminating and projecting the light and the focus lens system 9 for projecting the illumination light combined by the beam splitter 8 onto the image receiving surface 4 and for forming an image-forming relationship with the reference surface 12 and the test surface 14 Become.
【００１４】図５ａ〜ｃに示すマスターレンズ２は、そ
のマーキングをマスターレンズ２の基準面を形成してい
る座標を基準とて行ったものである。マーキング方法
は、マスターレンズ２にスケールを当てて拡大投影器で
位置を計りながら行う。この時、図５ａに示すごとく、
座標はマスターレンズ２の原点より直交座標ｘ′，
ｙ′，ｚをとる。マスターレンズ２の基準面は設計上、
ｘ′方向に断面形状を表わす関数、ｚ＝ｆ（ｘ′）の関
係があるとし、マスターレンズ２上のマーキングポイン
トａはThe master lens 2 shown in FIGS. 5A to 5C is one in which the marking is performed with reference to the coordinates forming the reference surface of the master lens 2. The marking method is performed by applying a scale to the master lens 2 and measuring the position with a magnifying projector. At this time, as shown in FIG.
The coordinates are orthogonal coordinates x ′ from the origin of the master lens 2,
Take y'and z. The reference surface of the master lens 2 is designed,
Assuming that there is a relation of z = f (x '), which is a function expressing the cross-sectional shape in the x'direction, the marking point a on the master lens 2 is
【数２】 の関係がある。[Equation 2] Have a relationship.
【００１５】[0015]
【数２】[Equation 2]
【００１６】ただし、ｘ′ｉはｘｉに対するｘ′座標の
位置であり、ｙ′ｉはｙｉに対するｙ′座標の位置であ
る。ｘｉ，ｙｉはマスターレンズ２面上の座標ｘ，ｙの
マーキングポイント位置である。この関係は、同様にｚ
とｙ′とｙｉについてもHere, x'i is the position of the x'coordinate with respect to xi, and y'i is the position of the y'coordinate with respect to yi. xi and yi are marking point positions of coordinates x and y on the surface of the master lens 2. This relationship is likewise z
And y'and yi
【数３】 に示す様に成り立つ。[Equation 3] It holds as shown in.
【００１７】[0017]
【数３】[Equation 3]
【００１８】また、マーキングポイントａは、前述の様
に、極座標ρ1 ，ρ2 ，ρ3 上の多数の点で、またρ2
上の線としてマスターレンズ２の周長上の座標で表わさ
れ、円周上にマーキングされ、各円周上で番号（図５ｂ
に1 ，2 ，3 にて図示）が付されている。図６は、受像
面４の座標のマーキングポイント像ａ′（図６中に点で
示す）と理想結像点ｂ（図６中に×で示す）である。こ
の理想結像点ｂは、計算上で求められるもので、受像面
４には表われないが、理解を容易にするために開示して
ある。As described above, the marking points a are a large number of points on the polar coordinates ρ 1 , ρ 2 , ρ 3 , and ρ 2
Expressed as coordinates on the circumference of the master lens 2 as the upper line, marked on the circumference and numbered on each circumference (Fig. 5b).
Are shown as 1 , 2 , 3 ). FIG. 6 shows a marking point image a ′ (indicated by a dot in FIG. 6) and an ideal image forming point b (indicated by a cross in FIG. 6) at the coordinates of the image receiving surface 4. This ideal image formation point b is obtained by calculation and does not appear on the image receiving surface 4, but is disclosed for easy understanding.
【００１９】以下、上記構成を用いての干渉測定方法を
説明する。干渉計１において、被検面１４の形状を測定
するとき、被検面１４の代わりにマスターレンズ２を取
り付ける。マスターレンズ２は、図５ａ〜ｃの関係より
マーキングされ、干渉計１の光源５と照明用光学系６と
ビームスプリッタ８と対物レンズ７により照明される。
この時、マスターレンズ２のマーキングポイントａは、
測定光学系３により、干渉計１の受像面４に投影され
る。すなわち、対物レンズ７とビームスプリッタ８とフ
ォーンスレンズ系９により受像面４に投影される。この
時、マーキングポイントが受像面４で鮮明に観察される
ように参照面１２をはずしておく。An interference measuring method using the above configuration will be described below. In the interferometer 1, when measuring the shape of the test surface 14, the master lens 2 is attached instead of the test surface 14. The master lens 2 is marked according to the relationship shown in FIGS. 5A to 5C and is illuminated by the light source 5, the illumination optical system 6, the beam splitter 8 and the objective lens 7 of the interferometer 1.
At this time, the marking point a of the master lens 2 is
It is projected onto the image receiving surface 4 of the interferometer 1 by the measurement optical system 3. That is, the image is projected onto the image receiving surface 4 by the objective lens 7, the beam splitter 8 and the forens lens system 9. At this time, the reference surface 12 is removed so that the marking point can be clearly observed on the image receiving surface 4.
【００２０】マスターレンズ２のマーキングポイントａ
は、図６に示す様に、受像面４においてマーキングポイ
ント像ａ′の位置に写り、測定用カメラ１０によりマー
キングポイント像ａ′をとらえ、画像情報をコンピュー
タ１１に送り座標位置（極座標位置）を求める。このと
き、マスターレンズのマーキングポイントａの原点の投
影像を受像面４の座標の原点とするため、各マーキング
ポイント像ａ′を原点に合わせて、極座標変換する。マ
ーキングポイントの同じ円周上に付された番号（図５ｂ
における1 ，2 ，3 ）により各位置関係を判断する。ま
た、マスターレンズ２のマーキングポイントａの受像面
４における理想結像点ｂは、測定光学系３の倍率βによ
り、Marking point a of the master lens 2
As shown in FIG. 6, the image is captured at the position of the marking point image a ′ on the image receiving surface 4, the marking point image a ′ is captured by the measuring camera 10, and the image information is sent to the computer 11 to determine the coordinate position (polar coordinate position). Ask. At this time, since the projected image of the origin of the marking point a of the master lens is used as the origin of the coordinates of the image receiving surface 4, each marking point image a ′ is adjusted to the origin and polar coordinate conversion is performed. Numbers on the same circumference of the marking points (Fig. 5b
Each positional relationship is judged by 1 , 2 , and 3 ) in. Further, the ideal image formation point b on the image receiving surface 4 of the marking point a of the master lens 2 is determined by the magnification β of the measurement optical system 3.
【数１】の式で線型変換される。Linear conversion is performed using the equation (1).
【００２１】ａ′は極座標で、ａ′（ρ′，θ′）と表
わされる。この時、マスターレンズ２のマーキングポイ
ントをａ（ρｉ，θｉ）として、それに対する受像面の
マーキングポイント像をａ′（ρ′ｉ，θ′ｉ）とす
る。また、ａ（ρｉ，θｉ）に対する理想結像点をｂ
（ρ″ｉ，θ″ｉ）とする。ここで、ａ′（ρ′ｉ，
θ′ｉ）をｂ（ρ″ｉ，θ″ｉ）に変換する関係、写像
Ｇ、（ρ″，θ″）＝Ｇ（ρ′，θ′）を求める。A'is a polar coordinate and is represented by a '(ρ', θ '). At this time, the marking point of the master lens 2 is a (ρi, θi), and the marking point image on the image receiving surface for it is a ′ (ρ′i, θ′i). In addition, the ideal image formation point for a (ρi, θi) is b
(Ρ ″ i, θ ″ i). Where a '(ρ'i,
A relation for converting θ′i) into b (ρ ″ i, θ ″ i), mapping G, (ρ ″, θ ″) = G (ρ ′, θ ′) is obtained.
【００２２】写像Ｇをもとめるとき、ρｉ＝一定とした
条件でρ′とθ′の変換ρ′＝ｆ（θ′）の関係で、ス
プライン補間法により、円周上に補間する。また、θ″
とθ′の変換θ″＝ｇ（θ′）の関係で、スプライン補
間法により、理想結像点ｂとマーキングポイント像ａ′
の円周上の写像関係を求める。さらに、同様の方法で、
θｉ＝一定とした条件で、θ′とρ′の変換θ′＝ｆ
（ρ′）の関係で、スプライン補間法により、放射線上
に補間する。また、ρ″とθ′の変換ρ″＝ｇ（ρ′）
の関係でスプライン補間法により、理想結像点ｂとマー
キングポイント像ａの放射線上の写像関係を求める。When the mapping G is obtained, interpolation is carried out on the circumference by the spline interpolation method in accordance with the relationship of the transformation ρ '= f (θ') under the condition that ρi = constant. Also, θ ″
And θ ′ conversion θ ″ = g (θ ′), the ideal image forming point b and the marking point image a ′ by the spline interpolation method.
Find the mapping relation on the circumference of. Furthermore, in the same way,
Conversion of θ ′ and ρ ′ under the condition that θi = constant θ ′ = f
With the relation of (ρ ′), interpolation is performed on the radiation by the spline interpolation method. Also, the conversion of ρ ″ and θ ′ ρ ″ = g (ρ ′)
The relationship between the ideal imaging point b and the marking point image a on the radiation is obtained by the spline interpolation method.
【００２３】次に、被検面１４の形状を測定するため、
マスターレンズ２と被検面１４とを交換する。また、参
照面１２を取り付け、干渉計１により受像面４上に干渉
縞を形成させる。このとき、コンピュータ１１によりピ
エゾ１３を制御して参照面１２を動かし、フリンジスキ
ャン法により、参照面１２と干渉縞の移動関係により、
被検面１４の形状を求める。この求められた形状をコン
ピュータ１１により、マーキングポイント像と理想結像
点との写像関係より、形状データを並べかえて歪みを補
正する。Next, in order to measure the shape of the test surface 14,
The master lens 2 and the test surface 14 are exchanged. Further, the reference surface 12 is attached, and the interferometer 1 forms an interference fringe on the image receiving surface 4. At this time, the computer 11 controls the piezo 13 to move the reference surface 12, and by the fringe scan method, the movement relationship between the reference surface 12 and the interference fringes
The shape of the test surface 14 is obtained. The computer 11 corrects the determined shape by rearranging the shape data based on the mapping relationship between the marking point image and the ideal image forming point.
【００２４】本実施例によれば、マーキングポイント像
ａ′と理想結像点ｂの写像関係を求めるとき、スプライ
ン補間法を用いることにより、マーキングされていない
ところでも写像関係が求められるため、補正精度をあげ
ることができ、より測定精度をあげることができる。According to the present embodiment, when the mapping relationship between the marking point image a'and the ideal image forming point b is obtained, the mapping relationship is obtained even in the unmarked area by using the spline interpolation method. The accuracy can be improved and the measurement accuracy can be further improved.
【００２５】尚、本実施例では非球面レンズの干渉測定
方法について述べたが、これに限らず、球面レンズにつ
いても適用可能である。Although the interference measuring method for the aspherical lens has been described in the present embodiment, the present invention is not limited to this and can be applied to a spherical lens.
【００２６】[0026]
【実施例２】本実施例では、前記実施例１におけるθ′
をθ′≒θ″として、ρ′とρ″の関係を求めるとき、
ディストーションの式、ρ′＝Ｃ3 （ρ″）3 ＋Ｃ
5 （ρ″）5 に最小二乗法により近似をして、ディスト
ーションの３次および５次の係数（Ｃ3 およびＣ5 ）を
求め、この式を用いρ″とρ′の写像関係をもとめて補
正を行う。その他の構成および作用は前記実施例１と同
一であり、その説明を省略する。[Embodiment 2] In this embodiment, θ ′ in the above Embodiment 1 is used.
When θ ′ ≈ θ ″ is set and the relationship between ρ ′ and ρ ″ is obtained,
Distortion formula, ρ ′ = C 3 (ρ ″) 3 + C
5 (ρ ″) 5 is approximated by the least-squares method to obtain the third and fifth-order coefficients (C 3 and C 5 ) of the distortion, and using this equation, find the mapping relation between ρ ″ and ρ ′. Make a correction. Other configurations and operations are the same as those in the first embodiment, and the description thereof will be omitted.
【００２７】本実施例において、ρ′とρ″の関係を求
めるとき、ディストーションの式ρ′＝Ｃ3 （ρ″）3
＋Ｃ5 （ρ″）5 に、最小二乗法により近似をするが、
このときρ″ｉに対するρ′ｉに対して、ディストーシ
ョンの係数Ｃ3 およびＣ5 を求める。補正を行うとき
は、ディストーションの式を用い、ρ″に対するρ′の
解を求め、形状データを並びかえる。In the present embodiment, when obtaining the relationship between ρ'and ρ ", the distortion equation ρ '= C 3 (ρ") 3
Approximate to + C 5 (ρ ″) 5 by the method of least squares,
At this time, distortion coefficients C 3 and C 5 are obtained for ρ′i with respect to ρ ″ i. When performing correction, a distortion equation is used to obtain a solution of ρ ′ with respect to ρ ″, and the shape data are arranged. Frog.
【００２８】本実施例によれば、干渉縞の歪み具合を光
学的収差のディストーションとして、歪みの大きさを定
量的に評価でき、また、コマ収差等の非対称な収差によ
り受像面上のマーキングポイントの形状が変形して、座
標位置を求めるときに誤差が出るときでも、補正精度を
上げることができる。According to the present embodiment, the degree of distortion can be quantitatively evaluated by using the degree of distortion of the interference fringes as the distortion of optical aberrations, and the marking point on the image receiving surface due to asymmetrical aberrations such as coma. Even when the shape is deformed and an error occurs when the coordinate position is obtained, the correction accuracy can be improved.
【００２９】[0029]
【発明の効果】以上説明した様に、本発明に係る干渉測
定方法によれば、被検面の形状が非球面の場合でも、被
検面の形状および干渉計の測定光学系による干渉縞の歪
みを補正することができ、面形状測定の測定精度の向上
を図ることができる。As described above, according to the interference measuring method of the present invention, even if the shape of the surface to be inspected is aspherical, the shape of the surface to be inspected and the interference fringes due to the measuring optical system of the interferometer The distortion can be corrected and the measurement accuracy of the surface shape measurement can be improved.
【図１】ａ，ｂ，ｃはそれぞれ本発明を示し、ａは斜視
図、ｂは平面図、ｃは断面図である。1A, 1B and 1C show the present invention, where a is a perspective view, b is a plan view, and c is a sectional view.
【図２】本発明を示す正面図である。FIG. 2 is a front view showing the present invention.
【図３】本発明を示す説明図である。FIG. 3 is an explanatory diagram showing the present invention.
【図４】実施例１を示す概略構成図である。FIG. 4 is a schematic configuration diagram showing a first embodiment.
【図５】ａ，ｂ，ｃはそれぞれ本実施例１を示し、ａは
断面図、ｂは平面図、ｃは斜視図である。5A, 5B and 5C show the first embodiment, a is a sectional view, b is a plan view, and c is a perspective view.
【図６】実施例１を示す正面図である。FIG. 6 is a front view showing the first embodiment.
１ 干渉計 ２ マスターレンズ ３ 測定用光学系 ４ 受像面 ５ 光源 ６ 照明光学系 ７ 対物レンズ ８ ビームスプリッタ ９ フォーカスレンズ系 １０ 測定用カメラ １１ コンピュータ １２ 参照面 １３ ピエゾ １４ 被検面 DESCRIPTION OF SYMBOLS 1 Interferometer 2 Master lens 3 Measurement optical system 4 Image receiving surface 5 Light source 6 Illumination optical system 7 Objective lens 8 Beam splitter 9 Focus lens system 10 Measurement camera 11 Computer 12 Reference surface 13 Piezo 14 Test surface
Claims (1)
の分割光束を参照面に、他方の分割光束を被検面にそれ
ぞれ入射させ、各々の反射光を干渉させて得られた干渉
縞から被検面の形状を測定する干渉計を用い、マーキン
グされた被検面を前記干渉計の受像面に投影し、その投
影されたマーキングポイント像と干渉計の光学系の投影
倍率により線型変換された受像面上の理想結像点との写
像関係から、前記干渉縞の歪みを補正することを特徴と
する干渉測定方法。1. Interference obtained by dividing a light beam emitted from a light source into two, making one divided light beam incident on a reference surface, and making the other divided light beam incident on a surface to be inspected, and interfering each reflected light beam. Using an interferometer that measures the shape of the surface to be inspected from the stripes, the marked surface to be inspected is projected onto the image receiving surface of the interferometer, and a linear type is created depending on the projected marking point image and the projection magnification of the optical system of the interferometer. An interference measuring method, characterized in that distortion of the interference fringes is corrected based on a mapping relationship with the converted ideal image forming point on the image receiving surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34801493A JP3349235B2 (en) | 1993-12-24 | 1993-12-24 | Interference measurement method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34801493A JP3349235B2 (en) | 1993-12-24 | 1993-12-24 | Interference measurement method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07190738A true JPH07190738A (en) | 1995-07-28 |
| JP3349235B2 JP3349235B2 (en) | 2002-11-20 |
Family
ID=18394159
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34801493A Expired - Fee Related JP3349235B2 (en) | 1993-12-24 | 1993-12-24 | Interference measurement method |
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| Country | Link |
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| JP (1) | JP3349235B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002071312A (en) * | 2000-08-25 | 2002-03-08 | Topcon Corp | Irradiation location measuring device |
| JP2006317199A (en) * | 2005-05-11 | 2006-11-24 | Canon Inc | Surface measuring method and device |
-
1993
- 1993-12-24 JP JP34801493A patent/JP3349235B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002071312A (en) * | 2000-08-25 | 2002-03-08 | Topcon Corp | Irradiation location measuring device |
| JP2006317199A (en) * | 2005-05-11 | 2006-11-24 | Canon Inc | Surface measuring method and device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3349235B2 (en) | 2002-11-20 |
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