JP2010281998A - Polarizable diffraction grating - Google Patents
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本発明は、偏光回折能をする偏光性回折格子に関するものである。 The present invention relates to a polarizing diffraction grating having polarization diffraction ability.
マスク露光や２光束の干渉縞を利用して回折格子やホログラフィーを作製する材料としては、写真などにも使われているようなハロゲン化銀感光材料、ゼラチン膜を重クロム酸アンモニウム水溶液に浸して感光性を付与した重クロム酸ゼラチン、半導体集積回路などの作製に用いるフォトレジスト、モノマーの光重合による屈折率変調を利用したフォトポリマーなどが挙げられる。このような材料を用いた回折格子やホログラムは、光ディスク、ＣＤなどで各種の信号を取り出すための光ピックアップ素子、バーコードスキャナーなどのビームを走査するための素子、情報処理関連ではホログラフィックメモリー、光インターコネクトなどへの応用が検討され、実際に利用もされてきており、更に、このような回折格子やホログラム素子に偏光性を付与する、更には、同一素子内に格子をパターン化させることにより、光磁気ディスクヘッドにおける検光子機能の複合化などその応用範囲が拡大する可能性がある。
このような偏光性回折格子の応用例として、Ｙ．Ｕｒｉｎｏ ｅｔ ａｌ．，Ｔｅｃｈ．Ｄｉｇｅｓｔ ｏｆ ＯＥＣ ’８８，３Ｃ２−１，１６７−１６９（１９８８）に複屈折性を有するＬｉＮｂＯ3を用いた偏光性回折格子の例が提案されている。この例では、ＬｉＮｂＯ3基材上にプロトン交換領域と誘電体膜からなる２層の格子を形成する手法がとられており、その製造法は、ＬｉＮｂＯ3基材上へのフォトリソグラフィによる金属のパターンの形成、プロトン交換領域形成工程、誘電体製膜およびパターン化など製造法が非常に煩雑である。更には、このような製造法では、ＬｉＮｂＯ3基材の複屈折性を用いているため、同一素子内に屈折率が最大となる方向が異なる複屈折領域を同一格子状に形成することは困難である。
偏光性回折格子を作製する他の手法として、ＵＳ−５１６１０３９号には、対称的な側鎖を有するポリシラン重合体、例えばポリ（ジ−ｎ−ヘキシルシラン）やポリ（ジ−ｎ−ペンチルシラン）などのような非線形性の材料に２光子吸収を利用して複屈折性を発現させ複屈折性をパターン化させた事例が提案されている。このような２光子吸収のような手法を用いる方法では照射光源として大出力のレーザーを用いる必要があるなど製造上の問題点が残る。また、同材料を用いて直線偏光性の紫外線でも複屈折性が発現するデータが記載されているが複屈折値は０．００５以下であり実用性に乏しい。
As materials for producing diffraction gratings and holography using mask exposure and two-beam interference fringes, silver halide photosensitive materials such as those used in photography and gelatin films are immersed in an aqueous solution of ammonium dichromate. Examples thereof include dichromated gelatin imparted with photosensitivity, a photoresist used for manufacturing a semiconductor integrated circuit, a photopolymer utilizing refractive index modulation by photopolymerization of a monomer, and the like. Diffraction gratings and holograms using such materials include optical pickup elements for extracting various signals on optical disks, CDs, etc., elements for scanning beams such as barcode scanners, holographic memories for information processing, Application to optical interconnects has been studied and has been used in practice. Furthermore, by imparting polarization to such diffraction gratings and hologram elements, and by patterning the gratings within the same element There is a possibility that the application range of the analyzer function in the magneto-optical disk head is expanded.
As an application example of such a polarizing diffraction grating, Y. et al. Urino et al. , Tech. Digest of OEC '88, 3C2-1, 167-169 (1988) proposes an example of a polarizing diffraction grating using LiNbO 3 having birefringence. In this example, has been taken a technique of forming a grid of two layers of a proton exchange region and a dielectric film on a LiNbO 3 substrate, its preparation, the metal by photolithography to LiNbO 3 substrate on Manufacturing methods such as pattern formation, proton exchange region forming step, dielectric film formation and patterning are very complicated. Furthermore, in such a manufacturing method, since the birefringence of the LiNbO 3 base material is used, it is difficult to form birefringent regions having different refractive index directions in the same element in the same lattice. It is.
As another method for producing a polarizing diffraction grating, US-5161039 discloses a polysilane polymer having a symmetrical side chain, such as poly (di-n-hexylsilane) or poly (di-n-pentylsilane). A case has been proposed in which birefringence is expressed by utilizing two-photon absorption in a nonlinear material such as the above, and the birefringence is patterned. In such a method using a technique such as two-photon absorption, it is necessary to use a high-power laser as an irradiation light source, and problems in manufacturing remain. In addition, data showing that birefringence develops even with linearly polarized ultraviolet rays using the same material is described, but the birefringence value is 0.005 or less, which is not practical.
本発明は、上記の従来技術の課題に鑑みて、従来技術に比して実用性が高く、量産性にすぐれる偏光性回折格子の構成を提供する。 In view of the above-described problems of the prior art, the present invention provides a configuration of a polarizing diffraction grating that is more practical than the prior art and has excellent mass productivity.
以下に、本発明の詳細を説明する。
本発明では、透光材からなる基材の一表面に複数の平行な溝線が形成されており、これらの溝線に複屈折性の材料を充填した構成によって偏光性回折格子を得ており、特には、前記の複屈折性の材料を、偏光照射と加熱・冷却によって複屈折性を生じる光配向材とすることによって、実用性（複屈折値）が高く、量産性にすぐれる回折格子を得るものである。
まず、本願の構成によって偏光回折格子が得られる仕組みと、その作用について説明する。
光学的に等方性の基材の一表面に、前記基材の厚さ方向の深さがｔの矩形断面の複数の平行な溝線が形成され、これら溝線には光配向材が充填されており、ここで溝線に充填された光配向材の前記溝線の長手向と平行方向の屈折率がｎ／／であり、光配向材の前記溝線の長手向と直交する方向の屈折率がｎ⊥であり、また、基材の屈折率はｎ⊥と等しいものとする。
このような位相格子の光の透過率Ｔは、式（１）で表される。ここで、位相格子とは、入射光に対し、その位相を変化させる特性を持つ回折格子を意味する。
（式）
Ｔ＝ｃｏｓ2（φ／２）・・・式（１）
ここで、φは、溝線内部と溝線間部（基材内部）を通過する光の位相差である。
本願の構成では、溝線に直交する向きの偏光に対しては、φ＝０となるため透過率は１となる。これに対し、溝線と平行方向の偏光に対しては、φ＝２π（ｎ／／−ｎ⊥）ｔ／λ（λは入射光の波長）となるため、φ＝πとなるようにｔを設定すれば透過率は０となり入射光は完全に回折されるので、偏光性回折格子を作製することができる。
Details of the present invention will be described below.
In the present invention, a plurality of parallel groove lines are formed on one surface of a base material made of a translucent material, and a polarizing diffraction grating is obtained by a configuration in which a birefringent material is filled in these groove lines. In particular, by using the above-described birefringent material as a photo-alignment material that generates birefringence by polarized light irradiation and heating / cooling, the diffraction grating has high practicality (birefringence value) and excellent mass productivity. Is what you get.
First, the mechanism by which the polarization diffraction grating is obtained by the configuration of the present application and the operation thereof will be described.
A plurality of parallel groove lines having a rectangular cross section having a depth t in the thickness direction of the substrate are formed on one surface of an optically isotropic substrate, and these groove lines are filled with a photo-alignment material. Here, the refractive index in the direction parallel to the longitudinal direction of the groove line of the photo-alignment material filled in the groove line is n //, and the refractive index in the direction orthogonal to the longitudinal direction of the groove line of the photo-alignment material is It is assumed that the refractive index is n 基材 and the refractive index of the substrate is equal to n⊥.
The light transmittance T of such a phase grating is expressed by Expression (1). Here, the phase grating means a diffraction grating having a characteristic of changing the phase of incident light.
(formula)
T = cos 2 (φ / 2) Expression (1)
Here, φ is the phase difference of light that passes through the groove line and between the groove lines (inside the base material).
In the configuration of the present application, for polarized light in a direction orthogonal to the groove line, φ = 0, and thus the transmittance is 1. On the other hand, for polarized light parallel to the groove line, φ = 2π (n // − n⊥) t / λ (λ is the wavelength of incident light), so that φ = π so that φ = π. Is set, the transmittance becomes 0 and incident light is completely diffracted, so that a polarizing diffraction grating can be produced.
以下、図面をもとに、本発明の偏光回折格子について詳細を説明する。
本発明の偏光性回折格子は、図1の本発明の偏光回折格子の断面図に示すように透光材からなる基材（１１）の一表面に複数の等間隔で平行な溝線が形成されており、これらの溝線に複屈折性の材料（１２）を充填してなる構成である。
透光性の基材（１１）の材料としては光学的に等方性であるものが好ましく、たとえば、溶媒キャストで得られるプラスチック材料、無機ガラスなどが用いられる。
溝線の形状としては、断面が矩形であるものが本発明に適し、その深さは、使用する波長と光配向材の複屈折の大きさで決まる。溝線の幅は回折させる光の回折角の大きさで決まるが、一般的に１ｍｍ以下であれば回折格子として機能し得る。
溝線の断面形状としては矩形以外では、三角波状、サイン波状も可能である。
溝線の長手方向の形態としては、等間隔で平行な直線状のものが本発明に適するが、平行な曲線状のものや、同心円状のものも可能である。溝線が周期的に配置されていればよい。
複屈折性の材料としては、本発明者が特開２００２−２０２４０９号、特開２００４−１７０５９５号などに提案している光配向材を用いることができる。
該光配向材は、偏光照射する工程と加熱冷却する工程により複屈折性を誘起する材料（以降、複屈折誘起材料と呼ぶ）に、偏光照射、加熱・冷却の処理をして、複屈折性をさせた材料である。複屈折誘起材料の例として、ポリ｛〔４−シンナモイルオキシエチルオキシ−４´−（６−メタクリロイルオキシヘキシルオキシ）ビフェニル〕0.85−ｃｏ−（メチルメタクリレート）0.15｝が挙げられる。光配向材の分子構造はメソゲン成分として多用されているビフェニル、ターフェニル、フェニルベンゾエートなどの置換基とシンナモイル基（または、その誘導体基）などの感光性基を結合した構造を含む側鎖を有し、該側鎖が単炭化、アルキルエーテルなどの屈曲性部分を介して、炭化水素、アクリレート、メタクリレート、シロキサンなど主鎖に結合した構造からなる繰り返し単位を少なくとも有する液晶性を有する重合体が挙げられる。更に、本発明者は、複屈折性を増強するために、４，４´−ビス（６−メタクリロイルオキシヘキシルオキシ）ビフェニルのような低分子化合物を混合添加する手法も提案している。
複屈折誘起材料は、基板上に塗布（スピンコート）製膜することが可能であり、製膜した膜は複屈折を有していないが、続く偏光照射する工程の前に、必要であれば加熱急冷処理により等方性となり、この等方性の膜に直線偏光性の紫外線を照射すると、照射した直線偏光性の紫外線の電界振動方向に沿って配置されている感光性基の２量化が選択的に起こり、続く加熱による分子運動により光２量化しなかった側鎖も光２量化した側鎖と同じ方向に配列し、塗布膜全体において側鎖が配列し、大きな複屈折を発現するという、特異な性質を有する材料である。
光配向材を、基材に形成された溝線に充填する方法としては、複屈折誘起材料を溶媒に溶解し、この溶液を溝線の形成された基材に塗布する方法が挙げられる。塗布後乾燥すると溝線に複屈折誘起材料が充填される。続く偏光照射する工程の前に、必要であれば加熱急冷処理により複屈折誘起材料を等方性とし、直線偏光性の紫外線を照射する。
次に、複屈折誘起材料の等方相転移温度以上に加熱した後、徐冷する。これにより、溝線に充填した複屈折誘起材料に配向が生じ複屈折を誘起する。このようにして光配向材を充填することができる。更に、紫外線を照射することにより、配向を固定することができる。
Hereinafter, the polarization diffraction grating of the present invention will be described in detail with reference to the drawings.
As shown in the cross-sectional view of the polarizing diffraction grating of the present invention in FIG. 1, the polarizing diffraction grating of the present invention has a plurality of grooves formed at equal intervals on one surface of the base material (11) made of a light transmitting material. The groove line is filled with a birefringent material (12).
As the material of the translucent substrate (11), an optically isotropic material is preferable. For example, a plastic material obtained by solvent casting, inorganic glass, or the like is used.
As the shape of the groove line, one having a rectangular cross section is suitable for the present invention, and the depth is determined by the wavelength used and the magnitude of the birefringence of the photo-alignment material. The width of the groove line is determined by the size of the diffraction angle of the light to be diffracted, but generally it can function as a diffraction grating if it is 1 mm or less.
As the cross-sectional shape of the groove line, other than the rectangular shape, a triangular wave shape and a sine wave shape are also possible.
As the shape of the groove line in the longitudinal direction, a straight linear shape at equal intervals is suitable for the present invention, but a parallel curved shape or a concentric shape is also possible. The groove line should just be arrange | positioned periodically.
As the birefringent material, a photo-alignment material proposed by the present inventor in Japanese Patent Application Laid-Open Nos. 2002-202409 and 2004-170595 can be used.
The photo-alignment material is obtained by subjecting a material that induces birefringence by a step of irradiating polarized light and a step of heating and cooling (hereinafter referred to as birefringence inducing material) to the treatment of polarized light irradiation and heating / cooling to produce birefringence. It is the material that made it. An example of a birefringence inducing material is poly {[4-cinnamoyloxyethyloxy-4 ′-(6-methacryloyloxyhexyloxy) biphenyl] 0.85 -co- (methyl methacrylate) 0.15 }. The molecular structure of the photo-alignment material has side chains including a structure in which substituents such as biphenyl, terphenyl, and phenylbenzoate, which are frequently used as mesogenic components, and photosensitive groups such as cinnamoyl groups (or their derivative groups) are combined. And a polymer having liquid crystallinity having at least a repeating unit having a structure in which the side chain is bonded to the main chain such as hydrocarbon, acrylate, methacrylate, and siloxane via a flexible portion such as single carbonized or alkyl ether. It is done. Furthermore, the present inventor has also proposed a method of adding a low molecular weight compound such as 4,4′-bis (6-methacryloyloxyhexyloxy) biphenyl in order to enhance birefringence.
The birefringence inducing material can be applied (spin coat) to be formed on the substrate, and the formed film does not have birefringence, but if necessary, before the subsequent polarized irradiation step When the isotropic film is made isotropic by heating and quenching treatment, when the linearly polarized ultraviolet light is irradiated to the isotropic film, the dimerization of the photosensitive group arranged along the electric field vibration direction of the irradiated linearly polarized ultraviolet light is caused. Side chains that occur selectively and are not photodimerized due to subsequent molecular motion due to heating are arranged in the same direction as the photodimerized side chains, and the side chains are arranged in the entire coating film, thereby expressing a large birefringence. , A material with unique properties.
Examples of the method of filling the photo-alignment material in the groove line formed on the substrate include a method in which the birefringence inducing material is dissolved in a solvent and this solution is applied to the substrate on which the groove line is formed. When the coating is dried, the groove is filled with the birefringence inducing material. Before the subsequent step of irradiating polarized light, if necessary, the birefringence inducing material is made isotropic by heating and cooling treatment, and linearly polarized ultraviolet rays are irradiated.
Next, after heating above the isotropic phase transition temperature of the birefringence inducing material, it is gradually cooled. As a result, orientation occurs in the birefringence inducing material filled in the groove line and induces birefringence. In this way, the photo-alignment material can be filled. Furthermore, the orientation can be fixed by irradiating with ultraviolet rays.
基材に形成される溝線には、基材表面にダイヤモンドバイトにより直接凹凸形状を切削加工で作製したもの、フォトリソグラフィの技術を用いてフォトレジストを塗布した基材にフォトマスクや干渉法によって周期的に強度変調した紫外線によって露光し表面に凹凸を形成して作製したもの、更には、金属表面にダイヤモンドバイトで凹凸形状を切削加工した型、フォトレジストを塗布した基材に、フォトマスクや干渉法によって周期的に強度変調した紫外線によって露光し、表面に凹凸を有する回折格子を形成した型を母型として、高分子材料の溶液を塗布し乾燥し塗膜を剥離することにより転写したもの、紫外線硬化性樹脂や熱硬化性樹脂を塗布して硬化させ転写したもの、射出成形や熱スタンプ成形などのプラスチック成形により複製したものなどを用いることができる。
図２には、本発明における回折格子を製造する方法の例を、図を用いて説明する。
まず、片面に所定間隔の複数の凸条が形成された母型（２１）を準備し、この母型（２１）に対して透光材をあらかじめ溶媒に溶解しておき、母型（２１）の凸条を形成した面を覆うように塗布して乾燥し、所定の厚さに付与して、透光材が固化した後、母型（２１）から脱型することにより、凸条に対応する溝線を転写した透光材からなる基材（２２）を作製する。
次に、この基材（２２）に形成された溝線にあらかじめ溶媒に溶解しておいた複屈折誘起材料（２３）を塗布するなどして充填する。その後、溝線に充填された複屈折誘起材料に前述のような偏光照射する工程と加熱冷却する工程により複屈折性を誘起させた光配向材とする。必要により光配向材の配向を固定した後、透光材からなる基材の一表面に形成した複数の平行な溝線に光配向材を充填してなる偏光性回折格子を製造できる。
The groove line formed on the substrate is made by cutting the surface of the substrate directly with a diamond bite by cutting, using a photomask or interference method on a substrate coated with photoresist using photolithography technology It is produced by exposing the surface to irregularities on the surface by periodically exposing the intensity-modulated ultraviolet rays, and further, a mold having a concave and convex shape cut with a diamond bit on a metal surface, a substrate coated with a photoresist, a photomask or Transferred by applying a polymer material solution, drying and peeling the coating film, using a mold with a diffraction grating with irregularities on the surface as a matrix, exposed to ultraviolet light whose intensity is periodically modulated by interferometry , UV curable resin or thermosetting resin applied, cured and transferred, or by plastic molding such as injection molding or heat stamping Etc. can be used with.
In FIG. 2, the example of the method of manufacturing the diffraction grating in this invention is demonstrated using figures.
First, a mother die (21) having a plurality of ridges with predetermined intervals formed on one side is prepared, and a translucent material is previously dissolved in a solvent for the mother die (21). It is applied so as to cover the surface on which the ridges are formed, dried, applied to a predetermined thickness, and after the translucent material is solidified, it is removed from the mother die (21) to cope with the ridges. The base material (22) which consists of a translucent material which transferred the groove line to perform is produced.
Next, the groove line formed on the base material (22) is filled with a birefringence inducing material (23) previously dissolved in a solvent. Thereafter, the birefringence inducing material filled in the groove line is made into a photo-alignment material in which birefringence is induced by the above-described polarization irradiation step and heating and cooling step. If necessary, after fixing the orientation of the photo-alignment material, it is possible to manufacture a polarizing diffraction grating in which a plurality of parallel groove lines formed on one surface of a base material made of a light-transmitting material are filled with the photo-alignment material.
本発明において、ＴＭ光、ＴＥ光（ここで、ＴＭ光は、基材の溝線方向と入射光の電界振動方向が垂直である光、ＴＥ光は、基材の溝線方向と入射光の電界振動方向が平行である光である）のどちらか一方を回折させる場合、溝線凸条部の屈折率は、光配向材の常光屈折率または異常光屈折率と実質的に等しくすることが望ましい。また、溝線を形成する基材が実質的に光学的等方性の材料からなることが望ましい。しかしながら、基材に形成された格子が光学的異方性の材料からなっていても、その常光屈折率または異常光屈折率のどちらか一方において、光配向材の常光屈折率または異常光屈折率のどちらかと実質的に一致していれば、ＴＭ光、ＴＥ光のどちらか一方のみを回折させる偏光性回折格子を作製することができる。 In the present invention, TM light and TE light (where TM light is light in which the direction of the electric field vibration of the incident light is perpendicular to the groove line direction of the base material, and TE light is the direction of the groove line direction of the base material and the incident light. The refractive index of the groove ridges may be substantially equal to the ordinary or extraordinary refractive index of the photo-alignment material. desirable. Further, it is desirable that the base material forming the groove line is made of a substantially optically isotropic material. However, even if the grating formed on the substrate is made of an optically anisotropic material, the ordinary refractive index or the extraordinary refractive index of the photo-alignment material in either the ordinary refractive index or the extraordinary refractive index. If it substantially corresponds with either of these, the polarizing diffraction grating which diffracts only any one of TM light and TE light can be produced.
更には、溝線を形成する基材の屈折率と光配向材の常光屈折率または異常光屈折率と実質的に一致していなくとも、ＴＭ光またはＴＥ光のどちらか一方において、予め基材に形成された凸条部を透過する光と溝線内に光配向材が充填された領域を透過する光との間に位相差が生じなければ、ＴＭ光、ＴＥ光のどちらか一方のみを回折させる偏光性回折格子を作製することができる。
図３に示すように、予め基材（３１）に形成された凸部領域（３１ａ）と基材の溝線内に光配向材が充填された領域（３１ｂ）の光学距離〔屈折率ｎの媒質において、光の進む道筋の長さＬと、その道筋に沿った媒質の屈折率との積（＝ｎ×Ｌ）〕を同一にすることも有効である。
図３において、ＴＭ光またはＴＥ光のどちらか一方において、ｎ1×ｌ1＝ｎ2×ｌ2＋ｎ3×ｌ3であればＴＥ光またはＴＭ光のどちらか一方を回折させる偏光性回折格子を作製することができる。ここで、ｎ1は、溝線を形成する基材の屈折率、ｌ1は、溝線の深さ、ｎ2は、光配向材の常光屈折率または異常光屈折率、ｌ2は、溝線内に充填された光配向材の厚さ、ｎ3は、回折格子の置かれた雰囲気の屈折率、ｌ3は、溝線の深さと溝線内に充填された光配向材の厚さの差である。
Furthermore, even if the refractive index of the base material forming the groove line and the ordinary light refractive index or extraordinary light refractive index of the photo-alignment material do not substantially coincide with each other, either the TM light or the TE light is used in advance. If there is no phase difference between the light transmitted through the ridges formed on the light source and the light transmitted through the region filled with the photo-alignment material in the groove line, only one of TM light and TE light is used. A polarizing diffraction grating to be diffracted can be produced.
As shown in FIG. 3, the optical distance [of the refractive index n of the convex part area | region (31a) previously formed in the base material (31) and the area | region (31b) with which the photoalignment material was filled in the groove line of a base material. In the medium, it is also effective to make the product (= n × L)] of the length L of the path along which light travels and the refractive index of the medium along the path equal.
In FIG. 3, a polarizing diffraction grating that diffracts either TE light or TM light if n 1 × l 1 = n 2 × l 2 + n 3 × l 3 in either TM light or TE light. Can be produced. Here, n 1 is the refractive index of the substrate forming the groove line, l 1 is the depth of the groove line, n 2 is the ordinary or extraordinary refractive index of the photo-alignment material, and l 2 is the groove. The thickness of the photo-alignment material filled in the line, n 3 is the refractive index of the atmosphere in which the diffraction grating is placed, and l 3 is the depth of the groove line and the thickness of the photo-alignment material filled in the groove line Is the difference.
更には、本発明の偏光性回折格子およびその製造方法では、基材の溝線に充填された複屈折誘起材料に直線偏光性の紫外線を照射する工程をとり、この際、照射する直線偏光性の紫外線の電界振動方向を領域によって変えれば、光配向材の配向軸方向が異なる領域を形成でき、同一の回折格子内で領域によって入射光の電界振動方向に対して異なる偏光回折性を有する回折格子を製造することも容易にできる。 Furthermore, in the polarizing diffraction grating and the manufacturing method thereof according to the present invention, the step of irradiating the birefringence inducing material filled in the groove line of the base material with linearly polarized ultraviolet light is performed. If the direction of the electric field oscillation of the UV light is changed depending on the region, regions with different alignment axis directions of the photo-alignment material can be formed, and diffraction having different polarization diffraction characteristics with respect to the direction of the electric field oscillation of the incident light in the same diffraction grating. It is also easy to manufacture the grid.
以下は、本発明の偏光性回折格子を作製した例である。
（実施例１）
ポリビニルアルコール樹脂（ナカライテスク株式会社製、商品名：ポリビニルアルコール、重合度：約５００）を母材樹脂とし、母型を用いて、溝線の幅５．０μｍ、深さ２．８μｍの矩形断面の直線状の多数の平行な溝線を、溝線と溝線の間隔６．５μｍ （＝ピッチ１１．５μｍ）で母材の表面に転写形成して実施例１の基材（厚さ５０μｍ）を形成した。
次に複屈折誘起材料の母材として、ポリ｛〔４−シンナモイルオキシエチルオキシ−４´−（６−メタクリロイルオキシヘキシルオキシ）ビフェニル〕0.85−ｃｏ−（メチルメタクリレート）0.15｝７８．４重量％に４，４´−ビス（６−メタクリロイルオキシヘキシルオキシ）ビフェニル１９．６重量％の混合物を用い、ここに、光増感剤として４，４´−ビス（ジメチルアミノ）ベンゾフェノン２重量％を添加した。該複屈折誘起材料の母材をｏ−ジクロロベンゼンに１５重量％の濃度で溶解し、前記基材の溝線を形成した表面を覆うようにスピンコーター（回転数：２０００ｒｐｍ）を用いて溝線が埋まるように塗布した。
次いで、前記のように複屈折誘起材料を溝線に充填した基材を透明なカバーガラス上に載置し、この基材にグランテーラープリズムを介して直線偏光性とした紫外線（電界振動方向は基材の溝線の長手方向と垂直方向のもの）を塗布面側から３００ｍＪ／ｃｍ2照射（２００秒間）し、次に基材の裏面側からも３００ｍＪ／ｃｍ2照射（２００秒間）した。
照射後、１００℃まで加熱後徐冷（１００℃から５０℃まで降温した。降温速度は、２℃／ｍｉｎである。）することにより複屈折誘起材料内に所定の配向を誘起し、最後に高圧水銀灯からの紫外線を、グランテーラープリズムを介さず１．０Ｊ／ｃｍ2照射（１５０秒間）して複屈折誘起材料に誘起させた配向を固定した。
このようにして作製した偏光性回折格子は、基材の溝線が複屈折を有する光配向材で充填されており、表面形状を測定したところ表面の凹凸は０．１μｍ以下であり、略平坦な表面形状を有していることが分った。この回折格子を偏光顕微鏡のクロスニコル下での観察した顕微鏡写真を図４に示す。図４に示されるとおり複屈折を有する領域（光が透過し明るい領域）と複屈折を有さない領域（光が透過せず暗い領域）が明暗の縞模様となって観察された。このように明暗の縞模様が観察されたということは、すなわち複屈折を有する領域が溝線部に形成されたことを意味しているので、実施例１では溝線部に光配向材を形成することができたことが確認できた。また、基材の溝線に充填された光配向材の位相差値は、セナルモン法によって測定した結果、２９０．２ｎｍであった。
ここで、溝線を形成する基材の屈折率が、光配向材の常光屈折率または異常光屈折率と一致した場合について考えると、段落０００５に記載した式（１）から、偏光性回折格子に入射した光の透過率が０となる条件は、φ＝πのときである。このことから、溝線に充填された光配向材の位相差値が、２９０．２ｎｍのとき光の透過率を０にする条件としては、入射光の波長が５８０．４ｎｍの場合である。 これを検証するための試験として、実施例１で作製した回折格子の偏光性特性を、分光光度計を用いて測定した結果を図５に示す。なお、この試験では入射光は偏光板を用いて直線偏光性とした。
図５に示されるように、ＴＭ光は回折され、すなわち、図５中のＴＭ曲線は透過率が低下しており、特に５９０ｎｍ近辺の波長において光の透過率が２％程度と低い。一方、ＴＥ光は回折されることなく、すなわち、図５中のＴＥ曲線は透過率が大きく低下しておらず、５９０ｎｍ近辺の波長における透過率は７０％程度である。このことから、入射光の偏光方向によって透過率が異なるという偏光回折格子に必要な特性が確認されたから、実施例１の偏光回折格子が実際に偏光回折性を有することが分った。また、その偏光特性は、先述した溝線内に充填した光配向材の位相差の測定値２９０．２ｎｍのとき理論上の数値である５８０．４ｎｍの波長の光が回折されことと良く一致することが確認された。このことからも、式（１）が成り立っていることがいえる。
The following is an example of producing the polarizing diffraction grating of the present invention.
Example 1
Polyvinyl alcohol resin (manufactured by Nacalai Tesque Co., Ltd., trade name: polyvinyl alcohol, degree of polymerization: about 500) is used as a base resin, and a rectangular cross section having a groove line width of 5.0 μm and a depth of 2.8 μm using a matrix. The base material of Example 1 (thickness: 50 μm) was transferred and formed on the surface of the base material at a distance of 6.5 μm (= pitch: 11.5 μm) between the groove lines. Formed.
Next, poly {[4-cinnamoyloxyethyloxy-4 '-(6-methacryloyloxyhexyloxy) biphenyl] 0.85- co- (methyl methacrylate) 0.15 } 78.4% by weight as a base material for the birefringence inducing material. 4,4′-bis (6-methacryloyloxyhexyloxy) biphenyl 19.6% by weight of a mixture was used, and 4% of 4,4′-bis (dimethylamino) benzophenone was added as a photosensitizer. did. The base material of the birefringence inducing material is dissolved in o-dichlorobenzene at a concentration of 15% by weight, and the groove line is formed using a spin coater (rotation speed: 2000 rpm) so as to cover the surface of the base material on which the groove line is formed. It was applied to fill up.
Next, the base material filled with the birefringence inducing material as described above is placed on a transparent cover glass, and ultraviolet light (the electric field vibration direction is made linearly polarized on this base material via a Grand Taylor prism). 300 mJ / cm 2 irradiated from the coating side ones longitudinal and vertical groove lines of the substrate) to (200 seconds), then also 300 mJ / cm 2 irradiated from the back side of the substrate (200 seconds) was.
After irradiation, the film was heated to 100 ° C. and then slowly cooled (the temperature was decreased from 100 ° C. to 50 ° C. The temperature decreasing rate was 2 ° C./min.) To induce a predetermined orientation in the birefringence inducing material. The orientation induced in the birefringence inducing material was fixed by irradiating ultraviolet rays from a high pressure mercury lamp with 1.0 J / cm 2 (150 seconds) without passing through the Grand Taylor prism.
The polarizing diffraction grating produced in this way is filled with a photo-alignment material having birefringence in the groove line of the base material. When the surface shape is measured, the surface unevenness is 0.1 μm or less and is substantially flat. It has been found that it has a different surface shape. FIG. 4 shows a photomicrograph of the diffraction grating observed under a crossed Nicol polarization microscope. As shown in FIG. 4, a region having birefringence (a region where light is transmitted and bright) and a region having no birefringence (a region where light is not transmitted and dark) were observed as bright and dark stripes. The fact that bright and dark stripes were observed in this way means that a region having birefringence was formed in the groove line portion, so in Example 1, a photo-alignment material was formed in the groove line portion. I was able to confirm that I was able to. Further, the retardation value of the photo-alignment material filled in the groove line of the base material was 290.2 nm as a result of measurement by the Senarmon method.
Here, considering the case where the refractive index of the base material forming the groove line coincides with the ordinary light refractive index or the extraordinary light refractive index of the photo-alignment material, from the formula (1) described in paragraph 0005, the polarizing diffraction grating The condition under which the transmittance of light incident on is 0 is when φ = π. From this, when the phase difference value of the photo-alignment material filled in the groove line is 290.2 nm, the condition for setting the light transmittance to 0 is the case where the wavelength of the incident light is 580.4 nm. As a test for verifying this, the result of measuring the polarization property of the diffraction grating produced in Example 1 using a spectrophotometer is shown in FIG. In this test, incident light was linearly polarized using a polarizing plate.
As shown in FIG. 5, TM light is diffracted, that is, the TM curve in FIG. 5 has reduced transmittance, and the light transmittance is as low as about 2% particularly at wavelengths around 590 nm. On the other hand, the TE light is not diffracted, that is, the transmittance of the TE curve in FIG. 5 is not greatly reduced, and the transmittance at a wavelength near 590 nm is about 70%. From this, it was confirmed that the polarization diffraction grating required in the polarization diffraction grating of Example 1 actually has polarization diffractive properties since the necessary characteristics of the polarization diffraction grating that the transmittance varies depending on the polarization direction of the incident light. Further, the polarization characteristics agree well with the fact that light having a wavelength of 580.4 nm, which is a theoretical value, is diffracted when the measured value of the phase difference of the photo-alignment material filled in the groove line is 290.2 nm. It was confirmed. From this, it can be said that the formula (1) is established.
（実施例２）
実施例１と同様に、ポリビニルアルコール樹脂（ナカライテスク株式会社製、商品名：ポリビニルアルコール、重合度：約５００）を母材樹脂とし、母型を用いて、溝線の幅５．０μｍ、深さ２．８μｍの矩形断面の直線状の多数の平行な溝線を、溝線と溝線の間隔６．５μｍ （＝ピッチ１１．５μｍ）で母材の表面に転写形成して実施例１の基材（厚さ５０μｍ）を形成し、実施例１と同じ複屈折誘起材料を（前記基材の溝線を形成した表面を覆うよう）にスピンコーター（回転数：２０００ｒｐｍ）を用いて溝線が埋まるように塗布した。
次に、上記のようにして形成した溝線に複屈折誘起材料を充填した基材の２つの領域にそれぞれの直線偏光性の紫外線の電界振動方向が互いに４５°異なるよう実施例１と同じ条件で直線偏光性の紫外線を照射し、照射後の加熱徐冷、配向の固定も実施例１と同条件で実施した。
このようにして作製した回折格子を偏光顕微鏡のクロスニコル下で観察したところ、図６（ａ）、図６（ｂ）のように、４５°異なる軸方向の観察において（図６（ａ）中のａ´、ａ´´、図６（ｂ）中のｂ´、ｂ´´は、偏光顕微鏡観察時の偏光板の吸収軸方向を示す。）、複屈折を有する領域と複屈折を有さない領域がそれぞれの領域で格子状となって形成され、且つ、照射した直線偏光性の紫外線の電界振動方向が互いに４５°異なる２つの領域において、複屈折を有する領域の配向方向が互いに４５°異なることが確認された。更に、この回折格子ではその偏光回折特性も、それぞれの領域において互いに電界振動方向が４５°異なる光が回折されることも確認した。
(Example 2)
As in Example 1, a polyvinyl alcohol resin (manufactured by Nacalai Tesque Co., Ltd., trade name: polyvinyl alcohol, polymerization degree: about 500) was used as a base material resin, and the width of the groove line was 5.0 μm and the depth using the mother die. A large number of straight parallel groove lines having a rectangular cross section of 2.8 μm are transferred and formed on the surface of the base material at intervals of 6.5 μm (= pitch 11.5 μm) between the groove lines. A base material (thickness of 50 μm) is formed, and the same birefringence inducing material as in Example 1 is formed on a groove line using a spin coater (rotation speed: 2000 rpm) (so as to cover the surface of the base material on which the groove line is formed). It was applied to fill up.
Next, the same conditions as in Example 1 are set so that the field oscillation directions of the linearly polarized ultraviolet rays are different from each other by 45 ° in the two regions of the base material in which the groove line formed as described above is filled with the birefringence inducing material. Then, irradiation with linearly polarized ultraviolet rays was performed, followed by heating and cooling after irradiation and fixing of orientation under the same conditions as in Example 1.
When the diffraction grating thus produced was observed under a crossed Nicol of a polarizing microscope, as shown in FIGS. 6 (a) and 6 (b), it was observed in an axial direction different by 45 ° (in FIG. 6 (a)). A ′, a ″, b ′, b ″ in FIG. 6B indicate the absorption axis direction of the polarizing plate when observed with a polarizing microscope), and has birefringence and birefringence. In the two regions where the non-regions are formed in a lattice pattern in each region and the electric field vibration directions of the irradiated linearly polarized ultraviolet rays are different from each other by 45 °, the orientation directions of the regions having birefringence are 45 ° to each other. It was confirmed that it was different. Furthermore, in this diffraction grating, the polarization diffraction characteristics were also confirmed, and light having different electric field vibration directions by 45 ° was diffracted in each region.
本発明では、透光性（光学的に等方性）の基材の一表面に複数の平行な溝線が形成されており、その溝線に複屈折性の材料を充填した構成によって偏光性回折格子が比較的簡素な製造方法で提供できる。これにより従来技術の問題点を解決することができる。 In the present invention, a plurality of parallel groove lines are formed on one surface of a light-transmitting (optically isotropic) base material, and the polarizing property is obtained by filling the groove lines with a birefringent material. The diffraction grating can be provided by a relatively simple manufacturing method. Thereby, the problems of the prior art can be solved.
１１： 基材
１２： 複屈折性の材料
２１： 母型
２２： 基材
２３： 複屈折誘起材料
３１： 基材
３１ａ： 凸部領域
３１ｂ： 光配向材が充填された領域
ｌ1： 格子の溝深さ
ｌ2： 光配向材が充填された距離
ｌ3： ｌ1とｌ2の差
ｎ1： 基材に形成された格子の屈折率
ｎ2： 光配向材の常光屈折率または異常光屈折率
ｎ3： 回折格子の置かれた雰囲気の屈折率
DESCRIPTION OF SYMBOLS 11: Base material 12: Birefringent material 21: Master mold 22: Base material 23: Birefringence inducing material 31: Base material 31a: Convex region 31b: Region filled with photo-alignment material l 1 : Lattice of lattice Depth l 2 : Distance filled with photo-alignment material l 3 : Difference between l 1 and l 2 n 1 : Refractive index of grating formed on substrate n 2 : Ordinary refractive index or extraordinary light refraction of photo-alignment material Index n 3 : Refractive index of the atmosphere where the diffraction grating is placed
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012137762A (en) * | 2010-12-27 | 2012-07-19 | Boe Technology Group Co Ltd | Polarizer, display device and method of manufacturing polarizer |
| WO2015024810A1 (en) * | 2013-08-19 | 2015-02-26 | Rolic Ag | Photo-alignable object |
| JP2017190017A (en) * | 2016-04-12 | 2017-10-19 | 林テレンプ株式会社 | Vehicular interior article |
| WO2018159922A1 (en) * | 2017-02-28 | 2018-09-07 | 경북대학교 산학협력단 | Viewing angle controllable display device |
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2009
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| US9217818B2 (en) | 2010-12-27 | 2015-12-22 | Boe Technology Group Co., Ltd. | Polarizer, display device and manufacturing method of polarizer |
| WO2015024810A1 (en) * | 2013-08-19 | 2015-02-26 | Rolic Ag | Photo-alignable object |
| CN105473317A (en) * | 2013-08-19 | 2016-04-06 | 罗利克有限公司 | Photo-alignable object |
| US10286616B2 (en) | 2013-08-19 | 2019-05-14 | Rolic Ag | Photo-alignable object |
| US11235543B2 (en) | 2013-08-19 | 2022-02-01 | Rolic Ag | Photo-alignable object |
| JP2017190017A (en) * | 2016-04-12 | 2017-10-19 | 林テレンプ株式会社 | Vehicular interior article |
| WO2017179426A1 (en) * | 2016-04-12 | 2017-10-19 | 林テレンプ株式会社 | Vehicle interior accessory |
| WO2018159922A1 (en) * | 2017-02-28 | 2018-09-07 | 경북대학교 산학협력단 | Viewing angle controllable display device |
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