JP2018194455A - Polarization property measurement method and polarization property measurement device - Google Patents
Polarization property measurement method and polarization property measurement device Download PDFInfo
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この発明は、試料の偏光特性を求める偏光特性測定方法および偏光特性測定装置に関するものである。 The present invention relates to a polarization property measuring method and a polarization property measuring apparatus for obtaining a polarization property of a sample.
従来より、光学器材などの光学特性を測定するとき、ミュラー行列を用いて偏光解析を行う測定方法ならびに装置がある（例えば、特許文献１参照）。この測定方法等は、入射窓と出射窓について各々ミュラー行列や逆行列などを求め、これら窓材の複屈折位相差などを用いた特性測定を行っている。
また、被測定対象の光学特性を伝達関数として測定する方法ならびに装置がある（例えば、特許文献２参照）。この測定方法等では、ジョーンズ行列を使用して周波数変調による偏光状態を測定している。
また、偏光素子の回転角を変数として光強度を求め、この光強度に対して位相差や方位角の誤差を補正する技術がある（例えば、非特許文献１参照）。
2. Description of the Related Art Conventionally, there is a measurement method and apparatus for performing polarization analysis using a Mueller matrix when measuring optical characteristics of an optical device or the like (see, for example, Patent Document 1). In this measurement method, the Mueller matrix and the inverse matrix are obtained for the entrance window and the exit window, respectively, and the characteristics are measured using the birefringence phase difference of these window materials.
Further, there is a method and apparatus for measuring the optical characteristics of a measurement target as a transfer function (see, for example, Patent Document 2). In this measurement method or the like, the polarization state by frequency modulation is measured using the Jones matrix.
In addition, there is a technique in which the light intensity is obtained using the rotation angle of the polarizing element as a variable and a phase difference or an azimuth angle error is corrected with respect to the light intensity (see, for example, Non-Patent Document 1).
従来の偏光特性を測定する技術は、上記のようなものであり、位相板等が有している波長依存性の影響を受けることになる。そのため、偏光特性の測定精度を高めるためには、波長依存性を有していないクロマティック波長板やフレネルロムなどの高価な光学素子を備えなければならない。
また、従来の複屈折測定等ではミュラー行列を用いて解析を行う際に、特定の偏光特性に限定して処理を行っており、例えばミュラー行列等を用いて光学素子の偏光特性を全体的に測定することは行われておらず、このような処理の手法は確立されていなかった。
The conventional technique for measuring polarization characteristics is as described above, and is affected by the wavelength dependency of the phase plate and the like. Therefore, in order to increase the measurement accuracy of polarization characteristics, it is necessary to provide expensive optical elements such as a chromatic wave plate and Fresnel ROM that do not have wavelength dependency.
In addition, when performing analysis using a Mueller matrix in conventional birefringence measurement or the like, processing is limited to a specific polarization characteristic. For example, the polarization characteristic of an optical element is entirely changed using a Mueller matrix or the like. No measurement has been performed, and such a processing method has not been established.
また、ジョーンズ行列等を伝達行列に用いて偏光特性を測定すると、完全偏光についての特性測定は可能であるが、光学系の散乱などに起因する偏光を解消して、試料等が有する偏光特性を精度良く測定することは困難であった。
また、偏光特性の解析にミュラー行列を用いる場合には、一般的にはＤＦＴを使用し、光強度について最低でも３２点のサンプリングを行う必要がある。そのため、画像撮影の露光時間を長くしなければならないときには、特性の測定時間が相当に長くなる。また、サンプリング数が多くなることから、処理するデータ量も多大になり演算処理に関する負荷が重くなって解析に要する時間が長くなるという問題点があった。
In addition, if the polarization characteristics are measured using the Jones matrix as a transfer matrix, it is possible to measure the characteristics of complete polarization, but the polarization characteristics caused by scattering of the optical system are eliminated, and the polarization characteristics of the sample etc. are eliminated. It was difficult to measure accurately.
In addition, when a Mueller matrix is used for analyzing polarization characteristics, it is generally necessary to use DFT and perform sampling at least 32 points with respect to light intensity. For this reason, when it is necessary to lengthen the exposure time for image capturing, the characteristic measurement time becomes considerably long. Further, since the number of samplings increases, the amount of data to be processed increases, and there is a problem that the time required for analysis becomes longer due to a heavy load related to arithmetic processing.
本発明は上記のような課題に鑑みなされたもので、サンプリング数を抑制して演算処理の負荷を軽減するとともに、偏光特性を精度良く測定することができる偏光特性測定方法および偏光特性測定装置を提供することを目的とする。 The present invention has been made in view of the problems as described above, and provides a polarization characteristic measurement method and a polarization characteristic measurement apparatus capable of reducing the load of calculation processing by suppressing the number of samplings and accurately measuring the polarization characteristic. The purpose is to provide.
この発明に係る偏光特性測定方法は、光源が発光する光波長と異なる設計光波長の位相板を用いており、前記位相板を備えた偏光解析部を介して検出器が検出した光強度を用いて前記位相板の位相差を演算手段が算出する第１過程と、前記第１過程で算出した位相差を用いて前記位相板を備えた偏光解析部のストークスベクトルを前記演算手段が算出する第２過程と、を有し、前記第１過程は、前記光源と前記偏光解析部との間に設置される偏光変調部および前記偏光解析部の位相方位角度ならびに透過方位角度を任意の角度に設定する第３過程と、前記第３過程で任意の角度に設定した状態において前記検出器が撮影した画像ファイルを記憶手段へ記憶させる第４過程と、を有し、前記第３過程および第４過程を所定回数繰り返すことにより、前記位相方位角度ならびに透過方位角度の設定角度を変更して撮影させた画像ファイルを順次記憶させ、該記憶させた各画像ファイルの光強度を用いて前記位相板の位相差を算出し、前記第２過程は、前記第１過程で算出した位相差および前記位相方位角度ならびに透過方位角度の各設定角度を用いて、所定の演算により前記位相板のストークスベクトルの各係数を求める第５過程と、前記各係数を要素とする伝達行列およびその逆行列を求め、前記各画像ファイルの光強度を要素とする光強度行列と前記逆行列とを用いた演算により、前記ストークスベクトルを求める第６過程と、を有することを特徴とする。 The polarization characteristic measuring method according to the present invention uses a phase plate having a design light wavelength different from the light wavelength emitted from the light source, and uses the light intensity detected by the detector via the polarization analyzer provided with the phase plate. The calculating means calculates the Stokes vector of the polarization analyzer having the phase plate using the first process in which the calculating means calculates the phase difference of the phase plate and the phase difference calculated in the first process. And the first process sets the phase azimuth angle and the transmission azimuth angle of the polarization modulation unit and the polarization analysis unit installed between the light source and the polarization analysis unit to arbitrary angles. A third process, and a fourth process for storing the image file taken by the detector in the storage means in a state set at an arbitrary angle in the third process, and the third process and the fourth process. Is repeated a predetermined number of times. , Sequentially storing the image files photographed by changing the setting angle of the phase azimuth angle and transmission azimuth angle, calculating the phase difference of the phase plate using the light intensity of each of the stored image files, The second process includes a fifth process for obtaining each coefficient of the Stokes vector of the phase plate by a predetermined calculation using the phase difference calculated in the first process and the set angles of the phase azimuth angle and the transmission azimuth angle. A sixth process of obtaining a Stokes vector by calculating a transfer matrix having each coefficient as an element and an inverse matrix thereof, and using a light intensity matrix having the light intensity of each image file as an element and the inverse matrix It is characterized by having.
また、この発明に係る偏光特性測定方法は、光源が発光する光波長と異なる設計光波長の位相板を用いており、前記光源から光入射して試料へ光出射する偏光変調部と、前記試料から光入射して検出器へ光出射する偏光解析部と、の間に前記試料を設置していない第１の状態で前記検出器へ光入射を行い、このときの前記検出器の出力信号を用いて演算手段が前記第１の状態を示す第１ストークスベクトルを求める第１過程と、前記偏光変調部と前記偏光解析部との間に前記試料を設置した第２の状態で前記検出器へ光入射を行い、このときの前記検出器の出力信号を用いて前記演算手段が前記第２の状態を示す第２ストークスベクトルを求める第２過程と、前記第１ストークスベクトルを示す行列と前記第２ストークスベクトルを示す行列とを用いて前記試料の偏光特性を示すミュラー行列を求める第３過程と、を有することを特徴とする。 Further, the polarization characteristic measuring method according to the present invention uses a phase plate having a design light wavelength different from the light wavelength emitted from the light source, the polarization modulation unit that makes light incident from the light source and emits the light to the sample, and the sample The light is incident on the detector and the light is incident on the detector in a first state where the sample is not placed between the polarization analyzer and the light output to the detector. The output signal of the detector at this time is To the detector in a second state in which the sample is placed between the polarization modulation unit and the polarization analysis unit, and a first process in which the calculating means uses the first Stokes vector indicating the first state. A second step in which light is incident and the calculation means obtains a second Stokes vector indicating the second state using an output signal of the detector at this time; a matrix indicating the first Stokes vector; Matrix indicating two Stokes vectors And having a third process of obtaining a Mueller matrix indicating the polarization characteristics of the sample used.
また、前記第１過程は、前記偏光変調部および前記偏光解析部の位相方位角度ならびに透過方位角度を任意の角度に設定する第４過程と、前記第４過程で任意の角度に設定した状態において前記検出器が撮影した画像ファイルを記憶手段へ記憶させる第５過程と、前記第４過程および第５過程を所定回数繰り返すことにより、前記位相方位角度ならびに透過方位角度意の設定角度を変更して撮影させた画像ファイルを順次記憶させ、該記憶させた各画像ファイルの光強度を用いて、前記第１の状態における前記偏光解析部に備えた位相板の位相差を算出し、前記算出した位相差および前記位相方位角度ならびに透過方位角度の各設定角度を用いて、所定の演算により前記第１ストークスベクトルの各係数を求める第６過程と、前記第６過程で求めた各係数を要素とする伝達行列およびその逆行列を求め、前記第１の状態における各画像ファイルの光強度を要素とする光強度行列と前記逆行列とを用いた演算により、前記第１ストークスベクトルを求める第７過程と、を有し、前記第２過程は、前記偏光変調部および前記偏光解析部の位相方位角度ならびに透過方位角度を任意の角度に設定する第８過程と、前記第８過程で任意の角度に設定した状態において前記検出器が撮影した画像ファイルを記憶手段へ記憶させる第９過程と、前記第８過程および第９過程を所定回数繰り返すことにより、前記位相方位角度ならびに透過方位角度の設定角度を変更して撮影させた画像ファイルを順次記憶させ、該記憶させた各画像ファイルの光強度を用いて、前記第２の状態における前記偏光解析部に備えた位相板の位相差を算出し、前記算出した位相差および前記位相方位角度ならびに透過方位角度の各設定角度を用いて、所定の演算により前記第２ストークスベクトルの各係数を求める第１０過程と、前記第１０過程で求めた各係数を要素とする伝達行列およびその逆行列を求め、前記第２の状態における各画像ファイルの光強度を要素とする光強度行列と前記逆行列とを用いた演算により、前記第２ストークスベクトルを求める第１１過程と、を有することを特徴とする。 The first process includes a fourth process in which the phase azimuth angle and the transmission azimuth angle of the polarization modulator and the polarization analyzer are set to arbitrary angles, and a state in which the arbitrary angle is set in the fourth process. By repeating the fifth process of storing the image file captured by the detector in the storage means, and the fourth process and the fifth process a predetermined number of times, the set angles of the phase azimuth angle and the transmission azimuth angle are changed. The captured image files are sequentially stored, and using the light intensity of each stored image file, the phase difference of the phase plate provided in the polarization analyzer in the first state is calculated, and the calculated level is calculated. In the sixth process and the sixth process, each coefficient of the first Stokes vector is obtained by a predetermined calculation using the phase difference, the phase azimuth angle, and the transmission azimuth angle. A transfer matrix having each coefficient as an element and an inverse matrix thereof are obtained, and the first matrix is calculated by using a light intensity matrix having the light intensity of each image file in the first state as an element and the inverse matrix. A seventh step of obtaining a Stokes vector, wherein the second step is an eighth step of setting the phase azimuth angle and transmission azimuth angle of the polarization modulator and the polarization analyzer to arbitrary angles, and The ninth step of storing the image file captured by the detector in the storage means in a state set at an arbitrary angle in the eight steps, and the eighth step and the ninth step are repeated a predetermined number of times, whereby the phase azimuth angle and The image files photographed by changing the setting angle of the transmission azimuth angle are sequentially stored, and the polarization solution in the second state is used by using the stored light intensity of each image file. Calculating a phase difference of the phase plate provided in the unit, and obtaining each coefficient of the second Stokes vector by a predetermined calculation using each of the calculated phase difference, the phase azimuth angle, and the transmission azimuth angle. 10 processes, a transfer matrix having each coefficient obtained in the 10th process as an element and its inverse matrix, and a light intensity matrix having the light intensity of each image file in the second state as an element and the inverse matrix And an eleventh step of obtaining the second Stokes vector by an operation using.
また、前記第３過程は、前記試料の偏光特性を示すミュラー行列の所定の要素を用いて所定の演算を行い、前記試料の偏光特性を定量化する過程を含む、ことを特徴とする。 The third step includes a step of performing a predetermined calculation using a predetermined element of the Mueller matrix indicating the polarization characteristic of the sample to quantify the polarization characteristic of the sample.
また、この発明に係る偏光特性測定装置は、光源と、前記光源からの光を入射して試料へ出射する偏光変調部と、前記試料からの光を入射して画像を撮影する検出器へ出射する偏光解析部と、前記偏光解析部から出力された信号を用いて所定の演算処理を行う演算手段と、を備え、前記偏光変調部および前記偏光解析部は、前記光源の発光波長と異なる設計光波長の位相板を有し、位相方位角度ならびに透過方位角度を所定の角度へ設定可能に構成されており、前記演算手段は、前記試料を前記偏光変調部と前記偏光解析部の間に設置していない第１の状態で前記検出器へ光入射を行い、このときの前記検出器の出力信号を用いて前記位相板の位相差を求め、該位相差および前記偏光変調部および前記偏光解析部に設定された位相方位角度ならびに透過方位角度を用いて前記第１の状態における第１ストークスベクトルを求め、前記試料を前記偏光変調部と前記偏光解析部の間に設置した第２の状態で前記検出器へ光入射を行い、このときの前記検出器の出力信号を用いて前記位相板の位相差を求め、該位相差および前記偏光変調部および前記偏光解析部に設定された位相方位角度ならびに透過方位角度を用いて前記第２の状態における第２ストークスベクトルを求め、前記第１ストークスベクトルを示す行列と前記第２ストークスベクトルを示す行列とを用いて前記試料の偏光特性を示すミュラー行列を求める、ことを特徴とする。 In addition, the polarization characteristic measuring apparatus according to the present invention includes a light source, a polarization modulation unit that receives light from the light source and emits the light to the sample, and a light that enters the sample and emits the light to a detector that captures an image. A polarization analyzer and a calculation means for performing a predetermined calculation process using a signal output from the polarization analyzer, and the polarization modulator and the polarization analyzer are designed differently from the emission wavelength of the light source. It has a phase plate of light wavelength, and is configured to be able to set a phase azimuth angle and a transmission azimuth angle to predetermined angles, and the calculation means places the sample between the polarization modulator and the polarization analyzer In the first state, light is incident on the detector, and the phase difference of the phase plate is obtained using the output signal of the detector at this time, and the phase difference, the polarization modulator, and the polarization analysis Phase azimuth angle set in the First, the first Stokes vector in the first state is obtained using the transmission azimuth angle, and light is incident on the detector in the second state in which the sample is placed between the polarization modulator and the polarization analyzer. The phase difference of the phase plate is obtained using the output signal of the detector at this time, and the phase difference and the phase azimuth angle and the transmission azimuth angle set in the polarization modulator and the polarization analyzer are used. A second Stokes vector in a second state is obtained, and a Mueller matrix showing polarization characteristics of the sample is obtained using a matrix showing the first Stokes vector and a matrix showing the second Stokes vector. .
この発明によれば、測定サンプリング数を抑えて演算処理の負荷を軽減するとともに、測定誤差を低減することができる。 According to the present invention, it is possible to reduce the measurement processing load by reducing the number of measurement samplings and to reduce measurement errors.
以下、この発明の実施の一形態を説明する。
なお、本明細書においては、図面ならびに数式において太字表記したベクトルを、『［］』を用いて表記する。
（実施例）
図１は、本発明の実施例による偏光特性測定装置の概略構成を示す説明図である。図示した測定装置１は、所定波長の光を試料１３へ向けて出射する光源１１、試料１３へ入射させる光を変調する偏光変調部１２を備えている。
また、測定装置１は、試料１３から出射された光に所定の偏光等を施し、後述する演算に対応させる偏光解析部１４、偏光解析部１４から出射された光を入射し、所定の電気信号へ変換出力する検出器１５、検出器１５の出力信号を用いて所定演算を行う演算手段１６を備えている。
An embodiment of the present invention will be described below.
In the present specification, vectors shown in bold in the drawings and mathematical expressions are written using “[]”.
(Example)
FIG. 1 is an explanatory diagram showing a schematic configuration of a polarization characteristic measuring apparatus according to an embodiment of the present invention. The illustrated measuring apparatus 1 includes a light source 11 that emits light having a predetermined wavelength toward the sample 13 and a polarization modulator 12 that modulates the light incident on the sample 13.
The measuring apparatus 1 applies predetermined polarization or the like to the light emitted from the sample 13 and enters the light emitted from the polarization analyzing unit 14 and the polarization analyzing unit 14 which correspond to the calculation described later, and receives a predetermined electric signal. A detector 15 that converts and outputs the signal and a calculation means 16 that performs a predetermined calculation using the output signal of the detector 15 are provided.
なお、具体的な測定装置１として、例えば、光源１１と偏光調整部１２との間に、図示を省略したコリメータレンズユニット等を設置し、当該コリメータレンズユニット等と偏光解析部１４との間に試料１３を設置固定する試料ステージ（図示省略）を設置し、試料１３と偏光解析部１４との間に適当な対物レンズ（図示省略）を設置し、偏光解析部１４と検出器１５との間に無限遠補正が可能な鏡筒（図示省略９を設置し、また、上記の光源１１から検出器１５までの間に光導波路等（図示省略）を適当に設けて、顕微鏡型の偏光測定装置として構成してもよい。 As a specific measuring apparatus 1, for example, a collimator lens unit or the like (not shown) is installed between the light source 11 and the polarization adjusting unit 12, and the collimator lens unit or the like and the polarization analyzing unit 14 are installed. A sample stage (not shown) for setting and fixing the sample 13 is set, an appropriate objective lens (not shown) is set between the sample 13 and the polarization analysis unit 14, and between the polarization analysis unit 14 and the detector 15. A microscope-type polarization measuring device in which a lens barrel capable of infinity correction (not shown 9 is installed and an optical waveguide (not shown) is appropriately provided between the light source 11 and the detector 15 is provided. You may comprise as.
光源１１は、例えば、波長が７８０ｎｍの光を発光するＬＥＤ等の準単色発光体や光学フィルタなどを備え、一定の光強度で出射するように構成されている。
偏光変調部１２は、偏光子Ｐ１と位相板Ｒ１を有し、偏光子Ｐ１は、例えば直線偏光素子であり、透過軸方位を所望の角度へ回転させて設定調整することを可能に構成された例えばホルダ等によって支持されている。位相板Ｒ１は、例えば波長６３３ｎｍの入射光に対して位相を１／４波長分遅延させるλ／４波長板であり、主軸方位を所望の角度へ回転させて設定調整することを可能に構成された例えばホルダ等によって支持されている。
偏光変調部１２と偏光解析部１４の間には、前述の図示を省略した試料ステージが設置されており、この試料ステージ等を用いて試料１３が測定装置１の所定位置に固定されている。
The light source 11 includes, for example, a quasi-monochromatic light emitter such as an LED that emits light having a wavelength of 780 nm, an optical filter, and the like, and is configured to emit light with a constant light intensity.
The polarization modulation unit 12 includes a polarizer P1 and a phase plate R1, and the polarizer P1 is, for example, a linear polarization element, and is configured to be able to set and adjust by rotating the transmission axis direction to a desired angle. For example, it is supported by a holder or the like. The phase plate R1 is a λ / 4 wavelength plate that delays the phase by a quarter wavelength with respect to incident light having a wavelength of 633 nm, for example, and is configured to be able to set and adjust by rotating the principal axis direction to a desired angle. For example, it is supported by a holder or the like.
A sample stage (not shown) is installed between the polarization modulation unit 12 and the polarization analysis unit 14, and the sample 13 is fixed at a predetermined position of the measuring apparatus 1 using the sample stage or the like.
偏光解析部１４は、位相板Ｒ２と偏光子Ｐ２を有し、位相板Ｒ２は、例えば波長６３３ｎｍの入射光に対して位相を１／４波長分遅延させるλ／４波長板であり、主軸方位を所望の角度へ回転させて設定調整することを可能に構成された例えばホルダ等によって支持されている。また、偏光子Ｐ２は、例えば直線偏光素子であり、透過軸方位を所望の角度へ回転させて設定調整することを可能に構成された例えばホルダ等によって支持されている。
検出器１５は、例えば、画像等を撮影可能な撮像素子や分光機構などを備えたＣＣＤカメラ等であり、撮影したカラー画像を表す信号を出力するように構成されている。
なお、測定装置１は、例えば、前述の光導波路等によって接続された、光源１１、偏光変調部１２、偏光解析部１４、検出器１５などにより測定光学系を構成している。特に、検出器１５に偏光解析部１４から出射された光以外が入射しないように、測定装置１内部、もしくは当該測定装置１を設置する場所は、暗室環境とする必要がある。
The polarization analysis unit 14 includes a phase plate R2 and a polarizer P2. The phase plate R2 is a λ / 4 wavelength plate that delays the phase by ¼ wavelength with respect to incident light having a wavelength of 633 nm, for example. Is supported by, for example, a holder or the like configured to be able to be set and adjusted by rotating it to a desired angle. The polarizer P2 is, for example, a linearly polarizing element, and is supported by, for example, a holder configured to be able to set and adjust the transmission axis direction by rotating it to a desired angle.
The detector 15 is, for example, a CCD camera or the like provided with an image pickup device capable of taking an image or the like, a spectral mechanism, and the like, and is configured to output a signal representing a taken color image.
Note that the measurement apparatus 1 includes a measurement optical system including, for example, the light source 11, the polarization modulation unit 12, the polarization analysis unit 14, and the detector 15 that are connected by the above-described optical waveguide and the like. In particular, the inside of the measuring apparatus 1 or the place where the measuring apparatus 1 is installed needs to be a dark room environment so that light other than the light emitted from the polarization analyzer 14 does not enter the detector 15.
演算手段１６は、検出器１５から出力された画像信号等を入力し、この画像信号に含まれる例えば光強度などに関する演算や取得したデータの処理などを行うプロセッサ、必要に応じて所定のデータ等を記憶するメモリ、演算処理結果などを出力表示するディスプレイ装置等を備えた、例えばパーソナルコンピュータなどの情報処理装置である。
なお、測定装置１の測定精度を高めるため、単色性の良好な光源１１、ならびに波長分解能の良好な検出器１５を使用することが好ましい。
The calculation means 16 inputs the image signal output from the detector 15 and performs a calculation related to, for example, light intensity included in the image signal, processing of the acquired data, predetermined data as necessary, etc. Is an information processing apparatus such as a personal computer provided with a memory for storing information, a display device for outputting and displaying the results of arithmetic processing, and the like.
In order to increase the measurement accuracy of the measuring apparatus 1, it is preferable to use a light source 11 having good monochromaticity and a detector 15 having good wavelength resolution.
偏光変調部１２の偏光子Ｐ１および位相板Ｒ１、ならびに偏光解析部１４の位相板Ｒ２および偏光子Ｐ２は、前述のようにホルダ等によって回転可能に支持されている。このホルダ等を回転駆動する機構部を設置し、当該機構部の動作を、例えば演算手段１６によって制御するように構成してもよい。即ち、プロセッサやメモリなどを備えた演算手段１６を、測定装置１の各部動作を制御する制御手段とし、あるいは演算手段１６を制御手段に含めて構成し、例えば、この制御手段になされた入力操作等に応じて、あるいは予め設定されたデータ等に則して、上記の各光学素子の方位などを設定、ならびに変更するように構成してもよい。また、上記の制御手段等により、光源１１、検出器１５などの動作を併せて制御するように構成してもよい。
また、演算手段１６は、偏光子Ｐ１、位相板Ｒ１、位相板Ｒ２、偏光子Ｐ２等の光学素子の方位角度等を示す値を取得するように構成されており、例えば、上記の各光学素子を支持するホルダ等にセンサを備え、このセンサの出力信号から方位角度等の値を表すデータを取得するように構成されている。
The polarizer P1 and the phase plate R1 of the polarization modulator 12 and the phase plate R2 and the polarizer P2 of the polarization analyzer 14 are rotatably supported by a holder or the like as described above. A mechanism unit that rotationally drives the holder or the like may be installed, and the operation of the mechanism unit may be controlled by, for example, the calculation means 16. That is, the arithmetic means 16 provided with a processor, a memory, etc. is used as a control means for controlling the operation of each part of the measuring apparatus 1, or the arithmetic means 16 is included in the control means, for example, an input operation performed on this control means. Depending on the above, or in accordance with preset data or the like, the orientation of each optical element may be set and changed. Moreover, you may comprise so that operation | movement of the light source 11, the detector 15, etc. may be controlled collectively by said control means.
Further, the calculation means 16 is configured to acquire values indicating the azimuth angles of optical elements such as the polarizer P1, the phase plate R1, the phase plate R2, and the polarizer P2, and each of the optical elements described above, for example, The holder is supported by a sensor, and data representing values such as the azimuth angle is obtained from the output signal of the sensor.
次に動作について説明する。
ここでは、
ｉ）偏光変調部１２について、
偏光子Ｐ１の透過軸方位をθＰ１、
位相板Ｒ１の主軸方位をθＲ１，位相差（任意）をδ１（δ１≠180×n度）
ii）偏光解析部１４について、
位相板Ｒ２の主軸方位をθＲ２，位相差（任意）をδ２（δ２≠180×n度）、
偏光子Ｐ２の透過軸方位をθＰ２、
と定義して説明する。
Next, the operation will be described.
here,
i) About the polarization modulator 12
The transmission axis direction of the polarizer P1 is θ P1,
The principal axis direction of the phase plate R1 is θ R1 , and the phase difference (arbitrary) is δ 1 (δ 1 ≠ 180 × n degrees)
ii) About the ellipsometer 14
The principal axis direction of the phase plate R2 is θ R2 , the phase difference (arbitrary) is δ 2 (δ 2 ≠ 180 × n degrees),
The transmission axis direction of the polarizer P2 is θ P2 ,
It is defined and explained.
測定装置１による偏光特性の測定は、概ね次のように動作する。
初めに、偏光解析部１４の位相板Ｒ２の位相差δ２を、測定光学系を稼働させて測定する（Ｓｔｅｐ１）。
次に、Ｓｔｅｐ１において測定した位相差δ２を示すデータを用いて、偏光解析部１４の伝達行列（４×４）を求め、この伝達行列の逆行列と検出器１５が検出した光強度とを用いて、偏光解析部１４の光入射側における偏光特性（ストークスベクトル・４×１）を求める（Ｓｔｅｐ２）。
また、試料１３の偏光特性を測定する動作では、試料１３がない状態で得られるストークスベクトル［Ｓｉｎ］と、試料１３を透過したときのストークスベクトル［Ｓｏｕｔ］とをＳｔｅｐ２の処理動作によって求める。これらから試料１３の偏光特性を示すミュラー行列を求め、当該ミュラー行列の要素を用いて試料１３の偏光特性を定量化する（Ｓｔｅｐ３）。
The measurement of the polarization characteristic by the measuring apparatus 1 generally operates as follows.
First, the phase difference δ 2 of the phase plate R2 of the polarization analyzer 14 is measured by operating the measurement optical system (Step 1).
Next, using the data indicating the phase difference δ 2 measured in Step 1, the transfer matrix (4 × 4) of the polarization analyzer 14 is obtained, and the inverse matrix of this transfer matrix and the light intensity detected by the detector 15 are obtained. Then, the polarization characteristic (Stokes vector · 4 × 1) on the light incident side of the polarization analyzer 14 is obtained (Step 2).
Further, in the operation of measuring the polarization characteristics of the sample 13, the Stokes vector [S in ] obtained without the sample 13 and the Stokes vector [S out ] when transmitted through the sample 13 are obtained by the processing operation of Step 2. . From these, the Mueller matrix indicating the polarization characteristics of the sample 13 is obtained, and the polarization characteristics of the sample 13 are quantified using the elements of the Mueller matrix (Step 3).
次に各Ｓｔｅｐの動作を説明する。
なお、下記のＳｔｅｐ１およびＳｔｅｐ２で説明する動作処理は、後述するＳｔｅｐ３において行われる動作処理の一部分である。
＜Ｓｔｅｐ１＞
１−１．例えば、偏光変調部１２の偏光子Ｐ１の透過軸方位θＰ１に対して、位相板Ｒ１の主軸方位θＲ１および位相板Ｒ２の主軸方位θＲ２を、平行となる、または直交する方位に設定する。このとき、各位相板の主軸方位を進相軸あるいは遅相軸のどちらに設定してもよい。
１−２．偏光解析部１４の位相板Ｒ２の主軸方位θＲ２を、例えば、上記の項目１−１で設定した状態から４５×（２ｎ＋１）度回転させる。
１−３．偏光解析部１４の主軸方位θＲ２を、上記の項目１−２で設定した状態としておき、当該偏光解析部１４の偏光子Ｐ２の透過軸方位θＰ２を、偏光変調部１２の偏光子Ｐ１の透過軸方位θＰ１に対して平行状態に設定したときの光強度と、直交状態に設定したときの光強度を、順次、演算手段１６のメモリ等に記憶させる。
Next, the operation of each step will be described.
Note that the operation process described in Step 1 and Step 2 below is a part of the operation process performed in Step 3 described later.
<Step 1>
1-1. For example, with respect to the transmission axis azimuth theta P1 of the polarizer P1 of the polarization modulator 12, the principal axis directions theta R2 of the spindle orientation theta R1 and the phase plate R2 of the phase plate R1, is set to be parallel or perpendicular orientation . At this time, the main axis direction of each phase plate may be set to either the fast axis or the slow axis.
1-2. The principal axis directions theta R2 of the phase plate R2 of the polarization analyzer 14, for example, 45 × from the state set in the above items 1-1 (2n + 1) degree rotation.
1-3. The principal axis directions theta R2 polarization analyzer 14, leave a state of being set in the above items 1-2, the transmission axis azimuth theta P2 polarizer P2 of the polarization analyzer 14, the polarization modulator 12 of the polarizer P1 and the light intensity when set to the parallel state to the transmission axis azimuth theta P1, the light intensity when set to orthogonal states, sequentially, and stored in the memory of the arithmetic unit 16.
１−４．項目１−３にて記憶させた各光学素子の状態（方位角度）における光強度を用いて、偏光解析部１４の位相板Ｒ２の位相差δ２を算出する。
例えば、偏光子Ｐ１の透過軸方位θＰ１＝０度、位相板Ｒ１の主軸方位θＲ１＝０度、位相板Ｒ２の主軸方位θＲ２＝４５度と設定し、偏光子Ｐ２の透過軸方位θＰ２＝０度（θＰ１と平行状態）において検出器１５が検出した光強度をＩ０、透過軸方位θＰ２＝９０度（θＰ１と直交状態）において検出器１５が検出した光強度をＩ９０としたとき、位相板Ｒ２の位相差δ２は、次の式（１）によって求められる。
1-4. The phase difference δ 2 of the phase plate R2 of the polarization analysis unit 14 is calculated using the light intensity in the state (azimuth angle) of each optical element stored in item 1-3.
For example, the transmission axis azimuth θ P1 = 0 degree of the polarizer P1, the main axis azimuth θ R1 = 0 degree of the phase plate R1, the main axis azimuth θ R2 = 45 degrees of the phase plate R2, and the transmission axis azimuth θ of the polarizer P2. The light intensity detected by the detector 15 at P2 = 0 degree (parallel to θ P1 ) is I 0 , and the light intensity detected by the detector 15 at transmission axis orientation θ P2 = 90 degrees (state orthogonal to θ P1 ) is I When 90 , the phase difference δ 2 of the phase plate R2 is obtained by the following equation (1).
Ｓｔｅｐ１において、測定装置１は、試料１３の偏光測定時と同じ状態とされ、例えば、図示を省略した各部レンズの倍率などは最適な値に設定されている。このように各部を設定した状態において、試料ステージ等に試料１３を設置固定することなく、前述のように各光学素子（偏光子Ｐ１、位相板Ｒ１、位相板Ｒ２、偏光子Ｐ２）の方位等を設定し、例えば、上記の各光学素子を図９の表１に示した各値に設定して、偏光解析部１４からの出射光を検出器１５へ入射し、光強度を測定する。 In Step 1, the measurement apparatus 1 is in the same state as when the polarization of the sample 13 is measured. For example, the magnification of each part lens (not shown) is set to an optimum value. In the state where each part is set as described above, the orientation of each optical element (polarizer P1, phase plate R1, phase plate R2, polarizer P2), etc., as described above, without installing and fixing the sample 13 on the sample stage or the like. For example, each optical element described above is set to each value shown in Table 1 of FIG. 9, the outgoing light from the polarization analysis unit 14 is incident on the detector 15, and the light intensity is measured.
検出器１５は、撮影した画像を示す信号として、例えばＲＡＷデータを出力し、演算手段１６は、適宜、検出器１５から出力されたＲＡＷ形式の画像ファイルを、自ら備えるメモリ等の記憶手段に保存する。即ち、Ｓｔｅｐ１において、上記の記憶手段に記憶する画像ファイルは、前述の項目１−３にて説明した２つの状態（各光学素子の方位角度）において撮影されたものである。
演算手段１６は、前述の記憶した２枚の（２つの状態で撮影された）画像ファイルについて、これら画像の各ピクセルに存在する光強度を抽出し、項目１−４で説明した式（１）の演算をピクセル毎に行って、位相板Ｒ２が有する位相差δ２の二次元分布を表す画像データを生成する。
The detector 15 outputs, for example, RAW data as a signal indicating a photographed image, and the calculation unit 16 appropriately stores the RAW format image file output from the detector 15 in a storage unit such as a memory provided therein. To do. That is, in Step 1, the image file stored in the storage means is taken in the two states (azimuth angles of the optical elements) described in the above item 1-3.
The calculation means 16 extracts the light intensity existing in each pixel of these two stored image files (captured in two states), and the expression (1) described in item 1-4. Is calculated for each pixel to generate image data representing a two-dimensional distribution of the phase difference δ 2 of the phase plate R2.
＜Ｓｔｅｐ２＞
２−１．偏光解析部１４の直前（光入射側）の偏光状態をストークスベクトル［Ｓ］＝（Ｓ０，Ｓ１，Ｓ２，Ｓ３）と表し、前述の各光学素子に対応するミュラー行列から、検出器５を用いた場合の光強度Ｉｉを算出する式を生成する。ここで例示する測定装置１では、次の式（２）のように定められる。
<Step 2>
2-1. The polarization state immediately before the polarization analysis unit 14 (light incident side) is expressed as Stokes vector [S] = (S 0 , S 1 , S 2 , S 3 ), and is detected from the Mueller matrix corresponding to each of the optical elements described above. An expression for calculating the light intensity I i when the device 5 is used is generated. In the measuring apparatus 1 exemplified here, the following equation (2) is determined.
式（２）において、
In equation (2),
２−２．偏光解析部１４を構成する各光学素子（位相板Ｒ２、偏光子Ｐ１）の方位角度を任意の値に設定し、これら方位角度とＳｔｅｐ１において求めた位相差δ２とを用いて、ストークスベクトル［Ｓ］の上記の係数Ａｉ，Ｂｉ，Ｃｉ，Ｄｉを算出する。
２−３．偏光解析部１４の各光学素子の方位θＲ２及び方位θＰ２の各角度を任意に設定し、ある射偏光状態の光が偏光解析部１４を透過した後の光強度Ｉｉを測定し、この測定値を例えば前述のメモリ等に記憶させる。
２−４．偏光解析部１４の各光学素子の方位θＲ２及び方位θＰ２の角度設定を４回変更して、項目２−３で説明した動作処理を繰り返す（ｉ＝１〜４）。
ここで、光学素子の方位角度を変更して光強度Ｉｉを繰り返し測定するとき、方位θＲ２，θＰ２の各角度は、順次、任意に設定するが、上記のθａが同一とならないように設定する。
2-2. The azimuth angle of each optical element (phase plate R2 and polarizer P1) constituting the polarization analysis unit 14 is set to an arbitrary value, and using these azimuth angles and the phase difference δ 2 obtained in Step 1, the Stokes vector [ The above-described coefficients A i , B i , C i , and D i of S] are calculated.
2-3. Each angle of the azimuth θ R2 and the azimuth θ P2 of each optical element of the polarization analysis unit 14 is arbitrarily set, and the light intensity I i after the light in a certain polarization state is transmitted through the polarization analysis unit 14 is measured. The measured value is stored in, for example, the aforementioned memory.
2-4. Change 4 times the angle setting of the orientation theta R2 and orientation theta P2 of the respective optical elements of the polarization analyzer 14 repeats the operation processing described in item 2-3 (i = 1~4).
Here, when the azimuth angle of the optical element is changed and the light intensity I i is repeatedly measured, the angles of the azimuth θ R2 and θ P2 are arbitrarily set sequentially, but the above θa is not the same. Set.
２−５．前述の項目２−１から項目２−４において、算出される係数Ａｉ，Ｂｉ，Ｃｉ，Ｄｉ、偏光解析部１４直前（光入射側）におけるストークスベクトル［Ｓ］、測定・記憶される光強度Ｉｉは、次の行列式（３）のように表記される。 2-5. In the above items 2-1 to 2-4, the calculated coefficients A i , B i , C i , D i , and the Stokes vector [S] immediately before the polarization analysis unit 14 (light incident side) are measured and stored. The light intensity I i is expressed as the following determinant (3).
上記の行列式（３）より、係数Ａｉ，Ｂｉ，Ｃｉ，Ｄｉを行列の要素とする、偏光解析部１４の伝達行列Ａ、ならびに、その逆行列Ａ−１と、各画像ファイルの光強度Ｉｉを要素とする光強度行列Ｉとを用いて、次の式（４）に示したようにストークスベクトル［Ｓ］を求めることができる。 From the above determinant (3), the transfer matrix A of the ellipsometer 14 having coefficients A i , B i , C i and D i as elements of the matrix, and its inverse matrix A −1 , and each image file The Stokes vector [S] can be obtained as shown in the following equation (4) using the light intensity matrix I having the light intensity I i as an element.
Ｓｔｅｐ２において、測定装置１の演算手段１６は、前述の項目２−１で説明したように光強度Ｉｉを算出する式を定め、項目２−２で説明したようにストークスベクトル［Ｓ］の各係数Ａｉ，Ｂｉ，Ｃｉ，Ｄｉを算出する。
また、演算手段１６は、項目２−３で説明したように、偏光解析部１４の各光学素子について、例えば、前述の機構部等を制御して当該光学素子を支持するホルダ等を回転させ、図１０の表２に示すように方位角度を設定する。また、検出器１５を用いて各方位角度における撮影を行い、撮影した各画像ファイルの光強度Ｉｉを前述のメモリ等に記憶させ、これらの動作処理を項目２−４で説明したように繰り返して、伝達行列Ａ、さらに逆行列Ａ−１を求め、偏光解析部１４直前の偏光状態を示すストークスベクトル［Ｓ］を求める。
測定装置１は、次に説明するＳｔｅｐ３の動作処理によって試料１３の偏光特性を測定する。Ｓｔｅｐ３は、後述する各光学素子に設定された様々な方位角度等についてＳｔｅｐ１ならびにＳｔｅｐ２で説明した動作処理（演算処理）等を行うものである。
In Step 2, the calculation means 16 of the measuring apparatus 1 determines an expression for calculating the light intensity I i as described in the above item 2-1, and each Stokes vector [S] as described in the item 2-2. The coefficients A i , B i , C i , and D i are calculated.
In addition, as described in item 2-3, the calculation unit 16 controls, for example, the mechanism unit described above for each optical element of the polarization analysis unit 14 to rotate a holder or the like that supports the optical element, The azimuth angle is set as shown in Table 2 of FIG. In addition, the detector 15 is used to perform imaging at each azimuth angle, and the light intensity I i of each captured image file is stored in the above-described memory or the like, and these operation processes are repeated as described in item 2-4. Thus, the transfer matrix A and further the inverse matrix A −1 are obtained, and the Stokes vector [S] indicating the polarization state immediately before the polarization analyzer 14 is obtained.
The measuring apparatus 1 measures the polarization characteristic of the sample 13 by the operation process of Step 3 described below. Step 3 performs the operation processing (calculation processing) and the like described in Step 1 and Step 2 for various azimuth angles set in each optical element to be described later.
＜Ｓｔｅｐ３＞
３−１．測定装置１に試料１３を設置しない状態、例えば、前述の試料ステージを空の状態として光源１１を発光させ、偏光変調部１２の位相板Ｒ１の方位θＲ１を任意の角度に設定し、前述Ｓｔｅｐ１ならびにＳｔｅｐ２で説明した演算処理を行って入射ストークスベクトル［Ｓｉｎｊ］を算出する。
３−２．上記の項目３−１で説明した動作ならびに演算処理は、偏光状態が重複しないように偏光変調部１２の条件（方位θＲ１の設定角度）を変更して、入射ストークスベクトル［Ｓｉｎｊ］の算出を４回繰り返し（ｊ＝１〜４）、入射ストークスベクトル［Ｓｉｎ１］，［Ｓｉｎ２］，［Ｓｉｎ３］，［Ｓｉｎ４］を求める。
<Step 3>
3-1. In a state where the sample 13 is not installed in the measuring apparatus 1, for example, the above-described sample stage is emptied, the light source 11 is caused to emit light, the direction θ R1 of the phase plate R1 of the polarization modulator 12 is set to an arbitrary angle, and the above Step 1 In addition, the calculation process described in Step 2 is performed to calculate the incident Stokes vector [S inj ].
3-2. In the operation and the arithmetic processing described in the item 3-1, the incident Stokes vector [S inj ] is calculated by changing the condition (setting angle of the azimuth θ R1 ) of the polarization modulator 12 so that the polarization states do not overlap. Is repeated four times (j = 1 to 4), and incident Stokes vectors [S in1 ], [S in2 ], [S in3 ], [S in4 ] are obtained.
３−３．測定装置１に試料１３を設置固定した状態で光源１１を発光させ、項目３−１もしくは項目３−２と同一の条件下で試料１３に入射光を照射し、この状態で検出した光強度を用いて前述のＳｔｅｐ１ならびにＳｔｅｐ２で説明した演算処理を行って、試料を透過した透過後ストークスベクトル［Ｓｏｕｔｊ］を算出する。即ち、項目３−２の動作処理において設定した４つの方位θＲ１毎に（ｊ＝１〜４）、透過後ストークスベクトル［Ｓｏｕｔ１］，［Ｓｏｕｔ２］，［Ｓｏｕｔ３］，［Ｓｏｕｔ４］を求める。
３−４．ここで、試料１３の偏光特性をミュラー行列Ｍとして表す場合、入射ストークスルベクトル［Ｓｉｎｊ］と透過後ストークスルベクトル［Ｓｏｕｔｊ］との関係は、次の式（５）のように表記することができる。
3-3. The light source 11 emits light with the sample 13 placed and fixed on the measuring apparatus 1, and the sample 13 is irradiated with incident light under the same conditions as in item 3-1 or item 3-2, and the light intensity detected in this state is calculated. The post-transmission Stokes vector [S outj ] transmitted through the sample is calculated by performing the arithmetic processing described in Step 1 and Step 2 described above. That is, the post-transmission Stokes vectors [S out1 ], [S out2 ], [S out3 ], [S out4 ] for each of the four directions θ R1 set in the operation process of the item 3-2 (j = 1 to 4). Ask for.
3-4. Here, when the polarization characteristic of the sample 13 is expressed as a Mueller matrix M, the relationship between the incident Stoke Thru vector [S inj ] and the post-transmission Stoke thru vector [S outj ] is expressed as the following equation (5). be able to.
上記の式（５）に基づき、項目３−１〜項目３−３の各動作処理によって得られた入射ストークスペクトル［Ｓｉｎｊ］と透過後ストークススペクトル［Ｓｏｕｔｊ］を、それぞれ４×４の行列要素として、行列Ｓ’ｉｎおよび行列Ｓ’ｏｕｔに行列化すると、次の式（６）のように表記することができる。 Based on the above equation (5), the incident Stoke spectrum [S inj ] and the post-transmission Stokes spectrum [S outj ] obtained by the operation processes of the items 3-1 to 3-3 are each a 4 × 4 matrix. When elements are matrixed into a matrix S ′ in and a matrix S ′ out , they can be expressed as the following equation (6).
上記の式（６）より、各入射ストークスベクトルからなる行列Ｓ’ｉｎの逆行列と、各透過後ストークスベクトルからなる行列Ｓ’ｏｕｔを用いて、試料１３のミュラー行列Ｍの要素が，次の式（７）によって求められる。 From the above equation (6), using the inverse matrix of the matrix S ′ in composed of each incident Stokes vector and the matrix S ′ out composed of each post-transmission Stokes vector, the elements of the Mueller matrix M of the sample 13 are It is calculated | required by Formula (7).
Ｓｔｅｐ３において、測定装置１の演算手段１６は、項目３−１および項目３−２で説明したように、測定装置１に試料１３を設置しない状態で入射ストークスベクトル［Ｓｉｎｊ］を求めるとき、｛偏光変調部１２における４パターンの方位（θＲ１）の入射偏光｝×｛偏光解析部１４直前の偏光状態を示す４つの要素（Ｓ０，Ｓ１，Ｓ２，Ｓ３）＝１６の要素を算出する。これは、前述のＳｔｅｐ２で説明した偏光解析部１４に関するストークスベクトル［Ｓ］が、４つの要素（Ｓ０，Ｓ１，Ｓ２，Ｓ３）で構成されていることと同義である。なお、これらの演算は、前述のＳｔｅｐ１で説明したように、画像ファイルのピクセル毎に行われる。 In Step 3, as described in Item 3-1 and Item 3-2, the computing means 16 of the measuring device 1 obtains the incident Stokes vector [S inj ] without installing the sample 13 in the measuring device 1. 4 patterns of azimuth (θ R1 ) incident polarization in the polarization modulator 12 × {four elements (S 0 , S 1 , S 2 , S 3 ) = 16 indicating the polarization state immediately before the polarization analyzer 14 calculate. This is synonymous with the fact that the Stokes vector [S] related to the polarization analysis unit 14 described in the above Step 2 is composed of four elements (S 0 , S 1 , S 2 , S 3 ). Note that these calculations are performed for each pixel of the image file as described in Step 1 above.
図２は、図１の演算手段１６が求める入射ストークスベクトルを示す説明図である。
演算手段１６は、入射ストークススベクトル［Ｓｉｎｊ］を求めるとき、前述の各光学素子を、例えば、図１０の表２に示した、いずれかの方位角度（θＰ１，θＲ１，θＲ２，θＰ２）に設定し、設定した方位角度について、項目３−１で説明したようにＳｔｅｐ１ならびにＳｔｅｐ２の処理動作を行って、測定装置１に試料１３を設置していないときの伝達行列Ａならびに逆行列Ａ−１を求め、これを用いて入射ストークスベクトル［Ｓｉｎ１］，［Ｓｉｎ２］，［Ｓｉｎ３］，［Ｓｉｎ４］を求める。なお、これらの入射ストークスベクトルは、図２に示したように各々４つの要素からなるものである。
FIG. 2 is an explanatory diagram showing an incident Stokes vector obtained by the calculation means 16 of FIG.
When calculating the incident Stokes vector [S inj ], the calculating means 16 determines each of the optical elements described above as one of the azimuth angles (θ P1 , θ R1 , θ R2 , θ P2 ), the processing operation of Step 1 and Step 2 is performed for the set azimuth angle as described in Item 3-1, and the transfer matrix A and the inverse when the sample 13 is not installed in the measuring apparatus 1 The matrix A −1 is obtained, and the incident Stokes vectors [S in1 ], [S in2 ], [S in3 ], [S in4 ] are obtained using the matrix A− 1 . These incident Stokes vectors are each composed of four elements as shown in FIG.
具体的には、演算手段１６は、設定されている（例えば、図１０の表２に示した入射パターン１の）位相板Ｒ２と偏光子Ｐ２の各方位θＲ２，θＰ２の値を示すデータを取得し、これらの値とＳｔｅｐ１で求めた位相差δ２とを用いて、式（２）の演算を行う。また、式（２）の演算によって取得した光強度Ｉ１−１〜Ｉ４−１を用いて伝達行列Ａを求め、さらに逆行列Ａ−１を求める。
次に、当該入射パターン１で取得した各光強度と逆行列Ａ−１とを用いて、前述の式（４）から入射ストークスベクトル［Ｓｉｎ１］の要素（Ｓ０ｉｎ１，Ｓ１ｉｎ１，Ｓ２ｉｎ１，Ｓ３ｉｎ１）を算出する。
この後、項目３−２で説明したように偏光状態が重複しないように、各光学素子の方位角度等を設定し、例えば図１０の表２に示した入射パターン２〜４に示した各設定値についても、入射パターン１と同様な演算処理を行い、図２に示した４つのパターンの偏光状態を示す４つの入射ストークスベクトル［Ｓｉｎ１］，［Ｓｉｎ２］，［Ｓｉｎ３］，［Ｓｉｎ４］、もしくは、これらのベクトル要素を求める。
Specifically, the calculation means 16 is data indicating values of the respective orientations θ R2 and θ P2 of the set phase plate R2 and the polarizer P2 (for example, the incident pattern 1 shown in Table 2 of FIG. 10). And using these values and the phase difference δ2 obtained in Step 1, the calculation of Expression (2) is performed. Also, determine the transfer matrix A with the light intensity I 1-1 ~I 4-1 obtained by the calculation of equation (2), further obtains the inverse matrix A -1.
Then, by using the the incident pattern 1 each light intensity and the inverse matrix A -1 obtained in the elements of the incident Stokes vector [S in1] from the above-mentioned formula (4) (S 0in1, S 1in1, S 2in1, S3in1 ) is calculated.
Thereafter, as described in item 3-2, the azimuth angle of each optical element is set so that the polarization states do not overlap. For example, each setting shown in the incident patterns 2 to 4 shown in Table 2 of FIG. For the values, the same calculation process as that of the incident pattern 1 is performed, and the four incident Stokes vectors [S in1 ], [S in2 ], [S in3 ], [S] indicating the polarization states of the four patterns shown in FIG. in4 ] or these vector elements.
図３は、図１の演算手段１６が求める透過後ストークスベクトルを示す説明図である。
演算手段１６は、透過後ストークススペクトル［Ｓoutｊ］を求めるとき、前述の各光学素子を、例えば、図１０の表２に示したいずれかの方位角度（θＰ１，θＲ１，θＲ２，θＰ２）に設定し、設定した方位角度について、項目３−３で説明したようにＳｔｅｐ１ならびにＳｔｅｐ２の動作処理を行って、測定装置１に試料１３を設置して光入射させたときの伝達行列Ａならびに逆行列Ａ−１を求め、これを用いて透過後ストークスベクトル［Ｓout１］，［Ｓout２］，［Ｓout３］，［Ｓout４］を求める。なお、これらの透過後ストークスベクトルは、図３に示したように各々４つの要素からなる。
FIG. 3 is an explanatory diagram showing a post-transmission Stokes vector obtained by the calculation means 16 of FIG.
When calculating the post-transmission Stokes spectrum [S outj ], the calculation means 16 is configured to change the above-described optical elements to, for example, any one of the azimuth angles (θ P1 , θ R1 , θ R2 , θ shown in Table 2 of FIG. P2 ), and for the set azimuth angle, the transfer matrix A when the operation process of Step 1 and Step 2 is performed as described in Item 3-3, and the sample 13 is placed in the measuring apparatus 1 and light is incident thereon. In addition, an inverse matrix A −1 is obtained, and a post-transmission Stokes vector [S out1 ], [S out2 ], [S out3 ], [S out4 ] is obtained using this. These post-transmission Stokes vectors are each composed of four elements as shown in FIG.
図４は、図１の測定装置１に設置される試料１３の一例を示す説明図である。図示した試料１３は、例えば、２種類の位相差フィルムをガラス基板に貼り付け固定し、各位相差フィルムの主軸方位が直交するように構成されたものである。
具体的に透過後ストークスベクトル［Ｓoutｊ］を求めるとき、測定装置１の試料ステージに、例えば、図４に示した試料１３を設置固定し、光源１１から光照射を行って、偏光変調部１２を介して試料１３へ入射させ、試料１３の出射光を偏光解析部１４を介して検出器１５へ入射させる。このとき、偏光変調部１２の偏光子Ｐ１と位相板Ｒ１、および偏光解析部１４の位相板Ｒ２と偏光子Ｐ２の各方位角度等は、入射ストークスベクトル［Ｓｉｎ１］を求めたときと同様に、例えば図１０の表２に示した値に設定され、演算手段１６は、例えば入射パターン１の各値に設定されたときの各光強度を測定してメモリ等に記憶させる。
FIG. 4 is an explanatory diagram showing an example of the sample 13 installed in the measurement apparatus 1 of FIG. The illustrated sample 13 is configured such that, for example, two types of retardation films are attached and fixed to a glass substrate, and the principal axis directions of the respective retardation films are orthogonal to each other.
Specifically, when obtaining the post-transmission Stokes vector [S outj ], for example, the sample 13 shown in FIG. 4 is placed and fixed on the sample stage of the measurement apparatus 1, and light irradiation is performed from the light source 11, and the polarization modulation unit 12. Then, the light emitted from the sample 13 is incident on the detector 15 via the polarization analyzer 14. At this time, the azimuth angles of the polarizer P1 and the phase plate R1 of the polarization modulator 12 and the phase plate R2 and the polarizer P2 of the polarization analyzer 14 are the same as when the incident Stokes vector [S in1 ] is obtained. For example, the values shown in Table 2 of FIG. 10 are set, and the calculation means 16 measures each light intensity when it is set to each value of the incident pattern 1 and stores it in a memory or the like.
この後、メモリ等に記憶させた光強度を用いて、前述の入射ストークスベクトル［Ｓｉｎ１］の要素（Ｓ０ｉｎ１，Ｓ１ｉｎ１，Ｓ２ｉｎ１，Ｓ３ｉｎ１）を求めたときと同様な演算処理を行い、試料１３を設置したとき（試料１３透過後）の透過後ストークスベクトル（Ｓ０ｏｕｔ１）の要素（Ｓ０ｏｕｔ１，Ｓ１ｏｕｔ１，Ｓ２ｏｕｔ１，Ｓ３ｏｕｔ１）を算出する。
次に、前述の入射ストークスベクトル［Ｓｉｎ１］を求めたときと同様に、偏光状態が重複しないように各光学素子の方位角度等を設定し、例えば表２に示した入射パターン２〜４に示した各設定値についても、入射パターン１と同様な演算処理を行い、図３に示した４つのパターンの偏光状態を示す４つの透過後ストークスベクトル［Ｓｏｕｔ１］，［Ｓｏｕｔ２］，［Ｓｏｕｔ３］，［Ｓｏｕｔ４］、もしくは、これらのベクトル要素を求める。
Thereafter, using the light intensity stored in the memory or the like, the same calculation process as that for obtaining the elements (S 0in1 , S 1in1 , S 2in1 , S 3in1 ) of the incident Stokes vector [S in1 ] is performed. Then, the elements (S 0out1 , S 1out1 , S 2out1 , S 3out1 ) of the post-transmission Stokes vector (S 0out1 ) when the sample 13 is installed (after the sample 13 is transmitted) are calculated.
Next, as in the case where the above-described incident Stokes vector [S in1 ] is obtained, the azimuth angle of each optical element is set so that the polarization states do not overlap, and the incident patterns 2 to 4 shown in Table 2, for example, are set. For each set value shown, the same calculation process as that of the incident pattern 1 is performed, and four post-transmission Stokes vectors [S out1 ], [S out2 ], [S] indicating the polarization states of the four patterns shown in FIG. out3 ], [ Sout4 ], or their vector elements.
このように求めた入射ストークスベクトル［Ｓｉｎ１］［Ｓｉｎ２］，［Ｓｉｎ３］，［Ｓｉｎ４］と透過後ストークスベクトル［Ｓｏｕｔ１］，［Ｓｏｕｔ２］，［Ｓｏｕｔ３］，［Ｓｏｕｔ４］を用いて、試料１３のミュラー行列Ｍを式（７）の演算によって算出する。
図５は、演算手段１６が算出した試料１３のミュラー行列Ｍを示す説明図である。この図は、図４に示した試料１３について、測定装置１を用いて求めたミュラー行列Ｍを示したものである。図５（ａ）は、ミュラー行列Ｍを構成する各要素の偏光状態をグラフィカルに示し、図５（ｂ）は、当該ミュラー行列Ｍの各要素の大きさ、もしくは数値を示している。
The incident Stokes vectors [S in1 ] [S in2 ], [S in3 ], [S in4 ] and post-transmission Stokes vectors [S out1 ], [S out2 ], [S out3 ], [S out4 ]. Is used to calculate the Mueller matrix M of the sample 13 by the calculation of Expression (7).
FIG. 5 is an explanatory diagram showing the Mueller matrix M of the sample 13 calculated by the calculation means 16. This figure shows the Mueller matrix M calculated | required using the measuring apparatus 1 about the sample 13 shown in FIG. 5A graphically shows the polarization state of each element constituting the Mueller matrix M, and FIG. 5B shows the size or numerical value of each element of the Mueller matrix M.
次に、演算手段１６は、算出したミュラー行列Ｍの要素から、各偏光状態を抽出する。具体的には、式（６）に示したミュラー行列Ｍの各要素を用いて次の各式の演算を行い、試料１３の偏光特性を定量化する。 Next, the calculation means 16 extracts each polarization state from the calculated element of the Mueller matrix M. Specifically, the following formulas are calculated using each element of the Mueller matrix M shown in Formula (6), and the polarization characteristics of the sample 13 are quantified.
図６は、ミュラー行列の要素から抽出した偏光状態を示す説明図である。この図は、上記の各式を用いて算出した、試料１３の偏光特性の解析結果を示したもので、図６（ａ）は試料１３の複屈折位相差を示し、図６（ｂ）は試料１３の主軸方位を示し、図６（ｃ）は試料１３の特性測定における偏光解消度を示している。 FIG. 6 is an explanatory diagram showing the polarization state extracted from the elements of the Mueller matrix. This figure shows the analysis result of the polarization characteristics of the sample 13 calculated using the above equations. FIG. 6 (a) shows the birefringence phase difference of the sample 13, and FIG. 6 (b) The principal axis direction of the sample 13 is shown, and FIG. 6C shows the degree of depolarization in the characteristic measurement of the sample 13.
図７は、図１の測定装置１を用いて測定した偏光特性の一例を示す説明図である。例えば、設計波長が６３３ｎｍの位相板（位相差９０度のλ／４板）を試料１３として偏光特性を測定したとき、測定装置１の光源１１は波長が７８０ｎｍなので、この試料１３によって生じる位相差は約７５度となり、上記のように光源１１の波長と試料１３の設計波長が異なる場合では、図７に示した程度の誤差が測定結果に生じる。
図８は、本発明を用いた測定結果と一般的な測定（解析）方法を用いた測定結果を示す説明図である。この図は、試料１３（図中サンプルと表記）の複屈折位相差を測定したときの測定（解析）結果を示したもので、縦軸に解析結果（位相差の角度）を示し、横軸に試料１３（サンプル）の位相差（角度）を示している。なお、この図に示した、一般的な解析方法を用いた測定装置の測定（解析）結果については、当該装置に備えられた、試料からの出射光を入射する位相板Ｒ２（本発明の測定装置１においては偏光解析部１４の位相板Ｒ２に相当するもの）として、位相差６０度〜１２０度の範囲内において、いずれかの角度に固定されたものを用いて測定している。
FIG. 7 is an explanatory diagram showing an example of polarization characteristics measured using the measuring apparatus 1 of FIG. For example, when the polarization characteristic is measured using a phase plate having a design wavelength of 633 nm (λ / 4 plate having a phase difference of 90 degrees) as the sample 13, the light source 11 of the measuring apparatus 1 has a wavelength of 780 nm. When the wavelength of the light source 11 and the design wavelength of the sample 13 are different as described above, an error as shown in FIG.
FIG. 8 is an explanatory diagram showing a measurement result using the present invention and a measurement result using a general measurement (analysis) method. This figure shows the measurement (analysis) result when measuring the birefringence phase difference of the sample 13 (denoted as the sample in the figure). The vertical axis shows the analysis result (phase difference angle), and the horizontal axis Shows the phase difference (angle) of the sample 13 (sample). As for the measurement (analysis) result of the measurement apparatus using the general analysis method shown in this figure, the phase plate R2 that is provided in the apparatus and that receives the light emitted from the sample (measurement of the present invention) In the apparatus 1, the measurement is performed by using one that is fixed at any angle within the range of the phase difference of 60 degrees to 120 degrees as the one corresponding to the phase plate R <b> 2 of the ellipsometer 14.
図８に示した一般的な測定装置の測定（解析）結果は、複屈折率位相差の誤差が１０〜２０％程度となる。これに対して、本発明の測定装置１の測定（解析）結果は、図１１の表３に示したように誤差が約５％以内となる。
このことから、本発明の測定装置１は、演算手段１６がミュラー行列Ｍを用いた演算処理を行うことにより、当該測定装置１に備えられた光学素子等に存在する偏光を解消して試料１３が有する本来の偏光特性に、より近い結果を得ることができる。換言すると、各光学素子等によって生じる偏光を補正して、当該光学素子等による偏光の影響を解消することができるという効果が得られる。
The measurement (analysis) result of the general measuring apparatus shown in FIG. 8 shows that the error of the birefringence phase difference is about 10 to 20%. On the other hand, the measurement (analysis) result of the measurement apparatus 1 of the present invention has an error within about 5% as shown in Table 3 of FIG.
Therefore, in the measurement apparatus 1 of the present invention, the calculation means 16 performs a calculation process using the Mueller matrix M, thereby eliminating the polarization existing in the optical element or the like provided in the measurement apparatus 1 and the sample 13. It is possible to obtain a result closer to the original polarization characteristic possessed by. In other words, it is possible to obtain an effect of correcting the polarization generated by each optical element or the like and eliminating the influence of the polarization caused by the optical element or the like.
また、光学素子等が有する偏光特性を補正して解消することができるので、試料１３と各光学素子等に設定されている光波長が異なっている場合でも、精度良く試料１３の偏光特性を測定することができる。
また、偏光特性を測定するときのサンプリング数を１６に抑制することができ、測定結果を算出するまでの時間を短時間に抑えることが可能になる。
In addition, since the polarization characteristic of the optical element or the like can be corrected and eliminated, the polarization characteristic of the sample 13 can be accurately measured even when the light wavelength set in the sample 13 and each optical element or the like is different. can do.
Further, the number of samplings when measuring the polarization characteristics can be suppressed to 16, and the time until the measurement result is calculated can be suppressed in a short time.
１測定装置
１１光源
１２偏光変調部
１３試料
１４偏光解析部
１５検出器
１６演算手段
DESCRIPTION OF SYMBOLS 1 Measuring apparatus 11 Light source 12 Polarization modulation part 13 Sample 14 Polarization analysis part 15 Detector 16 Calculation means
Claims (5)
前記位相板を備えた偏光解析部を介して検出器が検出した光強度を用いて前記位相板の位相差を演算手段が算出する第１過程と、
前記第１過程で算出した位相差を用いて前記位相板を備えた偏光解析部のストークスベクトルを前記演算手段が算出する第２過程と、
を有し、
前記第１過程は、
前記光源と前記偏光解析部との間に設置される偏光変調部および前記偏光解析部の位相方位角度ならびに透過方位角度を任意の角度に設定する第３過程と、
前記第３過程で任意の角度に設定した状態において前記検出器が撮影した画像ファイルを記憶手段へ記憶させる第４過程と、
を有し、前記第３過程および第４過程を所定回数繰り返すことにより、前記位相方位角度ならびに透過方位角度の設定角度を変更して撮影させた画像ファイルを順次記憶させ、該記憶させた各画像ファイルの光強度を用いて前記位相板の位相差を算出し、
前記第２過程は、
前記第１過程で算出した位相差および前記位相方位角度ならびに透過方位角度の各設定角度を用いて、所定の演算により前記位相板のストークスベクトルの各係数を求める第５過程と、
前記各係数を要素とする伝達行列およびその逆行列を求め、前記各画像ファイルの光強度を要素とする光強度行列と前記逆行列とを用いた演算により、前記ストークスベクトルを求める第６過程と、
を有することを特徴とする偏光特性測定方法。 A polarization characteristic measuring method using a phase plate having a design light wavelength different from the light wavelength emitted from the light source,
A first step in which the calculation means calculates the phase difference of the phase plate using the light intensity detected by the detector via the polarization analyzer provided with the phase plate;
A second step in which the computing means calculates a Stokes vector of the polarization analyzer provided with the phase plate using the phase difference calculated in the first step;
Have
The first process includes
A third step of setting the phase azimuth angle and the transmission azimuth angle of the polarization modulation unit and the polarization analysis unit installed between the light source and the polarization analysis unit to arbitrary angles;
A fourth step of storing an image file captured by the detector in a state set at an arbitrary angle in the third step in a storage unit;
And repeating the third process and the fourth process a predetermined number of times to sequentially store the image files photographed by changing the set angles of the phase azimuth angle and the transmission azimuth angle, and each of the stored images Calculate the phase difference of the phase plate using the light intensity of the file,
The second process includes
A fifth step of obtaining each coefficient of the Stokes vector of the phase plate by a predetermined calculation using the phase difference calculated in the first step and the set angles of the phase azimuth angle and the transmission azimuth angle;
A sixth process of obtaining a Stokes vector by calculating a transfer matrix having each coefficient as an element and an inverse matrix thereof, and performing an operation using the light intensity matrix having the light intensity of each image file as an element and the inverse matrix; ,
A method for measuring polarization characteristics, comprising:
前記光源から光入射して試料へ光出射する偏光変調部と、前記試料から光入射して検出器へ光出射する偏光解析部と、の間に前記試料を設置していない第１の状態で前記検出器へ光入射を行い、このときの前記検出器の出力信号を用いて演算手段が前記第１の状態を示す第１ストークスベクトルを求める第１過程と、
前記偏光変調部と前記偏光解析部との間に前記試料を設置した第２の状態で前記検出器へ光入射を行い、このときの前記検出器の出力信号を用いて前記演算手段が前記第２の状態を示す第２ストークスベクトルを求める第２過程と、
前記第１ストークスベクトルを示す行列と前記第２ストークスベクトルを示す行列とを用いて前記試料の偏光特性を示すミュラー行列を求める第３過程と、
を有することを特徴とする偏光特性測定方法。 A polarization characteristic measuring method using a phase plate having a design light wavelength different from the light wavelength emitted from the light source,
In a first state in which the sample is not installed between the polarization modulation unit that makes light incident from the light source and emits light to the sample, and the polarization analysis unit that makes light incident from the sample and emits light to the detector A first step in which light is incident on the detector, and a calculation unit obtains a first Stokes vector indicating the first state using an output signal of the detector at this time;
Light is incident on the detector in a second state in which the sample is placed between the polarization modulator and the polarization analyzer, and the computing means uses the output signal of the detector at this time to calculate the first A second step of obtaining a second Stokes vector indicating the state of 2,
A third step of obtaining a Mueller matrix indicating a polarization characteristic of the sample using a matrix indicating the first Stokes vector and a matrix indicating the second Stokes vector;
A method for measuring polarization characteristics, comprising:
前記偏光変調部および前記偏光解析部の位相方位角度ならびに透過方位角度を任意の角度に設定する第４過程と、
前記第４過程で任意の角度に設定した状態において前記検出器が撮影した画像ファイルを記憶手段へ記憶させる第５過程と、
前記第４過程および第５過程を所定回数繰り返すことにより、前記位相方位角度ならびに透過方位角度意の設定角度を変更して撮影させた画像ファイルを順次記憶させ、該記憶させた各画像ファイルの光強度を用いて、前記第１の状態における前記偏光解析部に備えた位相板の位相差を算出し、前記算出した位相差および前記位相方位角度ならびに透過方位角度の各設定角度を用いて、所定の演算により前記第１ストークスベクトルの各係数を求める第６過程と、
前記第６過程で求めた各係数を要素とする伝達行列およびその逆行列を求め、前記第１の状態における各画像ファイルの光強度を要素とする光強度行列と前記逆行列とを用いた演算により、前記第１ストークスベクトルを求める第７過程と、
を有し、
前記第２過程は、
前記偏光変調部および前記偏光解析部の位相方位角度ならびに透過方位角度を任意の角度に設定する第８過程と、
前記第８過程で任意の角度に設定した状態において前記検出器が撮影した画像ファイルを記憶手段へ記憶させる第９過程と、
前記第８過程および第９過程を所定回数繰り返すことにより、前記位相方位角度ならびに透過方位角度の設定角度を変更して撮影させた画像ファイルを順次記憶させ、該記憶させた各画像ファイルの光強度を用いて、前記第２の状態における前記偏光解析部に備えた位相板の位相差を算出し、前記算出した位相差および前記位相方位角度ならびに透過方位角度の各設定角度を用いて、所定の演算により前記第２ストークスベクトルの各係数を求める第１０過程と、
前記第１０過程で求めた各係数を要素とする伝達行列およびその逆行列を求め、前記第２の状態における各画像ファイルの光強度を要素とする光強度行列と前記逆行列とを用いた演算により、前記第２ストークスベクトルを求める第１１過程と、
を有することを特徴とする請求項２に記載の偏光特性測定方法。 The first process includes
A fourth step of setting the phase azimuth angle and the transmission azimuth angle of the polarization modulation unit and the polarization analysis unit to arbitrary angles;
A fifth step of storing an image file captured by the detector in a state set at an arbitrary angle in the fourth step in a storage means;
By repeating the fourth process and the fifth process a predetermined number of times, the image files captured by changing the phase azimuth angle and the transmission azimuth angle are sequentially stored, and the light of each stored image file is stored. The intensity is used to calculate the phase difference of the phase plate provided in the polarization analysis unit in the first state, and the calculated phase difference, the phase azimuth angle, and the transmission azimuth angle are used as predetermined angles. A sixth step of obtaining each coefficient of the first Stokes vector by the calculation of
A transfer matrix having each coefficient obtained in the sixth process as an element and its inverse matrix are obtained, and an operation using the light intensity matrix having the light intensity of each image file in the first state as an element and the inverse matrix A seventh step of obtaining the first Stokes vector;
Have
The second process includes
An eighth step of setting the phase azimuth angle and the transmission azimuth angle of the polarization modulator and the polarization analyzer to arbitrary angles;
A ninth step of storing in the storage means an image file taken by the detector in a state set at an arbitrary angle in the eighth step;
By repeating the eighth process and the ninth process a predetermined number of times, the image files photographed by changing the set angles of the phase azimuth angle and the transmission azimuth angle are sequentially stored, and the light intensity of each stored image file Is used to calculate the phase difference of the phase plate provided in the polarization analyzer in the second state, and using the calculated phase difference and the set angles of the phase azimuth angle and the transmission azimuth angle, A tenth step of calculating each coefficient of the second Stokes vector by calculation;
A transfer matrix having each coefficient obtained in the tenth process as an element and an inverse matrix thereof are obtained, and an operation using the light intensity matrix having the light intensity of each image file in the second state as an element and the inverse matrix An eleventh step of obtaining the second Stokes vector;
The method for measuring polarization characteristics according to claim 2, wherein:
前記試料の偏光特性を示すミュラー行列の所定の要素を用いて所定の演算を行い、前記試料の偏光特性を定量化する過程を含む、
ことを特徴とする請求項２または３に記載の偏光特性測定方法。 The third process includes
Performing a predetermined calculation using a predetermined element of the Mueller matrix indicating the polarization property of the sample, and quantifying the polarization property of the sample,
The method for measuring polarization characteristics according to claim 2 or 3.
前記光源からの光を入射して試料へ出射する偏光変調部と、
前記試料からの光を入射して画像を撮影する検出器へ出射する偏光解析部と、
前記偏光解析部から出力された信号を用いて所定の演算処理を行う演算手段と、
を備え、
前記偏光変調部および前記偏光解析部は、前記光源の発光波長と異なる設計光波長の位相板を有し、位相方位角度ならびに透過方位角度を所定の角度へ設定可能に構成されており、
前記演算手段は、
前記試料を前記偏光変調部と前記偏光解析部の間に設置していない第１の状態で前記検出器へ光入射を行い、このときの前記検出器の出力信号を用いて前記位相板の位相差を求め、該位相差および前記偏光変調部および前記偏光解析部に設定された位相方位角度ならびに透過方位角度を用いて前記第１の状態における第１ストークスベクトルを求め、
前記試料を前記偏光変調部と前記偏光解析部の間に設置した第２の状態で前記検出器へ光入射を行い、このときの前記検出器の出力信号を用いて前記位相板の位相差を求め、該位相差および前記偏光変調部および前記偏光解析部に設定された位相方位角度ならびに透過方位角度を用いて前記第２の状態における第２ストークスベクトルを求め、
前記第１ストークスベクトルを示す行列と前記第２ストークスベクトルを示す行列とを用いて前記試料の偏光特性を示すミュラー行列を求める、
ことを特徴とする偏光特性測定装置。 A light source;
A polarization modulation unit that enters the light from the light source and emits the light to the sample; and
An ellipsometer that emits light from the sample and emits it to a detector that captures an image;
A calculation means for performing a predetermined calculation process using a signal output from the polarization analysis unit;
With
The polarization modulation unit and the polarization analysis unit have a phase plate with a design light wavelength different from the emission wavelength of the light source, and are configured to be able to set a phase azimuth angle and a transmission azimuth angle to a predetermined angle,
The computing means is
Light is incident on the detector in a first state where the sample is not installed between the polarization modulator and the polarization analyzer, and the position of the phase plate is measured using the output signal of the detector at this time. Obtaining a phase difference, obtaining a first Stokes vector in the first state using the phase difference and the phase azimuth angle and transmission azimuth angle set in the polarization modulator and the polarization analyzer;
Light is incident on the detector in a second state in which the sample is placed between the polarization modulator and the polarization analyzer, and the phase difference of the phase plate is calculated using the output signal of the detector at this time. Determining the second Stokes vector in the second state using the phase difference and the phase azimuth angle and transmission azimuth angle set in the polarization modulator and the polarization analyzer,
Obtaining a Mueller matrix indicating polarization characteristics of the sample using a matrix indicating the first Stokes vector and a matrix indicating the second Stokes vector;
An apparatus for measuring polarization characteristics.
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