JP2007240344A - Dynamic shape measuring method and dynamic shape measuring device - Google Patents

Dynamic shape measuring method and dynamic shape measuring device Download PDF

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JP2007240344A
JP2007240344A JP2006063685A JP2006063685A JP2007240344A JP 2007240344 A JP2007240344 A JP 2007240344A JP 2006063685 A JP2006063685 A JP 2006063685A JP 2006063685 A JP2006063685 A JP 2006063685A JP 2007240344 A JP2007240344 A JP 2007240344A
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measurement target
measurement
height
trajectory
dynamic shape
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Fumiyuki Takahashi
文之 高橋
Takashi Fuse
貴史 布施
Hiroyuki Tsukahara
博之 塚原
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Fujitsu Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To largely shorten the measurement time for acquiring height data at a plurality of times required for displaying moving image display of an MEMS (Micro Electro Mechanical System) operation. <P>SOLUTION: A stroboscopic phase shift interference device sets optical path difference, measures the height of the MEMS under operation at a plurality of phases at three or more points with respect to the set optical path difference, calculates an estimation equation of height locus of the MEMS under operation, and determines the shape of the MEMS under operation by calculation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は3次元計測技術に係り、特に周期的動作をする計測対象の動的変位・変形計測を高速に行う方法および装置に関するものである。   The present invention relates to a three-dimensional measurement technique, and more particularly to a method and apparatus for performing dynamic displacement / deformation measurement of a measurement target that performs a periodic operation at high speed.

周期的に動作を行う計測対象としてMEMS(Micro Electro Mechanical Systems)がある。MEMSを応用したデバイスとしては光スキャナ、ジャイロなどがある。光スキャナは光を走査するために、ジャイロは角速度を検出するためにデバイスの一部あるいは全体が周期的に高速動作する。図7は光スキャナを構成するミラーの姿勢の一例を示す図である。回転軸を中心として計測対象のミラーが往復運動を行うことにより、光を1軸方向に走査することができる。図7の(1)はミラー角度最大付近時刻t=t1におけるミラーの姿勢を、図7の(2)はミラー角度最小付近時刻t=t2におけるミラーの姿勢を示している。図7のp1、p2は各々の時刻におけるミラー上の特定の位置を示している。   There is a MEMS (Micro Electro Mechanical Systems) as a measurement target that periodically operates. Devices using MEMS include optical scanners and gyros. An optical scanner scans light, and a gyro detects an angular velocity, and a part or the whole of the device periodically operates at high speed. FIG. 7 is a view showing an example of the posture of the mirror constituting the optical scanner. When the mirror to be measured reciprocates around the rotation axis, light can be scanned in one axial direction. (1) in FIG. 7 shows the attitude of the mirror at the time t = t1 near the maximum mirror angle, and (2) in FIG. 7 shows the attitude of the mirror at the time t = t2 near the minimum mirror angle. P1 and p2 in FIG. 7 indicate specific positions on the mirror at the respective times.

図8は図7のミラーをy方向からみた場合の姿勢変化を示す図である。図の白丸は時刻t1、t2、t3におけるp1、p2の位置を示している。周期的な高速動作により計測対象が変形した場合、変形の程度によっては光走査あるいは角速度検出性能低下の原因となるため動的な変位・変形などの動的挙動を計測する必要がある。   FIG. 8 is a view showing a change in posture when the mirror of FIG. 7 is viewed from the y direction. White circles in the figure indicate the positions of p1 and p2 at times t1, t2, and t3. When the measurement object is deformed by periodic high-speed operation, depending on the degree of deformation, it may cause a decrease in optical scanning or angular velocity detection performance, so it is necessary to measure dynamic behavior such as dynamic displacement and deformation.

周期的に動作する計測対象の動的挙動を確認するには計測対象が時刻ごとに変化する様子を動画表示するなどして連続的に示すとわかりやすいことが多い。このような動画表示を行うためには計測対象の動作1周期内で、複数の位相(時刻)における高さを計測する必要がある。   In order to confirm the dynamic behavior of a measurement object that operates periodically, it is often easy to understand if the measurement object is continuously displayed by displaying a moving image or the like. In order to display such a moving image, it is necessary to measure the height at a plurality of phases (time) within one cycle of the operation to be measured.

図9は高速周期運動をする計測対象の従来計測例を示す図である。図9は図7に示したスキャナの1周期の動作を20分割して計測した場合の例である。図9の(2)は計測位置p1における高さの計測値時間変化を示し、図9の(3)は計測位置p2における高さ計測値の時間変化を示している。従来方法では、図7に示したミラー動作の動画表示を行うために表示に必要な全ての時刻における計測が必要であり、計測時間が非常に多く掛かる問題がある。   FIG. 9 is a diagram illustrating a conventional measurement example of a measurement target that performs high-speed periodic motion. FIG. 9 shows an example in which one-cycle operation of the scanner shown in FIG. (2) in FIG. 9 shows a change in the height measurement value at the measurement position p1, and (3) in FIG. 9 shows a change in the height measurement value in the measurement position p2. In the conventional method, since the moving image display of the mirror operation shown in FIG. 7 is performed, measurement at all the times necessary for display is necessary, and there is a problem that it takes a very long measurement time.

高速に周期動作する計測対象の変位・変形をナノメートル精度で面計測する公知技術としてはストロボ干渉法がある。図10はストロボ干渉計の光学系と原理を示す図である。図10の(1)はストロボ干渉計の光学系を示し、ストロボ光源1から出射した可干渉性の強い光をハーフミラー2で分割し、MEMS3と参照ミラー4に照射する。双方から反射した光を再びハーフミラー2で合わせて得られる干渉縞から対象の形状を算出することができる。   There is a strobe interferometry as a well-known technique for measuring a surface of a displacement / deformation of a measurement object that periodically operates at high speed with nanometer accuracy. FIG. 10 is a diagram showing the optical system and principle of the strobe interferometer. (1) of FIG. 10 shows the optical system of the strobe interferometer, which divides the coherent light emitted from the strobe light source 1 by the half mirror 2 and irradiates the MEMS 3 and the reference mirror 4. The shape of the object can be calculated from the interference fringes obtained by combining the light reflected from both sides with the half mirror 2 again.

図10の(2)は高速動作する計測対象の特定位相(時刻)において、計測対象の動作周波数と同じ発光タイミングで照射する。これにより所定の位相における干渉縞のみをフリーズして撮像する事ができる。また、ストロボ発光開始のタイミング(初期位相)を1周期の間で調整する事により希望の位相(時刻)における高さを計測することができる。   (2) of FIG. 10 irradiates with the same light emission timing as the operation frequency of a measurement object in the specific phase (time) of the measurement object operating at high speed. Thereby, only the interference fringes in a predetermined phase can be frozen and imaged. Also, the height at the desired phase (time) can be measured by adjusting the strobe light emission start timing (initial phase) during one period.

ストロボ干渉法では、物体の動作速度が速くなり、ストロボ発光時間中に計測対象が大きく動いてしまうと、干渉縞がぼやけてしまうため、計測対象の速度に応じてストロボ光の発光時間を短くする必要がある。しかし発光時間が短くなるとCCDに入射する光量が減少するため計測に必要な干渉縞強度が不足する場合がある。この状況において十分な干渉縞強度を得るためには露光時間を長くする必要があり、1枚の干渉縞撮像時間が増加する。したがって多数の時刻で干渉縞を取得すると、干渉縞画像の撮像枚数が増え、計測時間が非常にかかる問題がある。   In the strobe interferometry, the speed of object movement increases, and if the object to be measured moves greatly during the strobe light emission time, the interference fringes blur. Therefore, the strobe light emission time is shortened according to the speed of the object to be measured. There is a need. However, if the light emission time is shortened, the amount of light incident on the CCD decreases, and the interference fringe intensity necessary for measurement may be insufficient. In this situation, in order to obtain sufficient interference fringe intensity, it is necessary to lengthen the exposure time, and the time for imaging one interference fringe increases. Therefore, if interference fringes are acquired at a large number of times, the number of interference fringe images to be captured increases, and there is a problem that it takes a very long measurement time.

干渉縞から計測対象の高さを算出する方法として、位相シフト法が知られている。位相シフト法は図10のピエゾステージ5で参照ミラー4やMEMS3を動かして、ハーフミラー2とMEMS3との光路長とハーフミラー2と参照ミラー4の間の光路長の差である光路差を段階的に変化させながら複数の干渉縞画像を撮像し、撮像した光路差の異なる複数の干渉画像から計測対象の高さを高精度に算出する方法である。   A phase shift method is known as a method for calculating the height of a measurement target from interference fringes. In the phase shift method, the reference mirror 4 and the MEMS 3 are moved by the piezo stage 5 in FIG. 10, and the optical path difference which is the difference between the optical path length between the half mirror 2 and the MEMS 3 and the optical path length between the half mirror 2 and the reference mirror 4 is stepped. In this method, a plurality of interference fringe images are picked up while being changed, and the height of the measurement object is calculated with high accuracy from the picked up interference images having different optical path differences.

以下に位相シフト法で高さを計測する方法について詳細を述べる。なお簡単のため、計測対象が止まっている場合について説明する。一般に干渉光学系で撮像した干渉縞の強度I(x,y)は以下となる。   The details of the method of measuring the height by the phase shift method will be described below. For simplicity, a case where the measurement target is stopped will be described. In general, the intensity I (x, y) of interference fringes imaged by an interference optical system is as follows.

Figure 2007240344
Figure 2007240344

ここで、A(x,y)は干渉縞振幅のバイアス成分、B(x,y)は干渉縞振幅の変調成分である。A(x,y)、B(x,y)は光学系の背景光やシェーディングなどの状態によって変化する。またφ(x,y)は干渉計の光路差d(x,y)、すなわち測定物の高さ変化に比例する。関係を下式に示す。   Here, A (x, y) is a bias component of interference fringe amplitude, and B (x, y) is a modulation component of interference fringe amplitude. A (x, y) and B (x, y) vary depending on the background light of the optical system and the state of shading. Φ (x, y) is proportional to the optical path difference d (x, y) of the interferometer, that is, the height change of the measurement object. The relationship is shown in the following equation.

Figure 2007240344
Figure 2007240344

ここでλは光源波長である。位相シフト法では光路差を変化させた複数の干渉縞画像からφ(x,y)を求める。光路差を変化させた場合の干渉縞の位相変化をΔφとすると(1)式は以下のように表現することができる。   Here, λ is a light source wavelength. In the phase shift method, φ (x, y) is obtained from a plurality of interference fringe images in which the optical path difference is changed. If the phase change of the interference fringes when the optical path difference is changed is Δφ, equation (1) can be expressed as follows.

Figure 2007240344
Figure 2007240344

光路差はピエゾステージなどによりミラーあるいは計測対象を動かすことにより制御する。Δφが0、π/2、π、3π/2の4つの状態での干渉縞強度I1、I2、I3、I4
は以下となる。
The optical path difference is controlled by moving a mirror or a measurement object by a piezo stage or the like. Interference fringe intensities I1, I2, I3, I4 in four states where Δφ is 0, π / 2, π, 3π / 2
Is as follows.

Figure 2007240344
Figure 2007240344

式4よりφ(x,y)を式5により算出する。   Φ (x, y) is calculated from Equation 4 using Equation 5.

Figure 2007240344
Figure 2007240344

算出したφ(x,y)より光路差d(x,y)を求め、アンラッピング処理により高さを算出する。上記は光路差を4通りに変化させる例であるが、4通り以上に光路差を変更し高さを求めることができる。ただし、ここでは4通り以上の方法についての詳細な説明は省略する。   The optical path difference d (x, y) is obtained from the calculated φ (x, y), and the height is calculated by unwrapping processing. The above is an example of changing the optical path difference in four ways, but the height can be obtained by changing the optical path difference in four or more ways. However, detailed description of four or more methods is omitted here.

位相シフト法を用いたストロボ干渉法は例えば非特許文献1で開示されている。しかしながら移動速度が速い計測対象を動画表示するために、干渉縞画像を多数撮像しなければならない場合に計測時間がかかる問題があることは前述の通りである。   For example, Non-Patent Document 1 discloses a strobe interference method using a phase shift method. However, as described above, there is a problem that measurement time is required when a large number of interference fringe images must be taken in order to display a moving image of a measurement object having a high moving speed.

特許文献1では、ストロボ干渉法に用いる干渉法としてキャリア周波数を与えた干渉縞を使用する空間キャリア法を用いて周期運動するマイクロマシンの形状を測定する方法が示されている。空間キャリア法は位相シフト法より計測時間の点で有利であるが、空間分解能が落ちる問題があり、また、高さ計測値に誤差が乗りやすいといった問題の他に、ミラーの角度が変わると干渉縞に重畳するキャリア周波数が変化し、ミラー角度によっては高精度の高さ検出が出来ないといった問題がある。
Matthew R.Hart et al.‘Strobscopic Interferometer System for Dynamic MEMS Chracteraization’、JOURNAL OF MICROELECTRONICAL SYSTEMS、VOL.9、NO4、DECEMBER 2000。
Patent Document 1 discloses a method of measuring the shape of a micromachine that periodically moves using a spatial carrier method using an interference fringe given a carrier frequency as an interference method used for strobe interferometry. The spatial carrier method is more advantageous in terms of measurement time than the phase shift method. However, there are problems in that the spatial resolution is reduced, and in addition to the problem that errors in the height measurement value are likely to occur, interference occurs when the mirror angle changes. There is a problem that the carrier frequency to be superimposed on the fringe changes, and the height cannot be detected with high accuracy depending on the mirror angle.
Matthew R.M. Hart et al. 'Strobscopter Intersystem System for Dynamic MEMS Chromatography', JOURNAL OF MICROELECTRONIC SYSTEMS, VOL. 9, NO4, DECEMBER 2000.


特開2003−222508号公報JP 2003-222508 A

解決しようとする課題は、高速周期的動作をしているMEMSの形状計測において、干渉縞強度を得るために露光時間を長くとる必要があり、これによりMEMS動作の動画表示に必要な複数時刻のデータを取得するための計測時間が非常に多くなる問題である。   The problem to be solved is that it is necessary to take a long exposure time in order to obtain the interference fringe intensity in the measurement of the shape of the MEMS performing the high-speed periodic operation. This is a problem that the measurement time for acquiring data becomes very long.

第1の発明は、周期的動作をしている計測対象に対しストロボ光源から前記計測対象と参照ミラーに照射して前記計測対象から反射した光と前記参照ミラーから反射した光の干渉縞より前記計測対象の動的形状を計測する動的形状計測方法である。   The first invention is based on the interference fringes of the light reflected from the measurement object and the light reflected from the measurement object by irradiating the measurement object and the reference mirror from the strobe light source to the measurement object performing a periodic operation. This is a dynamic shape measurement method for measuring the dynamic shape of a measurement target.

前記計測対象の動作周期に同期させて前記計測対象の軌跡を推定する少なくとも3点以上の複数位相で指定する軌跡推定点において前記計測対象の干渉縞を撮像して高さを計測し、前記軌跡推定点で計測した高さより前記計測対象の周期動作の高さ軌跡を推定する軌跡推定式を算出し、前記算出した軌跡推定式より前記計測対象の任意の位相における動的形状を算出する。   The trajectory of the measurement object is imaged at a trajectory estimation point specified by at least three or more phases for estimating the trajectory of the measurement object in synchronization with the operation cycle of the measurement object, and the height is measured. A trajectory estimation formula for estimating the height trajectory of the periodic movement of the measurement target is calculated from the height measured at the estimation point, and a dynamic shape at an arbitrary phase of the measurement target is calculated from the calculated trajectory estimation formula.

第2の発明は、周期的動作をしている計測対象に対しストロボ光源から前記計測対象と参照ミラーに照射して前記計測対象から反射した光と前記参照ミラーから反射した光の干渉縞より前記計測対象の動的形状を計測する動的形状計測方法である。   According to a second aspect of the present invention, an interference fringe of light reflected from the measurement object and light reflected from the reference mirror by irradiating the measurement object and the reference mirror from a strobe light source to the measurement object performing a periodic operation This is a dynamic shape measurement method for measuring the dynamic shape of a measurement target.

前記計測対象を動作させて前記ストロボ光源から照射し前記計測対象と前記参照ミラー間の光路差を干渉法に必要な複数の状態に変更し、前記各光路差に対し前記計測対象の軌跡を推定する少なくとも3点以上の複数位相で指定する軌跡推定点において干渉縞画像を撮像して高さを計測し、前記軌跡推定点で計測した高さより前記計測対象の高さ軌跡を推定する軌跡推定式を算出し、前記算出した軌跡推定式より前記計測対象の任意位相における動的形状を算出する。   Operate the measurement object and irradiate from the strobe light source, change the optical path difference between the measurement object and the reference mirror to a plurality of states necessary for interferometry, and estimate the trajectory of the measurement object for each optical path difference A trajectory estimation formula that measures the height by capturing an interference fringe image at a trajectory estimation point designated by at least three or more phases and estimates the height trajectory of the measurement object from the height measured at the trajectory estimation point And the dynamic shape at an arbitrary phase of the measurement target is calculated from the calculated locus estimation formula.

第3の発明は第2の発明の動的形状計測方法に、さらに前記軌跡推定式の検証を行う少なくも1点以上の軌跡検証点で前記計測対象の高さを計測し、前記軌跡推定式からの前記計測対象の高さと前記軌跡検証点で計測した高さとの差を閾値により評価し、前記閾値による評価が予め定めた評価基準を満たさない場合は前記軌跡推定点を追加して前記計測対象の高さを計測し、前記軌跡推定式を新たに算出する手順を加える。   According to a third aspect of the invention, in the dynamic shape measurement method of the second aspect of the invention, the height of the measurement object is measured at least at one or more trajectory verification points for verifying the trajectory estimation formula, and the trajectory estimation formula The difference between the height of the measurement object from the height and the height measured at the locus verification point is evaluated by a threshold, and if the evaluation by the threshold does not satisfy a predetermined evaluation criterion, the locus estimation point is added and the measurement is performed. A procedure for measuring the height of the object and newly calculating the trajectory estimation formula is added.

第4の発明は、周期的動作をしている計測対象に対しストロボ光源から前記計測対象と参照ミラーに照射して前記計測対象から反射した光と前記参照ミラーから反射した光の干渉縞より前記計測対象の動的形状を計測する動的形状計測装置である。   According to a fourth aspect of the present invention, there is an interference fringe of light reflected from the measurement object and light reflected from the reference mirror by irradiating the measurement object and the reference mirror from a strobe light source to the measurement object performing a periodic operation. It is a dynamic shape measuring device that measures the dynamic shape of a measurement target.

前記動的形状計測装置は、前記計測対象と前記参照ミラーの間の光路差を変更する手段と前記光路差に対し前記計測対象の軌跡を推定する少なくとも3点以上の複数位相で指定する軌跡推定点において前記計測対象の高さを計測する手段とを備える。   The dynamic shape measuring apparatus includes: a means for changing an optical path difference between the measurement target and the reference mirror; and a path estimation specified by at least three or more phases for estimating the path of the measurement target with respect to the optical path difference. Means for measuring the height of the measurement object at a point.

第5の発明は、第4の発明の動的形状計測装置に、前記軌跡推定点で計測した高さより前記計測対象の周期動作の高さ軌跡を推定する推定式を算出する手段と前記軌跡推定式から算出して任意位相における計測対象の形状を予測する手段をさらに備える。   According to a fifth aspect of the invention, in the dynamic shape measuring apparatus according to the fourth aspect of the invention, means for calculating an estimation formula for estimating a height trajectory of the periodic motion of the measurement object from the height measured at the trajectory estimation point and the trajectory estimation Means for predicting the shape of the measurement target in an arbitrary phase by calculating from the equation is further provided.

本発明により、高速で周期的動作をしているMEMSの形状の動的変化を少ない位相点での計測結果から予測することによりMEMS動作の動画表示に必要な複数時刻の高さデータを取得するための計測時間を大幅に短縮できる。   According to the present invention, it is possible to obtain height data at a plurality of times necessary for displaying a moving image of a MEMS operation by predicting a dynamic change in the shape of the MEMS performing a periodic operation at high speed from a measurement result at a small number of phase points. Measurement time can be greatly reduced.

(実施例1)
周期運動をしている計測対象の干渉縞の撮像には図10の(2)に示すように、ある1つの位相に対し複数の時刻でストロボ発光し干渉縞を撮像する。この周期運動における「位相」表現と位相シフト法での「位相」表現の区別が付き難いと考えられる。このため、以下では本来周期運動における「位相」と表現すべき部分もストロボ発光時刻に対応する「時刻」と表現することにする。
Example 1
As shown in FIG. 10 (2), the interference fringes of the measurement target that is in periodic motion are imaged by strobe emission at a plurality of times for a certain phase. It is difficult to distinguish between the “phase” expression in the periodic motion and the “phase” expression in the phase shift method. For this reason, hereinafter, the portion that should be originally expressed as “phase” in the periodic motion is also expressed as “time” corresponding to the strobe light emission time.

図1は本発明対象のMEMSの計測装置を示す図である。ストロボ位相シフト干渉装置として知られている。レーザなどの可干渉性のよい光源1、光源1から出た検査光を計測対象の計測サンプル3と参照ミラー4に分割照射するハーフミラー2、計測サンプル3の位置を微小に動かして光路差を変更するためのピエゾステージ5、サンプル位置制御を行うためのサンプル位置姿勢制御用ステージ6、計測サンプル3と参照ミラー4から反射した光をハーフミラー2で再び重ねて干渉させた干渉縞をCCDカメラ8に結像させるための結像レンズ7で基本構成し、基本構成に補助機能、制御機能等のための信号制御回路9、PC10、モニタ11、パルス発生器12、光源ドライバ13、サンプル駆動ドライバ14で構成する。   FIG. 1 is a diagram showing a MEMS measuring apparatus according to the present invention. It is known as a strobe phase shift interferometer. A light source 1 with good coherence such as a laser, a half mirror 2 that divides and irradiates inspection light emitted from the light source 1 onto a measurement sample 3 and a reference mirror 4 to be measured, and a position of the measurement sample 3 are moved minutely to change an optical path difference A piezo stage 5 for changing, a sample position / orientation control stage 6 for performing sample position control, and interference fringes obtained by causing the reflected light from the measurement sample 3 and the reference mirror 4 to overlap and interfere with each other by the half mirror 2 are CCD cameras. 8 includes an image forming lens 7 for forming an image, and a signal control circuit 9 for an auxiliary function and a control function, a PC 10, a monitor 11, a pulse generator 12, a light source driver 13, and a sample driving driver. 14.

信号制御回路9はCCDカメラ8からの撮影映像を受け、コンピュータ処理用データ生成の前処理を行いパソコンなどの演算処理装置PC10に送信する。さらに光源1の発光タイミング、計測サンプル3の駆動のための制御信号を発生するためのパルス発生器12へ信号を発生する。   The signal control circuit 9 receives a photographed image from the CCD camera 8, performs preprocessing for generating data for computer processing, and transmits it to an arithmetic processing unit PC 10 such as a personal computer. Further, a signal is generated to the pulse generator 12 for generating a light emission timing of the light source 1 and a control signal for driving the measurement sample 3.

PC10で処理された撮影データをモニタ11でモニタする。パルス発生器12は信号制御回路9からの信号を受信し、光源1の発光タイミングを制御する光源ドライバ13、計測サンプル3の駆動を制御するサンプル駆動ドライバ14に制御信号を送る。光源ドライバ13はパルス発生器12から受信した信号を基に光源1の発光タイミング信号を発生する。光源ドライバ13が発生する発光タイミング信号はパルス発生器12に同期し、かつ、任意の時刻における計測が可能なように発光タイミングを調節可能である。   The photographing data processed by the PC 10 is monitored by the monitor 11. The pulse generator 12 receives a signal from the signal control circuit 9 and sends a control signal to the light source driver 13 that controls the light emission timing of the light source 1 and the sample drive driver 14 that controls the driving of the measurement sample 3. The light source driver 13 generates a light emission timing signal of the light source 1 based on the signal received from the pulse generator 12. The light emission timing signal generated by the light source driver 13 is synchronized with the pulse generator 12, and the light emission timing can be adjusted so that measurement at an arbitrary time is possible.

同様にサンプル駆動ドライバ14は計測サンプル3の駆動制御信号を発生し、パルス発生器12に同期してサンプルの駆動を行う。   Similarly, the sample drive driver 14 generates a drive control signal for the measurement sample 3 and drives the sample in synchronization with the pulse generator 12.

図2は本発明におけるMEMSの高さ軌跡算出の基本手順を示す図である。少なくも3点以上の複数時刻での高さ計測値から軌跡を推定し必要な計測点での高さを算出する手順である。なお、軌跡を推定するために計測を行う時刻を軌跡推定点とする。
S1:少なくとも3点以上の軌跡推定点で計測対象の高さを計測する。なお計測対象の高さ計測手順は後述のS11からS16で説明する。
S2、S3:軌跡推定点で計測した高さから計測対象の高さ変化軌跡を推定する軌跡z(x,y,t)を算出する。
S3:軌跡z(x,y,t)より計測対象の動画表示等での表示に必要な時刻での高さを算出する。
FIG. 2 is a diagram showing a basic procedure for calculating a MEMS height trajectory in the present invention. This is a procedure for calculating a height at a necessary measurement point by estimating a locus from height measurement values at a plurality of times at least three points. Note that the time at which measurement is performed to estimate the trajectory is defined as a trajectory estimation point.
S1: The height of the measurement object is measured with at least three or more locus estimation points. The height measurement procedure for the measurement target will be described in S11 to S16 described later.
S2, S3: A trajectory z (x, y, t) for estimating the height change trajectory of the measurement target is calculated from the height measured at the trajectory estimation point.
S3: The height at the time required for display in the moving image display or the like to be measured is calculated from the trajectory z (x, y, t).

S2で述べた複数の軌跡推定点での計測対象の高さ測定値から任意時刻の計測対象の高さを推定する軌跡z(x,y,t)の算出方法を述べる。高さ軌跡を推定する際に各画素の高さの変化z(x,y,t)を以下のような周期関数であると仮定する。   A method of calculating the trajectory z (x, y, t) for estimating the height of the measurement target at an arbitrary time from the height measurement values of the measurement target at the plurality of trajectory estimation points described in S2 will be described. When estimating the height trajectory, it is assumed that the change in height z (x, y, t) of each pixel is the following periodic function.

Figure 2007240344
Figure 2007240344

ここでTは計測対象の駆動周期、あるいはストロボ発光周期である。   Here, T is a driving cycle of a measurement target or a strobe light emission cycle.

図3は本発明におけるMEMSの高さ軌跡算出を示す図である。例えば干渉縞を撮像する時刻tをT/4ステップ幅ごとにt=0、T/4、T/2とし、各発光タイミングにおいて、光路差を前述した式4の4通りに変更して高さを計測する。   FIG. 3 is a diagram showing the calculation of the MEMS height trajectory in the present invention. For example, the time t at which the interference fringe is imaged is set to t = 0, T / 4, and T / 2 for each T / 4 step width, and the height of the light emission timing is changed by changing the optical path difference to the above-described four formulas (4). Measure.

各発光タイミングにおける高さ計測値をz(x,y,0)、z(x,y,T/4)z(x,y,T/2)とすると、式1におけるα(x,y),β(x,y),δ(x,y)は以下となる。 If the height measurement value at each light emission timing is z 1 (x, y, 0), z 2 (x, y, T / 4) z 3 (x, y, T / 2), then α (x , Y), β (x, y), δ (x, y) are as follows.

Figure 2007240344
Figure 2007240344

図3の(2)、(3)に示す2つのグラフにおける黒マークは実際に計測を行った箇所である。また点線は式7で得た係数を用い、式6で推定した画素位置p1、p2における高さの変化の軌跡z(x,y,t)である。算出した計測対象の高さ軌跡を動的挙動としてモニタ画面に必要により正規化し表示する。ここでは時刻t=0、T/4,T/2の3点から高さを算出する例を示したが、軌跡算出に使用する点(時刻)を増やして算出することも可能であり、後述の実施例2の説明でその例を示す。   The black marks in the two graphs shown in (2) and (3) of FIG. 3 are the places where the actual measurement was performed. The dotted line is the locus z (x, y, t) of the change in height at the pixel positions p1 and p2 estimated by Expression 6, using the coefficient obtained by Expression 7. The calculated height trajectory of the measurement target is normalized and displayed as a dynamic behavior on the monitor screen if necessary. Here, an example is shown in which the height is calculated from the three points of time t = 0, T / 4, and T / 2, but it is also possible to increase the number of points (time) used for locus calculation, which will be described later. An example is shown in the description of the second embodiment.

図4は本発明におけるMEMSの高さ計測手順を示す図である。干渉法に位相シフト法を用いたストロボ干渉法により計測対象の高さを算出する手順を示している。図1で示すMEMS計測装置のサンプル駆動ドライバ14、光源ドライバ13を制御してピエゾステージ5上の計測サンプル3を動かし計測を行う。本手順は図3の手順におけるS1、図5の手順におけるS21、S22、S29で計測対象の高さを計測する手順に相当する。
S11:ピエゾステージで計測対象の位置を動かし、所定の光路差に変更する。
FIG. 4 is a diagram showing a procedure for measuring the height of the MEMS in the present invention. A procedure for calculating the height of a measurement object by strobe interferometry using a phase shift method as the interferometry is shown. The sample driving driver 14 and the light source driver 13 of the MEMS measuring apparatus shown in FIG. 1 are controlled to move the measurement sample 3 on the piezo stage 5 and perform measurement. This procedure corresponds to the procedure of measuring the height of the measurement object in S1 in the procedure of FIG. 3 and S21, S22, and S29 in the procedure of FIG.
S11: The position of the measurement target is moved on the piezo stage and changed to a predetermined optical path difference.

複数の光路差の変更と複数の光源発光タイミングの変更順序として、1つの光路差に対し複数の発光タイミングで計測する手順を選択する。通常位相シフト法を行うための光路差の変更には、計測対象か参照ミラーをピエゾステージで動かすことによるピエゾステージの静定時間が必要となる。すなわち、光路差の変更に要する時間はストロボ発光タイミングを変更するより時間がかかる。   As a change order of a plurality of light path differences and a plurality of light source light emission timings, a procedure for measuring at a plurality of light emission timings for one light path difference is selected. In order to change the optical path difference for performing the normal phase shift method, it takes time to stabilize the piezo stage by moving the measurement target or the reference mirror on the piezo stage. That is, the time required for changing the optical path difference takes more time than changing the strobe light emission timing.

したがって、最初の光路差に対し、全ての必要なストロボ発光タイミングにおける干渉縞を撮像し、次に2番目の光路差に変更する手順で行う。最終的には、同じ発光タイミングで撮像した複数の光路差における干渉縞の画像を1組とし上述した方法により高さを算出する。これにより位相シフトを行うための光路差の変更回数を少なくし、計測時間の短縮を図る。
S12:光源ドライバで所定の光源の発光タイミングに変更し、ハーフミラーを介して計測サンプルと参照ミラーに照射する。
S13:結像レンズで結ばれた干渉縞をCCDカメラで撮影し、PCや信号制御回路内のメモリに干渉縞画像を格納する。
S14:予め設定した全てのストロボ発光タイミングでの撮影を終えたならS15に進み、終えていないならS12に戻り次ぎの発光タイミングでの照射を行う。
S15:位相シフト法で高さを算出するために必要な複数の光路差を設定しておき、設定した全ての光路差での撮影を終えたならS16に進み、終えていないならS11に戻り、次ぎの光路差に変更する。
S16:PCあるいは信号制御回路内の全ての干渉縞画像から計測対象の動的状態の高さを算出する。高さの算出方法は前述の位相シフトで説明した方法で行う。例えば4点で算出場合式4と式5で行う。
(実施例2)
これまでの説明では計測対象の挙動が式6におよそ従うものとしたが、もともと計測対象の動的挙動が式6に従わない場合や、動的挙動は式6に従うが、計測ノイズなどの原因により推定結果が不正確になる場合が考えられる。
Therefore, for the first optical path difference, the interference fringes at all necessary strobe emission timings are imaged and then changed to the second optical path difference. Finally, the height is calculated by the above-described method with a set of images of interference fringes at a plurality of optical path differences captured at the same light emission timing. As a result, the number of changes in the optical path difference for phase shift is reduced, and the measurement time is shortened.
S12: The light source driver changes the light emission timing to a predetermined light source, and irradiates the measurement sample and the reference mirror via the half mirror.
S13: The interference fringes connected by the imaging lens are photographed by the CCD camera, and the interference fringe images are stored in the PC or the memory in the signal control circuit.
S14: If photographing at all preset flash emission timings has been completed, the process proceeds to S15. If not, the process returns to S12 to perform irradiation at the next emission timing.
S15: A plurality of optical path differences necessary for calculating the height by the phase shift method are set. If photographing is completed for all the set optical path differences, the process proceeds to S16, and if not completed, the process returns to S11. Change to the next optical path difference.
S16: The height of the dynamic state of the measurement target is calculated from all the interference fringe images in the PC or signal control circuit. The method for calculating the height is performed by the method described in the above phase shift. For example, in the case of calculation with 4 points, the calculation is performed using Expression 4 and Expression 5.
(Example 2)
In the description so far, the behavior of the measurement target roughly follows Equation 6, but when the dynamic behavior of the measurement target originally does not follow Equation 6, or the dynamic behavior follows Equation 6, the cause of measurement noise, etc. As a result, the estimation result may be inaccurate.

図5は本発明における検証手順を備えたMEMSの高さ軌跡算出手順を示す図である。本手順は軌跡の正確度を検証するための軌跡検証点を設定し、その軌跡検証点での検証結果から計測対象の高さを算出する手順である。
S21:図2あるいは図4で述べた複数の軌跡推定点で計測した高さから軌跡z(x,y,t)を推定する。
S22:予め定めた少なくも1点以上の軌跡検証点で計測対象の高さを計測する。
S23:軌跡検証点での高さ計測値と軌跡推定式から算出した高さの差D(x,y)を求める。
S24:高さの差D(x,y)の値より軌跡z(x,y,t)の妥当性を評価する。評価基準として例えば、複数画素のD(x,y)を平均した値である平均誤差<D>があらかじめ指定した閾値Dth以下である場合、軌跡z(x,y,t)は適切と判断する。適切と判断した場合はS25に進み、そうでない場合はS26に進む。
S25:軌跡z(x,y,t)は適切として、必要な全ての時刻における高さ軌跡z(x,y,t)より算出し、モニタ表示などの後処理を行う。
S26、S27:軌跡推定点を追加する。
FIG. 5 is a diagram showing a procedure for calculating the height trajectory of the MEMS provided with the verification procedure in the present invention. This procedure is a procedure for setting a trajectory verification point for verifying the accuracy of the trajectory and calculating the height of the measurement object from the verification result at the trajectory verification point.
S21: The trajectory z (x, y, t) is estimated from the height measured at the plurality of trajectory estimation points described in FIG. 2 or FIG.
S22: The height of the measurement target is measured with at least one predetermined locus verification point.
S23: A height difference D (x, y) calculated from the height measurement value at the locus verification point and the locus estimation formula is obtained.
S24: The validity of the trajectory z (x, y, t) is evaluated from the value of the height difference D (x, y). For example, when the average error <D>, which is a value obtained by averaging D (x, y) of a plurality of pixels, is equal to or less than a predetermined threshold value Dth, the trajectory z (x, y, t) is determined to be appropriate. . If it is determined to be appropriate, the process proceeds to S25, and if not, the process proceeds to S26.
S25: The trajectory z (x, y, t) is appropriately calculated from the height trajectory z (x, y, t) at all necessary times, and post-processing such as monitor display is performed.
S26, S27: A locus estimation point is added.

軌跡推定点を追加した場合の式6の各係数について述べる。図6は本発明におけるMEMSの計測時刻を追加した高さ軌跡係数算出を説明する図である。図6の(1)は前述した時刻t=0、T/4,T/2の3点を軌跡推定点とした場合における式6の係数である。図6の(2)はさらに時刻としてt=3T/4を増やした4点での式6の係数、図6の(3)はt=Tをさらに増やした5点での式6の係数であり、各々式8、式9となる。5点以上の係数については省略する。   Each coefficient of Equation 6 when a locus estimation point is added will be described. FIG. 6 is a diagram for explaining the calculation of the height trajectory coefficient to which the MEMS measurement time is added according to the present invention. (1) in FIG. 6 is a coefficient of Equation 6 when the above-described three points of time t = 0, T / 4, and T / 2 are used as the locus estimation points. (2) in FIG. 6 is the coefficient of Equation 6 at four points with t = 3T / 4 further increased as time, and (3) in FIG. 6 is the coefficient of Equation 6 at five points with further increased t = T. There are Expressions 8 and 9, respectively. Coefficients of 5 points or more are omitted.

Figure 2007240344
Figure 2007240344

Figure 2007240344
Figure 2007240344

追加軌跡推定点を併せた軌跡推定点の数が所定数を超えた場合はS28に進み、所定数以下の場合はS29に進む。
S28:軌跡推定点の総数が所定数Nthを越えても平均誤差<D>が閾値Dth以下とならない場合には、もともとの動的挙動が式6に従わないものと判断し、動的表示に必要な全ての位相を計測するモードに切り替える。
S29:追加した軌跡推定点で計測対象の高さを測定し、追加した軌跡推定点を併せた高さの高さ計測値から算出した軌跡z(x,y,t)を算出・更新し、S23に戻る。
If the number of estimated trajectory points including the additional estimated trajectory points exceeds a predetermined number, the process proceeds to S28, and if the number is less than the predetermined number, the process proceeds to S29.
S28: If the average error <D> is not less than or equal to the threshold value Dth even if the total number of trajectory estimation points exceeds the predetermined number Nth, it is determined that the original dynamic behavior does not follow Equation 6, and the dynamic display is performed. Switch to the mode that measures all necessary phases.
S29: The height of the measurement target is measured at the added trajectory estimation point, and the trajectory z (x, y, t) calculated from the height measurement value including the added trajectory estimation point is calculated and updated. Return to S23.

なお、高さ推定の軌跡z(x,y,t)が適切か否かの評価判断の閾値Dthは、操作者が必要な精度を考慮してキーボードなどで指定するほかに、高精度ミラーなどの表面凹凸が少ない平面度のある計測対象であらかじめ装置の計測再現性σを評価しておき、あらかじめ予測される誤差量をもとに閾値(例えばDth=6σ)をシステムが自動的に決めるようにしても良い。同様に軌跡推定点の数についても予測可能な範囲の所定数を基にシステムが自動的に決めるようにしても良い。   Note that the threshold Dth for evaluating whether or not the height estimation trajectory z (x, y, t) is appropriate is specified by a keyboard or the like in consideration of the accuracy required by the operator, or a high-precision mirror or the like. The measurement reproducibility σ of the apparatus is evaluated in advance on a measurement target having a flatness with few surface irregularities, and the system automatically determines a threshold value (for example, Dth = 6σ) based on an error amount predicted in advance. Anyway. Similarly, the number of estimated trajectory points may be automatically determined by the system based on a predetermined number of predictable ranges.

また、計測対象がミラーである場合は、あらかじめ別のミラーで装置の計測再現性σを計測しておかなくても、計測対象自身の空間的な計測値ばらつき量σをもとにシステムが閾値Dthを自動的に決定してもよい。軌跡推定点数を追加するかどうかを判断する閾値Nthは操作者がキーボードなどで指定できるようにするほか、必要な分割点総数N0を元にシステムが例えばNth=N0/2のように自動的に決定しても良い。   In addition, when the measurement target is a mirror, even if the measurement reproducibility σ of the apparatus is not measured with another mirror in advance, the system uses the spatial measurement value variation σ of the measurement target itself to set the threshold value. Dth may be automatically determined. The threshold value Nth for determining whether or not to add the estimated number of trajectory points can be specified by the operator with a keyboard or the like, and the system automatically sets, for example, Nth = N0 / 2 based on the total number of division points N0. You may decide.

ここでは、干渉法として位相シフト法の例を説明したが、低コヒーレンス干渉法などの異なる干渉法を利用しても良い。異なる干渉法を用いる場合でも、干渉計測に必要な動作時間が少なくなる手順でストロボ発光タイミングの変更を行いながら計測を行う。
(付記1)
周期的動作をしている計測対象に対しストロボ光源から前記計測対象と参照ミラーに照射して前記計測対象から反射した光と前記参照ミラーから反射した光の干渉縞より前記計測対象の動的形状を計測する動的形状計測方法であって、
前記計測対象の動作周期に同期させて前記計測対象の軌跡を推定する少なくとも3点以上の複数位相で指定する軌跡推定点において前記計測対象の干渉縞を撮像して高さを計測し、
前記軌跡推定点で計測した高さより前記計測対象の周期動作の高さ軌跡を推定する軌跡推定式を算出し、
前記算出した軌跡推定式より前記計測対象の任意の位相における動的形状を算出することを特徴とする計測対象の動的形状計測方法。
(付記2)
周期的動作をしている計測対象に対しストロボ光源から前記計測対象と参照ミラーに照射して前記計測対象から反射した光と前記参照ミラーから反射した光の干渉縞より前記計測対象の動的形状を計測する動的形状計測方法であって、
前記計測対象を動作させ前記ストロボ光源から照射し前記計測対象と前記参照ミラー間の光路差を干渉法に必要な複数の状態に変更し、
前記各光路差に対し前記計測対象の軌跡を推定する少なくとも3点以上の複数位相で指定する軌跡推定点において干渉縞画像を撮像して高さを計測し、
前記軌跡推定点で計測した高さより前記計測対象の高さ軌跡を推定する軌跡推定式を算出し、
前記算出した軌跡推定式より前記計測対象の任意位相における動的形状を算出することを特徴とする計測対象の動的形状計測方法。
(付記3)
付記2記載の動的形状計測方法であって、
さらに前記軌跡推定式の検証を行う少なくも1点以上の軌跡検証点で前記計測対象の高さを計測し、
前記軌跡推定式からの前記計測対象の高さと前記軌跡検証点で計測した高さとの差を閾値により評価し、
前記閾値による評価が予め定めた評価基準を満たさない場合は前記軌跡推定点を追加して前記計測対象の高さを計測し、
前記軌跡推定式を新たに算出する手順を加えたことを特徴とする
付記2記載の計測対象の動的形状計測方法。
(付記4)
周期的動作をしている計測対象に対しストロボ光源から前記計測対象と参照ミラーに照射して前記計測対象から反射した光と前記参照ミラーから反射した光の干渉縞より前記計測対象の動的形状を計測する動的形状計測装置であって、
前記動的形状計測装置は、前記計測対象と前記参照ミラーの間の光路差を変更する手段と、
前記光路差に対し前記計測対象の軌跡を推定する少なくとも3点以上の複数位相で指定する軌跡推定点において前記計測対象の高さを計測する手段と、
を備えたことを特徴とする計測対象の動的形状計測装置。
(付記5)
付記4記載の周期的動作の計測対象の動的形状計測装置において、
前記軌跡推定点で計測した高さより前記計測対象の周期動作の高さ軌跡を推定する推定式を算出する手段と、
前記軌跡推定式から算出して任意位相における計測対象の形状を予測する手段と、
をさらに備えたことを特徴とする
付記4記載の計測対象の動的形状計測装置。
(付記6)
付記4記載の計測対象の動的形状計測装置において、
前記軌跡推定点で計測した前記計測対象の高さと前記軌跡推定式から算出した前記計測対象の高さを組み合わせて前記計測対象の周期的動作を動的表示する動的表示手段をさらに備えたことを特徴とする付記4記載の動的形状計測装置。
(付記7)
付記3記載の計測対象の動的形状計測方法であって、
前記閾値は予め計測再現性のある平面度の高い計測対象を計測評価した計測値標準偏差に所定の定数を乗じた値を設定すること特徴とする付記3記載の計測対象の動的形状計測方法。
(付記8)
付記3記載の計測対象の動的形状計測方法であって、
前記軌跡推定点を追加した点数があらかじめ定めた所定の定数を越えた場合は予め定めた全ての計測位相で計測する全位相計測モードに移行して前記計測対象の形状を計測すること特徴とする付記3記載の動的形状計測方法。
(付記9)
付記8記載の計測対象の動的形状計測方法であって、
前記全位相モードに移行判断する前記追加する軌跡推定点の数は前記計測対象に係る所定の数を予め設定することを特徴とする付記8記載の動的形状計測方法。
(付記10)
付記1記載の計測対象の動的形状計測方法であって、
前記軌跡推定式は前記計測対象の時間的変位、及び変形が周期的に変化することを前提に軌跡推定式を推定することを特徴とする付記1記載の動的形状計測方法。
Although an example of the phase shift method has been described here as an interference method, a different interference method such as a low coherence interference method may be used. Even when different interference methods are used, measurement is performed while changing the strobe light emission timing in a procedure that reduces the operation time required for interference measurement.
(Appendix 1)
The dynamic shape of the measurement target is obtained from interference fringes of light reflected from the measurement target and light reflected from the measurement target by irradiating the measurement target and the reference mirror from a strobe light source with respect to the measurement target performing periodic operation. A dynamic shape measuring method for measuring
Synchronize with the operation cycle of the measurement target, estimate the trajectory of the measurement target, measure the height by imaging the interference fringes of the measurement target at a trajectory estimation point specified by at least three or more phases,
Calculating a trajectory estimation formula for estimating the height trajectory of the periodic motion of the measurement target from the height measured at the trajectory estimation point;
A dynamic shape measurement method for a measurement target, wherein a dynamic shape at an arbitrary phase of the measurement target is calculated from the calculated locus estimation formula.
(Appendix 2)
The dynamic shape of the measurement target is obtained from interference fringes of light reflected from the measurement target and light reflected from the measurement target by irradiating the measurement target and the reference mirror from a strobe light source with respect to the measurement target performing periodic operation. A dynamic shape measuring method for measuring
Operate the measurement object and irradiate from the strobe light source, and change the optical path difference between the measurement object and the reference mirror to a plurality of states necessary for interferometry,
For each optical path difference, measure the height by capturing an interference fringe image at a trajectory estimation point designated by a plurality of phases of at least three points for estimating the trajectory of the measurement target,
Calculate a trajectory estimation formula for estimating the height trajectory of the measurement object from the height measured at the trajectory estimation point,
A dynamic shape measurement method for a measurement target, wherein a dynamic shape at an arbitrary phase of the measurement target is calculated from the calculated locus estimation formula.
(Appendix 3)
The dynamic shape measuring method according to appendix 2,
Further, the height of the measurement object is measured at least one locus verification point for verifying the locus estimation formula,
Evaluating the difference between the height of the measurement target from the trajectory estimation formula and the height measured at the trajectory verification point using a threshold value,
If the evaluation by the threshold does not satisfy a predetermined evaluation criterion, the trajectory estimation point is added to measure the height of the measurement target,
The dynamic shape measurement method for a measurement target according to appendix 2, wherein a procedure for newly calculating the trajectory estimation formula is added.
(Appendix 4)
The dynamic shape of the measurement target is obtained from interference fringes of light reflected from the measurement target and light reflected from the measurement target by irradiating the measurement target and the reference mirror from a strobe light source with respect to the measurement target performing periodic operation. A dynamic shape measuring device for measuring
The dynamic shape measuring device includes means for changing an optical path difference between the measurement object and the reference mirror;
Means for measuring the height of the measurement target at a trajectory estimation point specified by a plurality of phases of at least three or more points for estimating the trajectory of the measurement target with respect to the optical path difference;
An apparatus for measuring a dynamic shape of a measurement object.
(Appendix 5)
In the dynamic shape measuring apparatus as the measurement target of the periodic movement according to appendix 4,
Means for calculating an estimation formula for estimating a height trajectory of the periodic motion of the measurement target from the height measured at the trajectory estimation point;
Means for predicting the shape of the measurement target in an arbitrary phase calculated from the trajectory estimation formula;
The apparatus for measuring a dynamic shape of a measurement object according to appendix 4, further comprising:
(Appendix 6)
In the dynamic shape measuring device to be measured according to appendix 4,
Dynamic display means for dynamically displaying the periodic motion of the measurement object by combining the height of the measurement object measured at the locus estimation point and the height of the measurement object calculated from the locus estimation formula The dynamic shape measuring apparatus according to supplementary note 4, characterized by:
(Appendix 7)
A method for measuring a dynamic shape of a measurement target according to attachment 3,
The method for measuring a dynamic shape of a measurement object according to appendix 3, wherein the threshold value is set in advance by multiplying a measurement value standard deviation obtained by measuring and evaluating a measurement object having high reproducibility with high measurement reproducibility by a predetermined constant. .
(Appendix 8)
A method for measuring a dynamic shape of a measurement target according to attachment 3,
When the number of points to which the locus estimation points are added exceeds a predetermined constant, the measurement target shape is measured by shifting to an all-phase measurement mode in which measurement is performed at all predetermined measurement phases. The dynamic shape measuring method according to attachment 3.
(Appendix 9)
The method for measuring a dynamic shape of a measurement object according to appendix 8,
9. The dynamic shape measuring method according to claim 8, wherein a predetermined number related to the measurement target is set in advance as the number of the additional locus estimation points to be determined to shift to the all phase mode.
(Appendix 10)
A method for measuring a dynamic shape of a measurement object according to appendix 1,
2. The dynamic shape measurement method according to claim 1, wherein the trajectory estimation formula estimates the trajectory estimation formula on the assumption that the temporal displacement and deformation of the measurement object change periodically.

本発明対象のMEMSの計測装置を示す図である。It is a figure which shows the measuring device of MEMS of this invention object. 本発明におけるMEMSの高さ軌跡算出の基本手順を示す図である。It is a figure which shows the basic procedure of the height locus | trajectory calculation of MEMS in this invention. 本発明におけるMEMSの高さ軌跡算出を示す図である。It is a figure which shows the height locus calculation of MEMS in this invention. 本発明におけるMEMSの高さ計測手順を示す図である。It is a figure which shows the height measurement procedure of MEMS in this invention. 本発明における検証手順を備えたMEMSの高さ軌跡算出手順を示す図である。It is a figure which shows the height locus | trajectory calculation procedure of MEMS provided with the verification procedure in this invention. 本発明におけるMEMSの計測時刻を追加した高さ軌跡係数算出を説明する図である。It is a figure explaining the height locus coefficient calculation which added the measurement time of MEMS in the present invention. 光スキャナを構成するミラーの姿勢の一例を示す図である。It is a figure which shows an example of the attitude | position of the mirror which comprises an optical scanner. 図7のミラーをy方向からみた場合の姿勢変化を示す図である。It is a figure which shows the attitude | position change at the time of seeing the mirror of FIG. 7 from ay direction. 高速周期運動をする計測対象の従来計測例を示す図である。It is a figure which shows the example of a conventional measurement of the measurement object which carries out a high-speed periodic motion. ストロボ干渉計の光学系と原理を示す図である。It is a figure which shows the optical system and principle of a strobe interferometer.

符号の説明Explanation of symbols

1 光源
2 ハーフミラー
3 計測サンプル(MEMS)
4 参照ミラー
5 ピエゾステージ
6 サンプル位置制御用ステージ
7 結像レンズ
8 CCDカメラ
9 信号制御回路
10 PC
11 モニタ
12 パルス発生器
13 光源ドライバ
14 サンプル駆動ドライバ

1 Light source
2 Half mirror 3 Measurement sample (MEMS)
4 Reference mirror 5 Piezo stage 6 Sample position control stage 7 Imaging lens 8 CCD camera 9 Signal control circuit 10 PC
11 Monitor 12 Pulse generator 13 Light source driver 14 Sample drive driver

Claims (5)

周期的動作をしている計測対象に対しストロボ光源から前記計測対象と参照ミラーに照射して前記計測対象から反射した光と前記参照ミラーから反射した光の干渉縞より前記計測対象の動的形状を計測する動的形状計測方法であって、
前記計測対象の動作周期に同期させて前記計測対象の軌跡を推定する少なくとも3点以上の複数位相で指定する軌跡推定点において前記計測対象の干渉縞を撮像して高さを計測し、
前記軌跡推定点で計測した高さより前記計測対象の周期動作の高さ軌跡を推定する軌跡推定式を算出し、
前記算出した軌跡推定式より前記計測対象の任意の位相における動的形状を算出することを特徴とする計測対象の動的形状計測方法。
The dynamic shape of the measurement target is obtained from interference fringes of light reflected from the measurement target and light reflected from the measurement target by irradiating the measurement target and the reference mirror from a strobe light source with respect to the measurement target performing periodic operation. A dynamic shape measuring method for measuring
Synchronize with the operation cycle of the measurement target, estimate the trajectory of the measurement target, measure the height by imaging the interference fringes of the measurement target at a trajectory estimation point specified by at least three or more phases,
Calculating a trajectory estimation formula for estimating the height trajectory of the periodic motion of the measurement target from the height measured at the trajectory estimation point;
A dynamic shape measurement method for a measurement target, wherein a dynamic shape at an arbitrary phase of the measurement target is calculated from the calculated locus estimation formula.
周期的動作をしている計測対象に対しストロボ光源から前記計測対象と参照ミラーに照射して前記計測対象から反射した光と前記参照ミラーから反射した光の干渉縞より前記計測対象の動的形状を計測する動的形状計測方法であって、
前記計測対象を動作させ前記ストロボ光源から照射し前記計測対象と前記参照ミラー間の光路差を干渉法に必要な複数の状態に変更し、
前記各光路差に対し前記計測対象の軌跡を推定する少なくとも3点以上の複数位相で指定する軌跡推定点において干渉縞画像を撮像して高さを計測し、
前記軌跡推定点で計測した高さより前記計測対象の高さ軌跡を推定する軌跡推定式を算出し、
前記算出した軌跡推定式より前記計測対象の任意位相における動的形状を算出することを特徴とする計測対象の動的形状計測方法。
The dynamic shape of the measurement target is obtained from interference fringes of light reflected from the measurement target and light reflected from the measurement target by irradiating the measurement target and the reference mirror from a strobe light source with respect to the measurement target performing periodic operation. A dynamic shape measuring method for measuring
Operate the measurement object and irradiate from the strobe light source, and change the optical path difference between the measurement object and the reference mirror to a plurality of states necessary for interferometry,
For each optical path difference, measure the height by capturing an interference fringe image at a trajectory estimation point designated by a plurality of phases of at least three points for estimating the trajectory of the measurement target,
Calculate a trajectory estimation formula for estimating the height trajectory of the measurement object from the height measured at the trajectory estimation point,
A dynamic shape measurement method for a measurement target, wherein a dynamic shape at an arbitrary phase of the measurement target is calculated from the calculated locus estimation formula.
請求項2記載の動的形状計測方法であって、
さらに前記軌跡推定式の検証を行う少なくも1点以上の軌跡検証点で前記計測対象の高さを計測し、
前記軌跡推定式からの前記計測対象の高さと前記軌跡検証点で計測した高さとの差を閾値により評価し、
前記閾値による評価が予め定めた評価基準を満たさない場合は前記軌跡推定点を追加して前記計測対象の高さを計測し、
前記軌跡推定式を新たに算出する手順を加えたことを特徴とする請求項2記載の計測対象の動的形状計測方法。
The dynamic shape measuring method according to claim 2,
Further, the height of the measurement object is measured at least one locus verification point for verifying the locus estimation formula,
Evaluating the difference between the height of the measurement target from the trajectory estimation formula and the height measured at the trajectory verification point using a threshold value,
If the evaluation by the threshold does not satisfy a predetermined evaluation criterion, the trajectory estimation point is added to measure the height of the measurement target,
The method for measuring a dynamic shape of a measurement object according to claim 2, wherein a procedure for newly calculating the trajectory estimation formula is added.
周期的動作をしている計測対象に対しストロボ光源から前記計測対象と参照ミラーに照射して前記計測対象から反射した光と前記参照ミラーから反射した光の干渉縞より前記計測対象の動的形状を計測する動的形状計測装置であって、
前記動的形状計測装置は、前記計測対象と前記参照ミラーの間の光路差を変更する手段と、
前記光路差に対し前記計測対象の軌跡を推定する少なくとも3点以上の複数位相で指定する軌跡推定点において前記計測対象の高さを計測する手段と、
を備えたことを特徴とする計測対象の動的形状計測装置。
The dynamic shape of the measurement target is obtained from interference fringes of light reflected from the measurement target and light reflected from the measurement target by irradiating the measurement target and the reference mirror from a strobe light source with respect to the measurement target performing periodic operation. A dynamic shape measuring device for measuring
The dynamic shape measuring device includes means for changing an optical path difference between the measurement object and the reference mirror;
Means for measuring the height of the measurement target at a trajectory estimation point specified by a plurality of phases of at least three or more points for estimating the trajectory of the measurement target with respect to the optical path difference;
An apparatus for measuring a dynamic shape of a measurement object.
請求項4記載の周期的動作の計測対象の動的形状計測装置において、
前記軌跡推定点で計測した高さより前記計測対象の周期動作の高さ軌跡を推定する推定式を算出する手段と、
前記軌跡推定式から算出して任意位相における計測対象の形状を予測する手段と、
をさらに備えたことを特徴とする請求項4記載の計測対象の動的形状計測装置。
In the dynamic shape measuring apparatus of the measurement object of periodic operation according to claim 4,
Means for calculating an estimation formula for estimating a height trajectory of the periodic motion of the measurement target from the height measured at the trajectory estimation point;
Means for predicting the shape of the measurement target in an arbitrary phase calculated from the trajectory estimation formula;
The apparatus for measuring a dynamic shape of a measurement object according to claim 4, further comprising:
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