JP2014020890A - Polarization measurement method, polarization measurement device, and polarization measurement system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the polarization characteristics of polarized rays of light.SOLUTION: On the basis of light quantity I of the rays of light at each rotational angle θ to be acquired by detecting the rays of light successively transmitted through a wire grid polarizer 16 and a detection side polarizer 33 while rotating the detection side polarizer 33, a change curve Q showing the periodic change of the light quantity I when the detection side polarizer 33 is rotated is searched, and when the polarization characteristics of polarized rays of light F transmitted through the wire grid polarizer 16 are specified on the basis of the change curve Q, the change curve Q is searched on the basis of the light quantity I at the rotational angle θ included in a range W of the rotational angle θ in which a rotational angle θ=θa as one minimum point of the change curve Q is included, and the light quantity I becomes a predetermined value or less.

Description

本発明は、偏光光の測定技術に関する。   The present invention relates to a technique for measuring polarized light.

従来、配向膜、或いは配向層（以下、これらを「光配向膜」と称する）に偏光光を照射することで配向する光配向と呼ばれる技術が知られており、この光配向は、液晶表示パネルの液晶表示素子が備える液晶配向膜の配向等に広く応用されている。
光配向に用いる照射装置は、一般に、光源と、偏光子とを備え、光源の光を偏光子に通して偏光光を得る。近年では、長い帯状の光配向膜を光配向するために、光配向膜の幅相当の長さの棒状ランプを光源とし、複数の偏光子を棒状ランプの長軸方向に配列することでライン状の偏光光を照射する照射装置が知られており、この照射装置の偏光光の照射エリアが延びる方向に帯状の光配向膜の幅方向を合わせ、当該光配向膜を長さ方向に搬送することで帯状の光配向膜を均一に光配向する技術も提案されている（例えば、特許文献１参照）。
光配向の品位に影響を与える偏光光のファクターとしては、消光比と、偏光軸分布のバラツキとの２つが知られており、光配向に使用される照射装置としては、これらが高い精度で調整されていることが重要である。これら消光比や偏光軸を測定する技術としては、従来から各種の技術が提案されている（例えば、特許文献２〜特許文献４参照）。 Conventionally, a technique called photo-alignment is known in which alignment film or alignment layer (hereinafter referred to as “photo-alignment film”) is aligned by irradiating polarized light, and this photo-alignment is a liquid crystal display panel. The liquid crystal display element is widely applied to alignment of liquid crystal alignment films.
An irradiation device used for photo-alignment generally includes a light source and a polarizer, and obtains polarized light by passing light from the light source through the polarizer. In recent years, in order to photo-align a long strip-shaped photo-alignment film, a rod-shaped lamp having a length corresponding to the width of the photo-alignment film is used as a light source, and a plurality of polarizers are arranged in the longitudinal direction of the rod-shaped lamp to form a line shape. An irradiation apparatus that irradiates polarized light is known, and the width direction of the strip-shaped photo-alignment film is aligned with the direction in which the irradiation area of the polarized light of this irradiation apparatus extends, and the photo-alignment film is conveyed in the length direction. A technique for uniformly photo-aligning a strip-shaped photo-alignment film has also been proposed (see, for example, Patent Document 1).
There are two known factors for polarized light that affect the quality of photo-alignment: extinction ratio and variation in polarization axis distribution. These are adjusted with high accuracy as the irradiation device used for photo-alignment. It is important that Various techniques have been proposed for measuring these extinction ratios and polarization axes (see, for example, Patent Documents 2 to 4).

特開２００４−１６３８８１号公報JP 2004-163881 A 特開２００４−２２６２０９号公報JP 2004-226209 A 特開２００５−２２７０１９号公報JP 2005-227019 A 特開２００７−１２７５６７号公報JP 2007-127567 A

光配向を用いて高品位な液晶配光膜を得るために、消光比が高く、偏光軸が誤差０．１°以内の精度で調整される必要がある。偏光軸が誤差０．１°以内の精度で調整するためには測定精度として誤差０．０１°以内を要求されるが、放電灯を光源とする照射装置では、この放電灯の点灯電力の揺らぎ等に起因して光量に揺らぎ（ちらつき）が生じるためこのような要求を満足する精度で偏光光の偏光特性を測定できる技術が無かった。
従来の方法では、光量に揺らぎが生じるため、同じ測定を何度も繰り返し行って平均を取ることで、繰り返し精度を高める必要があり、測定に時間を要するという問題があった。
本発明は、上述した事情に鑑みてなされたものであり、光量に揺らぎのある偏光光の偏光特性を精度良く測定できる偏光測定方法、偏光測定装置、及び偏光測定システムを提供することを目的とする。 In order to obtain a high-quality liquid crystal light distribution film using photo-alignment, the extinction ratio must be high and the polarization axis must be adjusted with an accuracy of within 0.1 °. In order to adjust the polarization axis with an accuracy of 0.1 ° or less, the measurement accuracy requires an error of 0.01 ° or less. However, in an irradiation apparatus using a discharge lamp as a light source, fluctuations in the lighting power of the discharge lamp are required. Therefore, there is no technique that can measure the polarization characteristics of polarized light with an accuracy that satisfies such requirements.
In the conventional method, since the light amount fluctuates, it is necessary to increase the repeat accuracy by repeatedly performing the same measurement repeatedly and taking an average, and there is a problem that it takes time for the measurement.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a polarization measurement method, a polarization measurement device, and a polarization measurement system that can accurately measure the polarization characteristics of polarized light having fluctuations in the amount of light. To do.

上記目的を達成するために、本発明は、第１の偏光子、及び第２の偏光子を順に透過した光を前記第２の偏光子を回動させながら検出して得られる各回動角度での光の光量に基づいて、前記第２の偏光子が回転したときの前記光量の周期的な変化を示す変化曲線を求める第１ステップと、前記第１ステップで求めた変化曲線に基づいて前記第１の偏光子を透過した偏光光の偏光特性を特定する第２ステップと、を備え、前記第１ステップでは、前記変化曲線の１つの極小点を含み、かつ、前記光量が所定値以下となる前記回動角度の範囲に含まれる前記回動角度での前記光量に基づいて前記変化曲線を求めることを特徴とする偏光測定方法を提供する。   In order to achieve the above-described object, the present invention provides each rotation angle obtained by detecting light sequentially transmitted through the first polarizer and the second polarizer while rotating the second polarizer. A first step for obtaining a change curve indicating a periodic change in the light amount when the second polarizer rotates based on the light amount of the light, and the change curve obtained in the first step A second step of specifying a polarization characteristic of the polarized light transmitted through the first polarizer, wherein the first step includes one minimum point of the change curve and the light amount is equal to or less than a predetermined value. The polarization measuring method is characterized in that the change curve is obtained based on the light quantity at the rotation angle included in the rotation angle range.

また本発明は、上記偏光測定方法において、前記第１ステップと異なる１つの極小点を含み、かつ、前記光量が所定値以下となる前記回動角度の範囲に含まれる前記回動角度での前記光量に基づいて前記変化曲線を求める第３ステップと、前記第３ステップで求めた変化曲線に基づいて前記第１の偏光子を透過した偏光光の偏光特性を特定する第４ステップと、前記第２ステップ、及び第４ステップのそれぞれで特定された前記偏光特性の平均に基づき、前記第１の偏光子を透過した偏光光の偏光特性を特定する第５ステップとを備えたことを特徴とする。   In the polarization measurement method, the present invention includes the minimum angle different from the first step, and the rotation angle included in the rotation angle range in which the light amount is a predetermined value or less. A third step for obtaining the change curve based on the amount of light; a fourth step for specifying a polarization characteristic of the polarized light transmitted through the first polarizer based on the change curve obtained in the third step; And a fifth step of specifying a polarization characteristic of polarized light transmitted through the first polarizer based on an average of the polarization characteristics specified in each of the second step and the fourth step. .

また本発明は、上記偏光測定方法において、前記所定値は、前記光量の最大値の約２０％の光量であることを特徴とする。   In the polarization measurement method according to the invention, the predetermined value is approximately 20% of the maximum light amount.

また本発明は、上記偏光測定方法において、前記変化曲線が示す光量の最大値に対応する回動角度に基づいて前記第１の偏光子を透過した偏光光の偏光軸を特定し、及び／又は、前記変化曲線が示す最大値と最小値、或いは、前記変化曲線に基づき特定される偏光光の偏光軸の回動角度、及び当該偏光軸に直交する回動角度の各々に前記第２の偏光子が回動したときに測定された光量に基づいて前記第１の偏光子を透過した偏光光の消光比を特定することを特徴とする。   According to the present invention, in the polarization measurement method, the polarization axis of the polarized light transmitted through the first polarizer is specified based on a rotation angle corresponding to the maximum light amount indicated by the change curve, and / or , The maximum value and minimum value indicated by the change curve, or the rotation angle of the polarization axis of the polarized light specified based on the change curve, and the rotation angle orthogonal to the polarization axis, respectively. The extinction ratio of the polarized light transmitted through the first polarizer is specified based on the amount of light measured when the child rotates.

また上記目的を達成するために、本発明は、第１の偏光子、及び第２の偏光子を順に透過した光を前記第２の偏光子を回動させながら検出して得られる各回動角度での光の光量に基づいて、前記第２の偏光子が回転したときの前記光量の周期的な変化を示す変化曲線を求める変化曲線算出手段と、前記変化曲線に基づいて前記第１の偏光子を透過した偏光光の偏光特性を特定する偏光特性特定手段と、を備え、前記変化曲線算出手段は、前記変化曲線の１つの極小点を含み、かつ、前記光量が所定値以下となる前記回動角度の範囲に含まれる前記回動角度での前記光量に基づいて前記変化曲線を求めることを特徴とする偏光測定装置を提供する。   In order to achieve the above-mentioned object, the present invention provides each rotation angle obtained by detecting light sequentially transmitted through the first polarizer and the second polarizer while rotating the second polarizer. Change curve calculating means for obtaining a change curve indicating a periodic change in the light amount when the second polarizer rotates based on the light amount of the light at the first polarization based on the change curve Polarization characteristic specifying means for specifying polarization characteristics of polarized light transmitted through the optical element, and the change curve calculation means includes one minimum point of the change curve, and the light amount is equal to or less than a predetermined value. There is provided a polarization measuring device characterized in that the change curve is obtained based on the amount of light at the rotation angle included in a range of rotation angles.

また上記目的を達成するために、本発明は、第１の偏光子で偏光化された偏光光を入射する第２の偏光子を有し、前記第２の偏光子を透過する光の光量を前記第２の偏光子を回動させながら検出する検出部と、前記検出部の検出結果に基づいて、前記第１の偏光子を透過した偏光光の偏光特性を特定する偏光測定装置と、を備え、前記検出部は、斜入射成分を含む前記光を取り込み前記第２の偏光子に入射する第１のアパーチャと、前記第２の偏光子を透過した光を拡散する拡散手段と、前記拡散手段で拡散された光の一部を通す第２のアパーチャと、前記第２のアパーチャを通過した光を受光して前記光量を検出する受光センサと、を有し、前記偏光測定装置は、前記第２の偏光子の各回動角度での光の光量に基づいて、前記第２の偏光子が回転したときの前記光量の周期的な変化を示す変化曲線を求める変化曲線算出手段と、前記変化曲線に基づいて前記第１の偏光子を透過した偏光光の偏光特性を特定する偏光特性特定手段と、を備え、前記変化曲線算出手段は、前記変化曲線の１つの極小点を含み、かつ、前記光量が所定値以下となる前記回動角度の範囲に含まれる前記回動角度での前記光量に基づいて前記変化曲線を求めることを特徴とする偏光測定システムを提供する。   In order to achieve the above object, the present invention has a second polarizer for entering polarized light polarized by the first polarizer, and the amount of light transmitted through the second polarizer is reduced. A detection unit that detects the second polarizer while rotating, and a polarization measurement device that specifies polarization characteristics of polarized light that has passed through the first polarizer, based on a detection result of the detection unit. The detection unit includes a first aperture that takes in the light including a grazing incidence component and enters the second polarizer, a diffusion unit that diffuses light transmitted through the second polarizer, and the diffusion A second aperture that passes a part of the light diffused by the means, and a light receiving sensor that receives the light that has passed through the second aperture and detects the amount of light; Based on the amount of light at each rotation angle of the second polarizer, the second polarizer Change curve calculating means for obtaining a change curve indicating a periodic change in the amount of light when rotated, and polarization characteristic specifying means for specifying the polarization characteristic of the polarized light transmitted through the first polarizer based on the change curve And the change curve calculation means includes one minimum point of the change curve, and the light amount at the rotation angle included in the rotation angle range in which the light amount is equal to or less than a predetermined value. The polarization measurement system is characterized in that the change curve is obtained based on the above.

本発明によれば、第１の偏光子、及び第２の偏光子を順に透過した光を第２の偏光子を回動させながら検出して得られる各回動角度での光の光量に基づいて、第２の偏光子が回転したときの光量の周期的な変化を示す変化曲線を求めるに際し、変化曲線の１つの極小点を含み、かつ、光量が所定値以下となる回動角度の範囲に含まれる回動角度での光量に基づいて変化曲線を求める構成とした。
これにより、極大点近傍の光量の検出値に比べ、検出値に含まれるノイズ成分が小さい検出値に基づいて変化曲線が求められるため、変化曲線の精度が高められる。そして、この変化曲線から偏光特性を求めることで、精度良く偏光特性が求められる。
また極小点近傍での光量だけが測定されていれば良いため、少ない測定回数で高精度な測定が可能となる。 According to the present invention, based on the amount of light at each rotation angle obtained by detecting light sequentially transmitted through the first polarizer and the second polarizer while rotating the second polarizer. When determining a change curve indicating a periodic change in the amount of light when the second polarizer rotates, the rotation angle range includes one minimum point of the change curve and the light amount is equal to or less than a predetermined value. It was set as the structure which calculates | requires a change curve based on the light quantity in the included rotation angle.
Thereby, since the change curve is obtained based on the detection value having a small noise component included in the detection value as compared with the detection value of the light amount in the vicinity of the maximum point, the accuracy of the change curve is improved. And a polarization characteristic is calculated | required accurately by calculating | requiring a polarization characteristic from this change curve.
Further, since only the light quantity in the vicinity of the minimum point needs to be measured, high-precision measurement can be performed with a small number of measurements.

本発明の実施形態に係る偏光測定システムの構成を光配向装置とともに示す図である。It is a figure which shows the structure of the polarization measuring system which concerns on embodiment of this invention with a photo-alignment apparatus. 偏光測定システムの構成を光配向装置の平面視図とともに示す図である。It is a figure which shows the structure of a polarization measuring system with the top view of a photo-alignment apparatus. 検出部の構成を示す模式図である。It is a schematic diagram which shows the structure of a detection part. 検出光の変化曲線の模式図である。It is a schematic diagram of a change curve of detection light. 検出光の光量を検出する回動角度の範囲の説明図である。It is explanatory drawing of the range of the rotation angle which detects the light quantity of a detection light. 検出光の光量の検出の具体例の説明図である。It is explanatory drawing of the specific example of detection of the light quantity of a detection light. 偏光測定システムの測定動作を示すフローチャートである。It is a flowchart which shows the measurement operation | movement of a polarization measuring system. 検出部の構成を示し外観斜視図である。It is an external appearance perspective view which shows the structure of a detection part. 検出部の断面図である。It is sectional drawing of a detection part.

以下、図面を参照して本発明の実施形態について説明する。
図１は、本実施形態に係る偏光測定システム１の構成を光配向装置２とともに示す模試図である。
同図において、光配向装置２は、帯状の光配向対象物の光配向膜に偏光光を照射して光配向する装置であり、偏光測定システム１は、光配向装置２の偏光光の偏光特性を測定するものである。偏光特性としては、偏光光の偏光軸、及び消光比が測定される。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing the configuration of the polarization measuring system 1 according to the present embodiment together with the optical alignment device 2.
In the figure, a photo-alignment device 2 is a device that performs photo-alignment by irradiating a photo-alignment film of a strip-like photo-alignment object with polarized light. Is to measure. As the polarization characteristics, the polarization axis of the polarized light and the extinction ratio are measured.

光配向装置２は、防振構造の定盤３と、照射器設置架台４と、光配向対象物が載置されるワークステージ５とを備えている。
照射器設置架台４は、定盤３から所定距離離れた上方位置で定盤３の幅方向（後述する直動機構の直動方向Ｘに垂直な方向）に横架される箱体であり、その両端が定盤３に固定される。照射器設置架台４は照射器６を内蔵し、照射器６が直下に偏光光を照射する。なお、ワークステージ５の移動に伴う振動と照射器６の冷却に起因する振動とを分離するために、照射器設置架台４を定盤３に固定するのではなく当該定盤３と別置する構成でも良い。
定盤３には、直動方向Ｘに沿って定盤３の面上を照射器６の直下を通過するようにワークステージ５を移送する直動機構（図示せず）が内設されている。光配向対象物の光配向にあっては、ワークステージ５に載置された光配向対象物が、直動機構によってワークステージ５とともに移送されて照射器６の直下を通過し、この通過の際に偏光光に曝露されて光配向膜が配向される。 The optical alignment apparatus 2 includes a surface plate 3 having an anti-vibration structure, an irradiator installation base 4, and a work stage 5 on which an optical alignment target is placed.
The irradiator installation base 4 is a box body that is horizontally mounted in the width direction of the surface plate 3 (a direction perpendicular to the linear motion direction X of the linear motion mechanism described later) at an upper position separated from the surface plate 3 by a predetermined distance. Both ends thereof are fixed to the surface plate 3. The irradiator installation stand 4 has a built-in irradiator 6, and the irradiator 6 irradiates polarized light directly below. In order to separate the vibration caused by the movement of the work stage 5 and the vibration caused by the cooling of the irradiator 6, the irradiator installation base 4 is not fixed to the surface plate 3 but separately from the surface plate 3. It may be configured.
The platen 3 is provided with a linear motion mechanism (not shown) that moves the work stage 5 along the linear motion direction X so as to pass directly below the irradiator 6 on the surface of the surface plate 3. . In the photo-alignment of the photo-alignment target object, the photo-alignment target object placed on the work stage 5 is transferred together with the work stage 5 by the linear motion mechanism and passes directly below the irradiator 6. The photo-alignment film is oriented by being exposed to polarized light.

照射器６は、光源たるランプ７と、反射鏡８と、偏光子ユニット１０とを備え、集光する偏光光を直下に照射する。
ランプ７は、放電灯であり、少なくとも光配向対象物の幅と同等以上に延びる直管型（棒状）の紫外線ランプが用いられている。反射鏡８は、断面楕円形、かつランプ７の長手方向に沿って延びるシリンドリカル凹面反射鏡であり、ランプ７の光を集光して偏光子ユニット１０に向けて照射する。
偏光子ユニット１０は、反射鏡８と光配向対象物の間に配置され、光配向対象物に照射される光を偏光する。この偏光光が光配向対象物の光配向膜に照射されることで、当該光配向膜が偏光光の偏光軸方向に応じて配向される。 The irradiator 6 includes a lamp 7 serving as a light source, a reflecting mirror 8, and a polarizer unit 10, and irradiates the condensed polarized light directly below.
The lamp 7 is a discharge lamp, and a straight tube (rod-shaped) ultraviolet lamp extending at least equal to or greater than the width of the photo-alignment object is used. The reflecting mirror 8 is a cylindrical concave reflecting mirror having an elliptical cross section and extending along the longitudinal direction of the lamp 7. The light from the lamp 7 is collected and irradiated toward the polarizer unit 10.
The polarizer unit 10 is disposed between the reflecting mirror 8 and the photo-alignment target, and polarizes light irradiated on the photo-alignment target. By irradiating this polarized light onto the photo-alignment film of the photo-alignment object, the photo-alignment film is aligned according to the polarization axis direction of the polarized light.

図２は、偏光測定システム１を光配向装置２の平面視図とともに示す図である。なお、同図では、偏光子ユニット１０の構成の理解を容易にするために、照射器設置架台４の中に偏光子ユニット１０のみを示している。
同図に示すように、偏光子ユニット１０は、複数の単位偏光子ユニット（第１の偏光子）１２と、これら単位偏光子ユニット１２を横並びに一列に整列するフレーム１４とを備えている。フレーム１４は、各単位偏光子ユニット１２を連接配置する板状の枠体である。単位偏光子ユニット１２は、略矩形板状に形成されたワイヤーグリッド偏光子１６を備えている。
本実施形態では、各単位偏光子ユニット１２は、ワイヤーグリッド偏光子１６をワイヤー方向Ａが上記ワークステージ５の直動方向Ｘと平行になるように支持し、このワイヤー方向Ａと直交する方向と、ワイヤーグリッド偏光子１６の配列方向Ｂとが一致するようになされている。 FIG. 2 is a diagram illustrating the polarization measurement system 1 together with a plan view of the optical alignment device 2. In the figure, only the polarizer unit 10 is shown in the irradiator installation base 4 in order to facilitate understanding of the configuration of the polarizer unit 10.
As shown in the figure, the polarizer unit 10 includes a plurality of unit polarizer units (first polarizer) 12 and a frame 14 that aligns the unit polarizer units 12 side by side in a row. The frame 14 is a plate-like frame body in which the unit polarizer units 12 are connected and arranged. The unit polarizer unit 12 includes a wire grid polarizer 16 formed in a substantially rectangular plate shape.
In the present embodiment, each unit polarizer unit 12 supports the wire grid polarizer 16 so that the wire direction A is parallel to the linear motion direction X of the work stage 5, and a direction orthogonal to the wire direction A; The arrangement direction B of the wire grid polarizer 16 is made to coincide.

ワイヤーグリッド偏光子１６は、入射光のうちワイヤー方向Ａに平行な成分を反射し、このワイヤー方向Ａと直交する成分を透過して直線偏光光を得る直線偏光子の一種である。このワイヤーグリッド偏光子１６では、ワイヤー方向Ａと直交する方向が直線偏光の偏光軸Ｃ１（図３）と定義され、本実施形態では偏光軸Ｃ１が配列方向Ｂに揃えられている。上述の通り、ランプ７が棒状であることから、ワイヤーグリッド偏光子１６には、さまざまな角度の光が入射するが、ワイヤーグリッド偏光子１６は、斜めに入射する光であっても偏光軸Ｃ１（透過軸）の方向が合っていれば直線偏光化して透過する。
ワイヤーグリッド偏光子１６は、その法線方向を回動軸にして面内で回動させて偏光軸Ｃ１の方向を微調整できるように単位偏光子ユニット１２に支持されている。全ての単位偏光子ユニット１２について、ワイヤーグリッド偏光子１６の偏光軸Ｃ１が配列方向Ｂに揃うように微調整されることで、偏光子ユニット１０の長軸方向の全長に亘り偏光軸Ｃ１が高精度に揃えられた偏光光が得られ、高品位な光配向が可能となる。 The wire grid polarizer 16 is a type of linear polarizer that reflects a component parallel to the wire direction A of incident light and transmits a component orthogonal to the wire direction A to obtain linearly polarized light. In this wire grid polarizer 16, the direction orthogonal to the wire direction A is defined as the polarization axis C <b> 1 (FIG. 3) of linearly polarized light, and the polarization axis C <b> 1 is aligned with the arrangement direction B in this embodiment. As described above, since the lamp 7 is rod-shaped, light of various angles is incident on the wire grid polarizer 16, but the wire grid polarizer 16 has a polarization axis C1 even if it is incident obliquely. If the direction of (transmission axis) matches, the light is linearly polarized and transmitted.
The wire grid polarizer 16 is supported by the unit polarizer unit 12 so that the direction of the polarization axis C1 can be finely adjusted by rotating in the plane with the normal direction as the rotation axis. For all the unit polarizer units 12, the polarization axis C <b> 1 of the wire grid polarizer 16 is finely adjusted so as to align with the arrangement direction B, so that the polarization axis C <b> 1 is increased over the entire length of the polarizer unit 10 in the long axis direction. Polarized light with uniform accuracy can be obtained, and high-quality optical alignment is possible.

偏光測定システム１は、図１に示すように、偏光測定装置２０と、測定ユニット３０とを備えている。測定ユニット３０は、偏光光を検出する検出部３１を備え、偏光測定装置２０は、検出部３１による偏光光の検出結果に基づいて、当該偏光光の偏光軸、及び消光比を測定する。
測定ユニット３０は、ワイヤーグリッド偏光子１６ごとの個々の測定を容易にするために、図２に示すように、案内方向が配列方向Ｂと平行に設置され、検出部３１を直線に沿って案内するリニアガイド３２を備えている。偏光光測定時には、リニアガイド３２が上記ワークステージ５の進行方向側の側面５Ａに連結されて偏光子ユニット１０の直下に移送され、或いはリニアガイド３２が偏光子ユニット１０の直下に位置するように定盤３の面上に設置される。そして、微調整対象のワイヤーグリッド偏光子１６の直下に位置するように検出部３１をリニアガイド３２に沿って移動、或いは自走させ、その位置で当該ワイヤーグリッド偏光子１６を透過した偏光光を検出部３１で検出し、偏光光を測定する。 As shown in FIG. 1, the polarization measurement system 1 includes a polarization measurement device 20 and a measurement unit 30. The measurement unit 30 includes a detection unit 31 that detects polarized light, and the polarization measurement device 20 measures the polarization axis and extinction ratio of the polarized light based on the detection result of the polarized light by the detection unit 31.
In order to facilitate individual measurement for each wire grid polarizer 16, the measurement unit 30 is installed with the guide direction parallel to the arrangement direction B and guides the detection unit 31 along a straight line as shown in FIG. The linear guide 32 is provided. At the time of polarized light measurement, the linear guide 32 is connected to the side surface 5A on the traveling direction side of the work stage 5 and is transferred directly below the polarizer unit 10, or the linear guide 32 is positioned directly below the polarizer unit 10. Installed on the surface of the surface plate 3. And the detection part 31 is moved along the linear guide 32 so that it may be located just under the wire grid polarizer 16 of fine adjustment object, or self-propelled, and the polarized light which permeate | transmitted the said wire grid polarizer 16 in the position is used. It detects with the detection part 31, and measures polarized light.

図３は、検出部３１の構成を示す模式図である。
検出部３１は、検出側偏光子（第２の偏光子）３３と、受光センサ３４とを備えている。
検出側偏光子３３は、偏光軸Ｃ２を有する板状（図示例では円盤状）の光検出用の直線偏光子であり検光子とも称される。この検出側偏光子３３には、ワイヤーグリッド偏光子１６を透過して直線偏光化された偏光光Ｆが入射され、この偏光光Ｆを直線偏光化する。検出側偏光子３３には、直線偏光子であれば任意の偏光子を用いることができ、例えばワイヤーグリッド偏光子を用いても良い。
受光センサ３４は、検出側偏光子３３の偏光軸Ｃ２で直線偏光化された検出光Ｇを受光して光量Ｉを示す検出信号３５を偏光測定装置２０に出力する。 FIG. 3 is a schematic diagram illustrating the configuration of the detection unit 31.
The detection unit 31 includes a detection-side polarizer (second polarizer) 33 and a light receiving sensor 34.
The detection-side polarizer 33 is a plate-like (disk-like in the illustrated example) light-detecting linear polarizer having a polarization axis C2, and is also called an analyzer. The detection-side polarizer 33 receives the polarized light F that has been linearly polarized through the wire grid polarizer 16 and linearly polarizes the polarized light F. As the detection-side polarizer 33, any polarizer can be used as long as it is a linear polarizer. For example, a wire grid polarizer may be used.
The light receiving sensor 34 receives the detection light G linearly polarized by the polarization axis C <b> 2 of the detection side polarizer 33 and outputs a detection signal 35 indicating the light amount I to the polarization measuring device 20.

検出部３１では、検出側偏光子３３がその法線方向Ｓを回動軸にして、少なくとも１回転に亘り回転自在に設けられている。検出側偏光子３３の回動は、基準位置Ｐ０からの回動角度θによって規定される。本実施形態では、基準位置Ｐ０は、偏光軸Ｃ２の方向が上記ワイヤーグリッド偏光子１６の配列方向Ｂと一致する位置に設定されている。すなわち、検出部３１をリニアガイド３２にセットし、基準位置Ｐ０に検出側偏光子３３を合わせたときには、検出側偏光子３３の偏光軸Ｃ２が配列方向Ｂを向いた状態となる。   In the detection unit 31, the detection-side polarizer 33 is provided so as to be rotatable at least once with the normal direction S as a rotation axis. The rotation of the detection-side polarizer 33 is defined by the rotation angle θ from the reference position P0. In the present embodiment, the reference position P <b> 0 is set to a position where the direction of the polarization axis C <b> 2 coincides with the arrangement direction B of the wire grid polarizer 16. That is, when the detection unit 31 is set on the linear guide 32 and the detection-side polarizer 33 is aligned with the reference position P0, the polarization axis C2 of the detection-side polarizer 33 is in the state in which the arrangement direction B is directed.

偏光測定装置２０は、検出側偏光子３３が１回転するときの検出光Ｇの光量の周期的な変化に基づき、偏光光Ｆの偏光軸と消光比とを測定するものである。具体的には、偏光測定装置２０は、図２に示すように、回転駆動制御部２１と、入力部２２と、変化曲線算出部２３と、偏光特性特定部２４と、偏光特性出力部２５とを備えている。なお、偏光測定装置２０は、図２に示す各部を実現するコンピュータ読取可能なプログラムを、例えばパーソナルコンピュータに実行させることで実施することもできる。
回転駆動制御部２１は、検出部３１の検出側偏光子３３の回転を制御する。具体的には、検出部３１は、検出側偏光子３３を回動するロータリーアクチュエータを備え、回転駆動制御部２１がロータリーアクチュエータを制御し検出側偏光子３３を回動させることで、その偏光軸Ｃ２を所定の回動角度θの方向に合わせる。このときの回動角度θは変化曲線算出部２３に出力される。
入力部２２は、検出光Ｇの光量Ｉの検出値の入力を受け付ける手段であり、この入力部２２には検出部３１の検出信号３５が入力される。入力部２２は、当該検出信号３５から検出光Ｇの光量Ｉの検出値を取得し変化曲線算出部２３に出力する。 The polarization measuring device 20 measures the polarization axis and the extinction ratio of the polarized light F based on a periodic change in the amount of the detected light G when the detection-side polarizer 33 rotates once. Specifically, as shown in FIG. 2, the polarization measuring device 20 includes a rotation drive control unit 21, an input unit 22, a change curve calculation unit 23, a polarization characteristic specifying unit 24, and a polarization characteristic output unit 25. It has. Note that the polarization measuring device 20 can also be implemented by causing a personal computer to execute a computer-readable program that implements each unit illustrated in FIG. 2, for example.
The rotation drive control unit 21 controls the rotation of the detection side polarizer 33 of the detection unit 31. Specifically, the detection unit 31 includes a rotary actuator that rotates the detection-side polarizer 33, and the rotation drive control unit 21 controls the rotary actuator to rotate the detection-side polarizer 33, so that its polarization axis is adjusted. C2 is adjusted to the direction of a predetermined rotation angle θ. The rotation angle θ at this time is output to the change curve calculation unit 23.
The input unit 22 is means for receiving an input of a detection value of the light amount I of the detection light G, and the detection signal 35 of the detection unit 31 is input to the input unit 22. The input unit 22 acquires the detection value of the light amount I of the detection light G from the detection signal 35 and outputs it to the change curve calculation unit 23.

変化曲線算出部２３は、検出光Ｇの光量Ｉの検出値に基づき、検出側偏光子３３を１回転させたときの検出光Ｇの光量Ｉの周期的な変化を示す変化曲線Ｑを算出する。詳述すると、検出光Ｇは、前掲図３に示すように、ランプ７の放射光Ｅが、直線偏光子であるワイヤーグリッド偏光子１６、及び検出側偏光子３３を順に通って得られる光である。
したがって、検出側偏光子３３の回転に伴う検出光Ｇの光量Ｉの変化曲線Ｑは、理想的には、図４に示すように、検出側偏光子３３の偏光軸Ｃ２がワイヤーグリッド偏光子１６の偏光軸Ｃ１に平行である場合（本実施形態では回動角度θ＝０°、１８０°（極大点））に最大光量Ｉｍａｘ（極大値）となり、偏光軸Ｃ２が偏光軸Ｃ１に直交する場合（本実施形態では回動角度θ＝９０°、２７０°（極小点））に最小光量Ｉｍｉｎ（極小値）となるような１周期がπ［ｒａｄ］（=１８０°）の次式（１）に示す余弦波形となる（いわゆる、マリューの法則（Low of Malus））。 The change curve calculation unit 23 calculates a change curve Q indicating a periodic change in the light amount I of the detection light G when the detection-side polarizer 33 is rotated once based on the detection value of the light amount I of the detection light G. . More specifically, as shown in FIG. 3, the detection light G is light obtained by sequentially passing the radiation light E of the lamp 7 through the wire grid polarizer 16 that is a linear polarizer and the detection-side polarizer 33. is there.
Therefore, the change curve Q of the light amount I of the detection light G accompanying the rotation of the detection side polarizer 33 is ideally such that the polarization axis C2 of the detection side polarizer 33 is the wire grid polarizer 16 as shown in FIG. Is the maximum light amount Imax (maximum value) when the angle is parallel to the polarization axis C1 (in this embodiment, the rotation angle θ = 0 °, 180 ° (maximum point)), and the polarization axis C2 is orthogonal to the polarization axis C1. (In this embodiment, the rotation angle θ = 90 °, 270 ° (minimum point)) and the following formula (1) where one cycle is π [rad] (= 180 °) such that the minimum light amount Imin (minimum value) is obtained. (The so-called Low of Malus).

変化曲線Ｑ＝α×ｃｏｓ(β×（θ−γ）)＋ε （１）
ただし、αは振幅、βは周期、γは位相ズレ（基準位置Ｐ０に対するワイヤーグリッド偏光子１６の偏光軸Ｃ１の位相差）、εはバイアス成分である。 Change curve Q = α × cos (β × (θ−γ)) + ε (1)
Where α is the amplitude, β is the period, γ is the phase shift (phase difference of the polarization axis C1 of the wire grid polarizer 16 with respect to the reference position P0), and ε is the bias component.

しかしながら、発明者らは、鋭意実験を通じ、変化曲線Ｑについて次のような知見を得た。
すなわち、光配向装置２は、放電灯たるランプ７を光源としているため、ランプ７を点灯する電源装置の点灯電力の揺らぎやランプ７の冷却状態など様々な要因により、光源輝度が非常に短い時間周期で変動し揺らぎやちらつきが発生し、これが光源輝度のノイズ成分となる。
さらに、光配向装置２は、ランプ７から偏光子ユニット１０を通じて広い範囲に偏光光Ｆを照射するため、検出部３１の受光センサ３４には、種々の入射角度の偏光光Ｆが入射し、また調整対象のワイヤーグリッド偏光子１６に隣接する他のワイヤーグリッド偏光子１６を通過した偏光光Ｆも入射て検出される。
これら光源輝度のノイズ成分や偏光光Ｆの斜入射等に起因し、検出部３１の検出結果から求められた変化曲線Ｑは、理想的な余弦関数（上記（１）式）から歪み、この歪みは、次式（２）に示すｎ乗余弦波形（ｎ≧２）で十分に近似される。 However, the inventors have obtained the following knowledge about the change curve Q through intensive experiments.
That is, since the light alignment device 2 uses the lamp 7 as a discharge lamp as a light source, the light source luminance is very short due to various factors such as fluctuations in the lighting power of the power supply device that lights the lamp 7 and the cooling state of the lamp 7. It fluctuates with the period, and fluctuations and flickering occur, and this becomes a noise component of the light source luminance.
Further, since the optical alignment device 2 irradiates the polarized light F from the lamp 7 through the polarizer unit 10 to a wide range, the polarized light F having various incident angles is incident on the light receiving sensor 34 of the detection unit 31. Polarized light F that has passed through another wire grid polarizer 16 adjacent to the wire grid polarizer 16 to be adjusted is also incident and detected.
Due to the noise component of the light source luminance, the oblique incidence of the polarized light F, and the like, the change curve Q obtained from the detection result of the detection unit 31 is distorted from an ideal cosine function (the above formula (1)). Is sufficiently approximated by an n-th cosine waveform (n ≧ 2) shown in the following equation (2).

変化曲線Ｑ＝α×ｃｏｓ^ｎ(β×（θ−γ）)＋ε （２） Change curve Q = α × cos ⁿ (β × (θ−γ)) + ε (2)

以上の知見によれば、変化曲線Ｑとしては、検出光Ｇの光量の検出値に基づき、ｎ乗余弦波形を求めることが最良ではあるが、そうすると、多くの検出光Ｇの測定と計算を要するという問題がある。
また、消光比は、最小光量Ｉｍｉｎで最大光量Ｉｍａｘを除算することから、最小光量Ｉｍｉｎが小さくなるほど、この最小光量Ｉｍｉｎに占めるノイズ成分が消光比の値に大きく影響するが、上記（２）式で変化曲線Ｑを求めた場合、最小光量Ｉｍｉｎの繰り返し精度が悪いため、消光比が正確に求められなくなる。
そこで、所望の精度が得られるように、１つの変化曲線Ｑを求めるための測定点の数や、複数回の測定を繰り返して変化曲線Ｑを複数回求めて平均化する等すれば良いが、そうすると測定回数が非常に多くなることから測定に時間が掛かるという問題が生じる。 According to the above knowledge, as the change curve Q, it is best to obtain an n-th cosine waveform based on the detected value of the light amount of the detection light G, but in this case, a lot of measurement and calculation of the detection light G is required. There is a problem.
Further, since the extinction ratio divides the maximum light quantity Imax by the minimum light quantity Imin, the noise component that occupies the minimum light quantity Imin greatly affects the value of the extinction ratio as the minimum light quantity Imin decreases. When the change curve Q is obtained in (4), since the repeatability of the minimum light quantity Imin is poor, the extinction ratio cannot be obtained accurately.
Therefore, in order to obtain the desired accuracy, the number of measurement points for obtaining one change curve Q or the change curve Q may be obtained several times by repeating a plurality of measurements and averaged. If it does so, since the frequency | count of a measurement will increase very much, the problem that a measurement will take time will arise.

この問題を解決する手法としては、光源輝度のノイズ成分を検出部３１の検出信号３５から除去できるように、検出部３１とは別置の受光センサを用意し、別置の受光センサで検出光Ｇの光量Ｉを参照用として検出し、この参照用の検出結果に基づき検出部３１の検出信号３５からノイズ成分を除去する処理を行うことが考えられる。
しかしながら、偏光測定においては、一般に、ミラーやプリズム等の光学素子を光が経由することでも偏光状態が変化するため、別置の受光センサに検出部３１に入射する検出光Ｇを分岐させることができない。このため、検出部３１と別置の受光センサが受光する検出光Ｇが相違してしまい、ノイズ成分が正確に除去されない。 As a technique for solving this problem, a light receiving sensor provided separately from the detection unit 31 is prepared so that the noise component of the light source luminance can be removed from the detection signal 35 of the detection unit 31, and the detection light is detected by the separate light receiving sensor. It is conceivable to detect the amount of light I for G as a reference, and to perform a process of removing a noise component from the detection signal 35 of the detection unit 31 based on the detection result for reference.
However, in polarization measurement, since the polarization state generally changes even when light passes through an optical element such as a mirror or a prism, the detection light G incident on the detection unit 31 may be branched to a separate light receiving sensor. Can not. For this reason, the detection light G received by the detection unit 31 and a separate light receiving sensor is different, and the noise component is not accurately removed.

また検出部３１の受光センサ３４が検出する検出光Ｇの光量Ｉは、上記検出側偏光子３３の回転に伴い変化し、また光源輝度のノイズ成分の量もそれに伴い変わるため、別置の受光センサの検出値に対し検出側偏光子３３の回動角度θを反映する処理が必要となる。さらに検出部３１が備える受光センサ３４と別置の受光センサを比較する際には、センサ感度の経年変化や温度特性に起因するノイズなどに起因した両者の受光特性の差異を補正する必要もある。
このように、別置の受光センサを用いる測定手法は、高精度な測定を実現するために、解決しなければならない多くの問題を含む。 The light amount I of the detection light G detected by the light receiving sensor 34 of the detection unit 31 changes with the rotation of the detection-side polarizer 33, and the amount of noise component of the light source luminance also changes accordingly. Processing to reflect the rotation angle θ of the detection-side polarizer 33 with respect to the detection value of the sensor is required. Furthermore, when comparing the light receiving sensor 34 provided in the detection unit 31 with a separate light receiving sensor, it is also necessary to correct the difference between the light receiving characteristics due to changes in sensor sensitivity over time, noise due to temperature characteristics, and the like. .
As described above, the measurement method using the separate light receiving sensor includes many problems that need to be solved in order to realize highly accurate measurement.

そこで本実施形態では、変化曲線Ｑのカーブフィッティングに用いる光量Ｉの検出値を、図５に示すように、検出光Ｇの光量Ｉが最小となる極小点の近傍の範囲Ｗで検出されたものに制限することで、１個の受光センサ３４による測定でありながらも、少ない測定点で繰り返し精度が高い変化曲線Ｑを算出可能にしている。
詳述すると、検出光Ｇの光量Ｉに占める光源輝度のノイズ成分の割合が略一定であるとすると、ノイズ成分の大きさは、検出光Ｇの光量Ｉに比例して大きくなることから、前掲図４に示すように、ノイズ成分の大きさは、最大光量Ｉｍａｘ（極大点）の近傍に比べ、最小光量Ｉｍｉｎ（極小点）の近傍で小さくなる。換言すれば、最小光量Ｉｍｉｎの近傍では、最大光量Ｉｍａｘ近傍に比べ、光源輝度のノイズ成分の影響による光量Ｉの変動幅が小さい。
したがって、ノイズ成分の影響が少ない最小光量Ｉｍｉｎ近傍の光量Ｉの検出値を用いてカーブフィッティングにより上記変化曲線Ｑを求めることで、光源輝度の揺らぎなどの影響によるノイズ成分を抑えた変化曲線Ｑが得られるのである。そして、光源輝度のノイズ成分の影響が抑えられるため、繰り返し精度が高められ、１回の測定でも信頼性が高い変化曲線Ｑが得られることとなる。 Therefore, in the present embodiment, the detected value of the light quantity I used for curve fitting of the change curve Q is detected in a range W in the vicinity of the minimum point where the light quantity I of the detection light G is minimum as shown in FIG. By limiting to the above, it is possible to calculate the change curve Q with high repetitive accuracy at a small number of measurement points even though the measurement is performed by one light receiving sensor 34.
More specifically, if the ratio of the noise component of the light source luminance to the light amount I of the detection light G is substantially constant, the magnitude of the noise component increases in proportion to the light amount I of the detection light G. As shown in FIG. 4, the magnitude of the noise component is smaller in the vicinity of the minimum light amount Imin (minimum point) than in the vicinity of the maximum light amount Imax (maximum point). In other words, the fluctuation range of the light amount I due to the influence of the noise component of the light source luminance is smaller in the vicinity of the minimum light amount Imin than in the vicinity of the maximum light amount Imax.
Therefore, by obtaining the change curve Q by curve fitting using the detected value of the light quantity I in the vicinity of the minimum light quantity Imin that is less affected by the noise component, the change curve Q that suppresses the noise component due to the influence of the light source luminance fluctuation is obtained. It is obtained. Since the influence of the noise component of the light source luminance is suppressed, the repeatability is improved, and the change curve Q with high reliability can be obtained even by one measurement.

発明者らは、鋭意実験により、最小光量Ｉｍｉｎ近傍の範囲として、検出光Ｇの光量Ｉが最大光量Ｉｍａｘの２０％以下となる回動角度θの範囲Ｗであれば、その範囲Ｗの内での回動角度θで測定された検出光Ｇの光量Ｉに基づき、光源輝度のノイズ成分の影響を抑え、繰り返し精度が高い変化曲線Ｑが得られるとの知見を得た。さらに、発明者らは、最小光量Ｉｍｉｎが得られる回動角度θａを中心に±２０°の範囲であれば上記の範囲Ｗに含まれるとの知見を得た。
これらの知見に基づき、本実施形態では、図５に示すように、この範囲Ｗに含まれる４点の回動角度θ（θ＝θａ±１０°、θａ±２０°）で検出光Ｇの光量Ｉを検出し、各回動角度θでの光量Ｉに基づいて、カーブフィッティングにより上記変化曲線Ｑを求めることとしている。
検出光Ｇの光量Ｉを検出する回動角度θを１０°程度離すことで、検出光Ｇの光量Ｉの検出値の間に有意な差を生じさせることができるから、この検出値の差が光源輝度のノイズ成分に埋もれることがなく変化曲線Ｑを確実に求めることができる。
なお、検出光Ｇの光量Ｉを測定する回動角度θは、４点に限らず、上記範囲Ｗの範囲内であれば、少なくとも３点以上であれば良い。 The inventors of the present invention have conducted a diligent experiment in which the light amount I of the detection light G is 20% or less of the maximum light amount Imax as a range in the vicinity of the minimum light amount Imin. Based on the light amount I of the detection light G measured at the rotation angle θ, the influence of the noise component of the light source luminance was suppressed, and a change curve Q with high repetition accuracy was obtained. Further, the inventors have obtained knowledge that the range W is included in the range of ± 20 ° around the rotation angle θa at which the minimum light amount Imin is obtained.
Based on these findings, in the present embodiment, as shown in FIG. 5, the light amount of the detection light G at four rotation angles θ (θ = θa ± 10 °, θa ± 20 °) included in this range W. I is detected, and the change curve Q is obtained by curve fitting based on the light quantity I at each rotation angle θ.
By separating the rotation angle θ for detecting the light amount I of the detection light G by about 10 °, a significant difference can be generated between the detection values of the light amount I of the detection light G. The change curve Q can be reliably obtained without being buried in the noise component of the light source luminance.
Note that the rotation angle θ for measuring the light amount I of the detection light G is not limited to four points, and may be at least three or more as long as it is within the range W.

変化曲線算出部２３は、上記範囲Ｗに含まれる回動角度θでの検出光Ｇの光量Ｉの検出値に基づき、式（１）式に示した余弦波形をカーブフィッティング（曲線回帰とも呼ばれる）の手法により求め、これを偏光特性特定部２４に出力する。
偏光光Ｆの偏光方向が基準位置Ｐ０の方向からズレている場合、すなわちワイヤーグリッド偏光子１６の偏光軸Ｃ１の方向が基準位置Ｐ０の方向である配列方向Ｂからズレている場合には、図４に仮想線で示すように、そのズレが変化曲線Ｑに位相ズレγ（＞０）として現れることとなる。 The change curve calculation unit 23 performs curve fitting (also called curve regression) on the cosine waveform shown in the equation (1) based on the detected value of the light amount I of the detection light G at the rotation angle θ included in the range W. This is obtained by the above method and output to the polarization characteristic specifying unit 24.
When the polarization direction of the polarized light F is deviated from the direction of the reference position P0, that is, when the direction of the polarization axis C1 of the wire grid polarizer 16 is deviated from the arrangement direction B which is the direction of the reference position P0, FIG. As indicated by a virtual line in FIG. 4, the deviation appears in the change curve Q as a phase deviation γ (> 0).

偏光特性特定部２４は、変化曲線算出部２３によって求められた変化曲線Ｑに基づき、偏光光Ｆの偏光方向（すなわちワイヤーグリッド偏光子１６の偏光軸Ｃ１の方向）、及び消光比を特定し、偏光特性出力部２５に出力する。
具体的には、偏光特性特定部２４は、図４に示すように、変化曲線Ｑにおいて、検出光Ｇの最大光量Ｉｍａｘが得られる回動角度θ（極大点）である上記γを特定することで偏光軸Ｃ１の方向を特定し、また、変化曲線Ｑの最大光量Ｉｍａｘと最小光量Ｉｍｉｎの比（＝最大光量Ｉｍａｘ／最小光量Ｉｍｉｎ）に基づいて消光比を特定する。変化曲線Ｑにおける最大光量Ｉｍａｘは当該変化曲線Ｑに回動角度θ＝γ（極大点）を代入して求められ、また最小光量Ｉｍｉｎは回動角度θ＝９０°＋γ（極小点）を代入して求められる。 The polarization characteristic specifying unit 24 specifies the polarization direction of the polarized light F (that is, the direction of the polarization axis C1 of the wire grid polarizer 16) and the extinction ratio based on the change curve Q obtained by the change curve calculating unit 23. Output to the polarization characteristic output unit 25.
Specifically, as illustrated in FIG. 4, the polarization characteristic specifying unit 24 specifies the above-described γ that is the rotation angle θ (maximum point) at which the maximum light amount Imax of the detection light G is obtained in the change curve Q. Then, the direction of the polarization axis C1 is specified, and the extinction ratio is specified based on the ratio (= maximum light amount Imax / minimum light amount Imin) of the maximum light amount Imax and the minimum light amount Imin of the change curve Q. The maximum light amount Imax in the change curve Q is obtained by substituting the rotation angle θ = γ (maximum point) into the change curve Q, and the minimum light amount Imin is assigned the rotation angle θ = 90 ° + γ (minimum point). Is required.

偏光特性出力部２５は、偏光特性特定部２４によって特定された偏光特性（偏光軸、及び消光比）を出力するものである。この出力の態様は、ユーザが偏光特性を利用可能であれば任意であり、例えば表示、他の電子機器への出力、記録媒体への記録等が挙げられる。   The polarization characteristic output unit 25 outputs the polarization characteristics (polarization axis and extinction ratio) specified by the polarization characteristic specification unit 24. This output mode is arbitrary as long as the user can use the polarization characteristics, and examples thereof include display, output to another electronic device, and recording on a recording medium.

ここで、最小光量Ｉｍｉｎが得られる回動角度θａ（極小点）は、前掲図４に示すように、検出側偏光子３３が１回転する間（θ＝０〜３６０°）に、位相が１８０°（π）離れた２箇所に存在することから、本実施形態では、変化曲線算出部２３が２箇所の回動角度θ＝θａ、θａ＋１８０°のそれぞれについて、範囲Ｗの内の４点の回動角度θで検出光Ｇの光量Ｉを測定して２つの変化曲線Ｑを求め、偏光特性特定部２４が２本の変化曲線Ｑのそれぞれについて偏光軸、及び消光比を求め、それらの平均値を求めることで、偏光軸、及び消光比の測定精度を高めることとしている。   Here, the rotation angle θa (minimum point) at which the minimum light amount Imin is obtained has a phase of 180 during the rotation of the detection-side polarizer 33 (θ = 0 to 360 °) as shown in FIG. In this embodiment, the change curve calculation unit 23 performs the rotation of four points within the range W for each of the two rotation angles θ = θa and θa + 180 °. The light quantity I of the detection light G is measured at the moving angle θ to obtain two change curves Q, and the polarization characteristic specifying unit 24 obtains the polarization axis and the extinction ratio for each of the two change curves Q, and averages them. Thus, the measurement accuracy of the polarization axis and the extinction ratio is increased.

これに加え、本実施形態では、２箇所の回動角度θ＝θａ、θａ＋１８０°ごとの上記範囲Ｗの各々において、４点の回動角度θでの検出光Ｇの光量Ｉの検出精度を高めるべく、同じ回動角度θで光量Ｉの測定を複数回（例えば１０回）繰り返し行うこととしている。
この結果、図６に示すように、同一の回動角度θごとにＭ個（Ｍ≧２）の光量Ｉの検出値が得られる。変化曲線算出部２３が、これらの検出値から変化曲線Ｑを求める際には、各回動角度θにおいて、Ｎ個（Ｍ≧Ｎ≧１）の検出値を選択して、これらＮ個の検出値の平均値を求め、これらの平均値に基づいて変化曲線Ｑを求める。Ｍ個の検出値の中からＮ個を選択する際の組合せの数は_ＭＣ_ｎ個であるから、変化曲線算出部２３は、この_ＭＣ_ｎ個の組合せごとに変化曲線Ｑを求める。そして、偏光特性特定部２４が、_ＭＣ_ｎ個の変化曲線Ｑのそれぞれについて偏光軸、及び消光比を求め、各偏光軸、及び各消光比の平均値を求めることとしている。これにより、偏光軸、及び消光比が更に高精度に求められる。 In addition to this, in the present embodiment, the detection accuracy of the light quantity I of the detection light G at the four rotation angles θ is increased in each of the ranges W every two rotation angles θ = θa and θa + 180 °. Accordingly, the measurement of the light amount I is repeated a plurality of times (for example, 10 times) at the same rotation angle θ.
As a result, as shown in FIG. 6, M (M ≧ 2) detection values of the light quantity I are obtained at the same rotation angle θ. When the change curve calculation unit 23 obtains the change curve Q from these detection values, N detection values (M ≧ N ≧ 1) are selected at each rotation angle θ, and these N detection values are selected. Are obtained, and a change curve Q is obtained based on these average values. Since the number of combinations when N is selected from the M detection values is _M C _n , the change curve calculation unit 23 obtains a change curve Q for each of the _M C _n combinations. Then, the polarization characteristic specifying portion 24, is set to be polarization axis, and the extinction ratio obtained for each of the _M C _n-number of change curve Q, the average value of each polarization axis, and each extinction ratio. Thereby, the polarization axis and the extinction ratio are required with higher accuracy.

図７は、偏光測定システム１の測定動作を示すフローチャートである。
同図に示すように、偏光測定装置２０は、検出部３１の検出側偏光子３３の回動を制御し、回動角度θを測定点に合わせる（ステップＳ１）。本実施形態では、回動角度θの測定点は、図６に示すように、θ＝θａ±２０°、θａ±１０°、θａ＋１８０°±２０°、θａ＋１８０°±１０°の合計８点である。回動角度θａは、最小光量Ｉｍｉｎが得られる角度（極小点）であり、前掲図４に示すように、θａ＝９０°＋γによって規定される。本実施形態では、偏光軸Ｃ１にズレが無い理想的な状態ではγ＝０となる。したがって、上記ステップＳ１においては、偏光測定装置２０は、θａ＝９０°として回動角度θの測定点を決定する。
次いで、偏光測定装置２０は、検出光Ｇの光量Ｉの検出信号３５をＭ回に亘り間欠的に取り込み、Ｍ個の光量Ｉの検出値を取得する（ステップＳ２）。
偏光測定装置２０は、回動角度θの全ての測定点において、Ｍ個の光量Ｉの検出値を取得するまで（ステップＳ３：Ｙｅｓ）、上記ステップＳ１、及びステップＳ２を繰り返し実行する。 FIG. 7 is a flowchart showing the measurement operation of the polarization measurement system 1.
As shown in the figure, the polarization measuring device 20 controls the rotation of the detection-side polarizer 33 of the detection unit 31 and adjusts the rotation angle θ to the measurement point (step S1). In this embodiment, as shown in FIG. 6, the measurement points of the rotation angle θ are a total of eight points: θ = θa ± 20 °, θa ± 10 °, θa + 180 ° ± 20 °, and θa + 180 ° ± 10 °. . The rotation angle θa is an angle (minimum point) at which the minimum light amount Imin is obtained, and is defined by θa = 90 ° + γ as shown in FIG. In the present embodiment, γ = 0 in an ideal state where there is no deviation in the polarization axis C1. Therefore, in step S1, the polarization measuring device 20 determines the measurement point of the rotation angle θ by setting θa = 90 °.
Next, the polarization measuring device 20 intermittently takes in the detection signal 35 of the light amount I of the detection light G for M times, and acquires detection values of the M light amounts I (step S2).
The polarization measuring device 20 repeatedly executes the above steps S1 and S2 until the detection values of M light quantities I are obtained at all measurement points of the rotation angle θ (step S3: Yes).

偏光測定装置２０は、最小光量Ｉｍｉｎ近傍（極小点近傍）の光量Ｉの検出値を用いて変化曲線Ｑを求めるべく、回動角度θ＝θａ±２０°、θａ±１０°の４点での光量Ｉの検出値に基づきカーブフィッティングにより上記（１）式に従う変化曲線Ｑを求める（ステップＳ４）。詳述すると、偏光測定装置２０は、これらの回動角度θごとに、Ｎ個（Ｍ≧Ｎ≧１）の検出値を選択して、これらＮ個の検出値の平均値を求め、それを回動角度θの検出値としてカーブフィッティングにより変化曲線Ｑを求める。上述の通り、_ＭＣ_ｎ個の変化曲線Ｑが求められる。次いで偏光測定装置２０は、_ＭＣ_ｎ個の変化曲線Ｑのそれぞれについて偏光軸、及び消光比を求め、各偏光軸、及び各消光比の平均値を求める（ステップＳ５）。 The polarization measuring device 20 uses four detected values of rotation angles θ = θa ± 20 ° and θa ± 10 ° to obtain the change curve Q using the detected value of the light amount I in the vicinity of the minimum light amount Imin (near the minimum point). Based on the detected value of the light amount I, a change curve Q according to the above equation (1) is obtained by curve fitting (step S4). More specifically, the polarization measuring device 20 selects N (M ≧ N ≧ 1) detection values for each rotation angle θ, obtains an average value of these N detection values, and calculates it. A change curve Q is obtained by curve fitting as a detected value of the rotation angle θ. As described _above, M _{C n-number} of change curve Q is required. Next, the polarization measuring device 20 obtains the polarization axis and the extinction ratio for each of the _M C _n change curves Q, and obtains the average value of each polarization axis and each extinction ratio (step S5).

偏光測定装置２０は、ステップＳ４、及びＳ５と同様にして、回動角度θ＝θａ＋１８０°±２０°、θａ＋１８０°±１０°の４点での光量Ｉの検出値に基づきカーブフィッティングにより変化曲線Ｑを求め（ステップＳ６）、この変化曲線Ｑに基づき、偏光軸、及び消光比を特定する（ステップＳ７）。
そして、偏光測定装置２０は、ステップＳ５、及びステップＳ７で求めた偏光軸、及び消光比の平均値を求めることで、偏光光の偏光軸、及び消光比を特定する（ステップＳ８）。
これにより、偏光光の偏光軸、及び消光比が高精度に求められる。
なお、この測定において、偏光測定装置２０は、変化曲線Ｑに基づき、最小光量Ｉｍｉｎが得られる回動角度θ＝θａ、最大光量Ｉｍａｘが得られる回動角度θ＝γを特定し、検出部３１の検出側偏光子３３を回動して、それぞれの回動角度θで検出光Ｇの光量Ｉを実際に検出し、この検出値に基づいて消光比を求めても良い。
また、上記偏光測定において、ステップＳ６〜ステップＳ８の処理をせずとも、所望の精度が得られている場合には、これらステップＳ６〜ステップＳ８の処理を行わずに、ステップＳ５で特定された偏光軸、及び消光比を測定結果としても良い。また、これらステップＳ６〜ステップＳ８の処理を行うか否かを作業者等のユーザが選択可能にしても良い。 In the same manner as in steps S4 and S5, the polarization measuring device 20 changes the curve Q by curve fitting based on the detected values of the light quantity I at four points of rotation angles θ = θa + 180 ° ± 20 ° and θa + 180 ° ± 10 °. (Step S6), and based on the change curve Q, the polarization axis and the extinction ratio are specified (Step S7).
Then, the polarization measuring device 20 specifies the polarization axis and the extinction ratio of the polarized light by obtaining the average value of the polarization axis and the extinction ratio obtained in Step S5 and Step S7 (Step S8).
Thereby, the polarization axis and extinction ratio of polarized light are required with high accuracy.
In this measurement, the polarization measuring device 20 specifies the rotation angle θ = θa at which the minimum light amount Imin is obtained and the rotation angle θ = γ at which the maximum light amount Imax is obtained based on the change curve Q, and the detection unit 31. The detection-side polarizer 33 may be rotated to actually detect the light amount I of the detection light G at each rotation angle θ, and the extinction ratio may be obtained based on this detection value.
Further, in the above polarization measurement, if the desired accuracy is obtained without performing the processing of step S6 to step S8, the processing of step S6 to step S8 is not performed and the identification is performed in step S5. The polarization axis and the extinction ratio may be used as measurement results. Further, it may be possible for a user such as an operator to select whether or not to perform the processes in steps S6 to S8.

次いで、偏光測定システム１を用いた光配向装置２の偏光光の測定について説明する。
作業者は、先ず、測定ユニット３０を光配向装置２に設置する。この設置に際し、作業者は、リニアガイド３２の案内方向が上記ワイヤーグリッド偏光子１６の配列方向Ｂと平行になり、かつ、偏光子ユニット１０の直下に位置するようにリニアガイド３２を設置する。次いで、作業者は、検出部３１をリニアガイド３２で案内して測定対象のワイヤーグリッド偏光子１６の直下に配置し、偏光測定システム１を用いて、このワイヤーグリッド偏光子１６から出射される偏光光Ｆを検出し、そのワイヤーグリッド偏光子１６の偏光軸Ｃ１、及び消光比を測定する。作業者は、偏光軸Ｃ１の測定結果に基づき、必要に応じてワイヤーグリッド偏光子１６の回動を微調整することで、偏光軸Ｃ１の方向を所定方向（本実施形態では配列方向Ｂ）に合わせる。
作業者は、偏光子ユニット１０が備える全てのワイヤーグリッド偏光子１６について同様に偏光光Ｆの測定、この測定結果に基づき、偏光軸Ｃ１の方向を配列方向Ｂに合わせる作業を行うことで、全てのワイヤーグリッド偏光子１６の偏光軸Ｃ１の方向が配列方向Ｂに揃えられる。 Next, measurement of polarized light of the optical alignment apparatus 2 using the polarization measurement system 1 will be described.
The operator first installs the measurement unit 30 in the optical alignment apparatus 2. In this installation, the operator installs the linear guide 32 so that the guide direction of the linear guide 32 is parallel to the arrangement direction B of the wire grid polarizer 16 and is positioned directly below the polarizer unit 10. Next, the operator guides the detection unit 31 with the linear guide 32 and arranges it directly below the wire grid polarizer 16 to be measured, and uses the polarization measurement system 1 to output the polarized light emitted from the wire grid polarizer 16. The light F is detected, and the polarization axis C1 and the extinction ratio of the wire grid polarizer 16 are measured. The operator finely adjusts the rotation of the wire grid polarizer 16 as necessary based on the measurement result of the polarization axis C1, thereby setting the direction of the polarization axis C1 to a predetermined direction (the arrangement direction B in the present embodiment). Match.
The operator performs measurement of polarized light F in the same manner for all the wire grid polarizers 16 provided in the polarizer unit 10, and performs the work of adjusting the direction of the polarization axis C <b> 1 to the arrangement direction B based on the measurement result. The direction of the polarization axis C1 of the wire grid polarizer 16 is aligned with the arrangement direction B.

上述の通り、この偏光測定システム１によれば、同様の測定を複数回行わなくとも、繰り返し精度が高く信頼性が高い変化曲線Ｑが得られ、この変化曲線Ｑから偏光軸Ｃ１の方向が高精度に特定される。したがって、個々のワイヤーグリッド偏光子１６を微調整する際に、偏光光Ｆの測定回数を減らすことができ、また微調整作業を短時間で終えつつ、高い精度で偏光軸Ｃ１の方向を調整できる。   As described above, according to the polarization measurement system 1, a change curve Q with high repeatability and high reliability can be obtained without performing the same measurement a plurality of times, and the direction of the polarization axis C1 from the change curve Q is high. Specific to accuracy. Therefore, when finely adjusting each wire grid polarizer 16, the number of times of measurement of the polarized light F can be reduced, and the direction of the polarization axis C1 can be adjusted with high accuracy while finishing the fine adjustment work in a short time. .

ところで、光配向装置２にあっては、棒状のランプ７から放射されるさまざまな角度の放射光Ｅがワイヤーグリッド偏光子１６に入射し、ワイヤーグリッド偏光子１６で直線偏光化されて出射される。
一方、従来、グラントムソン偏光プリズムを検出側偏光子３３に用いた検出部が知られている。しかしながら、グラントムソン偏光プリズムを用いた検出部では、グラントムソン偏光プリズムの消光比が入射角によって大きく変わるため、この検出部に入射する入射角を極力小さくする必要がある。
したがって、従来の検出部では、ワイヤーグリッド偏光子１６から出力されるさまざまな角度成分を含んだ偏光光Ｆのうち、非常に制限された範囲の角度成分しか検出することができず、この偏光光Ｆを正確に測定することができない。
そこで、本実施形態では、以下に説明する構成の検出部３１を用いることで、さまざまな角度成分を含んだ偏光光Ｆであっても、広い角度成分の範囲を検出して偏光特性を測定可能としている。 By the way, in the optical alignment apparatus 2, the radiation light E of various angles emitted from the rod-shaped lamp 7 is incident on the wire grid polarizer 16, and is linearly polarized by the wire grid polarizer 16 and emitted. .
On the other hand, a detection unit using a Glan-Thompson polarizing prism for the detection-side polarizer 33 is conventionally known. However, in the detection unit using the Glan-Thompson polarizing prism, the extinction ratio of the Glan-Thompson polarizing prism varies greatly depending on the incident angle. Therefore, it is necessary to make the incident angle incident on the detection unit as small as possible.
Therefore, the conventional detection unit can detect only a very limited range of angle components of the polarized light F including various angle components output from the wire grid polarizer 16, and this polarized light can be detected. F cannot be measured accurately.
Therefore, in the present embodiment, by using the detection unit 31 having the configuration described below, it is possible to measure a polarization characteristic by detecting a wide range of angle components even for polarized light F including various angle components. It is said.

図８は検出部３１の構成を示し外観斜視図であり、図９は検出部３１の断面図である。
検出部３１は、これらの図に示すように、矩形板状のベースマウント７０を備え、その上に、受光センサユニット７１と、検出側偏光子３３と、回転ステージ７２と、検出光調整ユニット７３（図９）とを備えている。
受光センサユニット７１は、受光センサ３４の一例たる光電子増倍管７４と、この光電子増倍管７４を冷却して温度を一定に保ち光電子増倍管７４の温度特性によるノイズを低減する水冷ベース７５とを備え、光電子増倍管７４の検出信号３５（図３）が偏光測定装置２０に取り込まれる。 FIG. 8 is an external perspective view showing the configuration of the detection unit 31, and FIG. 9 is a cross-sectional view of the detection unit 31.
As shown in these drawings, the detection unit 31 includes a rectangular plate-shaped base mount 70 on which a light receiving sensor unit 71, a detection-side polarizer 33, a rotary stage 72, and a detection light adjustment unit 73 are provided. (FIG. 9).
The light receiving sensor unit 71 includes a photomultiplier tube 74 as an example of the light receiving sensor 34, and a water-cooled base 75 that cools the photomultiplier tube 74 to keep the temperature constant and reduce noise due to the temperature characteristics of the photomultiplier tube 74. The detection signal 35 (FIG. 3) of the photomultiplier tube 74 is taken into the polarization measuring device 20.

ベースマウント７０は、リニアガイド３２に係合して当該リニアガイド３２によって直線的に案内される。ベースマウント７０の所定の一辺をリニアガイド３２の長軸方向に合わせてセットすることで、基準位置Ｐ０、及び検出側偏光子３３の偏光軸Ｃ２が配列方向Ｂに向けられるように構成されている。なお、ベースマウント７０の所定の一辺を配列方向Ｂに合わせて設置可能であれば、必ずしもリニアガイド３２を用いる必要はない。   The base mount 70 engages with the linear guide 32 and is linearly guided by the linear guide 32. By setting a predetermined one side of the base mount 70 in accordance with the major axis direction of the linear guide 32, the reference position P0 and the polarization axis C2 of the detection-side polarizer 33 are configured to be directed in the arrangement direction B. . Note that the linear guide 32 is not necessarily used as long as a predetermined one side of the base mount 70 can be installed in the arrangement direction B.

検出側偏光子３３は、光電子増倍管７４の検出面７４Ａの直上に配置され、所定径の開口７６Ａが形成されたアパーチャ７６で検出光Ｇの入射側が覆われている。このアパーチャ７６は、検出側偏光子３３への入射光を制限するものではあるが、この検出部３１では、ワイヤーグリッド偏光子１６が斜入射の光も透過して偏光光Ｆを生成することに合わせ、これら斜入射の成分による偏光光Ｆも取り込むべく、開口７６Ａは入射角Ｙが０°〜７０°までの範囲の偏光光Ｆを通過するように形成されている。
なお、入射角Ｙの範囲は、検出部３１と、ワイヤーグリッド偏光子１６と、ランプ７のそれぞれの形状や配置関係に基づいて、ワイヤーグリッド偏光子１６から斜めに放射される偏光光Ｆの成分が取り込まれる角度に決定される。
回転ステージ７２は、偏光測定装置２０の制御の下、検出側偏光子３３を回転させるものであり、偏光軸の要求測定精度以上の分解能で回動可能なロータリーアクチュエータを内蔵する。 The detection-side polarizer 33 is disposed immediately above the detection surface 74A of the photomultiplier tube 74, and the incident side of the detection light G is covered with an aperture 76 in which an opening 76A having a predetermined diameter is formed. Although this aperture 76 restricts the incident light to the detection side polarizer 33, in this detection unit 31, the wire grid polarizer 16 also transmits obliquely incident light to generate polarized light F. In addition, the aperture 76A is formed so as to pass the polarized light F having an incident angle Y in the range of 0 ° to 70 ° so as to capture the polarized light F due to these obliquely incident components.
The range of the incident angle Y is a component of the polarized light F emitted obliquely from the wire grid polarizer 16 based on the shapes and arrangement relationships of the detector 31, the wire grid polarizer 16, and the lamp 7. Is determined as the angle at which is taken.
The rotation stage 72 rotates the detection-side polarizer 33 under the control of the polarization measuring device 20, and incorporates a rotary actuator that can be rotated with a resolution that exceeds the required measurement accuracy of the polarization axis.

検出光調整ユニット７３は、検出側偏光子３３と光電子増倍管７４の検出面７４Ａの間に配設された筒状の部材であり、筒体７７を備え、アパーチャ７６を通じて取り込まれて検出側偏光子３３を通過した検出光Ｇを筒体７７の上面から取り込み、内部で混合して下面から光電子増倍管７４に導くものである。
具体的には、検出光調整ユニット７３の筒体７７の上面には、アパーチャ７６が取り込む入射角Ｙまでの範囲の検出光Ｇを内部に通過させる開口７８Ａが形成されたアパーチャ７８が設けられている。 The detection light adjustment unit 73 is a cylindrical member disposed between the detection-side polarizer 33 and the detection surface 74A of the photomultiplier tube 74. The detection light adjustment unit 73 includes a cylindrical body 77 and is taken in through the aperture 76 and detected. The detection light G that has passed through the polarizer 33 is taken in from the upper surface of the cylindrical body 77, mixed inside, and guided to the photomultiplier tube 74 from the lower surface.
Specifically, the upper surface of the cylindrical body 77 of the detection light adjusting unit 73 is provided with an aperture 78 in which an opening 78A through which detection light G in a range up to an incident angle Y taken in by the aperture 76 passes is formed. Yes.

このアパーチャ７８から取り込まれた検出光Ｇには、比較的大きな入射角Ｙの成分が含まれ、そのままでは筒体７７の内壁面に入射して吸収等されてしまう。このような吸収が生じると、アパーチャ７６とワイヤーグリッド偏光子１６の相対位置関係によって吸収される成分が変わることから、検出部３１の設置位置に依存して測定結果が変わってしまう。これを防止すべく、光電子増倍管７４の検出面７４Ａをアパーチャ７８の近傍に配置してしまうと、外乱光の影響を受け易くなる。
そこで、筒体７７には、透過する光を拡散する拡散ユニット７９がアパーチャ７８の直下に隙間を空けずに設けられている。拡散ユニット７９は、所定間隔で対面配置された２枚の拡散板７９Ａ、７９Ｂを備え、各種の入射角Ｙの検出光Ｇを混合して出力する。拡散板７９Ａ、７９Ｂには、例えばフロスト型合成石英板が用いられている。 The detection light G taken in from the aperture 78 includes a component having a relatively large incident angle Y, and is incident on the inner wall surface of the cylindrical body 77 and is absorbed. When such absorption occurs, the component to be absorbed changes depending on the relative positional relationship between the aperture 76 and the wire grid polarizer 16, and the measurement result changes depending on the installation position of the detection unit 31. In order to prevent this, if the detection surface 74A of the photomultiplier tube 74 is disposed in the vicinity of the aperture 78, it is likely to be affected by disturbance light.
Therefore, the cylindrical body 77 is provided with a diffusing unit 79 for diffusing the transmitted light without a gap immediately below the aperture 78. The diffusing unit 79 includes two diffusing plates 79A and 79B arranged facing each other at a predetermined interval, and mixes and outputs the detection light G having various incident angles Y. For the diffusion plates 79A and 79B, for example, frost type synthetic quartz plates are used.

筒体７７の下面には、光電子増倍管７４への入射光量を制限するピンホール８０Ａが形成された板材８０が設けられ、このピンホール８０Ａを通った光が光電子増倍管７４の検出面７４Ａに入射される。
また、ピンホール８０Ａと光電子増倍管７４の検出面７４Ａの間には、ランプ７の発光波長（本実施形態では紫外波長域）以外の波長の光をカットする波長制限フィルタ８１が設けられており、波長制限フィルタ８１で外乱光がカットされた光が光電子増倍管７４に導かれる。 A plate member 80 formed with a pinhole 80A for limiting the amount of light incident on the photomultiplier tube 74 is provided on the lower surface of the cylindrical body 77, and light passing through the pinhole 80A is detected by the photomultiplier tube 74. It is incident on 74A.
Further, between the pinhole 80A and the detection surface 74A of the photomultiplier tube 74, a wavelength limiting filter 81 for cutting light having a wavelength other than the emission wavelength of the lamp 7 (ultraviolet wavelength region in the present embodiment) is provided. The light from which the disturbance light is cut by the wavelength limiting filter 81 is guided to the photomultiplier tube 74.

このように、検出部３１は、比較的大きな入射角Ｙの範囲まで偏光光Ｆを取り込み、内部で拡散させて光電子増倍管７４で光量を検出する構成としたため、棒状のランプ７の放射光Ｅをワイヤーグリッド偏光子１６に通して得られた偏光光Ｆのように、さまざまな角度成分を含んだ偏光光Ｆであっても、広い角度成分の範囲を検出して偏光特性を測定することができる。   As described above, the detection unit 31 is configured to take the polarized light F up to a relatively large incident angle Y, diffuse the inside thereof, and detect the amount of light by the photomultiplier tube 74. Even for polarized light F including various angle components, such as polarized light F obtained by passing E through the wire grid polarizer 16, a wide angle component range is detected to measure polarization characteristics. Can do.

以上説明したように、本実施形態によれば、ワイヤーグリッド偏光子１６、及び検出側偏光子３３を順に透過した検出光Ｇを検出側偏光子３３を回動させながら検出して得られる各回動角度θでの光量Ｉに基づいて、検出側偏光子３３を１回転させたときの光量Ｉの周期的な変化を示す変化曲線Ｑを求めるに際し、変化曲線Ｑの１つの極小点である回動角度θ＝θaを含み、かつ、光量Ｉが所定値以下（本実施形態では、最大光量Ｉｍａｘの約２０％以下）となる回動角度θの範囲Ｗに含まれる各回動角度θ＝θａ±２０°、θａ±１０°での光量Ｉに基づいて変化曲線Ｑを求める構成とした。
これにより、極大点である最大光量Ｉｍａｘ近傍の光量Ｉの検出値に比べ、検出値に含まれるノイズ成分が少ない検出値に基づいて変化曲線が求められるため、変化曲線の精度が高められる。この変化曲線から偏光特性を求めることで、精度良く偏光特性が求められる。
また極小点である最小光量Ｉｍｉｎ近傍での光量Ｉだけが測定されていれば良いため、少ない測定回数で高精度な測定が可能となる。 As described above, according to the present embodiment, each rotation obtained by detecting the detection light G that sequentially passes through the wire grid polarizer 16 and the detection side polarizer 33 while rotating the detection side polarizer 33. When obtaining a change curve Q indicating a periodic change in the light quantity I when the detection-side polarizer 33 is rotated once based on the light quantity I at the angle θ, the rotation that is one minimum point of the change curve Q Each rotation angle θ = θa ± 20 included in the range W of the rotation angle θ including the angle θ = θa and the light amount I being equal to or less than a predetermined value (in this embodiment, about 20% or less of the maximum light amount Imax). The change curve Q is obtained based on the light quantity I at °, θa ± 10 °.
As a result, since the change curve is obtained based on the detection value with less noise components included in the detection value than the detection value of the light amount I in the vicinity of the maximum light amount Imax, which is the maximum point, the accuracy of the change curve is improved. By obtaining the polarization characteristic from the change curve, the polarization characteristic can be obtained with high accuracy.
In addition, since only the light quantity I in the vicinity of the minimum light quantity Imin, which is a minimum point, needs to be measured, high-precision measurement can be performed with a small number of measurements.

また本実施形態によれば、上記の回動角度θ＝θａと異なる１つの極小点である回動角度θ＝θａ＋１８０°を含み、かつ、光量Ｉが所定値以下となる回動角度θの範囲Ｗに含まれる回動角度θ＝θａ＋１８０°±２０°、θａ＋１８０°±１０°での光量Ｉに基づいて変化曲線Ｑを求め、この変化曲線Ｑに基づいて偏光光Ｆの偏光特性を特定し、そして、上記の回動角度θ＝θａを含む範囲Ｗに対応する変化曲線Ｑから特定した偏光特性との平均に基づき、偏光光Ｆの偏光特性を特定する構成とした。
これにより、高精度な測定が必要な場合に、より精度良く偏光光Ｆの偏光特性が求められる。 Further, according to the present embodiment, the range of the rotation angle θ that includes the rotation angle θ = θa + 180 °, which is one minimum point different from the rotation angle θ = θa, and in which the light amount I is equal to or less than a predetermined value. A change curve Q is obtained based on the light amount I at the rotation angles θ = θa + 180 ° ± 20 ° and θa + 180 ° ± 10 ° included in W, and the polarization characteristic of the polarized light F is specified based on the change curve Q. And it was set as the structure which specifies the polarization characteristic of the polarized light F based on the average with the polarization characteristic specified from the change curve Q corresponding to the range W containing said rotation angle (theta) = (theta) a.
Thereby, when highly accurate measurement is required, the polarization characteristic of the polarized light F is calculated with higher accuracy.

また本実施形態では、上記範囲Ｗを、検出光Ｇの光量Ｉが最大光量Ｉｍａｘに対して約２０％の光量となる範囲とすることで、ノイズ成分の影響を抑えた高精度な変化曲線Ｑが得られる。   In the present embodiment, the above range W is set to a range in which the light amount I of the detection light G is approximately 20% of the maximum light amount Imax, so that the change curve Q with high accuracy in which the influence of the noise component is suppressed. Is obtained.

また本実施形態によれば、検出部３１は、斜入射成分を含む偏光光Ｆを取り込み検出側偏光子３３に入射するアパーチャ７６と、検出側偏光子３３を透過した光を拡散する拡散ユニット７９と、この拡散ユニット７９で拡散された光を受光して光量Ｉを検出する受光センサとしての光電子増倍管７４と、を有する構成とした。
これにより、棒状のランプ７の放射光Ｅをワイヤーグリッド偏光子１６に通して得られた偏光光Ｆのように、さまざまな角度成分を含んだ偏光光Ｆであっても、広い角度成分の範囲を検出して偏光特性を測定することができる。 Further, according to the present embodiment, the detection unit 31 takes in the polarized light F including the oblique incident component and enters the detection side polarizer 33, and the diffusion unit 79 that diffuses the light transmitted through the detection side polarizer 33. And a photomultiplier tube 74 as a light receiving sensor that receives the light diffused by the diffusing unit 79 and detects the light quantity I.
Thereby, even in the case of the polarized light F including various angular components, such as the polarized light F obtained by passing the radiated light E of the rod-shaped lamp 7 through the wire grid polarizer 16, a wide range of angular components is obtained. Can be detected to measure the polarization characteristics.

なお、上述した実施形態は、あくまでも本発明の一態様を例示するものであって、本発明の趣旨を逸脱しない範囲で任意に変形、及び応用が可能である。   The above-described embodiment is merely an example of the present invention, and can be arbitrarily modified and applied without departing from the spirit of the present invention.

例えば上述した実施形態では、偏光測定システム１が測定する偏光光の光源として、放電灯であるランプ７を例示したが、光源はこれに限定されるものではなく任意である。すなわち、本発明は、任意の光源の光が偏光子を透過して得られる直線偏光された偏光光の測定に用いることができる。また光源は、必ずしも線状光源である必要はない。
また例えば、上述した実施形態では、測定対象の偏光光を得る偏光子の一例として、ワイヤーグリッド偏光子１６を例示したが、偏光子はこれに限定されるものではない。すなわち、偏光子は、直線偏光された偏光光が得られる偏光子であれば任意である。 For example, in the above-described embodiment, the lamp 7 that is a discharge lamp is exemplified as the light source of the polarized light measured by the polarization measurement system 1, but the light source is not limited to this and is arbitrary. That is, the present invention can be used for measuring linearly polarized polarized light obtained by transmitting light from an arbitrary light source through a polarizer. The light source is not necessarily a linear light source.
Further, for example, in the above-described embodiment, the wire grid polarizer 16 is illustrated as an example of the polarizer that obtains the polarized light to be measured, but the polarizer is not limited to this. That is, the polarizer is arbitrary as long as it is a polarizer capable of obtaining linearly polarized polarized light.

また例えば、上述した実施形態では、偏光測定装置２０が偏光光の偏光軸と消光比の両方を測定する構成を例示したが、片方のみを測定しても良い。また、偏光測定装置２０が偏光光の偏光軸、及び／又は消光比に加え、光強度等の他の特性も測定しても良い。
また例えば、上述した実施形態では、検出部３１の検出信号３５を偏光測定装置２０に入力することで、偏光測定装置２０が検出光Ｇの光量を取得する構成としたが、これに限らない。すなわち、回動角度θと検出光Ｇの光量との対応が記録された記録データを、例えば他の電子機器や記録媒体（例えば、半導体メモリ等）から取得しても良い。 Further, for example, in the above-described embodiment, the configuration in which the polarization measuring device 20 measures both the polarization axis and the extinction ratio of the polarized light is exemplified, but only one of them may be measured. Further, the polarization measuring device 20 may measure other characteristics such as light intensity in addition to the polarization axis and / or the extinction ratio of the polarized light.
Further, for example, in the above-described embodiment, the polarization measurement device 20 acquires the light amount of the detection light G by inputting the detection signal 35 of the detection unit 31 to the polarization measurement device 20, but the configuration is not limited thereto. That is, the recording data in which the correspondence between the rotation angle θ and the amount of the detection light G is recorded may be acquired from, for example, another electronic device or a recording medium (for example, a semiconductor memory).

１ 偏光測定システム
２ 光配向装置
６ 照射器
７ ランプ
８ 反射鏡
１０ 偏光子ユニット
１６ ワイヤーグリッド偏光子（第１の偏光子）
２０ 偏光測定装置
２３ 変化曲線算出部
２４ 偏光特性特定部
３０ 測定ユニット
３１ 検出部
３２ リニアガイド
３３ 検出側偏光子（第２の偏光子）
３４ 受光センサ
７３ 検出光調整ユニット
７６ アパーチャ
７９ 拡散ユニット（拡散手段）
Ａ ワイヤー方向
Ｂ 配列方向
Ｅ 放射光
Ｆ 偏光光
Ｇ 検出光
Ｑ 変化曲線
Ｗ 範囲
Ｙ 入射角
θ 回動角度
θａ、θａ＋１８０° 極小点の回動角度
θａ＋９０°、θａ＋２７０° 極大点の回動角度
Ｃ１ 偏光軸
Ｐ０ 基準位置 DESCRIPTION OF SYMBOLS 1 Polarization measurement system 2 Optical orientation apparatus 6 Irradiator 7 Lamp 8 Reflector 10 Polarizer unit 16 Wire grid polarizer (1st polarizer)
DESCRIPTION OF SYMBOLS 20 Polarization measuring apparatus 23 Change curve calculation part 24 Polarization characteristic specific | specification part 30 Measurement unit 31 Detection part 32 Linear guide 33 Detection side polarizer (2nd polarizer)
34 Light receiving sensor 73 Detection light adjustment unit 76 Aperture 79 Diffusion unit (diffusion means)
A Wire direction B Array direction E Radiated light F Polarized light G Detected light Q Change curve W Range Y Incident angle θ Rotation angle θa, θa + 180 ° Rotation angle of minimum point θa + 90 °, θa + 270 ° Rotation angle of maximum point C1 Polarization Axis P0 Reference position

Claims (6)

第１の偏光子、及び第２の偏光子を順に透過した光を前記第２の偏光子を回動させながら検出して得られる各回動角度での光の光量に基づいて、前記第２の偏光子が回転したときの前記光量の周期的な変化を示す変化曲線を求める第１ステップと、
前記第１ステップで求めた変化曲線に基づいて前記第１の偏光子を透過した偏光光の偏光特性を特定する第２ステップと、を備え、
前記第１ステップでは、
前記変化曲線の１つの極小点を含み、かつ、前記光量が所定値以下となる前記回動角度の範囲に含まれる前記回動角度での前記光量に基づいて前記変化曲線を求める
ことを特徴とする偏光測定方法。 Based on the amount of light at each rotation angle obtained by detecting light passing through the first polarizer and the second polarizer in order while rotating the second polarizer, the second polarizer A first step for obtaining a change curve indicating a periodic change in the light amount when the polarizer rotates;
A second step of specifying a polarization characteristic of the polarized light transmitted through the first polarizer based on the change curve obtained in the first step,
In the first step,
The change curve is obtained based on the light amount at the rotation angle included in the range of the rotation angle including one minimum point of the change curve and the light amount being a predetermined value or less. Polarization measurement method. 前記第１ステップと異なる１つの極小点を含み、かつ、前記光量が所定値以下となる前記回動角度の範囲に含まれる前記回動角度での前記光量に基づいて前記変化曲線を求める第３ステップと、
前記第３ステップで求めた変化曲線に基づいて前記第１の偏光子を透過した偏光光の偏光特性を特定する第４ステップと、
前記第２ステップ、及び第４ステップのそれぞれで特定された前記偏光特性の平均に基づき、前記第１の偏光子を透過した偏光光の偏光特性を特定する第５ステップと
を備えたことを特徴とする請求項１に記載の偏光測定方法。 A third curve for obtaining the change curve based on the light amount at the rotation angle included in the range of the rotation angle including one minimum point different from the first step and the light amount being a predetermined value or less. Steps,
A fourth step of specifying a polarization characteristic of the polarized light transmitted through the first polarizer based on the change curve obtained in the third step;
And a fifth step of specifying a polarization characteristic of the polarized light transmitted through the first polarizer based on an average of the polarization characteristics specified in each of the second step and the fourth step. The polarization measurement method according to claim 1. 前記所定値は、前記光量の最大値の約２０％の光量であることを特徴とする請求項１又は２に記載の偏光測定方法。   The polarization measurement method according to claim 1, wherein the predetermined value is a light amount that is about 20% of a maximum value of the light amount. 前記変化曲線が示す光量の最大値に対応する回動角度に基づいて前記第１の偏光子を透過した偏光光の偏光軸を特定し、及び／又は、前記変化曲線が示す最大値と最小値に基づいて前記第１の偏光子を透過した偏光光の消光比を特定することを特徴とする請求項１乃至３のいずれかに記載の偏光測定方法。   The polarization axis of the polarized light transmitted through the first polarizer is specified based on the rotation angle corresponding to the maximum light amount indicated by the change curve, and / or the maximum value and the minimum value indicated by the change curve. The polarization measurement method according to claim 1, wherein an extinction ratio of the polarized light that has passed through the first polarizer is specified based on the above. 第１の偏光子、及び第２の偏光子を順に透過した光を前記第２の偏光子を回動させながら検出して得られる各回動角度での光の光量に基づいて、前記第２の偏光子が回転したときの前記光量の周期的な変化を示す変化曲線を求める変化曲線算出手段と、
前記変化曲線に基づいて前記第１の偏光子を透過した偏光光の偏光特性を特定する偏光特性特定手段と、を備え、
前記変化曲線算出手段は、
前記変化曲線の１つの極小点を含み、かつ、前記光量が所定値以下となる前記回動角度の範囲に含まれる前記回動角度での前記光量に基づいて前記変化曲線を求める
ことを特徴とする偏光測定装置。 Based on the amount of light at each rotation angle obtained by detecting light passing through the first polarizer and the second polarizer in order while rotating the second polarizer, the second polarizer A change curve calculating means for obtaining a change curve indicating a periodic change in the amount of light when the polarizer rotates;
Polarization characteristic specifying means for specifying the polarization characteristic of polarized light that has passed through the first polarizer based on the change curve, and
The change curve calculating means includes:
The change curve is obtained based on the light amount at the rotation angle included in the range of the rotation angle including one minimum point of the change curve and the light amount being a predetermined value or less. Polarization measuring device. 第１の偏光子で偏光化された偏光光を入射する第２の偏光子を有し、前記第２の偏光子を透過する光の光量を前記第２の偏光子を回動させながら検出する検出部と、
前記検出部の検出結果に基づいて、前記第１の偏光子を透過した偏光光の偏光特性を特定する偏光測定装置と、を備え、
前記検出部は、
斜入射成分を含む前記光を取り込み前記第２の偏光子に入射するアパーチャと、
前記第２の偏光子を透過した光を拡散する拡散手段と、
前記拡散手段で拡散された光を受光して前記光量を検出する受光センサと、を有し、
前記偏光測定装置は、
前記第２の偏光子の各回動角度での光の光量に基づいて、前記第２の偏光子が回転したときの前記光量の周期的な変化を示す変化曲線を求める変化曲線算出手段と、
前記変化曲線に基づいて前記第１の偏光子を透過した偏光光の偏光特性を特定する偏光特性特定手段と、を備え、
前記変化曲線算出手段は、
前記変化曲線の１つの極小点を含み、かつ、前記光量が所定値以下となる前記回動角度の範囲に含まれる前記回動角度での前記光量に基づいて前記変化曲線を求める
ことを特徴とする偏光測定システム。 A second polarizer for entering the polarized light polarized by the first polarizer, and detecting the amount of light transmitted through the second polarizer while rotating the second polarizer; A detection unit;
A polarization measuring device that specifies polarization characteristics of polarized light transmitted through the first polarizer, based on a detection result of the detection unit,
The detector is
An aperture that captures the light containing a grazing incidence component and is incident on the second polarizer;
Diffusing means for diffusing the light transmitted through the second polarizer;
A light receiving sensor that receives the light diffused by the diffusing means and detects the amount of light, and
The polarization measuring device includes:
A change curve calculating means for obtaining a change curve indicating a periodic change of the light quantity when the second polarizer rotates based on the light quantity of light at each rotation angle of the second polarizer;
Polarization characteristic specifying means for specifying the polarization characteristic of polarized light that has passed through the first polarizer based on the change curve, and
The change curve calculating means includes:
The change curve is obtained based on the light amount at the rotation angle included in the range of the rotation angle including one minimum point of the change curve and the light amount being a predetermined value or less. Polarization measurement system.

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