JP2009236678A - Device and method for measuring phase difference - Google Patents

Device and method for measuring phase difference Download PDF

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JP2009236678A
JP2009236678A JP2008083044A JP2008083044A JP2009236678A JP 2009236678 A JP2009236678 A JP 2009236678A JP 2008083044 A JP2008083044 A JP 2008083044A JP 2008083044 A JP2008083044 A JP 2008083044A JP 2009236678 A JP2009236678 A JP 2009236678A
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phase difference
receiving element
polarizer
optical compensator
light
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Koki Takahashi
弘毅 高橋
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Fujifilm Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for measuring phase difference, capable for accurately measuring phase differences of a plurality of portions of a sample. <P>SOLUTION: The phase difference measuring device, in which a light source, a polarizer, an optical compensator 1, a measuring stage, an analyzer and a light-receiving element array are arranged, in this order, has a means for rotating a lag axis of the optical compensator 1 and has no element that has a means for rotating an optical axis between the measuring stage and the light-receiving element array. For example, by using the device, a transmitted light Tθc at an angle θc that is formed by the lag axis of the optical compensator 1 relative to a transmission axis of the polarizer is detected at two or more areas on the light-receiving element array, and phase differences of two or more portions of a measuring sample are calculated respectively according to a relational equation of each Tθc and θc which are measured at the two or more areas. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は位相差測定装置及び位相差測定方法に関する。   The present invention relates to a phase difference measuring apparatus and a phase difference measuring method.

位相差の測定方法としては複数の方法が知られているが、複数部位の位相差を同時に測定可能な方法は、あまり知られていない。
一般的に位相差測定は、光源、偏光子、補償子、試料、任意で補償子、検光子、及び受光素子を、この順に配置して行われることが多い。例えば、非特許文献１に記載の方法においては、（１）上記各素子の角度を変化させた計16配置の測定、（２）検光子側の補償子のみを回転させた複数配置の測定、又は（３）２つの補償子のみを回転させた複数配置の測定から位相差を求めている。
このような方法を二次元的な位相差測定に応用し、受光素子として、複数部位に対する別個の受光が可能である受光素子としてCCDカメラを用いた例が、特許文献１に開示されている。本文献においては、試料と受光素子との間の光学素子を回転させる測定を行っている。しかし、この測定では、CCDの画素の大きさ以上の受光点のズレがこの回転に伴って円状に生じ、精度の高い位相差の測定はできないと考えられる。 A plurality of methods are known as a phase difference measurement method, but a method that can simultaneously measure a phase difference at a plurality of sites is not well known.
In general, the phase difference measurement is often performed by arranging a light source, a polarizer, a compensator, a sample, optionally a compensator, an analyzer, and a light receiving element in this order. For example, in the method described in Non-Patent Document 1, (1) measurement of a total of 16 arrangements in which the angle of each element is changed, (2) measurement of multiple arrangements in which only the compensator on the analyzer side is rotated, Or (3) The phase difference is obtained from the measurement of a plurality of arrangements in which only two compensators are rotated.
Patent Document 1 discloses an example in which such a method is applied to two-dimensional phase difference measurement and a CCD camera is used as a light receiving element that can receive light separately from a plurality of parts. In this document, measurement is performed by rotating an optical element between a sample and a light receiving element. However, in this measurement, the shift of the light receiving point that is larger than the size of the CCD pixel occurs in a circle with this rotation, and it is considered that a highly accurate phase difference cannot be measured.

上記の配置において、試料と受光素子との間の光学素子を回転させずに光源と試料との間の光学素子を回転させて位相差の測定を行うことは従来ほとんど行われておらず、そのような形態の装置に関する報告は特許文献２に記載の方法などに限られている。特許文献２においては、複数の波長を同時検出するフォトアレイを含む材料システムの回転補正器型分光検査システムが開示されている。上記の光学素子の配置で、光源と試料との間の光学素子を回転させているが検出器で同時に検出する情報は分光情報であり、複数部位の位相差の情報ではない。 In the above arrangement, it has been rarely performed to measure the phase difference by rotating the optical element between the light source and the sample without rotating the optical element between the sample and the light receiving element. The reports on the apparatus in such a form are limited to the method described in Patent Document 2. In Patent Document 2, a rotation corrector type spectroscopic inspection system of a material system including a photoarray for simultaneously detecting a plurality of wavelengths is disclosed. In the arrangement of the optical elements described above, the optical element between the light source and the sample is rotated, but the information detected simultaneously by the detector is spectral information, not phase difference information of a plurality of parts.

CCDを用いた位相差測定方法として、特許文献３においては干渉像を測定することによる測定法を開示している。この方法では、直線偏光を２つの直線偏光に分離して被測定物に透過させる際、これら２つの偏光成分をノマルスキープリズムにより、被測定物の干渉像を観察するＣＣＤカメラのエアリーディスク以上のシアリング量に分離する。この後、被測定物を透過した２つの直線偏光を重ね合わせて干渉させた被測定物の干渉像を観察し、かつ２つの直線偏光間の位相を変化させたときの被測定物の干渉像に基づいて位相差を測定している。しかし、この方法は、上記の原理からもわかるように位相差の二次元測定のための方法ではない。
特開2001-228034号公報 特表2000-509830号公報 特開平7-248261号公報 P.S.Hauge,"Mueller matrix ellipsometry with imperfect compensators,"J.Opt.Soc.Am.,68(11),1519-1528,(1978). As a phase difference measurement method using a CCD, Patent Document 3 discloses a measurement method by measuring an interference image. In this method, when linearly polarized light is separated into two linearly polarized lights and transmitted through the object to be measured, these two polarized components are sheared more than the Airy disk of a CCD camera for observing the interference image of the object to be measured by a Nomarski prism. Separate into quantities. Thereafter, an interference image of the object to be measured which is caused to interfere with the two linearly polarized light transmitted through the object to be measured is observed, and an interference image of the object to be measured when the phase between the two linearly polarized lights is changed. The phase difference is measured based on However, this method is not a method for two-dimensional measurement of phase difference, as can be seen from the above principle.
JP 2001-228034 A Special Table 2000-509830 Japanese Unexamined Patent Publication No. 7-248261 PSHauge, "Mueller matrix ellipsometry with imperfect compensators," J. Opt. Soc. Am., 68 (11), 1519-1528, (1978).

本発明は試料の複数部位の位相差を実質的に同時に高精度で測定可能な位相差測定装置の提供を課題とする。本発明はまた、試料の複数部位の位相差を実質的に同時に高精度で測定できる位相差測定方法の提供を課題とする。   An object of the present invention is to provide a phase difference measuring apparatus capable of measuring phase differences of a plurality of parts of a sample substantially simultaneously with high accuracy. Another object of the present invention is to provide a phase difference measurement method capable of measuring phase differences of a plurality of parts of a sample substantially simultaneously with high accuracy.

本発明者らは上記課題の解決のために鋭意研究を行った結果、受光素子として受光素子アレイを用い、かつ試料と受光素子の間に設ける光学素子を回転させない、すなわち、試料と受光素子の間に設ける光学素子の光軸を固定することによって、精度の高い二次元位相差測定が可能であることを見出し、この知見を基に本発明を完成した。すなわち、本発明は下記［１］〜［７］を提供するものである。 As a result of intensive studies for solving the above problems, the present inventors have used a light receiving element array as a light receiving element and do not rotate an optical element provided between the sample and the light receiving element. The present inventors have found that two-dimensional phase difference measurement with high accuracy is possible by fixing the optical axis of the optical element provided therebetween, and the present invention has been completed based on this knowledge. That is, the present invention provides the following [1] to [7].

［１］光源、偏光子、光学補償子１、測定ステージ、検光子、及び受光素子アレイがこの順に配置され、光学補償子１の遅相軸を回転させる手段を有し、かつ該測定ステージ及び該受光素子アレイの間に、光軸を回転させる手段を有する素子を有しない位相差測定装置。
［２］前記受光素子アレイにて得られた画像の輝度情報を測定試料の複数部位における光の透過量として読み取るためのデータ処理部を有する［１］に記載の位相差測定装置。
［３］前記測定ステージと前記検光子との間に光学補償子２が配置されている［１］又は［２］に記載の位相差測定装置。
［４］前記偏光子の透過軸方向に対して前記検光子の透過軸方向がなす角度が0°であり、かつ前記偏光子の透過軸方向に対して光学補償子２の遅相軸方向がなす角度が45°である［３］に記載の位相差測定装置。 [1] A light source, a polarizer, an optical compensator 1, a measurement stage, an analyzer, and a light receiving element array are arranged in this order, and have means for rotating the slow axis of the optical compensator 1, and the measurement stage and A phase difference measuring apparatus having no element having means for rotating the optical axis between the light receiving element arrays.
[2] The phase difference measuring apparatus according to [1], further including a data processing unit for reading luminance information of an image obtained by the light receiving element array as a light transmission amount in a plurality of parts of the measurement sample.
[3] The phase difference measuring apparatus according to [1] or [2], wherein an optical compensator 2 is disposed between the measurement stage and the analyzer.
[4] The angle formed by the transmission axis direction of the analyzer with respect to the transmission axis direction of the polarizer is 0 °, and the slow axis direction of the optical compensator 2 is relative to the transmission axis direction of the polarizer. The phase difference measuring apparatus according to [3], in which the formed angle is 45 °.

［５］前記光源がハロゲンランプ及び干渉フィルタを含み、かつ前記受光素子アレイがCCDカメラである［１］〜［４］のいずれか一項に記載の位相差測定装置。
［６］測定試料における２部位以上の位相差を決定する方法であって、
光源、偏光子、光学補償子１、測定試料、検光子、及び受光素子アレイがこの順に配置された光学系を用意すること；
該偏光子及び該測定試料と該受光素子アレイとの間の素子を固定して光学補償子１の遅相軸を回転させ、該偏光子の透過軸に対して光学補償子１の遅相軸がなす角度θｃにおいて、光源から単波長光を、偏光子、光学補償子１、測定試料、及び検光子を通過するように照射して得られる透過光Ｔθcを、受光素子アレイの２つ以上のエリアで検出すること；及び
前記の２つ以上のエリアで測定されたそれぞれのＴθcとθｃとの関係式から測定試料における２点以上の位相差をそれぞれ算出すること
を含む方法。
［７］前記光学系が、前記測定試料と前記検光子との間に、光学補償子２を有する［６］に記載の方法。 [5] The phase difference measuring apparatus according to any one of [1] to [4], wherein the light source includes a halogen lamp and an interference filter, and the light receiving element array is a CCD camera.
[6] A method for determining a phase difference at two or more sites in a measurement sample,
Providing an optical system in which a light source, a polarizer, an optical compensator 1, a measurement sample, an analyzer, and a light receiving element array are arranged in this order;
The polarizer and the element between the measurement sample and the light receiving element array are fixed, the slow axis of the optical compensator 1 is rotated, and the slow axis of the optical compensator 1 is rotated with respect to the transmission axis of the polarizer. Two or more transmitted light Tθ c obtained by irradiating a single wavelength light from a light source so as to pass through a polarizer, an optical compensator 1, a measurement sample, and an analyzer at an angle θc formed by it is detected in the area; and the method comprising calculating the two or more respectively measured in the area of the T.theta c and θc and two or more points from the relationship in the measurement sample the phase difference, respectively.
[7] The method according to [6], wherein the optical system includes an optical compensator 2 between the measurement sample and the analyzer.

本発明の位相差測定装置、又は本発明の測定方法により試料の複数部位の位相差を同時に高精度に測定することができる。 The phase difference measurement apparatus of the present invention or the measurement method of the present invention can simultaneously measure the phase differences of a plurality of parts of a sample with high accuracy.

以下、本発明を詳細に説明する。
なお、本明細書において「〜」とはその前後に記載される数値を下限値および上限値として含む意味で使用される。
本明細書において、角度について記載のある場合は、厳密な角度との誤差が±１度の範囲内であればよく、±０．１度の範囲内であることがより好ましい。
０度とは実質的に二つの軸の為す角度が平行である状態を表し、９０度とは実質的に二つの軸の為す角度が直交している状態を表す。 Hereinafter, the present invention will be described in detail.
In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
In the present specification, when an angle is described, an error from a strict angle may be within a range of ± 1 degree, and more preferably within a range of ± 0.1 degree.
0 degree represents a state in which the angles formed by the two axes are substantially parallel, and 90 degrees represents a state in which the angles formed by the two axes are substantially orthogonal.

本明細書において、位相差、レターデーション又はＲｅは面内のレターデーションを表す。本明細書において、位相差を決定する、測定する、または算出するというとき、遅相軸方向及び／又はレターデーション値を決定する、測定する、または算出することをそれぞれ意味する。 In the present specification, retardation, retardation, or Re represents in-plane retardation. In this specification, when a phase difference is determined, measured, or calculated, it means determining, measuring, or calculating a slow axis direction and / or retardation value, respectively.

本発明の位相差測定方法は、光源、偏光子、光学補償子１、測定ステージ、検光子、及び受光素子アレイをこの順に含む装置で行われる。そして、測定ステージと受光素子アレイの間に配置される素子は回転させずに、その光軸を固定して行うことを特徴とする。本明細書において素子とは光学補償子、偏光子、測定試料、検光子、受光素子などを含む素子を意味する。測定ステージと検光子との間にはさらにもう一つの光学補償子、光学補償子２が配置されていることが好ましい。光学補償子２も回転させずに、その遅相軸を固定して用いられる。固定の光学補償子を測定ステージと受光素子アレイとの間に配置させると、測定ができなくなる測定試料の遅相軸の角度が無くなるという利点があり、好ましい。
上記のように、偏光子、光学補償子１、任意で光学補償子２、検光子、及び受光素子アレイは光源からの光の進行方向においてこの順に配置されていればよい。偏光子、光学補償子及び検光子における各平面と受光素子アレイの受光面が平行になるように配置されればよい。 The phase difference measurement method of the present invention is performed by an apparatus including a light source, a polarizer, an optical compensator 1, a measurement stage, an analyzer, and a light receiving element array in this order. And the element arrange | positioned between a measurement stage and a light receiving element array is fixed and the optical axis is fixed, without rotating. In this specification, an element means an element including an optical compensator, a polarizer, a measurement sample, an analyzer, a light receiving element, and the like. It is preferable that another optical compensator, the optical compensator 2, is disposed between the measurement stage and the analyzer. The optical compensator 2 is also used with its slow axis fixed without rotating. It is preferable to dispose a fixed optical compensator between the measurement stage and the light receiving element array because there is an advantage that the angle of the slow axis of the measurement sample that cannot be measured is eliminated.
As described above, the polarizer, the optical compensator 1, the optional optical compensator 2, the analyzer, and the light receiving element array may be arranged in this order in the traveling direction of the light from the light source. What is necessary is just to arrange | position so that each plane in a polarizer, an optical compensator, and an analyzer and the light-receiving surface of a light receiving element array may become parallel.

測定ステージと受光素子アレイの間に配置される素子の光軸を固定した測定を行うことにより、受光素子アレイでの受光点のズレが生じない又は生じにくくなり、受光素子アレイにおける個々の受光画素（受光エリア）において、測定試料の一定の点の位相差の測定が可能となる。なお、受光素子アレイ及び測定試料も光の進行方向の垂直方向に平面を配置して固定されて（回転させないで）いることが好ましい。
本明細書において、それぞれ位相差が測定される測定試料の「部位」の大きさは、求められる測定の精度によって決定されればよい。もっとも小さい部位として測定される場合の部位の大きさは、用いられる受光素子アレイの画素の大きさによって決定されると考えればよく、通常円換算で直径５μｍ〜１５μｍ程度、好ましくは７μｍ程度の大きさとなる。
本発明の測定方法は、測定試料におけるこのような部位を2つ以上の位相差を同時に測定することができることを特徴とし、好ましくは、互いに直線上にない3つ以上の部位の位相差を同時に二次元的に測定することができることを特徴とする。 By performing the measurement with the optical axis of the element arranged between the measurement stage and the light receiving element array fixed, deviation of the light receiving point in the light receiving element array does not occur or hardly occurs, and each light receiving pixel in the light receiving element array In the (light receiving area), it is possible to measure the phase difference at a certain point of the measurement sample. Note that the light receiving element array and the measurement sample are also preferably fixed (not rotated) with a plane arranged in a direction perpendicular to the light traveling direction.
In the present specification, the size of the “part” of the measurement sample in which the phase difference is measured may be determined according to the required measurement accuracy. The size of the portion when measured as the smallest portion may be considered to be determined by the size of the pixel of the light receiving element array to be used. Usually, the diameter is about 5 μm to 15 μm, preferably about 7 μm in terms of a circle. It becomes.
The measurement method of the present invention is characterized in that two or more phase differences can be measured simultaneously for such a part in a measurement sample, and preferably, the phase differences of three or more parts that are not in a straight line are simultaneously measured. It can be measured two-dimensionally.

本発明の位相差測定方法に用いられる光源は単波長光を照射できる光源であれば特に限定されず、各種レーザー又は白色光源及びバンドパスフィルタの組み合わせを用いればよい。用いられる波長は特に限定されないが、435nm(青色)、545nm(緑色)、610nm(赤色)などが好ましい。
本発明の位相差測定方法に用いられる光学補償子は特に限定されず、従来の位相差測定装置で用いられている光学補償子及び市販の光学補償フィルムから選択される光学補償子のいずれを用いてもよい。通常、λ／４板として市販されている光学補償フィルムを用いればよい。
光源と試料ステージとの間に配置される光学補償子は回転可能に配置される。回転は、従来の位相差測定装置等の光学特性測定装置に用いられている回転手段により行えばよく、具体的な例としては駿河精機(株)製自動回転ステージなどが挙げられる。 The light source used in the phase difference measurement method of the present invention is not particularly limited as long as it is a light source capable of irradiating single wavelength light, and various lasers or a combination of a white light source and a band pass filter may be used. The wavelength used is not particularly limited, but 435 nm (blue), 545 nm (green), 610 nm (red), and the like are preferable.
The optical compensator used in the phase difference measuring method of the present invention is not particularly limited, and any one of an optical compensator used in a conventional phase difference measuring apparatus and an optical compensator selected from a commercially available optical compensation film is used. May be. Usually, an optical compensation film marketed as a λ / 4 plate may be used.
The optical compensator disposed between the light source and the sample stage is rotatably disposed. The rotation may be performed by a rotation means used in a conventional optical characteristic measurement device such as a phase difference measurement device, and a specific example is an automatic rotation stage manufactured by Suruga Seiki Co., Ltd.

本発明の位相差測定方法に用いられる偏光子又は検光子としては、非偏光を偏光させることができる素子であればいずれを用いてもよく、例えば、市販のいずれかの偏光子、又は液晶表示装置の偏光板などの作製に一般的に用いられている材料や手順により作製される素子を用いることができる。具体的な例としてはヨウ素ドープPVA偏光板、（例えばサンリッツ社製のフィルム状の偏光子）、又はグラントムソンプリズム (例：シグマ光機(株)製GTPC)などが挙げられる。素子の小型化という観点からはフィルム状のヨウ素ドープPVA偏光板が好ましく、また、測定精度向上という観点からは耐湿熱性に優れているグラントムソンプリズムが好ましい。
２つの偏光子（偏光子と検光子）の透過軸の向きは特に限定されないが、パラニコル配置又はクロスニコル配置となっていることが好ましい。また、偏光子の透過軸と光学補償子２の遅相軸とが為す角は約４５°となるように配置することが好ましい。 As the polarizer or analyzer used in the phase difference measuring method of the present invention, any element that can polarize non-polarized light may be used. For example, any commercially available polarizer or liquid crystal display may be used. An element manufactured by a material or a procedure generally used for manufacturing a polarizing plate of an apparatus can be used. Specific examples include an iodine-doped PVA polarizing plate (for example, a film-like polarizer manufactured by Sanlitz), or a Glan-Thompson prism (for example, GTPC manufactured by Sigma Koki Co., Ltd.). A film-like iodine-doped PVA polarizing plate is preferable from the viewpoint of miniaturization of the element, and a Glan-Thompson prism excellent in wet heat resistance is preferable from the viewpoint of improving measurement accuracy.
The directions of the transmission axes of the two polarizers (polarizer and analyzer) are not particularly limited, but are preferably in a paranicol arrangement or a crossed Nicol arrangement. The angle formed by the transmission axis of the polarizer and the slow axis of the optical compensator 2 is preferably arranged to be about 45 °.

本発明の位相差測定方法に用いられる受光素子アレイとしては、測定試料を垂直方向に通過した光を測定試料における部位ごとに別個に受光する機能を有する受光素子が用いられる。受光素子アレイとしては、複数の受光素子を有するものを特に限定なく用いることができるが、二次元的に受光可能である受光素子アレイが好ましい。例えば一般的なCCD（Charge Coupled Device、電荷結合素子）や、CMOS（Complementary Metal Oxide Semiconductor）を用いることができる。CCDの具体的な例としては、Sony(株)製のXCL-X700が挙げられる。
受光素子アレイとしてCCDやCMOSを用いる場合、数画素を１画素（１エリア）としてカウントしたり、数フレーム撮影して平均化したりすることがS/N比向上のため、好ましい。 As the light receiving element array used in the phase difference measuring method of the present invention, a light receiving element having a function of separately receiving light that has passed through the measurement sample in the vertical direction for each part of the measurement sample is used. As the light receiving element array, one having a plurality of light receiving elements can be used without particular limitation, but a light receiving element array capable of receiving light two-dimensionally is preferable. For example, a general CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) can be used. A specific example of the CCD is XCL-X700 manufactured by Sony Corporation.
When a CCD or CMOS is used as the light receiving element array, it is preferable to count several pixels as one pixel (one area) or to take several frames and average them to improve the S / N ratio.

受光素子アレイにて得られた画像から輝度情報を読み取り、受光素子アレイにおける各エリアについて光の受光量を求めることにより、光の透過率等を算出し、位相差の算出にもちいればよい。画像からの輝度情報の読み取りは、MATLAB（MathWorks社開発の数値解析ソフトウェア）を用いて行うことができるが、この手段に限定されるものではない。 Luminance information is read from an image obtained by the light receiving element array, and the amount of light received for each area in the light receiving element array is calculated to calculate the light transmittance and the like, which can be used for calculating the phase difference. Reading luminance information from an image can be performed using MATLAB (numerical analysis software developed by MathWorks), but is not limited to this means.

本発明の測定方法は、上記の各素子のほか、素子を制御する測定制御部；受光素子アレイにて得られた画像の輝度情報を測定試料の複数部位における光の透過量として読み取るためのデータ処理部；該輝度情報から各部位における光の透過率をそれぞれ算出し、各部位ごとの位相差計算を行うためのデータ処理部；画像や結果を表示する表示部；およびメモリなどを備えるシステムを用いて効率よく行うことが可能である。 The measurement method of the present invention includes, in addition to each of the above elements, a measurement control unit that controls the element; data for reading luminance information of an image obtained by the light receiving element array as a light transmission amount at a plurality of parts of the measurement sample A processing unit; a data processing unit for calculating light transmittance in each part from the luminance information and calculating a phase difference for each part; a display unit for displaying images and results; and a system including a memory It is possible to use it efficiently.

例えば、光源（単波長）、偏光子、回転手段を有する補償子（光学補償子１）、試料ステージ(例えばユニオプト(株)製)、検光子、CCDカメラをこの順に配置した装置を用いて、特定のエリアの位相差値の決定は以下のように行うことができる。
測定試料を試料ステージにのせたのち、測定試料及び、他の素子は固定したまま、光学補償子１を5°ずつ回転させ、各角度において画像を撮影する。各画像において測定するエリア(座標)を決め、そのエリアの透過率を算出する。各角度で測定された値(透過率)T0°、T5°、T10°、T15°、…と、下記式(1)とを引きあわせ二乗した総計(式(2))が最小となるα0、α4、β2、β4を求め (excelのソルバーなどを用いて計算すればよい)、そのうちのα0、α4を式(3)に代入し、透過率補正の係数Tを求める。この補正係数Tを測定値T0°、T5°、T10°、T15°…にかけた値に対して、上記と同様にα0、α4、β2、β4を求める。そのα0、α4、β2、β4を式(4)に代入し、式(4)が最小となるδs,θsを求め(excelのソルバーを用いて計算すればよい)、試料の位相差及び遅相軸角度を得る。式(4)中のα0 (δs,θs)、α4 (δs,θs)、β2 (δs,θs)、β4 (δs,θs)は、式(5)〜(8)で求められる値である。最小二乗法の実施方法としては上記に限らず、ガウスニュートン法や最急降下法等でもよい。 For example, using a device in which a light source (single wavelength), a polarizer, a compensator having a rotating means (optical compensator 1), a sample stage (for example, manufactured by UNIOPT Co., Ltd.), an analyzer, and a CCD camera are arranged in this order, The phase difference value for a specific area can be determined as follows.
After the measurement sample is placed on the sample stage, the optical compensator 1 is rotated by 5 ° while the measurement sample and other elements are fixed, and an image is taken at each angle. The area (coordinates) to be measured is determined for each image, and the transmittance of the area is calculated. The value (transmittance) measured at each angle T 0 °, T 5 °, T 10 °, T 15 °, ... and the sum of the following formula (1) and squared (formula (2)) is the smallest Α 0 , α 4 , β 2 , and β 4 (which can be calculated using an Excel solver, etc.) and substituting α 0 and α 4 into equation (3) for the coefficient of transmittance correction Find T. Α 0 , α 4 , β 2 , β 4 are obtained in the same manner as described above with respect to values obtained by multiplying the correction coefficient T by the measured values T 0 °, T 5 °, T 10 °, T 15 °,. Substituting the α 0 , α 4 , β 2 , and β 4 into equation (4), find δs and θs that minimize equation (4) (calculate using excel solver). Obtain the phase difference and slow axis angle. Α 0 (δs, θs), α 4 (δs, θs), β 2 (δs, θs), β 4 (δs, θs) in equation (4) can be obtained from equations (5) to (8). Value. The implementation method of the least square method is not limited to the above, and a Gauss-Newton method, a steepest descent method, or the like may be used.

Figure 2009236678
Figure 2009236678

CCDカメラなどの受光素子アレイの任意の複数のエリアにつき、上記のような測定及び算出を行うことにより、測定試料における２部位以上の位相差を実質的に同時に決定することができる。 By performing measurement and calculation as described above for an arbitrary plurality of areas of a light receiving element array such as a CCD camera, it is possible to determine phase differences at two or more sites in a measurement sample substantially simultaneously.

以下に実施例を挙げて本発明をさらに具体的に説明する。以下の実施例は本発明の趣旨から逸脱しない限り適宜変更することができる。従って、本発明の範囲は以下の具体例に制限されるものではない。   The present invention will be described more specifically with reference to the following examples. The following embodiments can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

光源と試料との間の光学補償子を回転させた時と、試料と検光子との間の光学補償子を回転させた時の画のズレを比較した。
評価は以下でのように行った。
（１）白色光源、回転機能付き補償子(補償子：(株)ルケオ製λ/4板、回転機能：駿河精機(株)製自動回転ステージ)、CCDカメラXCL-X700(Sony(株)製)をこの順に配置した。
（２）回転機能付き補償子の前または後ろに測定試料(シグマ光機(株)製テストターゲット)を配置した状態で補償子を回転させ、各角度での像をCCDカメラで撮影した。
（３）それらの画像中の任意の１点に注目し、その点が補償子回転によってずれる量(pixel数)を目視で検出した。
光源と試料との間の光学補償子を回転させた時の結果を表１及び図１に、試料と検光子との間の光学補償子を回転させた時の結果を表２及び図２に示す。 The image shift between when the optical compensator between the light source and the sample was rotated and when the optical compensator between the sample and the analyzer was rotated was compared.
Evaluation was performed as follows.
(1) White light source, compensator with rotation function (compensator: λ / 4 plate manufactured by Luceo Co., Ltd., rotation function: automatic rotation stage manufactured by Suruga Seiki Co., Ltd.), CCD camera XCL-X700 (manufactured by Sony Corporation) ) Are arranged in this order.
(2) The compensator was rotated with the measurement sample (SIGMA KOKI Co., Ltd. test target) placed in front of or behind the compensator with a rotation function, and images at various angles were taken with a CCD camera.
(3) Focusing on an arbitrary point in these images, the amount (number of pixels) that the point is displaced by the compensator rotation was visually detected.
Table 1 and FIG. 1 show the results when the optical compensator between the light source and the sample is rotated, and Tables 2 and 2 show the results when the optical compensator between the sample and the analyzer is rotated. Show.

Figure 2009236678
Figure 2009236678

Figure 2009236678
Figure 2009236678

表１及び２、並びに図1及び２の結果から分かるように、試料後ろに回転する素子が存在すると測定画像がCCD上で動いてしまい、正確な位相差測定に支障をきたす。 As can be seen from the results in Tables 1 and 2 and FIGS. 1 and 2, if there is a rotating element behind the sample, the measurement image moves on the CCD, which hinders accurate phase difference measurement.

（例２）
以下一例として、市販品λ/4板((株)ルケオ製)の二次元位相差を測定した例を示す。
装置としては、ハロゲンランプ、干渉フィルタ(透過波長=550nm)、偏光子((株)サンリッツ製)、回転機能付き補償子(補償子：(株)ルケオ製λ/4板、回転機能：駿河精機(株)製自動回転ステージ)、試料ステージ(ユニオプト(株))、検光子((株)サンリッツ製)、CCDカメラXCL-X700(Sony(株)製)をこの順に配置した装置を用いた。 (Example 2)
As an example, an example in which the two-dimensional phase difference of a commercially available λ / 4 plate (manufactured by Luceo Co., Ltd.) is measured is shown below.
Equipment includes halogen lamp, interference filter (transmission wavelength = 550 nm), polarizer (manufactured by Sanlitz), compensator with rotation function (compensator: λ / 4 plate manufactured by Luceo Co., Ltd.), rotation function: Suruga Seiki An automatic rotation stage manufactured by Co., Ltd.), a sample stage (Uniop Co., Ltd.), an analyzer (manufactured by Sanlitz Co., Ltd.), and a CCD camera XCL-X700 (manufactured by Sony Corporation) were used in this order.

試料挿入前、θc=0°状態での測定値をIoとした。試料挿入後の測定値をI0°、I5°、I10°、I15°…とし、透過率はT0°= I0°/Io、T5°= I5°/Io、T10°= I10°/Io、T15°= I15°/Ioと計算した。測定値I0°、I5°、I10°、I15°…は、撮影した画像からMATLABを用いて導出した輝度情報でから求めた。測定エリアは、光照射位置の中心付近の51pixel×51pixelとした。実測された透過率を表３、及び図３に示す。 The measured value in the state of θc = 0 ° before inserting the sample was defined as Io. The measured values after sample insertion are I 0 °, I 5 °, I 10 °, I 15 ° ..., and the transmittance is T 0 ° = I 0 ° / Io, T 5 ° = I 5 ° / Io, T 10 Calculated as ° = I 10 ° / Io, T 15 ° = I 15 ° / Io. The measured values I 0 °, I 5 °, I 10 °, I 15 °,... Were obtained from luminance information derived from the captured image using MATLAB. The measurement area was 51 pixels × 51 pixels near the center of the light irradiation position. The measured transmittance is shown in Table 3 and FIG.

Figure 2009236678
Figure 2009236678

表３に示した補正後の透過率を式(2)に代入し、これを最小とするα0、α4、β2、β4をexcelで導出すると

α0= 0.507544221915789
α4= 0.00727178672114849
β2= 0.497159465802939
β4= 0.000271068118724824

となった。これらの値を式(4)に代入し、これを最小とするδs,θsをexcelで導出すると

δs=136.23nm
θs=0.86°

となった。 Substituting the corrected transmittance shown in Table 3 into equation (2), and deriving α 0 , α 4 , β 2 , and β 4 that minimize this by excel

α 0 = 0.507544221915789
α 4 = 0.00727178672114849
β 2 = 0.497159465802939
β 4 = 0.000271068118724824

It became. Substituting these values into Equation (4) and deriving δs, θs that minimizes them with excel

δs = 136.23nm
θs = 0.86 °

It became.

上記と同様の手順にて、上記測定エリアの左側に隣接する51pixel×51pixelエリアのα0、α4、β2、β4を測定すると

α0= 0.507563144238063
α4= 0.0072900245310024
β2= 0.497305340065259
β4= -0.000265508397025878

となった。これらの値を式(4)に代入し、これを最小とするδs,θsをexcelで導出すると

δs=136.42nm
θs=0.86

となった。 Measure α 0 , α 4 , β 2 , β 4 in the 51pixel × 51pixel area adjacent to the left side of the measurement area using the same procedure as above.

α 0 = 0.507563144238063
α 4 = 0.0072900245310024
β 2 = 0.497305340065259
β 4 = -0.000265508397025878

It became. Substituting these values into Equation (4) and deriving δs, θs that minimizes them with excel

δs = 136.42nm
θs = 0.86

It became.

光源と試料との間の光学補償子を回転させたとき、画像中の点が該回転によってずれる量(pixel数)を検出した結果を示す図である。It is a figure which shows the result of having detected the amount (pixel number) which the point in an image shift | deviates by this rotation, when the optical compensator between a light source and a sample is rotated. 試料と検光子との間の光学補償子を回転させたとき、画像中の点が該回転によってずれる量(pixel数)を検出した結果を示す図である。It is a figure which shows the result of having detected the quantity (number of pixels) which the point in an image shifts | deviates by this rotation, when the optical compensator between a sample and an analyzer is rotated. 本発明の位相差測定装置でλ/4板を実測したときの光学補償子の遅相軸角度と透過率を示す図である。It is a figure which shows the slow axis angle and transmittance | permeability of an optical compensator when (lambda) / 4 board is actually measured with the phase difference measuring apparatus of this invention.

Claims (7)

光源、偏光子、光学補償子１、測定ステージ、検光子、及び受光素子アレイがこの順に配置され、光学補償子１の遅相軸を回転させる手段を有し、かつ該測定ステージ及び該受光素子アレイの間に、光軸を回転させる手段を有する素子を有しない位相差測定装置。 A light source, a polarizer, an optical compensator 1, a measurement stage, an analyzer, and a light receiving element array are arranged in this order, and have means for rotating the slow axis of the optical compensator 1, and the measurement stage and the light receiving element A phase difference measuring apparatus having no element having means for rotating the optical axis between the arrays. 前記受光素子アレイにて得られた画像の輝度情報を測定試料の複数部位における光の透過量として読み取るためのデータ処理部を有する請求項１に記載の位相差測定装置。 The phase difference measuring apparatus according to claim 1, further comprising a data processing unit for reading luminance information of an image obtained by the light receiving element array as a light transmission amount in a plurality of parts of the measurement sample. 前記測定ステージと前記検光子との間に光学補償子２が配置されている請求項１又は２に記載の位相差測定装置。 The phase difference measuring apparatus according to claim 1, wherein an optical compensator is disposed between the measurement stage and the analyzer. 前記偏光子の透過軸方向に対して前記検光子の透過軸方向がなす角度が0°であり、かつ前記偏光子の透過軸方向に対して光学補償子２の遅相軸方向がなす角度が45°である請求項３に記載の位相差測定装置。 The angle formed by the transmission axis direction of the analyzer with respect to the transmission axis direction of the polarizer is 0 °, and the angle formed by the slow axis direction of the optical compensator 2 with respect to the transmission axis direction of the polarizer is The phase difference measuring apparatus according to claim 3, which is 45 °. 前記光源がハロゲンランプ及び干渉フィルタを含み、かつ前記受光素子アレイがCCDカメラである請求項１〜４のいずれか一項に記載の位相差測定装置。 5. The phase difference measuring apparatus according to claim 1, wherein the light source includes a halogen lamp and an interference filter, and the light receiving element array is a CCD camera. 測定試料における２部位以上の位相差を決定する方法であって、
光源、偏光子、光学補償子１、測定試料、検光子、及び受光素子アレイがこの順に配置された光学系を用意すること；
該偏光子及び該測定試料と該受光素子アレイとの間の素子を固定して光学補償子１の遅相軸を回転させ、該偏光子の透過軸に対して光学補償子１の遅相軸がなす角度θｃにおいて、光源から単波長光を、偏光子、光学補償子１、測定試料、及び検光子を通過するように照射して得られる透過光Ｔθcを、受光素子アレイの２つ以上のエリアで検出すること；及び
前記の２つ以上のエリアで測定されたそれぞれのＴθcとθｃとの関係式から測定試料における２点以上の位相差をそれぞれ算出すること
を含む方法。 A method for determining a phase difference of two or more sites in a measurement sample,
Providing an optical system in which a light source, a polarizer, an optical compensator 1, a measurement sample, an analyzer, and a light receiving element array are arranged in this order;
The polarizer and the element between the measurement sample and the light receiving element array are fixed, the slow axis of the optical compensator 1 is rotated, and the slow axis of the optical compensator 1 is rotated with respect to the transmission axis of the polarizer. Two or more transmitted light Tθ c obtained by irradiating a single wavelength light from a light source so as to pass through a polarizer, an optical compensator 1, a measurement sample, and an analyzer at an angle θc formed by it is detected in the area; and the method comprising calculating the two or more respectively measured in the area of the T.theta c and θc and two or more points from the relationship in the measurement sample the phase difference, respectively. 前記光学系が、前記測定試料と前記検光子との間に、光学補償子２を有する請求項６に記載の方法。 The method according to claim 6, wherein the optical system includes an optical compensator 2 between the measurement sample and the analyzer.
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Publication number Priority date Publication date Assignee Title
US10823892B2 (en) 2016-09-02 2020-11-03 Lg Chem, Ltd. Device for testing optical properties and method for testing optical properties

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10823892B2 (en) 2016-09-02 2020-11-03 Lg Chem, Ltd. Device for testing optical properties and method for testing optical properties

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