JP5454769B2 - Spectroscopic solid shape measuring apparatus and spectral solid shape measuring method - Google Patents
Spectroscopic solid shape measuring apparatus and spectral solid shape measuring method Download PDFInfo
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Description
本発明は、分光立体形状測定装置及び分光立体形状測定方法に関し、特に、白色干渉を用いて被測定物の立体形状及び分光情報を測定する分光立体形状測定装置及び分光立体形状測定方法に関する。 The present invention relates to a spectroscopic three-dimensional shape measuring apparatus and a spectroscopic three-dimensional shape measuring method, and more particularly to a spectroscopic three-dimensional shape measuring apparatus and a spectroscopic three-dimensional shape measuring method for measuring a three-dimensional shape and spectral information of an object to be measured using white interference.
従来より、加工部品など、被測定物の形状を非接触で精密に測定する方法として、白色干渉の原理を用いた方法が提案されている。このような方法は、一般に、白色光源から放射された測定光を二つの光束に分割し、一方を被測定物で反射させ、他方を参照鏡で反射させて、それら光束を一つに合わせることにより干渉を生じさせる。この干渉により生じる白色干渉縞は、二つの光束間の光路長が略等しいときに観測される。その白色干渉縞では、二つの光束間の光路差が０となる場合に最も振幅が大きくなり、光路差が大きくなるにつれて急激に振幅が減少する。そこで、白色干渉縞の振幅が最大となるピーク位置を測定することにより、被測定物の測定対象寸法が求められる（例えば、特許文献１を参照）。 Conventionally, a method using the principle of white interference has been proposed as a method for accurately measuring the shape of an object to be measured, such as a machined part, in a non-contact manner. In general, such a method divides measurement light emitted from a white light source into two light beams, one is reflected by the object to be measured, and the other is reflected by a reference mirror, and these light beams are combined into one. Cause interference. White interference fringes caused by this interference are observed when the optical path lengths between the two light beams are substantially equal. The white interference fringe has the largest amplitude when the optical path difference between the two light fluxes becomes zero, and the amplitude sharply decreases as the optical path difference increases. Therefore, by measuring the peak position where the amplitude of the white interference fringe is maximized, the measurement target dimension of the object to be measured is obtained (see, for example, Patent Document 1).
このような白色干渉を用いた測定装置の中には、被測定物の立体形状だけでなく、非測定物の分光情報も測定可能な測定装置も提案されている（例えば、特許文献２を参照）。 例えば、特許文献２に開示された立体形状測定及び分析装置は、光源から照射され、被測定物で反射された光のうち、０次回折光を分別光学系により位相可変フィルタの可動反射部に、高次回折光を固定反射部に導いて、それぞれ反射させる。そしてその装置は、それら反射光を、干渉光学系により略１点に収束させて、干渉を生じさせる。この状態で位相可変フィルタの可動反射部を移動させることにより、干渉光学系の結像点における干渉光の強度は徐々に変化する。また干渉光のピーク点での可動反射部の位置は、被測定物における出発点と可動反射部との距離に依存する。そこでこの装置は、ピーク点での可動反射部の位置より、出発点の位置を算出する。このような測定及び計算を被測定物の像を構成する各点について行うことにより、この装置は被測定物の立体形状を測定できる。そして各点でのインターフェログラムをフーリエ変換することにより、各点の分析を行うことができる。 Among such measuring apparatuses using white interference, a measuring apparatus capable of measuring not only the three-dimensional shape of the object to be measured but also the spectral information of the non-measuring object has been proposed (for example, see Patent Document 2). ). For example, the three-dimensional shape measurement and analysis device disclosed in Patent Document 2 is configured such that, among the light irradiated from the light source and reflected by the object to be measured, the 0th-order diffracted light is separated into the movable reflection portion of the phase variable filter by the separation optical system. The high-order diffracted light is guided to the fixed reflecting portion and reflected respectively. Then, the apparatus converges the reflected light to approximately one point by the interference optical system, and causes interference. By moving the movable reflecting portion of the phase variable filter in this state, the intensity of the interference light gradually changes at the imaging point of the interference optical system. The position of the movable reflecting portion at the peak point of the interference light depends on the distance between the starting point and the movable reflecting portion in the object to be measured. Therefore, this apparatus calculates the position of the starting point from the position of the movable reflecting portion at the peak point. By performing such measurement and calculation for each point constituting the image of the object to be measured, this apparatus can measure the three-dimensional shape of the object to be measured. Each point can be analyzed by Fourier transforming the interferogram at each point.
特許文献２に開示された装置では、被測定物の立体形状の測定解像度を高くするためには、光源から放射される光の波長の範囲を広くしなければならない。可動反射部で反射される光の光路長と固定反射部で反射される光の光路長とが一致しなくなったときに、波長ごとの干渉強度が変わるため、放射される光の波長の範囲が広いほど干渉光の強度が急激に減少し、白色干渉縞のピッチ幅が狭くなるためである。しかし、光源から放射される光の波長の範囲が広くなるほど、被測定物の様々な点において反射された光が、それぞれの光路長差における白色干渉縞の生成に寄与することになるので、分光情報の解像度は低下してしまう。 In the apparatus disclosed in Patent Document 2, in order to increase the measurement resolution of the three-dimensional shape of the object to be measured, the wavelength range of light emitted from the light source must be widened. When the optical path length of the light reflected by the movable reflecting portion and the optical path length of the light reflected by the fixed reflecting portion no longer match, the interference intensity for each wavelength changes. This is because the larger the width is, the more rapidly the intensity of interference light decreases and the pitch width of white interference fringes becomes narrower. However, as the wavelength range of the light emitted from the light source becomes wider, the light reflected at various points of the object to be measured contributes to the generation of white interference fringes at each optical path length difference. The resolution of information is reduced.
そこで、本発明者等は、鋭意研究の結果、この白色干渉計による形状測定の原理をさらに発展させ、被測定物の立体形状の測定解像度を低下させることなく、被測定物の表面の分光情報も高い解像度で測定可能な干渉計測システムを開発した（例えば、非特許文献１及び２を参照）。 Therefore, as a result of earnest research, the present inventors have further developed the principle of shape measurement by the white interferometer, and without reducing the measurement resolution of the three-dimensional shape of the object to be measured, the spectral information on the surface of the object to be measured Has developed an interferometric measurement system that can measure at a high resolution (see, for example, Non-Patent Documents 1 and 2).
非特許文献１及び２に開示された干渉計測システムは、白色照明された被測定物により反射または散乱された光の波面をビームスプリッタにより二つの光束に分割する。そしてこの干渉計測システムは、二つの光束間に光路差を与えて再度一つに合わせることによって白色干渉を生じさせ、生じた白色干渉縞を２次元検出器により検出する。この干渉計測システムは、測定動作中、被測定物上の各点からの波面を再現するために、被測定物の位置を、ビームスプリッタの入射面に対して平行な面内で水平方向または垂直方向に移動させて、波面の異なる位置同士が干渉した干渉縞を取得する。またこの干渉計測システムは、測定動作中、被測定物上の各点から反射または散乱された光の波長を調べるために、二つの光束の光路差を変えて干渉縞を取得する。そのため、この干渉計測システムにより得られた測定データは５次元のデータとなる。すなわち、測定データには、２次元検出器上の各画素の水平方向の位置及び垂直方向の位置、被測定物の基準位置に対する水平方向のシフト量及び垂直方向のシフト量、及び二つの光束の光路差の各次元が含まれる。そのため、被測定物の立体形状及び分光情報を再現するために必要な演算量及びメモリの容量は、非常に膨大なものとなる。したがって、この計測システムでは、１回の測定に要する処理時間が非常に長く、あるいは、大容量のハードウェアリソースが必要であった。 The interference measurement systems disclosed in Non-Patent Documents 1 and 2 divide a wavefront of light reflected or scattered by an object to be measured illuminated with white light into two light beams by a beam splitter. In this interference measurement system, white light interference is generated by giving an optical path difference between two light beams and combining them again, and the generated white interference fringes are detected by a two-dimensional detector. In order to reproduce the wavefront from each point on the measured object during the measurement operation, the interferometric measurement system positions the measured object in a horizontal or vertical direction in a plane parallel to the incident surface of the beam splitter. By moving in the direction, an interference fringe in which positions having different wavefronts interfere with each other is acquired. In addition, during the measurement operation, this interference measurement system obtains interference fringes by changing the optical path difference between the two light beams in order to examine the wavelength of light reflected or scattered from each point on the object to be measured. Therefore, measurement data obtained by this interference measurement system is five-dimensional data. That is, the measurement data includes the horizontal position and the vertical position of each pixel on the two-dimensional detector, the horizontal shift amount and the vertical shift amount with respect to the reference position of the object to be measured, and the two light fluxes. Each dimension of the optical path difference is included. For this reason, the amount of calculation and the memory capacity necessary for reproducing the three-dimensional shape and spectral information of the object to be measured are extremely large. Therefore, in this measurement system, the processing time required for one measurement is very long, or a large-capacity hardware resource is required.
上記の問題点に鑑み、本発明の目的は、測定に必要なデータ量を抑制しつつ、被測定物の立体形状及び分光情報を測定することが可能な分光立体形状測定装置及び分光立体形状測定方法を提供することにある。 In view of the above problems, an object of the present invention is to provide a spectral three-dimensional shape measuring apparatus and a spectral three-dimensional shape measurement capable of measuring the three-dimensional shape and spectral information of an object to be measured while suppressing the amount of data necessary for measurement. It is to provide a method.
本発明の一つの実施態様によれば、被測定物の立体形状及び分光情報を測定する分光立体形状測定装置が提供される。係る分光立体形状測定装置は、白色光により照明された被測定物によって反射または散乱された測定光に対して白色干渉縞を生じさせる干渉計と、干渉計から出力された光の強度を測定する点検出器と、干渉計を移動させる第１の可動ステージと、点検出器と接続され、白色干渉縞信号から被測定物の立体形状及び分光情報を求めるコントローラとを有する。そして干渉計は、測定光を第１の光束と第２の光束に分割して出射させる光線分割素子と、第１の光束の波面を第１の方向に沿って反転させて、その波面が反転された第１の光束を光線分割素子へ向けて反射する第１の反射素子と、第２の光束の波面を、第１の方向と異なる第２の方向に沿って反転させて、波面が反転された第２の光束を、光線分割素子へ向けて反射する第２の反射素子と、第２の反射素子を、光線分割素子と第２の反射素子を結ぶ直線に平行な第３の方向に移動させることにより、光線分割素子と第２の反射素子の間隔を変更して、第１の光束と第２の光束との間に所定の光路差を生じさせる第２の可動ステージとを有する。またコントローラは、第１の可動ステージを制御して、干渉計と被測定物の相対的な位置を変えつつ、かつ第２の可動ステージを制御して、第２の反射素子を第３の方向に沿って移動させつつ、点検出器により受光された光の強度を測定することにより、白色干渉縞信号を取得し、白色干渉縞信号を、第１の光束と第２の光束間の光路差について周波数変換することにより、被測定物の所定点の分光情報を表す相互スペクトル密度を決定し、かつ相互スペクトル密度を干渉計の移動量について周波数変換することにより、被測定物上の所定点で反射または散乱された光の波面を決定する。 According to one embodiment of the present invention, a spectroscopic three-dimensional shape measuring apparatus for measuring the three-dimensional shape and spectral information of an object to be measured is provided. Such a spectroscopic three-dimensional shape measurement apparatus measures an intensity of light output from an interferometer that generates white interference fringes with respect to measurement light reflected or scattered by an object illuminated by white light, and the interferometer. A point detector, a first movable stage that moves the interferometer, and a controller that is connected to the point detector and obtains the three-dimensional shape and spectral information of the object to be measured from the white interference fringe signal. Then, the interferometer reverses the wavefront of the first light beam along the first direction by dividing the measurement light into the first light beam and the second light beam and emits the light, and the wave front is reversed. The wavefront is inverted by reversing the wavefront of the first light-reflecting element toward the beam splitting element and the wavefront of the second light flux along a second direction different from the first direction. The second reflecting element that reflects the second light flux thus directed toward the light beam splitting element, and the second reflecting element in a third direction parallel to a straight line connecting the light beam splitting element and the second reflecting element. A second movable stage that changes the distance between the light beam splitting element and the second reflecting element to cause a predetermined optical path difference between the first light flux and the second light flux by moving is provided. The controller controls the first movable stage to change the relative position between the interferometer and the object to be measured and also controls the second movable stage to move the second reflective element in the third direction. The white interference fringe signal is obtained by measuring the intensity of light received by the point detector while moving along the optical path difference between the first light flux and the second light flux. The cross-spectral density representing the spectral information of a predetermined point of the object to be measured is determined by frequency conversion, and the cross-spectral density is frequency-converted with respect to the amount of movement of the interferometer at a predetermined point on the target object. Determine the wavefront of the reflected or scattered light.
また、本発明において、コントローラは、干渉計と被測定物間の相対的な位置を変えるために、干渉計を、第１の方向または第２の方向に沿って移動させ、相互スペクトル密度を第１の方向の移動量及び第２の方向の移動量について周波数変換することにより、被測定物上の所定点で反射または散乱された光の波面を決定することが好ましい。 In the present invention, the controller moves the interferometer along the first direction or the second direction in order to change the relative position between the interferometer and the object to be measured, and sets the cross spectral density to the first value. It is preferable to determine the wavefront of light reflected or scattered at a predetermined point on the object to be measured by performing frequency conversion on the movement amount in the first direction and the movement amount in the second direction.
また、本発明において、第１の方向は、第１の反射素子及び光線分割素子が配置される水平面に直交する方向であり、かつ第２の方向は、水平面と平行な方向であることが好ましい。 In the present invention, it is preferable that the first direction is a direction orthogonal to a horizontal plane in which the first reflecting element and the light beam splitting element are arranged, and the second direction is a direction parallel to the horizontal plane. .
さらに、本発明に係る分光立体形状測定装置は、干渉計と点検出器の間に配置され、第１の反射素子の反射面を点検出器の検出面に結像する光学素子を有することが好ましい。 Furthermore, the spectroscopic three-dimensional shape measuring apparatus according to the present invention includes an optical element that is disposed between the interferometer and the point detector and forms an image of the reflecting surface of the first reflecting element on the detecting surface of the point detector. preferable.
また、本発明の他の実施態様によれば、白色光により照明された被測定物によって反射または散乱された測定光に対して白色干渉縞を生じさせる干渉計と、干渉計から出力された光の強度を測定する点検出器と、干渉計を移動させる第１の可動ステージとを有する分光立体形状測定装置による分光立体形状測定方法が提供される。係る分光立体形状測定方法において、干渉計は、測定光を第１の光束と第２の光束に分割して出射させる光線分割素子と、第１の光束の波面を第１の方向に沿って反転させて、波面が反転された第１の光束を光線分割素子へ向けて反射する第１の反射素子と、第２の光束の波面を、第１の方向と異なる第２の方向に沿って反転させて、波面が反転された第２の光束を、光線分割素子へ向けて反射する第２の反射素子と、第２の反射素子を、光線分割素子と第２の反射素子を結ぶ直線に平行な第３の方向に移動させることにより、光線分割素子と第２の反射素子の間隔を変更して、第１の光束と第２の光束との間に所定の光路差を生じさせる第２の可動ステージとを有する。そして分光立体形状測定方法は、第１の可動ステージを制御して、干渉計と被測定物の相対的な位置を変えつつ、かつ第２の可動ステージを制御して、第２の反射素子を第３の方向に沿って移動させつつ、点検出器により受光された光の強度を測定することにより、白色干渉縞信号を取得するステップと、白色干渉縞信号を、第１の光束と第２の光束間の光路差について周波数変換することにより、被測定物の所定点の分光情報を表す相互スペクトル密度を決定するステップと、相互スペクトル密度を干渉計の移動量について周波数変換することにより、被測定物上の所定点で反射光または散乱された光の波面を決定するステップとを含む。 According to another embodiment of the present invention, an interferometer that generates white interference fringes for measurement light reflected or scattered by an object illuminated by white light, and light output from the interferometer A spectroscopic three-dimensional shape measuring method using a spectroscopic three-dimensional shape measuring apparatus having a point detector for measuring the intensity of the first and a first movable stage for moving the interferometer is provided. In such a spectral three-dimensional shape measuring method, the interferometer includes a light beam splitting element that splits the measurement light into a first light beam and a second light beam, and inverts the wavefront of the first light beam along the first direction. The first reflecting element that reflects the first light flux whose wavefront is reversed toward the light beam splitting element, and the wavefront of the second light flux is reversed along a second direction different from the first direction. Thus, the second reflecting element that reflects the second light flux with the wavefront inverted toward the light beam splitting element and the second reflecting element are parallel to the straight line connecting the light beam splitting element and the second reflecting element. By moving the light beam in the third direction, the distance between the light beam splitting element and the second reflecting element is changed, and a second optical path difference is generated between the first light beam and the second light beam. And a movable stage. The spectroscopic three-dimensional shape measurement method controls the first movable stage to change the relative positions of the interferometer and the object to be measured, and also controls the second movable stage to control the second reflective element. The step of obtaining a white interference fringe signal by measuring the intensity of light received by the point detector while moving along the third direction, the white interference fringe signal, the first light flux and the second light flux By converting the frequency of the optical path difference between the two light beams, determining a cross spectral density representing spectral information at a predetermined point of the object to be measured, and converting the cross spectral density with respect to the amount of movement of the interferometer. Determining a wavefront of reflected or scattered light at a predetermined point on the measurement object.
本発明によれば、測定に必要なデータ量を抑制しつつ、被測定物の立体形状及び分光情報を測定することが可能な分光立体形状測定装置及び分光立体形状測定方法を提供することが可能となった。 According to the present invention, it is possible to provide a spectroscopic three-dimensional shape measuring apparatus and a spectroscopic three-dimensional shape measuring method capable of measuring the three-dimensional shape and spectral information of an object to be measured while suppressing the amount of data necessary for measurement. It became.
以下、本発明の実施形態に係る分光立体形状測定装置を、図を参照しつつ説明する。
本発明の一つの実施形態に係る分光立体形状測定装置は、白色光で照明された被測定物により反射または散乱された光を、干渉計の光線分割素子により二つの光束に分割する。そしてこの分光立体形状測定装置は、それら二つの光束を別個に配置された二つの反射部材でそれぞれ反射することにより、二つの光束間に所定の光路差を生じさせた後、再度一つの光束に合わせ、点検出器でその光束の強度を測定する。この分光立体形状測定装置は、各光束の波面の向き及び各光束間の波面間の着目するずれ量に対応する光束が点検出器の検出面に到達するように、各反射部材の反射面の向きを調節するとともに、二つの反射部材と光線分割素子を一体的に動かす。これにより、この分光立体形状測定装置は、被測定物及び点検出器を移動させることなく、白色干渉縞を得ることで、測定に要するデータ数を減らしつつ、被測定物の立体形状及び分光情報を測定するものである。
Hereinafter, a spectroscopic three-dimensional shape measuring apparatus according to an embodiment of the present invention will be described with reference to the drawings.
A spectroscopic three-dimensional shape measuring apparatus according to an embodiment of the present invention divides light reflected or scattered by an object illuminated with white light into two light beams by a light beam splitting element of an interferometer. The spectroscopic three-dimensional shape measuring apparatus reflects the two light beams by two separately arranged reflecting members to generate a predetermined optical path difference between the two light beams, and then again converts the light beams into one light beam. In addition, the intensity of the luminous flux is measured with a point detector. This spectroscopic three-dimensional shape measuring apparatus is configured so that the luminous flux corresponding to the direction of the wavefront of each luminous flux and the noted deviation between the wavefronts between the luminous fluxes reaches the detection surface of the point detector. While adjusting the direction, the two reflecting members and the beam splitting element are moved together. Thereby, this spectral solid shape measuring apparatus obtains white interference fringes without moving the measured object and the point detector, thereby reducing the number of data required for measurement and measuring the solid shape and spectral information of the measured object. Is to measure.
図１は、本発明の一つの実施形態に係る分光立体形状測定装置１の概略構成を示す図である。分光立体形状測定装置１は、干渉計２と、干渉計２が載置される可動ステージ３と、レンズ４と、点検出器５と、コントローラ６を有する。 FIG. 1 is a diagram showing a schematic configuration of a spectroscopic three-dimensional shape measuring apparatus 1 according to one embodiment of the present invention. The spectroscopic three-dimensional shape measuring apparatus 1 includes an interferometer 2, a movable stage 3 on which the interferometer 2 is placed, a lens 4, a point detector 5, and a controller 6.
干渉計２は、光線分割素子２１と、反射素子２２及び２３と、微動ステージ２４を有する。光線分割素子２１は、例えば、ビームスプリッタまたはハーフミラーの何れかで構成される。そして光線分割素子２１は、白色照明された被測定物１０により反射または散乱された光を、反射素子２２へ向かう第１の光束Ｂ１と反射素子２３へ向かう第２の光束Ｂ２に分割する。また光線分割素子２１は、反射素子２２により反射された第１の光束Ｂ１と反射素子２３により反射された第２の光束Ｂ２とを一つの光束に合わせて、レンズ４へ向けて出射する。
なお、被測定物１０を照明する光源の種類及び配置については、特に制限はなく、光源として、例えば、自然光、白色LEDなど、２種類以上の波長の光を放射する各種の光源を利用することができる。ただし、被測定物１０の測定対象となる面は、できるだけ均一な照度で照明されることが好ましい。
The interferometer 2 includes a light beam splitting element 21, reflecting elements 22 and 23, and a fine movement stage 24. The beam splitting element 21 is configured by, for example, either a beam splitter or a half mirror. The light beam splitting element 21 splits the light reflected or scattered by the object 10 illuminated with white light into a first light beam B1 directed to the reflective element 22 and a second light beam B2 directed to the reflective element 23. The beam splitting element 21 combines the first light beam B1 reflected by the reflection element 22 and the second light beam B2 reflected by the reflection element 23 into one light beam and emits the light toward the lens 4.
In addition, there is no restriction | limiting in particular about the kind and arrangement | positioning of the light source which illuminates the to-be-measured object 10, For example, various light sources which radiate | emit light of two or more types of wavelengths, such as natural light and white LED, are utilized as a light source. Can do. However, it is preferable that the surface to be measured of the DUT 10 is illuminated with as uniform illuminance as possible.
反射素子２２及び２３は、例えば、二つの反射面が直角をなして配置された直角ミラーまたは直角プリズムを有する。そして反射素子２２は、一方の反射面において、光線分割素子２１、反射素子２２及び２３が配置された水平面に対して直交する垂直方向または直角方法、かつ光束Ｂ１の入射方向に直交する方向に光束Ｂ１を反射する。さらに、反射素子２２は、その一方の反射面で反射された光束Ｂ１を、他方の反射面において、光束Ｂ１が反射素子２２に入射した方向と平行かつ逆の方向へ向けて反射する。その結果、反射素子２２で反射された光束Ｂ１は、その波面が水平面に垂直または直角な方向について反転され、再度光線分割素子２１へ向かう。 The reflection elements 22 and 23 include, for example, a right-angle mirror or a right-angle prism in which two reflection surfaces are arranged at a right angle. The reflecting element 22 has a light flux in one of the reflecting surfaces in a direction perpendicular to or perpendicular to the horizontal plane on which the light beam splitting element 21 and the reflecting elements 22 and 23 are arranged, and in a direction perpendicular to the incident direction of the light flux B1. Reflects B1. Further, the reflection element 22 reflects the light beam B1 reflected by one of the reflection surfaces in a direction parallel to and opposite to the direction in which the light beam B1 is incident on the reflection element 22 on the other reflection surface. As a result, the light beam B <b> 1 reflected by the reflecting element 22 is inverted in a direction in which the wavefront is perpendicular or perpendicular to the horizontal plane and travels again to the light beam splitting element 21.
一方、反射素子２３は、一方の反射面において、光線分割素子２１、反射素子２２及び２３が配置された水平面に対して平行な水平方向で、かつ光束Ｂ２の入射方向に直交する方向に光束Ｂ２を反射する。さらに、反射素子２３は、その一方の反射面で反射された光束Ｂ２を、他方の反射面において、光束Ｂ２が反射素子２３に入射した方向と平行かつ逆の方向へ向けて反射する。その結果、反射素子２３で反射された光束Ｂ２は、その波面が水平面に平行な方向について反転され、再度光線分割素子２１へ向かう。
このように、反射素子２２と反射素子２３が、それぞれ、光束Ｂ１の波面と光束Ｂ２の波面を互いに対して異なる方向に反転するように配置されている。そのため、干渉計２は、反射素子２２で反射された光束Ｂ１の波面と反射素子２３で反射された光束Ｂ２の波面とをずらすことができる。
On the other hand, the reflecting element 23 has a light beam B2 on one reflecting surface in a horizontal direction parallel to the horizontal plane on which the light beam splitting element 21, the reflecting elements 22 and 23 are arranged, and in a direction perpendicular to the incident direction of the light beam B2. To reflect. Further, the reflecting element 23 reflects the light beam B2 reflected by one of the reflecting surfaces in a direction parallel and opposite to the direction in which the light beam B2 is incident on the reflecting element 23 on the other reflecting surface. As a result, the light beam B <b> 2 reflected by the reflecting element 23 is inverted in the direction in which the wavefront is parallel to the horizontal plane, and travels again to the light beam splitting element 21.
As described above, the reflecting element 22 and the reflecting element 23 are arranged so as to invert the wavefront of the light beam B1 and the wavefront of the light beam B2 in different directions with respect to each other. Therefore, the interferometer 2 can shift the wavefront of the light beam B1 reflected by the reflecting element 22 and the wavefront of the light beam B2 reflected by the reflecting element 23.
微動ステージ２４は、例えば、ピエゾステージで構成される。そして微動ステージ２４上に反射素子２３が載置される。また微動ステージ２４は、コントローラ６と接続されており、コントローラ６からの制御信号に応じて、微動ステージ２４に載置された反射素子２３を、反射素子２３に対する光束Ｂ２の入射方向に沿って移動させる。そのため、反射素子２３と光線分割素子２１の間隔は、微動ステージ２４を動作させることにより調節可能となっている。一方、光線分割素子２１及び反射素子２２は、可動ステージ３上に固定されている。したがって、反射素子２３と光線分割素子２１の間隔を調整することにより、干渉計２は、光束Ｂ１と光束Ｂ２との間に所望の光路差を生じさせることができる。 The fine movement stage 24 is constituted by a piezo stage, for example. Then, the reflective element 23 is placed on the fine movement stage 24. The fine movement stage 24 is connected to the controller 6, and the reflection element 23 placed on the fine movement stage 24 is moved along the incident direction of the light beam B <b> 2 with respect to the reflection element 23 in accordance with a control signal from the controller 6. Let Therefore, the interval between the reflecting element 23 and the light beam splitting element 21 can be adjusted by operating the fine movement stage 24. On the other hand, the beam splitting element 21 and the reflecting element 22 are fixed on the movable stage 3. Therefore, the interferometer 2 can produce a desired optical path difference between the light beam B1 and the light beam B2 by adjusting the distance between the reflecting element 23 and the light beam splitting element 21.
なお、以下では、便宜上、光線分割素子２１、反射素子２２及び２３が配置された水平面に平行で、かつ、光束Ｂ１が反射素子２２へ向かう方向をx軸、その水平面に対して直角をなす方向をy軸、またその水平面に平行で、かつ、光束Ｂ２が反射素子２３へ向かう方向をz軸とする座標系を設定する。またこの座標系において、原点(0,0,0)は、レンズ４の光軸が存在する水平面における、被測定物１０が配置される近傍に設定される。 In the following, for the sake of convenience, the direction parallel to the horizontal plane on which the beam splitting element 21 and the reflecting elements 22 and 23 are arranged, and the direction of the light beam B1 toward the reflecting element 22 is the x-axis, and the direction perpendicular to the horizontal plane. Is set to a y-axis, parallel to the horizontal plane, and a coordinate system in which the z-axis is a direction in which the light beam B2 is directed to the reflecting element 23 is set. In this coordinate system, the origin (0, 0, 0) is set in the vicinity of the object to be measured 10 on the horizontal plane where the optical axis of the lens 4 exists.
可動ステージ３は、例えば、ステッピングモータまたはピエゾ素子で駆動される公知の２軸精密ステージとすることができる。そして可動ステージ３は、コントローラ６と接続点されており、検出器５上で白色干渉を生じさせる光束Ｂ１の波面と光束Ｂ２の波面の組み合わせを変えるために、コントローラ６からの制御信号に応じて干渉計２全体をx軸方向またはy軸方向に移動させる。 The movable stage 3 can be, for example, a known biaxial precision stage driven by a stepping motor or a piezo element. The movable stage 3 is connected to the controller 6 and changes the combination of the wavefront of the light beam B1 and the wavefront of the light beam B2 that cause white interference on the detector 5 in accordance with a control signal from the controller 6. The entire interferometer 2 is moved in the x-axis direction or the y-axis direction.
レンズ４は、光線分割素子２１から出射された光束を点検出器５の検出面に集光する。ここでレンズ４は、被写界深度をできるだけ狭くして、ｚ軸方向の解像度を高くするために、点検出器５の検出面と反射素子２２の反射面とが結像関係になるように配置される。ただし、レンズ４と干渉計２及び点検出器５の位置関係は、この例に限られず、例えば、レンズ４は、被測定物１０上の任意の点を点検出器５の検出面上に結像するように配置されてもよい。また、レンズ４の代わりに、反射鏡を用いてもよい。 The lens 4 condenses the light beam emitted from the light beam splitting element 21 on the detection surface of the point detector 5. Here, the lens 4 has an imaging relationship between the detection surface of the point detector 5 and the reflection surface of the reflection element 22 in order to reduce the depth of field as much as possible and increase the resolution in the z-axis direction. Be placed. However, the positional relationship between the lens 4 and the interferometer 2 and the point detector 5 is not limited to this example. For example, the lens 4 connects an arbitrary point on the object to be measured 10 on the detection surface of the point detector 5. It may be arranged to image. A reflecting mirror may be used instead of the lens 4.
点検出器５は、例えば、アバランシェフォトダイオード、PINフォトダイオードあるいは光電子増倍管などの光電変換器を有する。そして点検出器５は、コントローラ６と接続され、反射素子２２で反射された光束Ｂ１と反射素子２３で反射された光束Ｂ２を受光し、受光強度に応じた電気信号をコントローラ６へ出力する。なお、点検出器５は、光電変換器から出力された電気信号を増幅する増幅回路を有してもよい。さらに点検出器５は、光電変換器から出力された電気信号あるいは増幅回路により増幅された電気信号をデジタル電気信号に変換するアナログ−デジタルコンバータを有してもよい。さらにまた、点検出器５は、CCDまたはC-MOSなどの光電変換素子が２次元に配列された２次元検出器を有してもよい。この場合には、点検出器５は、光束Ｂ１及びＢ２が集光される位置に配置された、２次元検出器の各画素の出力信号の合計または平均値をコントローラ６へ出力する。 The point detector 5 includes a photoelectric converter such as an avalanche photodiode, a PIN photodiode, or a photomultiplier tube. The point detector 5 is connected to the controller 6, receives the light beam B 1 reflected by the reflecting element 22 and the light beam B 2 reflected by the reflecting element 23, and outputs an electrical signal corresponding to the received light intensity to the controller 6. Note that the point detector 5 may include an amplifier circuit that amplifies the electrical signal output from the photoelectric converter. Further, the point detector 5 may include an analog-digital converter that converts the electric signal output from the photoelectric converter or the electric signal amplified by the amplifier circuit into a digital electric signal. Furthermore, the point detector 5 may include a two-dimensional detector in which photoelectric conversion elements such as CCD or C-MOS are two-dimensionally arranged. In this case, the point detector 5 outputs to the controller 6 the total or average value of the output signals of each pixel of the two-dimensional detector arranged at the position where the light beams B1 and B2 are collected.
コントローラ６は、いわゆるコンピュータで構成される。そしてコントローラ６は、分光立体形状測定装置１全体を制御するとともに、点検出器５により得られた電気信号から被測定物１０上の各点から得られる波面を再生する。
図２に、コントローラ６の機能ブロック図を示す。図２に示すように、コントローラ６は、電気的に書き換え可能な不揮発性メモリ、磁気ディスク、光ディスク及びそれらの読取装置等の少なくとも一つを有する記憶部６１と、ＲＳ２３２Ｃ、イーサネット（登録商標）などの通信規格にしたがって構成されたインターフェース回路及びデバイスドライバなどのソフトウェアからなる通信部６２を有する。
さらにコントローラ６は、図示していないＣＰＵなどのプロセッサ、ＲＯＭ、ＲＡＭなどのメモリ、及びその周辺回路と、プロセッサ上で実行されるコンピュータプログラムによって実現される機能モジュールとして、分光立体形状測定装置１の各部を制御する制御部６３と、点検出器５により検出された信号に基づいて、被測定物１０の立体形状及び色を求める波面再生部６４とを有する。
The controller 6 is a so-called computer. The controller 6 controls the entire spectral solid shape measuring apparatus 1 and regenerates the wavefront obtained from each point on the device under test 10 from the electrical signal obtained by the point detector 5.
FIG. 2 shows a functional block diagram of the controller 6. As shown in FIG. 2, the controller 6 includes a storage unit 61 having at least one of an electrically rewritable nonvolatile memory, a magnetic disk, an optical disk, and a reading device thereof, RS232C, Ethernet (registered trademark), and the like. The communication unit 62 is composed of software such as an interface circuit and a device driver configured in accordance with the communication standards of the above.
Furthermore, the controller 6 is a functional module realized by a processor (not shown) such as a CPU, a memory such as a ROM and a RAM, and peripheral circuits thereof, and a computer program executed on the processor. A control unit 63 that controls each unit and a wavefront reproduction unit 64 that obtains the three-dimensional shape and color of the DUT 10 based on a signal detected by the point detector 5 are provided.
制御部６３は、通信部６２を介して制御信号を送信することにより可動ステージ３を制御して、干渉計２をx軸方向及びy軸方向の所定位置に移動させる。また制御部６３は、通信部６２を介して制御信号を送信することにより微動ステージ２４を制御して、反射素子２３と光線分割素子２１間の間隔を変更させて、光束Ｂ１と光束Ｂ２との間に所定の光路差を生じさせる。 The control unit 63 controls the movable stage 3 by transmitting a control signal via the communication unit 62 and moves the interferometer 2 to predetermined positions in the x-axis direction and the y-axis direction. In addition, the control unit 63 controls the fine movement stage 24 by transmitting a control signal via the communication unit 62 to change the interval between the reflection element 23 and the light beam splitting element 21, so that the light beams B <b> 1 and B <b> 2 are changed. A predetermined optical path difference is generated between them.
波面再生部６４は、点検出器５により検出された光強度信号に応じた電気信号により表される白色干渉縞から、被測定物１０の立体形状及び分光情報を求める。 The wavefront reproducing unit 64 obtains the three-dimensional shape and spectral information of the object to be measured 10 from the white interference fringes represented by the electrical signal corresponding to the light intensity signal detected by the point detector 5.
以下、分光立体形状測定装置１による被測定物１０の立体形状及び分光情報を測定するための原理について説明する。
まず、干渉計２をx軸方向に沿ってX/2、y軸方向に沿ってY/2だけ移動し、光束Ｂ１と光束Ｂ２の光路差をZとしたとき、点検出器５で検出される光強度I(X,Y,Z)は、次式で表される。
さらに、z0は、光束Ｂ１とＢ２の光路差が0のときの原点から反射素子２３の中心点までの距離を表す。また、I(p')は、光束Ｂ１の強度を表し、I(p)は光束Ｂ２の強度を表す。なお、位置p、p'において、それぞれ、X、Yの値が反転しているのは、反射素子２２及び２３によって、それぞれ、波面が垂直方向及び水平方向に反転されているためである。そしてΓ(p',p)は、位置p'における光束Ｂ１の複素振幅V(p')及び位置pにおける光束Ｂ２の複素振幅V(p)の空間コヒーレンス関数である。さらに、Γ*及びV*は、それぞれ、Γ及びVの複素共役を表す。
Hereinafter, the principle for measuring the three-dimensional shape and spectral information of the DUT 10 by the spectroscopic three-dimensional shape measuring apparatus 1 will be described.
First, when the interferometer 2 is moved by X / 2 along the x-axis direction and Y / 2 along the y-axis direction, and the optical path difference between the light beams B1 and B2 is Z, it is detected by the point detector 5. The light intensity I (X, Y, Z) is expressed by the following equation.
Further, z 0 represents the distance from the origin to the center point of the reflecting element 23 when the optical path difference between the light beams B1 and B2 is zero. I (p ′) represents the intensity of the light beam B1, and I (p) represents the intensity of the light beam B2. Note that the values of X and Y are inverted at the positions p and p ′, respectively, because the wavefronts are inverted in the vertical and horizontal directions by the reflecting elements 22 and 23, respectively. Γ (p ′, p) is a spatial coherence function of the complex amplitude V (p ′) of the light beam B1 at the position p ′ and the complex amplitude V (p) of the light beam B2 at the position p. Furthermore, Γ * and V * represent complex conjugates of Γ and V, respectively.
ここで、ω=ck=c/λ（ただしcは、光速であり、kは波数であり、λは波長である）とすると、Wiener-Khinchinの定理により、空間コヒーレンス関数Γ(p',p)を、光束Ｂ１とＢ２の光路差、すなわちZについて逆フーリエ変換することにより、近似的に被測定物１０から放射された光の波長情報を表す相互スペクトル密度W(p',p";ω)を求めることができる。ただし、p"=(0,-Y,z0)である。
F-1[I(p)+I(p')]+W(p',p";ω)+W*(p',p";ω) （３）
を得ることができる。なお、F-1[]は逆フーリエ変換を表す。しかし、I(p)+I(p')は、Zの値によらず一定であるため、F-1[I(p)+I(p')]はバイアス成分に過ぎない。また、W*(p',p";ω)は、W(p',p";ω)の複素共役である。そのため、コントローラ６は、（３）式からW(p',p";ω)を求めることができる。
Here, if ω = ck = c / λ (where c is the speed of light, k is the wave number, and λ is the wavelength), the spatial coherence function Γ (p ′, p is determined by Wiener-Khinchin's theorem. ) Is subjected to inverse Fourier transform with respect to the optical path difference between the light beams B1 and B2, that is, Z, so that the cross spectral density W (p ′, p ″; ω approximately representing the wavelength information of the light emitted from the DUT 10 is obtained. ) Where p "= (0, -Y, z 0 ).
F −1 [I (p) + I (p ′)] + W (p ′, p ″; ω) + W * (p ′, p ″; ω) (3)
Can be obtained. Note that F −1 [] represents an inverse Fourier transform. However, since I (p) + I (p ′) is constant regardless of the value of Z, F −1 [I (p) + I (p ′)] is only a bias component. W * (p ′, p ″; ω) is a complex conjugate of W (p ′, p ″; ω). Therefore, the controller 6 can obtain W (p ′, p ″; ω) from the equation (3).
一方、相互スペクトル密度W(p',p";ω)は、被測定物１０上の各点から放射された球面波のうち、光束Ｂ１の複素振幅の複素共役と光束Ｂ２の複素振幅の重ね合わせとして表現できるから、相互スペクトル密度W(p',p";ω)は、次式で表される。
従って、相互スペクトル密度W(p',p";ω)を求めることができれば、被測定物１０上の座標(x1,y1,z1)から放射される再生波面J(x1,y1,z1;ω)は、（４）式に表された相互スペクトル密度W(p',p";ω)をX、Yについて次式のように周波数変換することにより得られる。
図３に、分光立体形状測定装置１により取得される白色干渉縞信号の概略図を示す。図３に示されるように、白色干渉縞３００は、干渉計２の移動量の２倍であるX、Yと、光束Ｂ１とＢ２の光路差Zをそれぞれ互いに直交する軸とした直交座標系において、３次元状の干渉縞となる。そして白色干渉縞３００は、（４）式に表されるように、干渉計２の移動量の２倍であるX、Yにより表される面内では、双曲線状の干渉縞となる。一方、白色干渉縞３００は、光束Ｂ１とＢ２の光路差Zの方向には、（３）式に表されるようにZの長さに依存する同心円状の干渉縞となる。 In FIG. 3, the schematic of the white interference fringe signal acquired by the spectral solid shape measuring apparatus 1 is shown. As shown in FIG. 3, the white interference fringe 300 is an orthogonal coordinate system in which X and Y, which are twice the movement amount of the interferometer 2, and the optical path difference Z between the light beams B <b> 1 and B <b> 2 are orthogonal to each other. It becomes a three-dimensional interference fringe. The white interference fringe 300 becomes a hyperbolic interference fringe in the plane represented by X and Y, which is twice the movement amount of the interferometer 2, as represented by the equation (4). On the other hand, the white interference fringe 300 becomes a concentric interference fringe depending on the length of Z in the direction of the optical path difference Z between the light beams B1 and B2, as expressed in the equation (3).
図４に、被測定物１０の立体形状及び色を測定する際の分光立体形状測定装置１の動作フローチャートを示す。なお、以下に説明する動作は、コントローラ６により制御される。
測定が開始されると、コントローラ６の制御部６３は、通信部６２を介して可動ステージ３へ制御信号を送信することにより、干渉計２を所定の測定点へ移動させる（ステップＳ１０１）。次に、制御部６３は、通信部６２を介して微動ステージ２３へ制御信号を送信することにより、光束Ｂ１と光束Ｂ２の光路差を変えつつ、点検出器５により受光される光強度を測定する（ステップＳ１０２）。そして制御部６３は、点検出器５から受信した、その光強度に対応する電気信号により表される白色干渉縞信号を、干渉計２の移動量及び光束Ｂ１と光束Ｂ２の光路差を関連付けて、コントローラ６の記憶部６１に記憶する（ステップＳ１０３）。なお、上記のように、記憶部６１に記憶されたこれらの信号は、干渉計２のx軸方向及びy軸方向の移動量の２倍と、光束Ｂ１とＢ２間の光路差をそれぞれの軸とする３次元状の白色干渉縞を表す。そして制御部６３は、干渉計２に関する全ての測定点について干渉縞信号が得られたか否か判定する（ステップＳ１０４）。全ての測定点についての干渉縞信号が得られていない場合、制御部６３は、制御をステップＳ１０１へ戻し、干渉計２を次の測定点に移動させて、ステップＳ１０１〜Ｓ１０４の処理を繰り返す。
FIG. 4 shows an operation flowchart of the spectral three-dimensional shape measuring apparatus 1 when measuring the three-dimensional shape and color of the DUT 10. The operation described below is controlled by the controller 6.
When the measurement is started, the control unit 63 of the controller 6 transmits the control signal to the movable stage 3 via the communication unit 62, thereby moving the interferometer 2 to a predetermined measurement point (step S101). Next, the control unit 63 measures the light intensity received by the point detector 5 while changing the optical path difference between the light beams B1 and B2 by transmitting a control signal to the fine movement stage 23 via the communication unit 62. (Step S102). The control unit 63 associates the white interference fringe signal, which is received from the point detector 5 and represented by the electrical signal corresponding to the light intensity, with the movement amount of the interferometer 2 and the optical path difference between the light beams B1 and B2. And stored in the storage unit 61 of the controller 6 (step S103). Note that, as described above, these signals stored in the storage unit 61 represent twice the amount of movement of the interferometer 2 in the x-axis direction and the y-axis direction, and the optical path difference between the light beams B1 and B2, respectively. Represents a three-dimensional white interference fringe. And the control part 63 determines whether the interference fringe signal was acquired about all the measurement points regarding the interferometer 2 (step S104). When the interference fringe signals for all the measurement points are not obtained, the control unit 63 returns the control to step S101, moves the interferometer 2 to the next measurement point, and repeats the processes of steps S101 to S104.
一方、ステップＳ１０４において、全ての測定点についての干渉縞信号が得られている場合、コントローラ６の波面再生部６４は、記憶部６１に記憶された干渉縞信号を、上記の（２）式または（３）式に従って光束Ｂ１とＢ２間の光路差について逆フーリエ変換することにより、相互スペクトル密度W(p',p";ω)を算出する（ステップＳ１０５）。そして波面再生部６４は、得られた相互スペクトル密度W(p',p";ω)を、（５）式に従って干渉計２のx軸方向の移動量及びy軸方向の移動量に関して２次元の周波数変換を行うことにより、被測定物１０上の座標(x1,y1,z1)から放射される再生波面J(x1,y1,z1;ω)を求める（ステップＳ１０６）。そしてコントローラ６は処理を終了する。 On the other hand, when interference fringe signals for all measurement points are obtained in step S104, the wavefront reproduction unit 64 of the controller 6 uses the interference fringe signal stored in the storage unit 61 as the above equation (2) or The cross spectral density W (p ′, p ″; ω) is calculated by performing inverse Fourier transform on the optical path difference between the light beams B1 and B2 according to the equation (3) (step S105). By performing the two-dimensional frequency conversion of the obtained cross spectral density W (p ′, p ″; ω) with respect to the movement amount in the x-axis direction and the movement amount in the y-axis direction of the interferometer 2 according to the equation (5), A reproduction wavefront J (x 1 , y 1 , z 1 ; ω) radiated from coordinates (x 1 , y 1 , z 1 ) on the device under test 10 is obtained (step S106). Then, the controller 6 ends the process.
以上説明してきたように、本発明の一つの実施形態に係る分光立体測定装置は、白色照明された被測定物で反射または散乱された光を二つの光束に分割し、それら二つの光束の波面を反射部材で反転するとともに、干渉計と被測定物の相対的な位置関係を変えることにより、二つの光束の波面をずらして干渉を生じさせる。そしてこの分光立体形状測定装置は、各光束の波面の向き及び各光束間の波面間の着目するずれ量に対応する光束が点検出器の検出面に到達するように、各反射部材の反射面の向きを調節するとともに、二つの反射部材と光線分割素子を一体的に動かす。これにより、この分光立体形状測定装置は、被測定物及び点検出器を移動させることなく、被測定物上の各点からの波面による白色干渉縞を得ることができる。そしてこの分光立体形状測定装置は、二つの光束の波面の向きに応じて得られる白色干渉縞を、その干渉縞の形に応じた周波数変換式により再生波面を求めることで、測定に要するデータ数を減らしつつ、被測定物の立体形状及び分光情報を測定することができる。 As described above, the spectroscopic three-dimensional measurement apparatus according to one embodiment of the present invention divides the light reflected or scattered by the object illuminated with white light into two light beams, and the wave fronts of these two light beams. Is reversed by the reflecting member, and the relative positional relationship between the interferometer and the object to be measured is changed to cause interference by shifting the wavefronts of the two light beams. And this spectroscopic three-dimensional shape measuring apparatus is a reflection surface of each reflecting member so that the light beam corresponding to the direction of the wave front of each light beam and the noticed deviation amount between the wave fronts between each light beam reaches the detection surface of the point detector. And the two reflecting members and the beam splitting element are moved together. Thereby, this spectroscopic three-dimensional shape measuring apparatus can obtain white interference fringes due to the wavefront from each point on the measured object without moving the measured object and the point detector. This spectroscopic three-dimensional shape measuring device obtains the reproduction wavefront of the white interference fringes obtained according to the directions of the wavefronts of the two light fluxes by the frequency conversion formula according to the shape of the interference fringes, thereby obtaining the number of data required for the measurement. It is possible to measure the three-dimensional shape and spectroscopic information of the object to be measured while reducing the amount of light.
なお、本発明は、上記の実施形態に限定されるものではない。例えば、干渉計２が有する二つの反射素子２２及び２３が、光束Ｂ１及びＢ２の波面を反転する方向は、互いに対して異なっていればよく、上記の実施形態に示した方向に限られない。例えば、反射素子２２が、光線分割素子２１、反射素子２２及び２３が配置された水平面に沿って水平方向に光束Ｂ２の波面を反転させ、一方、反射素子２３が、その水平面に対して直交する垂直方向に波面を反転させるように、反射素子２２、２３を配置してもよい。さらに、反射素子２２は、光束Ｂ１の波面を上記の水平面及びその水平面と直交する方向に対して45°傾いた第１の方向に反転させ、反射素子２３は、光束Ｂ２の波面を第１の方向と90°をなす第２の方向に反転させてもよい。
また、光束Ｂ１とＢ２間の光路差を変更するために、反射素子２３を移動させる代わりに、反射素子２２を移動させて、反射素子２２と光線分割素子２１の間隔を変えてもよい。このように、光束Ｂ１及びＢ２の波面を反転させる方向及び反射素子の移動方向が設定される場合、その反転方向及び移動方向に応じて、上記の（１）〜（５）式を修正すればよい。
In addition, this invention is not limited to said embodiment. For example, the direction in which the two reflecting elements 22 and 23 included in the interferometer 2 invert the wavefronts of the light beams B1 and B2 need only be different from each other, and is not limited to the direction shown in the above embodiment. For example, the reflecting element 22 inverts the wavefront of the light beam B2 in the horizontal direction along the horizontal plane on which the beam splitting element 21 and the reflecting elements 22 and 23 are arranged, while the reflecting element 23 is orthogonal to the horizontal plane. The reflective elements 22 and 23 may be arranged so as to invert the wavefront in the vertical direction. Further, the reflecting element 22 inverts the wavefront of the light beam B1 in a first direction inclined by 45 ° with respect to the horizontal plane and the direction orthogonal to the horizontal plane, and the reflecting element 23 changes the wavefront of the light beam B2 to the first direction. You may invert to the 2nd direction which makes 90 degrees with a direction.
Further, in order to change the optical path difference between the light beams B1 and B2, instead of moving the reflecting element 23, the reflecting element 22 may be moved to change the interval between the reflecting element 22 and the light beam splitting element 21. Thus, when the direction for reversing the wavefronts of the light beams B1 and B2 and the moving direction of the reflecting element are set, the above equations (1) to (5) can be corrected according to the reversing direction and moving direction. Good.
また、本発明に係る分光立体測定装置と内視鏡を組み合わせることにより、直接的に視認不能な場所にある被測定物の立体形状及び分光情報を測定することもできる。この場合、内視鏡の観察範囲に被測定物が含まれるように、内視鏡の遠位端を被測定物に近接し、且つ被測定物へ向けて配置し、一方、内視鏡の近位端を、その近位端から出射される光が干渉計２へ向かうように配置すればよい。本発明に係る分光立体測定装置は、被測定物をコヒーレンス光で照明することを必要としないので、直接視認することができない被測定物についても、容易にその立体形状及び分光情報を測定することができる。
以上のように、当業者は、本発明の範囲内で、実施される形態に合わせて様々な変更を行うことができる。
Further, by combining the spectroscopic three-dimensional measuring apparatus and the endoscope according to the present invention, the three-dimensional shape and spectroscopic information of the object to be measured in a place where it cannot be directly visually recognized can be measured. In this case, the endoscope is arranged so that the distal end of the endoscope is close to the measured object and directed toward the measured object so that the measured object is included in the observation range of the endoscope. What is necessary is just to arrange | position a proximal end so that the light radiate | emitted from the proximal end may go to the interferometer 2. FIG. Since the spectroscopic three-dimensional measuring apparatus according to the present invention does not need to illuminate the object to be measured with coherence light, the three-dimensional shape and spectroscopic information can be easily measured even for the object that cannot be directly visually recognized. Can do.
As described above, those skilled in the art can make various modifications in accordance with the embodiment to be implemented within the scope of the present invention.
１ 分光立体測定装置
１０ 被測定物
２ 干渉計
２１ 光線分割素子
２２、２３ 反射素子
２４ 微動ステージ
３ 可動ステージ
４ レンズ
５ 点検出器
６ コントローラ
６１ 記憶部
６２ 通信部
６３ 制御部
６４ 波面再生部
DESCRIPTION OF SYMBOLS 1 Spectroscopic measuring apparatus 10 Measured object 2 Interferometer 21 Ray splitting element 22, 23 Reflective element 24 Fine movement stage 3 Movable stage 4 Lens 5 Point detector 6 Controller 61 Memory | storage part 62 Communication part 63 Control part 64 Wavefront reproduction | regeneration part
Claims (5)
白色光により照明された被測定物によって反射または散乱された測定光に対して白色干渉縞を生じさせる干渉計と、
前記干渉計から出力された光の強度を測定する点検出器と、
前記干渉計を移動させる第１の可動ステージと、
前記点検出器と接続され、前記白色干渉縞信号から被測定物の立体形状及び分光情報を求めるコントローラとを有し、
前記干渉計は、
前記測定光を第１の光束と第２の光束に分割して出射させる光線分割素子と、
前記第１の光束の波面を第１の方向に沿って反転させて、該波面が反転された前記第１の光束を前記光線分割素子へ向けて反射する第１の反射素子と、
前記第２の光束の波面を、前記第１の方向と異なる第２の方向に沿って反転させて、該波面が反転された前記第２の光束を、前記光線分割素子へ向けて反射する第２の反射素子と、
前記第２の反射素子を、前記光線分割素子と前記第２の反射素子を結ぶ直線に平行な第３の方向に移動させることにより、前記光線分割素子と前記第２の反射素子の間隔を変更して、前記第１の光束と前記第２の光束との間に所定の光路差を生じさせる第２の可動ステージとを有し、
前記コントローラは、
前記第１の可動ステージを制御して、前記干渉計と被測定物の相対的な位置を変えつつ、かつ前記第２の可動ステージを制御して、前記第２の反射素子を前記第３の方向に沿って移動させつつ、前記点検出器により受光された光の強度を測定することにより、白色干渉縞信号を取得し、
前記白色干渉縞信号を、前記第１の光束と前記第２の光束間の光路差について周波数変換することにより、被測定物の所定点の分光情報を表す相互スペクトル密度を決定し、かつ
前記相互スペクトル密度を前記干渉計の移動量について周波数変換することにより、被測定物上の前記所定点で反射または散乱された光の波面を決定する、
ことを特徴とする分光立体形状測定装置。 A spectroscopic three-dimensional shape measuring apparatus for measuring three-dimensional shape and spectral information of an object to be measured,
An interferometer that produces white interference fringes for measurement light reflected or scattered by the object illuminated by white light;
A point detector for measuring the intensity of light output from the interferometer;
A first movable stage for moving the interferometer;
A controller that is connected to the point detector and obtains the three-dimensional shape and spectral information of the object to be measured from the white interference fringe signal;
The interferometer is
A beam splitting element for splitting the measurement light into a first beam and a second beam,
A first reflecting element that inverts the wavefront of the first light flux along a first direction and reflects the first light flux with the wavefront reversed toward the beam splitting element;
A wavefront of the second light flux is inverted along a second direction different from the first direction, and the second light flux with the wavefront inverted is reflected toward the light beam splitting element. Two reflective elements;
The distance between the light beam splitting element and the second reflective element is changed by moving the second reflective element in a third direction parallel to a straight line connecting the light beam splitting element and the second reflective element. And a second movable stage that generates a predetermined optical path difference between the first light flux and the second light flux,
The controller is
The first movable stage is controlled to change the relative position of the interferometer and the object to be measured, and the second movable stage is controlled to change the second reflective element to the third By measuring the intensity of the light received by the point detector while moving along the direction, a white interference fringe signal is obtained,
The white interference fringe signal is frequency-converted with respect to the optical path difference between the first light flux and the second light flux, thereby determining a mutual spectral density representing spectral information at a predetermined point of the object to be measured, and Determining the wavefront of the light reflected or scattered at the predetermined point on the object to be measured by frequency-converting the spectral density with respect to the amount of movement of the interferometer;
A spectral three-dimensional shape measuring apparatus.
前記相互スペクトル密度を前記第１の方向の移動量及び前記第２の方向の移動量について周波数変換することにより、被測定物上の前記所定点から放射された光の波面を決定する、請求項１に記載の分光立体形状測定装置。 The controller moves the interferometer along the first direction or the second direction to change a relative position between the interferometer and the object to be measured;
The wavefront of light radiated from the predetermined point on the object to be measured is determined by frequency-converting the mutual spectral density with respect to the movement amount in the first direction and the movement amount in the second direction. 1. The spectral three-dimensional shape measuring apparatus according to 1.
前記干渉計は、
前記測定光を第１の光束と第２の光束に分割して出射させる光線分割素子と、
前記第１の光束の波面を第１の方向に沿って反転させて、該波面が反転された前記第１の光束を前記光線分割素子へ向けて反射する第１の反射素子と、
前記第２の光束の波面を、前記第１の方向と異なる第２の方向に沿って反転させて、該波面が反転された前記第２の光束を、前記光線分割素子へ向けて反射する第２の反射素子と、
前記第２の反射素子を、前記光線分割素子と前記第２の反射素子を結ぶ直線に平行な第３の方向に移動させることにより、前記光線分割素子と前記第２の反射素子の間隔を変更して、前記第１の光束と前記第２の光束との間に所定の光路差を生じさせる第２の可動ステージとを有し、
前記分光立体形状測定方法は、
前記第１の可動ステージを制御して、前記干渉計と被測定物の相対的な位置を変えつつ、かつ前記第２の可動ステージを制御して、前記第２の反射素子を前記第３の方向に沿って移動させつつ、前記点検出器により受光された光の強度を測定することにより、白色干渉縞信号を取得するステップと、
前記白色干渉縞信号を、前記第１の光束と前記第２の光束間の光路差について周波数変換することにより、被測定物の所定点の分光情報を表す相互スペクトル密度を決定するステップと、
前記相互スペクトル密度を前記干渉計の移動量について周波数変換することにより、被測定物上の前記所定点で反射または散乱された光の波面を決定するステップと、
を含むことを特徴とする分光立体形状測定方法。 An interferometer that generates white interference fringes with respect to measurement light reflected or scattered by an object illuminated by white light, a point detector that measures the intensity of light output from the interferometer, and the interference A spectral solid shape measuring method using a spectral solid shape measuring apparatus having a first movable stage for moving a meter,
The interferometer is
A beam splitting element for splitting the measurement light into a first beam and a second beam,
A first reflecting element that inverts the wavefront of the first light flux along a first direction and reflects the first light flux with the wavefront reversed toward the beam splitting element;
A wavefront of the second light flux is inverted along a second direction different from the first direction, and the second light flux with the wavefront inverted is reflected toward the light beam splitting element. Two reflective elements;
The distance between the light beam splitting element and the second reflective element is changed by moving the second reflective element in a third direction parallel to a straight line connecting the light beam splitting element and the second reflective element. And a second movable stage that generates a predetermined optical path difference between the first light flux and the second light flux,
The spectral three-dimensional shape measuring method is:
The first movable stage is controlled to change the relative position of the interferometer and the object to be measured, and the second movable stage is controlled to change the second reflective element to the third Obtaining a white interference fringe signal by measuring the intensity of light received by the point detector while moving along a direction;
Determining a cross spectral density representing spectral information of a predetermined point of the object to be measured by frequency-converting the white interference fringe signal with respect to an optical path difference between the first light flux and the second light flux;
Determining a wavefront of light reflected or scattered at the predetermined point on the object to be measured by frequency-converting the mutual spectral density with respect to the amount of movement of the interferometer;
A spectral three-dimensional shape measuring method comprising:
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