JP4116317B2 - Polarization separating element, method for manufacturing the same, bonding apparatus, and optical pickup apparatus - Google Patents

Description

回折格子の形成された領域内で「透過光に対する光路長」を一定にするために、有機複屈折膜の表面の平坦度を「概ね１μｍ以下」にすると良いことが実験結果から判っている。
【００４５】
基板体Ａ〜Ｆの平坦度を見ると、全条件において、面内５点全てにおいて平坦度は１μｍ以下となっており、有機複屈折膜の全表面に渡って良好な平坦性が得られていることが判る。また、中間完成体Ａ〜Ｆの全てでＴｃ＞Ｔａｄである。
【００４６】
上記基板体Ａ〜Ｆを用い、実施例１における「接着工程以後の工程」を実行して、５ｍｍ角の偏光分離素子を作製し、市販の波面収差測定装置：ザイゴ・マーク４を用いて波面収差を測定した結果、全チップとも０．０２λｒｍｓ（ルートミーンスクエア値）以下となっており、偏光分離素子によって回折する光の波面の乱れが小さいことが確認された。これは有機複屈折膜の平坦度が１μｍ以下と良好であるためと考えられる。
【００４７】
以上のように、実施例１の作製方法では、第２の回転によって有機複屈折膜や「透明基板に塗布された紫外線硬化型接着剤」に遠心力を作用させることにより、透明基板上の紫外線硬化型接着剤の層上に有機複屈折膜を載置したときに発生する「有機複屈折膜表面のうねりや波打ち等の凹凸」を改善しつつ、接着剤を振り切ることができ、紫外線硬化型接着剤の塗布後の層厚：Ｔｃ、硬化後の層厚：Ｔａｄの関係がＴｃ＞Ｔａｄとなる。
【００４８】
なお、透明基板をスピンテーブル１０に真空吸着して、アクリル系の紫外線硬化型接着剤を滴下し、スピンテーブル１０を回転（第１の回転）させて接着剤を透明基板全面に均一に塗布した後に、光学式の膜厚計を用いて紫外線硬化型接着剤の塗布後の膜厚：Ｔｃを直接求めても良い。
【００４９】
実施例１の作製方法において、直径：１００ｍｍ、厚さ：１．０ｍｍのショット製光学ガラスＢＫ７からなる円板形状の透明基板を、スピンテーブルに真空吸着で固定してアクリル系の紫外線硬化型接着剤を滴下し、スピンテーブルを回転（第１の回転）させて接着剤を透明基板全面に均一に塗布した。
【００５０】
この状態において、接着剤層上に載置する有機複屈折膜として、直径：１００ｍｍの円形状で、膜厚がそれぞれ、６μｍ、２０μｍ、５０μｍ、８０μｍ、１００μｍ、１５０μｍのものを用意し、それぞれを、その中心がスピンテーブルの回転中心にほぼ一致するようにして、紫外線硬化型接着剤の層上に載置装置を用いて載置し、スピンテーブルを再び回転（第２の回転）させて、紫外線硬化型接着剤を振り切り、有機複屈折膜表面を平坦化した。
【００５１】
その後、スピンテーブルの回転を停止し、メタルハライドランプを用いて紫外線を照射し、紫外線硬化型接着剤を硬化させて、前記「基板体」と同様のサンプルを６種作製した。
【００５２】
第１の回転の回転数は４００ｒｐｍ、第２の回転の回転数は１０００ｒｐｍである。これら６種のサンプルにおける有機複屈折膜表面の平坦度を上記と同様にして測定した。結果は、以下の如くである。

この結果から、有機複屈折膜の膜厚が５０μｍ以上の場合に、有機複屈折膜表面の「良好な平坦性」を確保できることがわかる。有機複屈折膜の膜厚が２０μｍ以下になると、有機複屈折膜の「腰の強さ」がきわめて弱くなり、また軽量のために作用する遠心力も小さくなり、第２の回転による遠心力でも表面の平坦化が不十分であると考えられる。
【００５３】
上記サンプル３〜６に対し、実施例１の「接着工程後の各工程」を実行して、多数の偏光分離素子を得た。有機複屈折膜の膜厚が５０μｍ以上あり、第２の回転によって有機複屈折膜表面が良好な平坦性を持つため、紫外線を照射することによって、良好な平坦性を保った状態で有機複屈折膜を透明基板に接着することができ、有機複屈折膜上に回折格子を形成し、対向透明基板を接着し、切断して多数の偏光分離素子を得るのに高い製造歩留を達成できた。
【００５４】
実施例２
図２を参照して実施例２を説明する。繁雑を避けるため、混同の虞がないと思われるものについては、全図面を通じて同一の符号を付することとする。
【００５５】
図２（ａ）、（ｂ）に示すように、実施例１におけると同様の直径：１００ｍｍ、厚さ：１．０ｍｍのショット製光学ガラスＢＫ７からなる円板形状の透明基板１をスピンテーブル１０に真空吸着して固定し、ディスペンサー１２により、屈折率：１．５２、粘度：５００ｃｐのアクリル系の紫外線硬化型接着剤（実施例１で用いたものと同じもの）３を滴下し、スピンテーブル１０を回転（第１の回転）させて接着剤３を透明基板全面に均一に塗布する。
【００５６】
次いでスピンテーブル１０の回転を停止し、図２（ｃ）、（ｄ）に示す如く、片面に粘着剤２を介して有機高分子による保護膜４を設けられた有機複屈折膜（直径：１００ｍｍ、厚さ：１００μｍ、円形状）５を、その中心をスピンテーブル１０の回転中心に略合致させるようにして、紫外線硬化型接着剤３の層上に、図示されない載置装置を用いて載置し、スピンテーブル１０を再回転（第２の回転）させ、剰余の紫外線硬化型接着剤を振り切って保護膜表面を平坦化する。
【００５７】
スピンテーブル１０の回転を停止後、保護膜４上から高圧水銀灯を用いて紫外線ＵＶを照射し、紫外線硬化型接着剤３を硬化させる（図２（ｅ））。紫外線は保護膜４での吸収を考慮して実施例１のエネルギー値の１．２倍を照射する。
【００５８】
紫外線硬化型接着剤３の硬化後、ピンセット等で、有機複屈折膜５から保護膜４を剥離する（図２（ｆ））。その後、基板１をスピンテーブル１０から外し、実施例１と同様のリソグラフィー／エッチングのプロセスにより回折格子を形成後、図２（ｇ）に示す如く、光学的に等方的なアクリル系の紫外線硬化型接着剤（等方性接着剤）６を用い、粘着剤８によってλ／４波長板７を貼付けられた直径：１００ｍｍ、厚み：１ｍｍの円板形状の対向透明基板（材質：ショット製光学ガラスＢＫ７）９を接着して中間完成体１Ａとする。対向透明基板９の自由表面（空気と接する面）には入射光の反射が最小となるように「反射防止膜（図示されず）」を形成する。
【００５９】
図２（ｈ）に示すように、中間完成体１Ａをダイシングソー１５で５ｍｍ角に切断し、複数の偏光分離素子１００を得る。
【００６０】
この作製方法によると、透明基板１と有機複屈折膜５の貼合せを行う「接着工程」を、有機複屈折膜５の回折格子形成面を保護膜４で被覆した状態で行うことができ、接着工程の際に「回折格子を形成する面」に異物が付着したり、傷がついたりすることがない。特に、スピンテーブル１０を回転させて剰余の紫外線硬化型接着剤を振り切る際、振り切られた接着剤のミストが「回折格子を形成する面」に付着しない（接着剤のミストは保護膜に付き、紫外線照射後保護膜を剥離するので、有機複屈折膜表面には残らない）ので、異物の非常に少ない有機複屈折膜表面を実現でき、リソグラフィー工程において異物やキズによって発生するパターン欠陥を低減でき、偏光分離素子の製造歩留を向上できる。
【００６１】
実施例２の作製方法において、直径：１００ｍｍ、厚さ：１．０ｍｍのショット製光学ガラスＢＫ７からなる円板形状の透明基板をスピンテーブルに真空吸着して固定し、アクリル系の紫外線硬化型接着剤を滴下し、スピンテーブルを回転（第１の回転）させて接着剤を透明基板全面に均一に塗布した。
【００６２】
この状態において、接着剤層上に載置する有機複屈折膜として、片面に粘着剤を介して「有機高分子からなる保護膜」が設けられた有機複屈折膜（直径：１００ｍｍ 円形状）として、膜厚がそれぞれ、６μｍ、２０μｍ、５０μｍ、８０μｍ、１００μｍ、１５０μｍのものを用意し（粘着剤の膜厚は９〜１４μｍ、保護膜の膜厚は２０μｍであり、このため有機複屈折膜・粘着剤・保護膜の膜厚の和である総膜厚は３５〜１８０μｍとなった。）、それぞれをその中心がスピンテーブル１０の回転中心にほぼ一致するようにして、紫外線硬化型接着剤の層上に載置装置を用いて載置し、スピンテーブルを再回転（第２の回転）させて剰余の紫外線硬化型接着剤を振り切り、有機複屈折膜表面を平坦化した。
【００６３】
その後、スピンテーブル１０の回転を停止し、保護膜上から高圧水銀灯を用いて紫外線を照射し、紫外線硬化型接着剤を硬化させた。紫外線の強度は実施例２と同じである。次いで、ピンセットを用いて、有機複屈折膜から保護膜を剥離して各々サンプル１〜６とした。
【００６４】
第１の回転の回転数は４００ｒｐｍ、第２の回転の回転数は１０００ｒｐｍである。これら６種のサンプルにおける有機複屈折膜表面の平坦度を上記と同様にして測定した。結果は、以下の如くである（単位は何れも「μｍ」である）。

この結果から、有機複屈折膜と粘着剤と保護膜の総膜厚が５０μｍ以上である場合に、有機複屈折膜表面の良好な平坦性を確保できることがわかる。有機複屈折膜、粘着剤、保護膜の総膜厚が３５μｍの場合は、保護膜・粘着剤・有機複屈折膜の全体の「腰の強さ」が十分に強くならないため、第２の回転の遠心力でも保護膜表面を十分に平坦化できず、有機複屈折膜表面の平坦性も低下したものと考えられる。
【００６５】
上記サンプル２〜６（有機複屈折膜の膜厚：２０〜１５０μｍ）に対し、実施例２の「接着工程後の各工程」を実行して、多数の偏光分離素子を得た。有機複屈折膜と粘着剤と保護膜の総膜厚が５０μｍ以上あり、第２の回転によって有機複屈折膜表面が良好な平坦性を持つため、紫外線を照射して紫外線硬化型接着剤を硬化し、有機複屈折膜から保護膜を剥離することによって、良好な平坦性を保った状態で有機複屈折膜を透明基板に接着することができ、有機複屈折膜上に回折格子を形成し、対向透明基板を接着し、切断して多数の偏光分離素子を得るのに高い製造歩留を達成できた。
【００６６】
また実施例２の作製方法によれば、実施例１の方法では平坦性を確保することが困難であった「より薄い有機複屈折膜」でも、良好な平坦性を保ちながら透明基板に接着することができることから、より広い膜厚範囲の有機複屈折膜を利用できる。
【００６７】
なお、上記例では、主に有機複屈折膜の膜厚をパラメータとして総膜厚を制御したが、粘着剤ないし保護膜の膜厚を変えて総膜厚を５０μｍ以上としても同様な効果を期待でき、有機複屈折膜、粘着剤、保護膜の膜厚を同時に変えて総膜厚を５０μｍ以上としても良い。
【００６８】
実施例３
図３を参照して、実施例３を説明する。
図３（ａ）、（ｂ）に示すように、直径：１００ｍｍ、厚さ：１．０ｍｍのショット製光学ガラスＢＫ７からなる円板形状の透明基板１をスピンテーブル１０に載置し、真空吸着によってスピンテーブル１０に固定し、スピンテーブル１０を１０〜５０ｒｐｍで回転させながら、ディスペンサー１２を用いて屈折率：１．５８、粘度：６００ｃｐのエポキシ系の紫外線硬化型接着剤３を、透明基板１の中央部に３〜１１ｇ滴下する。滴化後、スピンテーブル１０を１５０〜５００ｒｐｍで回転（第１の回転）させ、透明基板１の全面に紫外線硬化型接着剤を広げたのち、スピンテーブル１０の回転を停止する。
【００６９】
次いで、図３（ｃ）、（ｄ）に示すように、図示されない載置装置を用いて、直径：１００ｍｍ、厚さ：８０μｍで円形状の有機複屈折膜５を、その中心がスピンテーブル１０の回転中心に略合致するようにして、紫外線硬化型接着剤３の層上に載置し、スピンテーブル１０を１０００〜３０００ｒｐｍで６０秒間回転（第２の回転）させ、有機複屈折膜５の表面を概ね平坦化した後に、第２の回転を継続しつつ、図示されないメタルハライドランプを用いて紫外線ＵＶを照射し、紫外線硬化型接着剤３を硬化させる。
【００７０】
紫外線の強度を実施例１の場合の１／１０〜１／４と小さくして、紫外線照射中も紫外線硬化型接着剤３の振り切りが続くようにし、紫外線硬化型接着剤３が完全硬化するまで、有機複屈折膜５の表面の平坦化を進行させる。
【００７１】
接着剤３の硬化完了後、スピンテーブル１０の回転を停止し、有機複屈折膜５を接着した透明基板１（以下単に「基板」という）をスピンテーブル１０から外し、有機複屈折膜５上にポジレジストを１．５μｍの厚さに塗布し、８０℃の温度で３０分プリベークする。プリベーク後、基板を縮小投影露光装置（ＮＡ＝０．５４、σ＝０．６、波長；ｉ線）に装着し、「１０００周期分の１．０μｍのラインアンドスペースパターン」のレチクルを用いて露光し、現像液ＮＭＤ−３を用いて現像を行い、１００℃の温度で３０分ポストベークを行って、周期的なレジストパターンを完成させる。
【００７２】
前記レジストパターンを１１０℃の雰囲気で１，１，３，３−テトラメチルヘキサジシラザン蒸気にさらし、レジスト表面に１，１，３，３−テトラメチルヘキサジシラザンをドープし、その後「ＥＣＲエッチング装置」を用いて酸素ガスを主成分とするエッチングガス雰囲気中で、レジストパターンをマスクとして有機複屈折膜を深さ４μｍエッチングし、剥離液を用いてレジストパターンを除去して「１０００周期分の凹凸による回折格子」を多数形成する。
【００７３】
図３（ｅ）は、多数の回折格子（個々の回折格子は、図の上側面の「凹凸の各凸部」に形成されている）を形成された基板を示している。
【００７４】
平面加工した直径：２００ｍｍ、厚み：５０ｍｍのステンレス台上に、回折格子を形成した基板を置き、回折格子面に「光学的に等方的なエポキシ系の紫外線硬化型接着剤（等方性接着剤）」をマイクロシリンジで１．０ｍｌ滴下し、その上に「両面を光学研磨した直径：１００ｍｍ、厚み：１ｍｍの円板形状の対向透明基板（材質；ショット製光学ガラスＢＫ７）」を載置し、更に対向透明基板上に光学研磨した光学ガラスを乗せて１００ｇｆ／ｃｍ^２の圧力を加え、等方性接着剤を被接着面全面に広げる。
【００７５】
対向透明基板の被接着面と対向する面には、入射光の反射が最小となるよう反射防止膜（図示せず）を形成する。この状態で対向透明基板を通して紫外線を照射し、等方性接着剤を硬化する。このようにして、図３（ｆ）に示す中間完成体１Ｂが得られる。
【００７６】
最後に、図３（ｇ）に示すように、ダイシングソー１５を用いて中間完成体１Ｂを５ｍｍ角に切りだし、複数の偏光分離素子１０１を完成させる。
【００７７】
実施例３の作製方法によると、第１の回転により透明基板全面に紫外線硬化型接着剤が塗布されるため、透明基板上では接着剤が無い領域が発生せず、接着剤３が塗布された透明基板１に有機複屈折膜５を載置すると、有機複屈折膜５は全面に渡って接着剤３を介して透明基板１の表面と接するので、紫外線照射による全面接着が可能となる。
【００７８】
また第２の回転によって、有機複屈折膜５や、透明基板１に塗布された紫外線硬化型接着剤３に遠心力をかけることにより、有機複屈折膜１の表面のうねりや波打ち等の凹凸を改善しつつ接着剤を振り切ることができる。更に第２の回転中に紫外線を照射するので、有機複屈折膜表面のうねりや波打ち等の凹凸を改善した状態で接着剤が硬化され、良好な平面性を持つ有機複屈折膜の接着が可能となる。
【００７９】
実施例３では、透明基板１をスピンテーブル１０に固定した後、スピンテーブル１０を回転させながら、透明基板１の中央部にエポキシ系の接着剤３を滴下して接着剤３を塗布したが、接着剤３の塗付方法はこの方法に限定されるものではなく、透明基板１をスピンテーブル１０に固定後、スピンテーブル１０を停止したまま透明基板中央部に接着剤を滴下し、その後、スピンテーブル１０を回転させて透明基板全面に接着剤を広げても良い。
【００８０】
実施例４
図４を参照して、実施例４を説明する。
図４（ａ）、（ｂ）に示すように、直径：１００ｍｍ、厚さ：１．０ｍｍのショット製光学ガラスＢＫ７からなる円板形状の透明基板１をスピンテーブル１０に載置し、真空吸着によってスピンテーブル１０に固定した状態で、スプレー１３を用いて屈折率：１．５８、粘度：６００ｃｐのエポキシ系の紫外線硬化型接着剤（実施例３で用いたものと同じもの）３を、透明基板１の全面に均一に塗布する。紫外線硬化型接着剤３の塗布厚は４０〜８０μｍ程度が良い。
図４（ｃ）、（ｄ）に示すように、紫外線硬化型接着剤３上に、直径：１００ｍｍ、厚さ：８０μｍの円形状の有機複屈折膜５を、図示されない載置装置を用いて、膜中心がスピンテーブル１０の回転中心に略合致するように載置し、スピンテーブル１０を１０００〜３０００ｒｐｍで回転（第３の回転）させて剰余の接着剤を振り切り、接着剤層の厚さを基板面上で均一化して有機複屈折膜５の表面を平坦化する。
【００８１】
スピンテーブル１０の回転を停止して、図４（ｅ）に示すように、有機複屈折膜５の側から、高圧水銀灯を用いて紫外線を照射し、紫外線硬化型接着剤３を硬化させる。
【００８２】
以下、前述の実施例３の場合と同様にして、リソグラフィー／エッチングによって有機複屈折膜表面に回折格子を形成し、図４（ｆ）に示すように、光学的に等方的なエポキシ系の紫外線硬化型接着剤（等方性接着剤）６を用いて、直径：１００ｍｍ、厚み：１ｍｍの円板形状の対向透明基板（材質；ショット製光学ガラスＢＫ７）９を接着する。対向透明基板９の被接着面と対向する面には入射光の反射が最小となるよう反射防止膜を形成する。
【００８３】
このようにして得られる中間完成体１Ｂを、図４（ｇ）に示す如くダイシングソー１５を用いて５ｍｍ角に切断し、多数の偏光分離素子１０１を得る。
【００８４】
実施例４の作製方法によると、スプレー法によって透明基板１の全面に紫外線硬化型接着剤３が塗布されるため、透明基板１上には「接着剤が無い領域」が生じない。そのため、接着剤３が塗布された透明基板１に有機複屈折膜５を載置すると、有機複屈折膜５は全面に渡って接着剤層を介して透明基板表面と接するので、紫外線照射によって全面接着が可能となる。
【００８５】
また、第３の回転によって、有機複屈折膜５や紫外線硬化型接着剤３に遠心力をかけることによって、有機複屈折膜５の表面のうねりや波打ち等の凹凸を改善しながら、接着剤を振り切ることができ、その後に紫外線を照射することによって紫外線硬化型接着剤を硬化させるので、有機複屈折膜５の接着工程において平坦性の良い有機複屈折膜表面を得ることができる。
【００８６】
実施例４では、紫外線硬化型接着剤３を「室温」でスプレー塗布したが、紫外線硬化型接着剤３の粘度が高く、有機複屈折膜５を載せたときに紫外線硬化型接着剤３の流動性が乏しく、気泡を巻き込みやすい場合は、紫外線硬化型接着剤３が塗布された透明基板をオーブンや赤外線ランプ等で加熱し、紫外線硬化型接着剤３の粘度を低下させた後に有機複屈折膜５を載置するか、あるいは、紫外線硬化型接着剤３をオーブン等で予め加熱し、粘度を低下させた後にスプレー法によって透明基板１に塗布し、その後に有機複屈折膜５を載置するのが良い。
【００８７】
実施例５
図５を参照して実施例５を説明する。
図５（ａ）、（ｂ）に示すように、直径：１００ｍｍ、厚さ：１．０ｍｍのショット製光学ガラスＢＫ７からなる円板形状の透明基板１をスピンテーブル１０に載置し、真空吸着によってスピンテーブル１０に固定し、スプレー１３を用いて屈折率：１．５８、粘度：６００ｃｐのエポキシ系の紫外線硬化型接着剤（実施例３で用いたものと同じもの）３を透明基板１の全面に均一に塗布する。紫外線硬化型接着剤の塗布厚は４０〜８０μｍ程度が良い。
【００８８】
図５（ｃ）、（ｄ）に示すように、片面に粘着剤２を介して、有機高分子からなる保護膜４が設けられた有機複屈折膜（直径：１００ｍｍ、厚さ：５０μｍ 円形状）を、紫外線硬化型接着剤３上に、膜中心をスピンテーブル１０の回転中心に略合致させ、保護膜が自由表面となるようにして載置装置（図示されず）を用いて載置し、その後、スピンテーブル１０を１０００〜３０００ｒｐｍで６０秒回転（第３の回転）させ、保護膜表面を概ね平坦化した後に、第３の回転を継続しつつ高圧水銀灯（図示されず）を用いて紫外線ＵＶを照射し、紫外線硬化型接着剤３を硬化させる。
【００８９】
紫外線の強度を実施例４の１／１０〜１／４とし、紫外線照射中も紫外線硬化型接着剤の振り切りが続くようにし、紫外線硬化型接着剤が完全硬化するまで保護膜表面の平坦化を進行させる。
【００９０】
続いて、スピンテーブル１０の回転を停止し、ピンセット等を用いて保護膜４を有機複屈折膜５から剥離する（図５（ｅ））。
【００９１】
以下、実施例４と同様にして、リソグラフィー／エッチングによって有機複屈折膜表面に回折格子を形成し、図５（ｆ）に示す如く、光学的に等方的なエポキシ系の紫外線硬化型接着剤（等方性接着剤）６を用いて、直径：１００ｍｍ、厚み：１ｍｍの円板形状の対向透明基板（材質；ショット製光学ガラスＢＫ７）９を接着し、中間完成体１Ｂとする。対向透明基板９の面には入射光の反射が最小となるよう反射防止膜を形成する。
【００９２】
図５（ｇ）に示すように中間完成体１Ｂを、ダイシングソー１５で５ｍｍ角に切断し、多数の偏光分離素子１０１を得る。
【００９３】
実施例５の作製方法によると、スプレー法によって透明基板１の全面に紫外線硬化型接着剤３が塗布されるため、接着剤層３上に有機複屈折膜５を載置すると、有機複屈折膜５は全面に渡って接着剤層３を介して透明基板１の表面と接するので、紫外線照射によって全面接着が可能となる。また第３の回転によって有機複屈折膜５や紫外線硬化型接着剤３に遠心力をかけることによって、有機複屈折膜５の表面のうねりや波打ち等の凹凸を改善しつつ、剰余の接着剤を振り切ることができ、第３の回転中に紫外線照射を行って紫外線硬化型接着剤３を硬化するため、平坦な表面を持つ有機複屈折膜／接着層／透明基板を得ることができる。
【００９４】
更に、透明基板１と有機複屈折膜５を貼り合せる「接着工程」は、有機複屈折膜５における「回折格子形成面」を保護膜４で被覆した状態で行うことができ、接着工程で回折格子形成面にキズや異物が付くことがなく、偏光分離素子の製造歩留を向上できる。
【００９５】
実施例６
図６を参照して実施例６を説明する。
図６（ａ）、（ｂ）に示すように、直径：１００ｍｍ、厚さ：１．０ｍｍのショット製光学ガラスＢＫ７からなる円板形状の透明基板１をロールコーター１４に設置し、溝のないロールを用いて屈折率：１．５２、粘度：５００ｃｐのアクリル系の紫外線硬化型接着剤（実施例１で用いたものと同じもの）３を透明基板１の全面に均一に塗布する。紫外線硬化型接着剤３の塗布厚は４０〜８０μｍとする。
【００９６】
図６（ｃ）に示すように、直径：１００ｍｍ、厚さ：１００μｍの円形状の有機複屈折膜５を、図示されない載置装置を用いて、膜中心が透明基板１の中心に略合致するようにして紫外線硬化型接着剤３上に載置する。
【００９７】
図６（ｄ）に示すように、有機複屈折膜５を載置した透明基板１をスピンテーブル１０に載置し、真空吸着で固定し、スピンテーブル１０を１０００〜３０００ｒｐｍで６０秒間回転（第４の回転）させ、有機複屈折膜５の表面を概ね平坦化した後、第４の回転を継続しつつ図示されない高圧水銀灯を用いて紫外線ＵＶを照射し、紫外線硬化型接着剤３を硬化させる。
【００９８】
紫外線ＵＶの強度は、実施例１の１／１０〜１／４とし、紫外線照射中も剰余の紫外線硬化型接着剤３の振り切りが続くようにし、紫外線硬化型接着剤３が完全硬化するまで有機複屈折膜表面の平坦化を進行させる。
【００９９】
以下、スピンテーブル１０の回転を停止し、有機複屈折膜５を接着した透明基板（以下「基板」という）をスピンテーブル１０から外し、実施例１と同様にしてリソグラフィー／エッチングによって回折格子を形成する（図６（ｅ））。
【０１００】
実施例１と同様、アクリル系の紫外線硬化型接着剤（等方性接着剤）６を用い、粘着剤８によってλ／４波長板７が貼付けられた対向透明基板（ショット製光学ガラスＢＫ７、直径：１００ｍｍ、厚み：１ｍｍ 円板形状）９を基板に接着する。
【０１０１】
対向透明基板９の自由表面には入射光の反射が最小となるよう反射防止膜を形成する。このようにして、図６（ｆ）に示す如き中間完成体１Ａが得られる。
【０１０２】
最後に、中間完成体１Ａをダイシングソー１５で５ｍｍ角に切断し、複数の偏光分離素子１００を完成させる。
【０１０３】
実施例６の作製方法によると、ロールコーター１４によって透明基板１の全面に紫外線硬化型接着剤３が塗布されるため透明基板１上に「接着剤が無い領域」が生じない。そのため接着剤３が塗布された透明基板１に有機複屈折膜５を載置すると、有機複屈折膜５は全面に渡って接着剤層３を介して透明基板表面と接するので、紫外線照射によって全面接着が可能となる。
【０１０４】
また、第４の回転によって有機複屈折膜５や紫外線硬化型接着剤３に遠心力をかけることによって、有機複屈折膜５の表面のうねりや波打ち等の凹凸を改善しつつ、剰余の接着剤３を振り切ることができ、第４の回転中に紫外線を照射することによって、紫外線硬化型接着剤を硬化させるので、有機複屈折膜５の接着工程において平坦性の良い有機複屈折膜表面を得ることができる。
【０１０５】
なお、実施例６では「溝の無いロール」で透明基板１に紫外線硬化型接着剤３を塗布するため、比較的平面性の良い紫外線硬化型接着剤３の塗布層を得られるが、溝付きロールを用いた場合は接着剤表面に「筋状のムラ」が発生する。その場合は、紫外線硬化型接着剤３を塗布された透明基板１をオーブン等で加熱し、紫外線硬化型接着剤３の粘度を低下させて「塗布された接着剤の表面」の平坦性を改善するのが良い。
【０１０６】
また、実施例６では、紫外線硬化型接着剤３を「室温」で塗布したが、紫外線硬化型接着剤３の粘度が高く、有機複屈折膜５を載置したときに紫外線硬化型接着剤３の流動性が乏しく、気泡を巻き込みやすい場合は、紫外線硬化型接着剤３を塗布された透明基板をオーブンや赤外線ランプ等で加熱し、紫外線硬化型接着剤３の粘度を低下させた後に有機複屈折膜５を載置するか、オーブン等で予め加熱して粘度を低下させた紫外線硬化型接着剤３をロールコーターによって透明基板１に塗布し、その後に有機複屈折膜５を載置するのが良い。
【０１０７】
実施例７
図７を参照して、実施例７を説明する。
【０１０８】
図７（ａ）、（ｂ）に示すように、直径：１００ｍｍ、厚さ１．０ｍｍのショット製光学ガラスＢＫ７からなる円板形状の透明基板１をロールコーター１４にセットし、溝の無いロールを用いて屈折率：１．５２、粘度：５００ｃｐのアクリル系の紫外線硬化型接着剤（実施例１で用いたものと同じもの）３を透明基板１の全面に均一に塗布する。紫外線硬化型接着剤３の塗布厚は４０〜８０μｍとする。
【０１０９】
次いで、図７（ｃ）に示すように、片面に粘着剤２を介して有機高分子による保護膜４を設けられた有機複屈折膜（直径：１００ｍｍ、厚さ：５０μｍ、円形状）５を、その中心を透明基板１の中心にほぼ合せ、保護膜４側が自由表面となるようにして、図示されない載置装置を用いて紫外線硬化型接着剤３上に載置する。
【０１１０】
図７（ｄ）に示すように、後保護膜４で被覆された有機複屈折膜５を載置した透明基板１をスピンテーブル１０に乗せ、真空吸着で固定した後、スピンテーブル１０を１０００〜３０００ｒｐｍで回転（第４の回転）させ、保護膜表面を平坦化する。スピンテーブル１０の回転を停止し、図示されない高圧水銀灯を用いて紫外線ＵＶを照射し、紫外線硬化型接着剤を硬化させ（図７（ｅ））、その後、スピンテーブル１０の回転を停止し、ピンセット等を用いて有機複屈折膜５から保護膜４を剥離する。紫外線ＵＶの強度は保護膜での吸収を考慮し、実施例６における強度の１．２倍とする。
【０１１１】
有機複屈折膜５を接着された透明基板１をスピンテーブル１０から外し、実施例１と同様にして、リソグラフィー／エッチングによって回折格子を形成すると図７（ｇ）の如き状態となる。
【０１１２】
次いで、図７（ｈ）に示すように、実施例１と同様にアクリル系の紫外線硬化型接着剤（等方性接着剤）６を用い、粘着剤８によってλ／４波長板７が貼付けられた円板形状の対向透明基板（ショット製光学ガラスＢＫ７、直径：１００ｍｍ、厚み：１ｍｍ）９を接着すると中間完成体１Ａが得られる。
【０１１３】
最後に、中間完成体１Ａをダイシングソーで５ｍｍ角に切断し、複数の偏光分離素子１００を得る（図７（ｉ））。
【０１１４】
実施例７の作製方法によると、ロールコーター１４によって透明基板１の全面に紫外線硬化型接着剤３が塗布されるため、接着剤３が塗布された透明基板１に有機複屈折膜５を載置すると、有機複屈折膜５は全面に渡って接着剤層３を介して透明基板１の表面と接するので紫外線照射によって全面接着が可能となる。
【０１１５】
また第４の回転によって有機複屈折膜５や紫外線硬化型接着剤３に遠心力をかけることによって、有機複屈折膜５の表面のうねりや波打ち等の凹凸を改善しつつ剰余の接着剤を振り切ることができ、第４の回転後に紫外線照射を行って紫外線硬化型接着剤３を硬化するため、平坦な表面を持つ有機複屈折膜／接着層／透明基板を得ることができる。
【０１１６】
更に実施例３と同様、透明基板１と有機複屈折膜５の貼り合せを行う接着工程を、有機複屈折膜５の回折格子形成面を保護膜で被覆した状態で行うことができ、リソグラフィー工程において異物やキズによって発生するパターン欠陥を低減でき、偏光分離素子の製造歩留を向上できる。
【０１１７】
実施例７でも、溝の無いロールで透明基板に紫外線硬化型接着剤を塗布するため、紫外線硬化型接着剤３の比較的平面性の良い塗布層が得られるが、溝付ロールを用いる場合は接着剤層の表面に筋状のムラが発生する。その場合は、紫外線硬化型接着剤を塗布された透明基板をオーブンで加熱し、紫外線硬化型接着剤３の粘度を低下させて接着剤層表面の平坦性を改善するのが良い。
【０１１８】
【発明の実施の形態】
図８は、光ピックアップ装置の実施の１形態を示す。
この光ピックアップ装置はＣＤ用であり、レーザーダイオード８１から出射された波長：７８０ｎｍの光は偏光分離素子８３、コリメータレンズ８５、対物レンズ８７を通って光ディスクであるＣＤ―ＲＷ９０を照射し、記録面での反射光は戻り光束となり、偏光分離素子８３で回折され光検出素子８９に導光され、フォーカス検出・トラック検出・信号検出が行われる。
【０１１９】
偏光分離素子８３として、実施例１の作製方法で作製されたものを用いて図８の光ピックアップ装置を構成し、これを用いて、ＣＤ−ＲＷに信号を記録し、その後同じ光ピックアップ装置で信号の再生を行った所「プリズムを接着したビームスプリッタとλ／４波長板を組み合わせた従来の偏光分離素子」を用いた場合と同等の再生信号出力を得ることができ、この実施の形態の光ピックアップ装置が「従来のもの」と同等の記録／再生特性を持つことを確認できた。
【０１２０】
図８に示す実施の形態の光ピックアップ装置では、偏光分離素子８３が従来の「プリズムを接着したビームスプリッタ」よりも小さくなっており、かつ偏光分離素子にλ／４波長板も組み込んでいるため、従来の光ピックアップと比較して小型化を実現できる。
【０１２１】
図９は光ピックアップ装置の実施の別形態を示す。
この光ピックアップ装置はＤＶＤ用のものであり、レーザーダイオード８１から出射された波長：６８０ｎｍの光は偏光分離素子８３とコリメータレンズ８５、λ／４波長板８６、対物レンズ８７を通った後、光ディスクであるＤＶＤ９１を照射し、ＤＶＤ９１の記録面で反射された戻り光束はλ／４波長板８６で直線偏光になった後、偏光分離素子８３で回折して光検出素子８９に導光され、フォーカス検出・トラック検出・信号検出が行われる。
【０１２２】
偏光分離素子８３として、実施例３の作製方法で作製したものを用いて、図９の光ピックアップ装置を構成し、ＤＶＤ−ＲＯＭから情報信号の再生を行った所「プリズムを接着したビームスプリッタをλ／４波長板と組合せて用いる、従来のＤＶＤ用の光ピックアップ装置」と同等の信号出力を得ることができ、この実施の形態の光ピックアップ装置が、従来の光ピックアップ装置と同等の再生特性を持つことを確認できた。
【０１２３】
また図９の光ピックアップ装置では、偏光分離素子８３が「プリズムを接着したビームスプリッタ」よりも小さくなっているため、従来の光ピックアップ装置よりも小型になっている。
【０１２４】
図１０は、有機複屈折膜を接着するための「接着装置」の実施の１形態を示している。この接着装置は、透明基板１を保持するスピンテーブル１０と、スピンテーブル１０を回転させるステッピングモーター等からなる回転機構（図示されていない）と、透明基板１に紫外線硬化型接着剤を塗布するディスペンサー（ロボットアーム１２Ａで制御駆動される）１２からなる塗布機構と、２本の吸着アーム５０によって有機複屈折膜５の両端を保持し、透明基板１上に塗布された紫外線硬化型接着剤の層上に有機複屈折膜５を載置する載置機構５５と、紫外線硬化型接着剤に紫外線を照射する高圧水銀灯やメタルハライドランプ等からなる紫外線照射機構６０から構成されている。
【０１２５】
有機複屈折膜５を透明基板１に接着する手順は以下の如くである。
【０１２６】
直径：１００ｍｍ、厚さ：１．０ｍｍのショット製光学ガラスＢＫ７からなる透明基板１（円形状の一部を切り欠かれて「オリエンテーションフラット」を形成されている）をスピンテーブル１０に載置し、真空吸着によってスピンテーブル１０に固定する。次いで、ロボットアーム１２Ａによりディスペンサー１２を透明基板１の中央部上方に移動し、スピンテーブル１０を回転機構によって１０ｒｐｍで回転させながら、屈折率：１．５２、粘度：５００ｃｐのアクリル系の紫外線硬化型接着剤を４ｇ滴下する。
【０１２７】
その後、ディスペンサー１２を元位置に復帰させ、スピンテーブル１０を３００ｒｐｍで回転（第１の回転）させ、透明基板全面に紫外線硬化型接着剤を広げ、その後スピンテーブル１０の回転を停止する。
【０１２８】
続いて、直径：１００ｍｍ、厚さ：１００μｍで円形状（一部を切り欠かれて「オリエンテーションフラット」を形成されている）の有機複屈折膜５の両端を、載置機構の２本の吸着アーム５０に真空吸着して保持し、有機複屈折膜５を透明基板１上へ移動し、有機複屈折膜５の中心をスピンテーブル１０の回転中心にほぼ合せながら、２本の吸着アーム５０の真空吸着を徐々に解除して紫外線硬化型接着剤の上に有機複屈折膜を載置する。
【０１２９】
載置装置を元位置に戻したのち、スピンテーブル１０を１８００ｒｐｍで回転（第２の回転）させ、紫外線硬化型接着剤を振り切り、有機複屈折膜５の表面を平坦化したのち、スピンテーブル１０の回転を停止し、透明基板の上方へ紫外線照射機構６０を移動し、有機複屈折膜５側から紫外線を照射して紫外線硬化型接着剤を硬化させる。紫外線照射終了後、紫外線照射機構６０を元位置に戻し、スピンテーブル１０の真空吸着を解除して有機複屈折膜５を接着した透明基板１を取り出す。
【０１３０】
上記のように、この接着装置を用いると、実施例１の作製方法における接着工程を実現でき、透明基板に接着される有機複屈折膜表面の平面度を向上できる。
【０１３１】
図１０の実施の形態では、第２の回転の停止後に紫外線照射機構６０によって紫外線を照射したが、第２の回転中に透明基板１上に紫外線照射機構６０を移動し、有機複屈折膜５の側から紫外線を照射すると、実施例３の作製方法における接着工程を実現できる。更に、上記実施の形態では、紫外線硬化型接着剤の塗布にディスペンサー１２を用いているが、スプレーを用いることによって実施例４、５の作製方法における接着工程を実現でき、紫外線硬化型接着剤の塗布にロールコーターを用いると、実施例６、７の作製方法における定着工程を実現することができる。
【０１３２】
また、これらの実施の形態において、片面に粘着剤を介して有機高分子からなる保護膜が付いた有機複屈折膜を用いると、実施例２、５、７の作製方法における定着工程を実現できる。
【０１３３】
【発明の効果】
以上に説明したように、この発明によれば新規な偏光分離素子、その作成方法、光ピックアップ装置、定着装置を実現できる。
この発明の作製方法によれば、接着工程において有機複屈折膜の表面を極めて高精度に平坦化できる。そしてこの作成方法で作製された偏光分離素子は、透過光に対する光路長が回折格子形成領域で実質的に均一であり、回折光における波面の乱れを有効に軽減できる。従って、この偏光分離素子を用いた光ピックアップ装置は、光ディスクに対する情報の記録・再生・消去の１以上を良好に行うことができ、従来のものよりもコンパクトに構成できる。また、この発明の接着装置によれば、この発明の作製方法における接着工程を良好に実現できる。
【図面の簡単な説明】
【図１】実施例１の作製方法を説明するための図である。
【図２】実施例２の作製方法を説明するための図である。
【図３】実施例３の作製方法を説明するための図である。
【図４】実施例４の作製方法を説明するための図である。
【図５】実施例５の作製方法を説明するための図である。
【図６】実施例６の作製方法を説明するための図である。
【図７】実施例７の作製方法を説明するための図である。
【図８】光ピックアップ装置の実施の１形態を示す図である。
【図９】光ピックアップ装置の実施の別形態を示す図である。
【図１０】接着装置の実施の１形態を説明するための図である。
【符号の説明】
１ 透明基板
３ 紫外線硬化型接着剤
５ 有機複屈折膜
１００ 偏光分離素子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polarization separation element, a manufacturing method thereof, an adhesion apparatus, and an optical pickup apparatus.
[0002]
[Prior art]
In an optical pickup device for an optical disk, a polarization separation element is used to separate an incident light beam from a light source and a “return light beam reflected by the optical disk and bearing information on the optical disk”, and efficiently guide the return light beam to the light detection means. It is used. A “beam splitter with a prism attached” is used with a λ / 4 wave plate as a polarization separation element. In order to meet the demand for downsizing and cost reduction of optical pickup devices, “birefringence that can be reduced in thickness is available. The use of a “diffraction grating type polarization separation element” is intended.
[0003]
Japanese Patent Laid-Open No. 2000-7513 discloses, as this type of polarization separation element, an “organic birefringent film having a different refractive index with respect to different vibration surfaces of incident light” is adhered on a transparent substrate, and the surface of the organic birefringent film Discloses a diffraction grating having periodic unevenness. As the organic birefringent film, a “stretched organic polymer film” is used.
[0004]
In this polarization separation element, the organic birefringent film is bonded to the transparent substrate using an adhesive, but in order to make the optical path length constant for the light beam transmitted through the diffraction grating, the thickness of the adhesive layer And the surface of the organic birefringent film must be flattened, and it is necessary to prevent “undulation” and “waving” from occurring in the bonded organic birefringent film. Furthermore, if bubbles enter the adhesive layer, the incident / emitted light flux is scattered by the bubbles and the diffraction efficiency is lowered, so an adhesion method that does not involve the bubbles is required.
[0005]
[Problems to be solved by the invention]
In the manufacturing process of a polarization separation element using an organic birefringent film, the present invention makes the layer thickness of the adhesive layer uniform when adhering the organic birefringent film to a transparent substrate, so that the organic layer does not entrap air in the adhesive layer. “Polarization separation element manufacturing method” that can satisfactorily flatten the surface of the birefringent film, “Adhesion device” for realizing this method, “Polarization separation” that the surface of the organic birefringent film is made flat by the above method An object is to realize an “optical pickup device” using the polarization separation element.
[0006]
[Means for Solving the Problems]
  The manufacturing method of the polarization separation element according to the present invention is as follows. “Adhesion process of adhering organic birefringent films having different refractive indexes to different vibration surfaces of incident light on a transparent substrate, and a periodic mask on the organic birefringent film” A pattern is formed, and the organic birefringent film is etched using this mask pattern to form a diffraction grating with periodic irregularities.ManyAnd a process for forming the polarization separating element, which is characterized by the following points.
[0007]
That is, in the manufacturing method according to claim 1, the bonding step is “applying the first rotation to the transparent substrate to apply the ultraviolet curable adhesive to the entire surface of the transparent substrate and applying the organic composite onto the applied ultraviolet curable adhesive. From the step of placing the refractive film and applying the second rotation to the transparent substrate to flatten the surface of the organic birefringent film, and then irradiating the ultraviolet curable adhesive with ultraviolet rays to cure the ultraviolet curable adhesive. It is characterized by becoming.
[0008]
The manufacturing method according to claim 2, wherein the bonding step is “applying a first rotation to the transparent substrate to apply an ultraviolet curable adhesive to the entire surface of the transparent substrate, and an organic birefringent film on the applied ultraviolet curable adhesive. , And applying a second rotation to the transparent substrate to flatten the surface of the organic birefringent film, and irradiating the ultraviolet curable adhesive with ultraviolet rays during the second rotation to cure the ultraviolet curable adhesive. Process ”.
[0009]
The manufacturing method according to claim 3, wherein the bonding step is “by applying an ultraviolet curable adhesive on the entire surface of the transparent substrate by a spray method, placing an organic birefringent film on the applied ultraviolet curable adhesive, The third rotation is applied to flatten the surface of the organic birefringent film, and then the ultraviolet curable adhesive is irradiated with ultraviolet rays to cure the ultraviolet curable adhesive. The “third rotation” is named in this way to distinguish it from the “first and second rotations” described above.
[0010]
The manufacturing method according to claim 4, wherein the bonding step is “by applying an ultraviolet curable adhesive on the entire surface of the transparent substrate by a spray method, placing an organic birefringent film on the applied ultraviolet curable adhesive, And applying a third rotation to flatten the surface of the organic birefringent film and irradiating the ultraviolet curable adhesive with ultraviolet rays during the third rotation to cure the ultraviolet curable adhesive. And
[0011]
The manufacturing method according to claim 5, wherein the bonding step is “applying an ultraviolet curable adhesive to the entire surface of the transparent substrate by a roll coater, placing an organic birefringent film on the applied ultraviolet curable adhesive, And 4th rotation to flatten the surface of the organic birefringent film, and then irradiate the ultraviolet curable adhesive with ultraviolet rays to cure the ultraviolet curable adhesive. The “fourth rotation” is named in this way to distinguish from the “first, second, and third rotation” described above.
[0012]
The manufacturing method according to claim 6, wherein the bonding step is “applying an ultraviolet curable adhesive to the entire surface of the transparent substrate by a roll coater, placing an organic birefringent film on the applied ultraviolet curable adhesive, And applying a fourth rotation to flatten the surface of the organic birefringent film and irradiating the ultraviolet curable adhesive with ultraviolet rays during the fourth rotation to cure the ultraviolet curable adhesive. And
[0013]
  As described above, in the present invention, the organic birefringent film is adhered to the transparent substrate with the ultraviolet curable adhesive. However, as a method for coating and forming the layer of the ultraviolet curable adhesive on the transparent substrate, rotation is possible. Application by spraying, application by spraying, application by roll coater is possible. Placed on the layer of UV curable adhesive formed by these methodsBe doneOrganic birefringent filmIs a circular shape with a diameter of 100 mm and a thickness of 50 μm or more. The organic birefringent film is placed on the layer of the ultraviolet curable adhesive with the film center and the rotation center aligned.
  Rotation given to the transparent substrate (the second, third and fourth rotations)Has a rotation speed of 1000-3000rpm, this rotation"Wave" and "swell" are corrected under the action of centrifugal force.
[0014]
When this “rotation” is started, the ultraviolet curable adhesive is in a fluid state that has not yet solidified, and therefore, the layer thickness is made uniform by the action of centrifugal force.
[0015]
The timing of irradiating the ultraviolet curable adhesive with ultraviolet rays may be after the second, third, and fourth rotations as described above, or during the second, third, and fourth rotations. You can go. Irradiation with ultraviolet rays is usually performed through an organic birefringent film.
[0016]
The method for producing a polarization separation element according to any one of claims 1 to 6, wherein the layer thickness of the ultraviolet curable adhesive after application: Tc, the layer thickness of the ultraviolet curable adhesive after curing by ultraviolet irradiation. : Tad can satisfy Tc> Tad (Claim 7).
[0017]
  The method for producing a polarization separation element according to any one of claims 1 to 7,As above“The thickness of the organic birefringent film is 50 μm or more”Done.
[0018]
  The method for producing a polarization separation element according to any one of claims 1 to 7, wherein “an organic birefringent film provided with a protective film on a surface opposite to a surface bonded to a transparent substrate via an adhesive” The protective film can be peeled off from the organic birefringent film after being placed on the curable adhesive layer and curing the ultraviolet curable adhesive by ultraviolet irradiation (Claim 8).
[0019]
  The polarization separation element of the present invention is the aboveClaims 1-8It was produced by the production method described in any one of (Claim 9). The optical pickup device of the present invention isClaim 9Using the described polarization separation element (Claim 10).
[0020]
  The bonding apparatus of the present invention isClaims 1-8In the manufacturing method according to any one of the above, an apparatus for performing the bonding step, which includes a spin table, a rotation mechanism, a coating mechanism, a mounting mechanism, and an ultraviolet irradiation mechanism (Claim 11).
[0021]
The “spin table” is for holding a transparent substrate.
The “rotation mechanism” is a mechanism that rotates the spin table.
The “application mechanism” is a mechanism that applies an ultraviolet curable adhesive to a transparent substrate held on a spin table.
[0022]
The “placement mechanism” is a mechanism for placing an organic birefringent film on an ultraviolet curable adhesive applied on a transparent substrate.
The “ultraviolet irradiation mechanism” is a mechanism that irradiates an ultraviolet curable adhesive layered on a transparent substrate with ultraviolet rays.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
In the following, an embodiment of “a method for manufacturing a polarization separating element” will be described with reference to specific examples.
[0024]
【Example】
Example 1
In FIG. 1, reference numeral 10 denotes a spin table.
[0025]
As shown in FIG. 1A, the transparent substrate 1 is placed on the spin table 10. The transparent substrate 1 is made of shot optical glass “BK7”, has a disk shape with a diameter of 100 mm and a thickness of 1.0 mm, and is fixedly held on the spin table 10 by vacuum suction.
[0026]
After setting the transparent substrate 1, the dispenser 12 is used to rotate the spin table 10 at 10 to 50 rpm, and 3 to 10 g of an acrylic ultraviolet curable adhesive 3 having a refractive index of 1.52 and a viscosity of 500 cp, After dropping on the central portion of the transparent substrate 1 and then rotating the spin table 10 at 150 to 500 rpm (first rotation) to spread the UV curable adhesive 3 over the entire surface of the transparent substrate 1, the spin table 10 is rotated. To stop.
[0027]
In this state, a layer of the ultraviolet curable adhesive 3 is formed on the transparent substrate 1 as shown in FIG.
[0028]
Subsequently, as shown in FIG. 1C, an organic birefringent film 5 having a diameter of 100 mm and a thickness of 100 μm is placed on the center of rotation of the spin table 10 while using a mounting device (not shown). Then, after being placed on the layer of the ultraviolet curable adhesive 3, the spin table 10 is rotated at 1000 to 3000 rpm (second rotation), the remaining ultraviolet curable adhesive is shaken off, and the thickness of the adhesive layer Is made uniform on the substrate surface of the transparent substrate 1 and the surface of the organic birefringent film 5 is flattened (FIG. 1D).
[0029]
Thereafter, the rotation of the spin table 10 is stopped, and as shown in FIG. 1 (e), ultraviolet rays UV are irradiated from the organic birefringent film 5 side using a “high pressure mercury lamp” (not shown), and the ultraviolet curable adhesive 3. Is cured.
[0030]
The transparent substrate 1 to which the organic birefringent film 5 is bonded in this way (hereinafter simply referred to as “substrate”) is removed from the spin table 10, and a positive resist is formed on the organic birefringent film 5 to a thickness of 1.1 μm. After applying and pre-baking at a temperature of 90 ° C. for 30 minutes, the substrate is set in a “reduced projection exposure apparatus (NA = 0.45, σ = 0.6, wavelength: i-line)” and “1000 cycles Is exposed using a 1.5 μm line and space pattern reticle, developed using a developer NMD-3, and post-baked at 100 ° C. for 30 minutes to complete a periodic resist pattern. .
[0031]
Al is vapor-deposited on the resist pattern by sputtering, the resist is dissolved using acetone, and the Al is lifted off to complete an Al pattern in which the resist pattern is inverted. Next, oxygen gas is used using an ECR etching apparatus. Etch the organic birefringent film to a depth of 4 μm using the Al pattern as a metal mask in an etching gas atmosphere containing as a main component, remove the Al pattern using a phosphoric acid-based Al etching solution, and concavo-convex for 1000 cycles To complete the diffraction grating.
[0032]
FIG. 1F illustrates the state where the diffraction grating is formed.
In addition, in FIG. 1 (f), the “diffraction gratings with unevenness of 1000 periods” are formed in “individual convex portions” in the unevenness formed on the upper surface of the organic birefringent film 5. That is, several hundreds of the same diffraction gratings are formed on the upper surface of the organic birefringent film 5.
[0033]
The substrate on which the diffraction grating is formed as described above is placed on a stainless steel table having a diameter of 200 mm and a thickness of 50 mm, which is processed into a plane, and “optically isotropic acrylic UV-curable adhesive is attached to the diffraction grating surface. 1.0 ml of an agent (hereinafter referred to as “isotropic adhesive”) was dropped with a microsyringe, and both surfaces were optically polished. Diameter: 100 mm, thickness: 1 mm disk-shaped counter transparent substrate (Material: Shot-made optics) "Lambda / 4 wavelength plate coated with adhesive" is pasted on one side of glass BK7) and placed on the isotropic adhesive with the surface on which the λ / 4 wavelength plate is pasted facing the isotropic adhesive side To do.
[0034]
“Optical polished optical glass” is placed on the opposing transparent substrate and 100 gf / cm is applied to the opposing transparent substrate.²Is applied to spread the isotropic adhesive over the entire surface to be bonded. An antireflection film is formed on the surface of the counter transparent substrate that faces the surface to be bonded so as to minimize the reflection of incident light. In this state, the isotropic adhesive is cured by irradiating ultraviolet rays through the opposing transparent substrate.
[0035]
FIG.1 (g) has shown the state which hardened the isotropic adhesive agent. Reference numeral 6 indicates an “isotropic adhesive”, reference numeral 7 indicates a “λ / 4 wavelength plate”, reference numeral 8 indicates an “adhesive”, and reference numeral 9 indicates an “opposing transparent substrate”. The antireflection film is not shown. This state is called “intermediate finished product” and is denoted by reference numeral 1A.
[0036]
Next, as shown in FIG. 1 (h), several hundreds of diffraction gratings included in the intermediate finished product 1A are converted into “5 mm squares (each having one diffraction grating) using a dicing saw 15. To complete the polarization separating element 100 (plural).
[0037]
According to this manufacturing method, since the ultraviolet curable adhesive is applied to the entire surface of the transparent substrate by the first rotation, there is no “region without adhesive” on the transparent substrate. Therefore, when an organic birefringent film is placed on a transparent substrate coated with an adhesive, the organic birefringent film is in contact with the surface of the transparent substrate through the adhesive layer over the entire surface, so that the entire surface can be bonded by ultraviolet irradiation. .
[0038]
In the above example, after the transparent substrate 1 is fixed to the spin table 10, an acrylic UV curable adhesive is dropped onto the central portion of the transparent substrate 1 while rotating the spin table 10. The method of applying the agent is not limited to the above method, and the transparent substrate 1 is fixed to the spin table 10 and the adhesive is dropped on the central portion of the transparent substrate 1 while the spin table 10 is stopped. The table 10 may be rotated to spread the adhesive over the entire transparent substrate.
[0039]
In the above example, the ultraviolet curable adhesive 3 is applied at room temperature, but the viscosity of the ultraviolet curable adhesive 3 is high, and the fluidity of the ultraviolet curable adhesive 3 is poor when the organic birefringent film 5 is placed. When air bubbles are easily involved, the organic birefringent film 5 is mounted after the transparent substrate 1 coated with the ultraviolet curable adhesive 3 is heated with an oven or an infrared lamp to reduce the viscosity of the ultraviolet curable adhesive. Alternatively, the UV curable adhesive 3 is preheated in an oven or the like to reduce the viscosity of the UV curable adhesive 3 and then applied to the transparent substrate 1 by the first rotation, and then the organic birefringence is applied. The film 5 is preferably placed.
[0040]
Adhesion step of the fabrication process of Example 1 (Adhesive layer is applied and formed on a transparent substrate, an organic birefringent film is placed on the formed adhesive layer, and after the second rotation, the adhesive is irradiated by ultraviolet irradiation. In the case of solidifying the layer), the rotation speed of the first rotation is changed to 3 levels of 300 to 500 rpm, the rotation speed of the second rotation is changed to 4 levels of 1000 to 3000 rpm, and the other conditions are the same. Seed substrate body (diameter: 100 mm, thickness: 100 μm, circular organic birefringence of diameter: 100 mm, thickness: 100 μm on a transparent disk-shaped substrate having a thickness of 1 m via an ultraviolet curable adhesive coating layer Films adhered) A to F were prepared.
[0041]
For these substrate bodies A to F, the flatness of the surface of the organic birefringent film was measured with a stylus type surface roughness meter. “Flatness” is the “maximum surface roughness including undulations and undulations” of the surface of the organic birefringent film in the range of the maximum length (corresponding to 5 mm in the above example) of each polarization separation element as a finished product, “Maximum surface roughness including waviness and undulation” was measured at an arbitrary five points of the substrate bodies A to F at a measurement length of 5 mm, and the maximum value was defined as flatness.
[0042]
Thereafter, the substrate bodies A to F are cut in the diameter direction using a dicing saw, the cut surface is observed with a metal microscope having a magnification of 200 times, and the thickness of the adhesive layer of the ultraviolet curable adhesive after curing: Tad Was measured.
[0043]
On the other hand, an ultraviolet curable adhesive is applied to a transparent substrate under the first rotation conditions (3 levels of 300 to 500 rpm), and cured by irradiating with ultraviolet rays using a high-pressure mercury lamp without an organic birefringent film. Then, the substrate was cut in the direction of the substrate diameter using a dicing saw, and the cut surface was observed with a metal microscope having a magnification of 200 times to obtain the layer thickness T of the ultraviolet curable adhesive. Since the volume shrinkage at the time of curing of the UV curable adhesive is generally about several percent, the layer thickness T obtained by the above method is a difference of about several percent from the layer thickness Tc after the first rotation: Tc. Since it is considered that they coincide with each other, the layer thickness T is regarded as “layer thickness after application of the ultraviolet curable adhesive: Tc”.
[0044]
The Tc, Tad, and flatness of each of the substrate bodies A to F (the unit is “μm”) are as follows.

Experimental results show that the flatness of the surface of the organic birefringent film should be “approximately 1 μm or less” in order to make the “optical path length with respect to transmitted light” constant in the region where the diffraction grating is formed.
[0045]
Looking at the flatness of the substrate bodies A to F, the flatness is 1 μm or less at all five points in the plane under all conditions, and good flatness is obtained over the entire surface of the organic birefringent film. I know that. Moreover, Tc> Tad is satisfied in all the intermediate finished products A to F.
[0046]
Using the above-mentioned substrate bodies A to F, the “step after the bonding step” in Example 1 is executed to produce a polarization separation element of 5 mm square, and a wavefront using a commercially available wavefront aberration measuring device: Zygo Mark 4 As a result of measuring the aberration, all the chips were 0.02λrms (root mean square value) or less, and it was confirmed that the wavefront disturbance of the light diffracted by the polarization separation element was small. This is considered because the flatness of the organic birefringent film is as good as 1 μm or less.
[0047]
As described above, in the manufacturing method of Example 1, the centrifugal force is applied to the organic birefringent film or the “ultraviolet curable adhesive applied to the transparent substrate” by the second rotation, whereby the ultraviolet rays on the transparent substrate are applied. UV curable adhesive can be shaken off while improving the "undulations and undulations on the surface of the organic birefringent film" that occurs when an organic birefringent film is placed on the curable adhesive layer. The relationship between the layer thickness after application of the adhesive: Tc and the layer thickness after curing: Tad is Tc> Tad.
[0048]
The transparent substrate is vacuum-adsorbed on the spin table 10, an acrylic ultraviolet curable adhesive is dropped, and the spin table 10 is rotated (first rotation) to uniformly apply the adhesive to the entire transparent substrate. Later, the film thickness after application of the ultraviolet curable adhesive: Tc may be directly determined using an optical film thickness meter.
[0049]
In the production method of Example 1, an acrylic ultraviolet curable adhesive was prepared by fixing a disc-shaped transparent substrate made of shot optical glass BK7 having a diameter of 100 mm and a thickness of 1.0 mm to a spin table by vacuum suction. The agent was dropped and the spin table was rotated (first rotation) to uniformly apply the adhesive to the entire surface of the transparent substrate.
[0050]
In this state, as the organic birefringent film placed on the adhesive layer, a circular shape with a diameter of 100 mm and a film thickness of 6 μm, 20 μm, 50 μm, 80 μm, 100 μm, and 150 μm are prepared, respectively. The center of the spin table is substantially coincident with the center of rotation of the spin table, and is placed on the UV curable adhesive layer by using a placing device, and the spin table is rotated again (second rotation). The ultraviolet curable adhesive was shaken off to flatten the surface of the organic birefringent film.
[0051]
Thereafter, the rotation of the spin table was stopped, ultraviolet rays were irradiated using a metal halide lamp, and the ultraviolet curable adhesive was cured, and six types of samples similar to the “substrate body” were produced.
[0052]
The rotation speed of the first rotation is 400 rpm, and the rotation speed of the second rotation is 1000 rpm. The flatness of the organic birefringent film surface in these six types of samples was measured in the same manner as described above. The result is as follows.

From this result, it is understood that “good flatness” of the surface of the organic birefringent film can be ensured when the film thickness of the organic birefringent film is 50 μm or more. When the film thickness of the organic birefringent film is 20 μm or less, the “strength of the waist” of the organic birefringent film becomes extremely weak, and the centrifugal force acting due to the light weight becomes small. It is considered that the flattening of the film is insufficient.
[0053]
The samples 3 to 6 were subjected to “each step after the bonding step” in Example 1 to obtain a large number of polarization separation elements. The organic birefringence film has a film thickness of 50 μm or more, and the surface of the organic birefringence film has a good flatness by the second rotation. Therefore, the organic birefringence is maintained with good flatness by irradiating ultraviolet rays. The film can be bonded to a transparent substrate, and a high manufacturing yield can be achieved by forming a diffraction grating on an organic birefringent film, bonding an opposing transparent substrate, and cutting to obtain a large number of polarization separation elements. .
[0054]
Example 2
A second embodiment will be described with reference to FIG. In order to avoid complications, the same symbols are used throughout the drawings for those that are not likely to be confused.
[0055]
As shown in FIGS. 2A and 2B, a disk-shaped transparent substrate 1 made of shot optical glass BK7 having the same diameter: 100 mm and thickness: 1.0 mm as in Example 1 is used as a spin table 10. Then, an acrylic ultraviolet curable adhesive 3 having the refractive index of 1.52 and the viscosity of 500 cp (the same as that used in Example 1) 3 was dropped with a dispenser 12, and spin table 10 is rotated (first rotation) to uniformly apply the adhesive 3 to the entire surface of the transparent substrate.
[0056]
Next, the rotation of the spin table 10 is stopped, and as shown in FIGS. 2 (c) and 2 (d), an organic birefringent film (diameter: 100 mm) provided with a protective film 4 made of an organic polymer via an adhesive 2 on one side. (Thickness: 100 μm, circular shape) 5 is placed on the layer of the ultraviolet curable adhesive 3 by using a placement device (not shown) so that the center thereof is substantially matched with the rotation center of the spin table 10. Then, the spin table 10 is rotated again (second rotation), and the surplus ultraviolet curable adhesive is shaken off to flatten the surface of the protective film.
[0057]
After the rotation of the spin table 10 is stopped, ultraviolet rays UV are irradiated from above the protective film 4 using a high pressure mercury lamp to cure the ultraviolet curable adhesive 3 (FIG. 2E). In consideration of absorption by the protective film 4, the ultraviolet light is irradiated 1.2 times the energy value of the first embodiment.
[0058]
After the ultraviolet curable adhesive 3 is cured, the protective film 4 is peeled off from the organic birefringent film 5 with tweezers (FIG. 2F). Thereafter, the substrate 1 is removed from the spin table 10 and a diffraction grating is formed by the same lithography / etching process as in Example 1. Then, as shown in FIG. 2G, optically isotropic acrylic ultraviolet curing is performed. A plate-shaped counter transparent substrate (material: shot-made optical glass) having a diameter: 100 mm and a thickness: 1 mm, with a λ / 4 wavelength plate 7 pasted by a pressure-sensitive adhesive 8 using a mold adhesive (isotropic adhesive) 6 BK7) 9 is bonded to obtain an intermediate finished product 1A. An “antireflection film (not shown)” is formed on the free surface (the surface in contact with air) of the counter transparent substrate 9 so as to minimize the reflection of incident light.
[0059]
As shown in FIG. 2 (h), the intermediate finished product 1 </ b> A is cut into 5 mm square with a dicing saw 15 to obtain a plurality of polarized light separating elements 100.
[0060]
According to this manufacturing method, the “adhesion step” for bonding the transparent substrate 1 and the organic birefringent film 5 can be performed in a state where the diffraction grating forming surface of the organic birefringent film 5 is covered with the protective film 4. During the bonding process, no foreign matter adheres to the “surface on which the diffraction grating is to be formed” or is not scratched. In particular, when the spin table 10 is rotated to shake off the surplus UV curable adhesive, the mist of the adhesive that has been shaken off does not adhere to the “surface that forms the diffraction grating” (the adhesive mist is attached to the protective film, Since the protective film is peeled off after UV irradiation, it does not remain on the surface of the organic birefringent film), so the surface of the organic birefringent film with very little foreign matter can be realized, and pattern defects caused by foreign matter and scratches can be reduced in the lithography process. The manufacturing yield of the polarization separation element can be improved.
[0061]
In the manufacturing method of Example 2, a disk-shaped transparent substrate made of shot optical glass BK7 having a diameter of 100 mm and a thickness of 1.0 mm is vacuum-adsorbed and fixed to a spin table, and an acrylic ultraviolet curing adhesive is used. The agent was dropped and the spin table was rotated (first rotation) to uniformly apply the adhesive to the entire surface of the transparent substrate.
[0062]
In this state, as an organic birefringent film placed on the adhesive layer, an organic birefringent film (diameter: 100 mm circular shape) provided with a “protective film made of an organic polymer” on one side via an adhesive , Film thicknesses of 6 μm, 20 μm, 50 μm, 80 μm, 100 μm, and 150 μm are prepared (adhesive film thickness is 9-14 μm and protective film film thickness is 20 μm. The total film thickness, which is the sum of the film thickness of the pressure-sensitive adhesive and protective film, was 35 to 180 μm.), And the center of each of the UV-curable adhesive was made to substantially coincide with the rotation center of the spin table 10. It mounted on the layer using the mounting apparatus, the spin table was rotated again (2nd rotation), the surplus ultraviolet curable adhesive was shaken off, and the organic birefringent film surface was planarized.
[0063]
Thereafter, the rotation of the spin table 10 was stopped, and ultraviolet rays were irradiated from above the protective film using a high pressure mercury lamp to cure the ultraviolet curable adhesive. The intensity of the ultraviolet light is the same as in Example 2. Subsequently, using tweezers, the protective film was peeled from the organic birefringent film to obtain samples 1 to 6, respectively.
[0064]
The rotation speed of the first rotation is 400 rpm, and the rotation speed of the second rotation is 1000 rpm. The flatness of the organic birefringent film surface in these six types of samples was measured in the same manner as described above. The results are as follows (the unit is “μm”).

From this result, it can be seen that when the total thickness of the organic birefringent film, the adhesive, and the protective film is 50 μm or more, good flatness of the surface of the organic birefringent film can be secured. If the total film thickness of the organic birefringent film, adhesive, and protective film is 35 μm, the total “waist strength” of the protective film, adhesive, and organic birefringent film will not be sufficiently strong. It is considered that the surface of the protective film cannot be sufficiently flattened even by the centrifugal force, and the flatness of the surface of the organic birefringent film is also lowered.
[0065]
With respect to Samples 2 to 6 (film thickness of organic birefringent film: 20 to 150 μm), “each step after the bonding step” in Example 2 was executed to obtain a large number of polarization separation elements. The total thickness of the organic birefringent film, the adhesive, and the protective film is 50 μm or more, and the surface of the organic birefringent film has good flatness by the second rotation. Then, by peeling off the protective film from the organic birefringent film, the organic birefringent film can be adhered to the transparent substrate while maintaining good flatness, and a diffraction grating is formed on the organic birefringent film, A high production yield could be achieved to obtain a large number of polarized light separating elements by bonding and cutting the opposing transparent substrate.
[0066]
In addition, according to the manufacturing method of Example 2, the “thinner organic birefringent film”, which was difficult to ensure flatness by the method of Example 1, is adhered to the transparent substrate while maintaining good flatness. Therefore, an organic birefringent film having a wider film thickness range can be used.
[0067]
In the above example, the total film thickness was controlled mainly using the film thickness of the organic birefringent film as a parameter, but the same effect is expected even when the film thickness of the adhesive or the protective film is changed and the total film thickness is 50 μm or more. The total film thickness may be 50 μm or more by simultaneously changing the film thickness of the organic birefringent film, the adhesive, and the protective film.
[0068]
Example 3
A third embodiment will be described with reference to FIG.
As shown in FIGS. 3A and 3B, a disk-shaped transparent substrate 1 made of shot optical glass BK7 having a diameter of 100 mm and a thickness of 1.0 mm is placed on a spin table 10 and vacuum suction is performed. The epoxy ultraviolet curable adhesive 3 having a refractive index of 1.58 and a viscosity of 600 cp is applied to the transparent substrate 1 using the dispenser 12 while rotating the spin table 10 at 10 to 50 rpm. 3-11g is dripped at the center part. After droplet formation, the spin table 10 is rotated at 150 to 500 rpm (first rotation) to spread the ultraviolet curable adhesive on the entire surface of the transparent substrate 1, and then the rotation of the spin table 10 is stopped.
[0069]
Next, as shown in FIGS. 3 (c) and 3 (d), a circular organic birefringent film 5 having a diameter of 100 mm and a thickness of 80 μm is formed on a spin table 10 using a mounting device (not shown). Is placed on the layer of the ultraviolet curable adhesive 3 so as to substantially coincide with the rotation center of the organic birefringent film 5 by rotating the spin table 10 at 1000 to 3000 rpm for 60 seconds (second rotation). After the surface is substantially flattened, ultraviolet light UV is irradiated using a metal halide lamp (not shown) while continuing the second rotation to cure the ultraviolet curable adhesive 3.
[0070]
The intensity of the ultraviolet light is reduced to 1/10 to 1/4 of that in the case of Example 1 so that the ultraviolet curable adhesive 3 continues to be shaken out during the ultraviolet irradiation until the ultraviolet curable adhesive 3 is completely cured. Then, the surface of the organic birefringent film 5 is made flat.
[0071]
After the curing of the adhesive 3 is completed, the rotation of the spin table 10 is stopped, the transparent substrate 1 to which the organic birefringent film 5 is bonded (hereinafter simply referred to as “substrate”) is removed from the spin table 10, and the organic birefringent film 5 is placed on the organic birefringent film 5. A positive resist is applied to a thickness of 1.5 μm and prebaked at a temperature of 80 ° C. for 30 minutes. After pre-baking, the substrate is mounted on a reduced projection exposure apparatus (NA = 0.54, σ = 0.6, wavelength; i-line), and a “1.0 μm line and space pattern for 1000 cycles” reticle is used. Exposure is performed, development is performed using the developer NMD-3, and post-baking is performed at a temperature of 100 ° C. for 30 minutes to complete a periodic resist pattern.
[0072]
The resist pattern is exposed to 1,1,3,3-tetramethyl hexadisilazane vapor in an atmosphere of 110 ° C., and the resist surface is doped with 1,1,3,3-tetramethyl hexadisilazane. The apparatus is used to etch the organic birefringent film to a depth of 4 μm using a resist pattern as a mask in an etching gas atmosphere containing oxygen gas as a main component, and remove the resist pattern using a stripping solution. A large number of “diffraction gratings with unevenness” are formed.
[0073]
FIG. 3E shows a substrate on which a large number of diffraction gratings (individual diffraction gratings are formed on “protrusions of unevenness” on the upper surface of the figure).
[0074]
A substrate on which a diffraction grating is formed is placed on a stainless steel table having a diameter of 200 mm and a thickness of 50 mm, and an optically isotropic epoxy UV curing adhesive (isotropic bonding) is placed on the diffraction grating surface. Agent)) is dropped with a microsyringe, and a disk-shaped counter transparent substrate (material: Shot optical glass BK7) having a diameter of 100 mm and a thickness of 1 mm with both sides optically polished is placed thereon. Furthermore, an optical glass that has been optically polished is placed on the opposing transparent substrate and 100 gf / cm.²Is applied to spread the isotropic adhesive over the entire surface to be bonded.
[0075]
An antireflection film (not shown) is formed on the surface of the counter transparent substrate facing the surface to be bonded so as to minimize the reflection of incident light. In this state, the isotropic adhesive is cured by irradiating ultraviolet rays through the opposing transparent substrate. In this way, an intermediate finished product 1B shown in FIG. 3 (f) is obtained.
[0076]
Finally, as shown in FIG. 3G, the intermediate finished product 1B is cut into 5 mm square using a dicing saw 15 to complete a plurality of polarized light separating elements 101.
[0077]
According to the manufacturing method of Example 3, since the ultraviolet curable adhesive was applied to the entire surface of the transparent substrate by the first rotation, no adhesive-free region was generated on the transparent substrate, and the adhesive 3 was applied. When the organic birefringent film 5 is placed on the transparent substrate 1, the organic birefringent film 5 is in contact with the surface of the transparent substrate 1 through the adhesive 3 over the entire surface, so that the entire surface can be bonded by ultraviolet irradiation.
[0078]
In addition, by applying a centrifugal force to the organic birefringent film 5 and the ultraviolet curable adhesive 3 applied to the transparent substrate 1 by the second rotation, the surface of the organic birefringent film 1 is undulated and wavy. The adhesive can be shaken off while improving. Furthermore, since the ultraviolet rays are irradiated during the second rotation, the adhesive is cured with the unevenness of the surface of the organic birefringent film improved, such as undulations and undulations, and the organic birefringent film having good flatness can be bonded. It becomes.
[0079]
In Example 3, after fixing the transparent substrate 1 to the spin table 10, while rotating the spin table 10, the epoxy adhesive 3 was dropped onto the central portion of the transparent substrate 1 and the adhesive 3 was applied. The method of applying the adhesive 3 is not limited to this method. After fixing the transparent substrate 1 to the spin table 10, the adhesive is dropped on the center of the transparent substrate while the spin table 10 is stopped. The table 10 may be rotated to spread the adhesive over the entire transparent substrate.
[0080]
Example 4
A fourth embodiment will be described with reference to FIG.
As shown in FIGS. 4A and 4B, a disc-shaped transparent substrate 1 made of shot optical glass BK7 having a diameter of 100 mm and a thickness of 1.0 mm is placed on a spin table 10 and vacuum suction is performed. In the state fixed to the spin table 10 by using a spray 13, an epoxy-based ultraviolet curable adhesive (same as that used in Example 3) 3 having a refractive index of 1.58 and a viscosity of 600 cp is transparent. Apply uniformly to the entire surface of the substrate 1. The coating thickness of the ultraviolet curable adhesive 3 is preferably about 40 to 80 μm.
As shown in FIGS. 4C and 4D, a circular organic birefringent film 5 having a diameter of 100 mm and a thickness of 80 μm is formed on the ultraviolet curable adhesive 3 using a mounting device (not shown). The film center is placed so as to substantially match the rotation center of the spin table 10, the spin table 10 is rotated at 1000 to 3000 rpm (third rotation), the remaining adhesive is shaken off, and the thickness of the adhesive layer Is made uniform on the substrate surface to flatten the surface of the organic birefringent film 5.
[0081]
The rotation of the spin table 10 is stopped, and as shown in FIG. 4E, ultraviolet rays are irradiated from the organic birefringent film 5 side using a high-pressure mercury lamp to cure the ultraviolet curable adhesive 3.
[0082]
Thereafter, in the same manner as in Example 3 described above, a diffraction grating is formed on the surface of the organic birefringent film by lithography / etching, and an optically isotropic epoxy-based material is used as shown in FIG. A disk-shaped counter transparent substrate (material: Schott optical glass BK7) 9 having a diameter of 100 mm and a thickness of 1 mm is bonded using an ultraviolet curable adhesive (isotropic adhesive) 6. An antireflection film is formed on the surface of the counter transparent substrate 9 facing the surface to be bonded so as to minimize the reflection of incident light.
[0083]
The intermediate finished product 1B thus obtained is cut into 5 mm square using a dicing saw 15 as shown in FIG.
[0084]
According to the manufacturing method of Example 4, since the ultraviolet curable adhesive 3 is applied to the entire surface of the transparent substrate 1 by the spray method, no “region without adhesive” is generated on the transparent substrate 1. Therefore, when the organic birefringent film 5 is placed on the transparent substrate 1 to which the adhesive 3 is applied, the organic birefringent film 5 is in contact with the surface of the transparent substrate through the adhesive layer over the entire surface. Adhesion becomes possible.
[0085]
Further, by applying a centrifugal force to the organic birefringent film 5 and the UV curable adhesive 3 by the third rotation, the surface of the organic birefringent film 5 is improved in unevenness such as swells and undulations, and the adhesive is applied. Since the ultraviolet curable adhesive is cured by irradiating with ultraviolet rays thereafter, an organic birefringent film surface with good flatness can be obtained in the bonding process of the organic birefringent film 5.
[0086]
In Example 4, the ultraviolet curable adhesive 3 was spray-coated at “room temperature”, but the viscosity of the ultraviolet curable adhesive 3 was high, and the flow of the ultraviolet curable adhesive 3 when the organic birefringent film 5 was placed thereon. In the case where the property is poor and air bubbles are easily involved, the organic birefringent film is formed after the transparent substrate coated with the ultraviolet curable adhesive 3 is heated with an oven or an infrared lamp to reduce the viscosity of the ultraviolet curable adhesive 3 5, or the ultraviolet curable adhesive 3 is preheated in an oven or the like to reduce the viscosity, and then applied to the transparent substrate 1 by a spray method, and then the organic birefringent film 5 is placed. Is good.
[0087]
Example 5
Embodiment 5 will be described with reference to FIG.
As shown in FIGS. 5A and 5B, a disk-shaped transparent substrate 1 made of shot optical glass BK7 having a diameter of 100 mm and a thickness of 1.0 mm is placed on a spin table 10 and vacuum suction is performed. To the spin table 10, and using the spray 13, an epoxy-based ultraviolet curable adhesive (same as that used in Example 3) 3 having a refractive index of 1.58 and a viscosity of 600 cp is applied to the transparent substrate 1. Apply evenly over the entire surface. The coating thickness of the ultraviolet curable adhesive is preferably about 40 to 80 μm.
[0088]
As shown in FIGS. 5 (c) and 5 (d), an organic birefringent film (diameter: 100 mm, thickness: 50 μm circular shape) provided with a protective film 4 made of an organic polymer via an adhesive 2 on one side. ) Is placed on the ultraviolet curable adhesive 3 using a mounting device (not shown) so that the center of the film substantially matches the center of rotation of the spin table 10 and the protective film is a free surface. Thereafter, the spin table 10 is rotated at 1000 to 3000 rpm for 60 seconds (third rotation), and after the surface of the protective film is substantially planarized, a high pressure mercury lamp (not shown) is used while continuing the third rotation. Ultraviolet rays UV is irradiated and the ultraviolet curing adhesive 3 is hardened.
[0089]
The intensity of the ultraviolet light is set to 1/10 to 1/4 of that in Example 4, and the UV curable adhesive is continuously shaken out during the ultraviolet irradiation, and the surface of the protective film is flattened until the ultraviolet curable adhesive is completely cured. Make it progress.
[0090]
Subsequently, the rotation of the spin table 10 is stopped, and the protective film 4 is peeled off from the organic birefringent film 5 using tweezers or the like (FIG. 5E).
[0091]
Thereafter, in the same manner as in Example 4, a diffraction grating is formed on the surface of the organic birefringent film by lithography / etching, and as shown in FIG. 5 (f), an optically isotropic epoxy UV curable adhesive is used. (Isotropic adhesive) 6 is used to bond a disk-shaped counter transparent substrate (material: shot optical glass BK7) 9 having a diameter of 100 mm and a thickness of 1 mm to obtain an intermediate finished product 1B. An antireflection film is formed on the surface of the counter transparent substrate 9 so as to minimize the reflection of incident light.
[0092]
As shown in FIG. 5G, the intermediate finished product 1 </ b> B is cut into 5 mm squares with a dicing saw 15 to obtain a large number of polarization separation elements 101.
[0093]
According to the manufacturing method of Example 5, since the ultraviolet curable adhesive 3 is applied to the entire surface of the transparent substrate 1 by the spray method, when the organic birefringent film 5 is placed on the adhesive layer 3, the organic birefringent film is obtained. Since 5 is in contact with the surface of the transparent substrate 1 through the adhesive layer 3 over the entire surface, the entire surface can be bonded by ultraviolet irradiation. Further, by applying a centrifugal force to the organic birefringent film 5 and the ultraviolet curable adhesive 3 by the third rotation, the surplus adhesive is removed while improving the unevenness of the surface of the organic birefringent film 5 such as waviness and undulation. Since the UV curable adhesive 3 is cured by irradiating with ultraviolet rays during the third rotation, an organic birefringent film / adhesive layer / transparent substrate having a flat surface can be obtained.
[0094]
Furthermore, the “adhesion process” for bonding the transparent substrate 1 and the organic birefringent film 5 can be performed in a state where the “diffraction grating forming surface” of the organic birefringent film 5 is covered with the protective film 4. Scratches and foreign matter are not attached to the lattice forming surface, and the manufacturing yield of the polarization separation element can be improved.
[0095]
Example 6
A sixth embodiment will be described with reference to FIG.
As shown in FIGS. 6A and 6B, a disc-shaped transparent substrate 1 made of shot optical glass BK7 having a diameter of 100 mm and a thickness of 1.0 mm is installed on a roll coater 14 and has no groove. Using a roll, an acrylic ultraviolet curable adhesive 3 having the refractive index of 1.52 and a viscosity of 500 cp (the same as that used in Example 1) 3 is uniformly applied to the entire surface of the transparent substrate 1. The coating thickness of the ultraviolet curable adhesive 3 is 40 to 80 μm.
[0096]
As shown in FIG. 6C, the center of the film substantially coincides with the center of the transparent substrate 1 by using a mounting device (not shown) of the circular organic birefringent film 5 having a diameter of 100 mm and a thickness of 100 μm. In this way, it is placed on the ultraviolet curable adhesive 3.
[0097]
As shown in FIG. 6 (d), the transparent substrate 1 on which the organic birefringent film 5 is placed is placed on a spin table 10, fixed by vacuum suction, and the spin table 10 is rotated at 1000 to 3000 rpm for 60 seconds (first step). 4), the surface of the organic birefringent film 5 is substantially flattened, and then UV light is irradiated using a high-pressure mercury lamp (not shown) while continuing the fourth rotation to cure the ultraviolet curable adhesive 3. .
[0098]
The intensity of the ultraviolet ray UV is set to 1/10 to 1/4 of that of Example 1, and the remaining ultraviolet ray curable adhesive 3 is continuously shaken off during the ultraviolet ray irradiation, and the organic matter is cured until the ultraviolet ray curable adhesive 3 is completely cured. The planarization of the birefringent film surface is advanced.
[0099]
Thereafter, the rotation of the spin table 10 is stopped, the transparent substrate (hereinafter referred to as “substrate”) to which the organic birefringent film 5 is bonded is removed from the spin table 10, and a diffraction grating is formed by lithography / etching in the same manner as in Example 1. (FIG. 6 (e)).
[0100]
As in Example 1, an acrylic transparent UV curable adhesive (isotropic adhesive) 6 was used, and an opposing transparent substrate (Shot optical glass BK7, diameter) on which a λ / 4 wavelength plate 7 was attached by an adhesive 8 : 100 mm, thickness: 1 mm Disc shape) 9 is bonded to the substrate.
[0101]
An antireflection film is formed on the free surface of the counter transparent substrate 9 so as to minimize the reflection of incident light. In this way, an intermediate finished product 1A as shown in FIG. 6 (f) is obtained.
[0102]
Finally, the intermediate finished product 1A is cut into 5 mm squares with a dicing saw 15 to complete a plurality of polarization separation elements 100.
[0103]
According to the manufacturing method of Example 6, since the ultraviolet curable adhesive 3 is applied to the entire surface of the transparent substrate 1 by the roll coater 14, there is no “region without adhesive” on the transparent substrate 1. Therefore, when the organic birefringent film 5 is placed on the transparent substrate 1 to which the adhesive 3 is applied, the organic birefringent film 5 is in contact with the surface of the transparent substrate through the adhesive layer 3 over the entire surface. Adhesion becomes possible.
[0104]
Further, by applying a centrifugal force to the organic birefringent film 5 and the UV curable adhesive 3 by the fourth rotation, the surplus adhesive is improved while improving the unevenness of the surface of the organic birefringent film 5 such as waviness and undulation. 3 can be shaken out, and the ultraviolet curable adhesive is cured by irradiating ultraviolet rays during the fourth rotation, so that an organic birefringent film surface with good flatness is obtained in the bonding process of the organic birefringent film 5. be able to.
[0105]
In Example 6, since the UV curable adhesive 3 is applied to the transparent substrate 1 with a “roll without groove”, a coating layer of the UV curable adhesive 3 having relatively good flatness can be obtained. When a roll is used, “streaky unevenness” occurs on the adhesive surface. In that case, the transparent substrate 1 coated with the UV curable adhesive 3 is heated in an oven or the like to reduce the viscosity of the UV curable adhesive 3 and improve the “surface of the applied adhesive” flatness. Good to do.
[0106]
In Example 6, the ultraviolet curable adhesive 3 was applied at “room temperature”. However, the ultraviolet curable adhesive 3 has a high viscosity, and when the organic birefringent film 5 is placed, the ultraviolet curable adhesive 3 is applied. In the case where the air flow is poor and air bubbles are easily involved, the transparent substrate coated with the UV curable adhesive 3 is heated with an oven or an infrared lamp to reduce the viscosity of the UV curable adhesive 3 and then the organic compound. The refractive film 5 is placed, or an ultraviolet curable adhesive 3 whose viscosity is lowered by heating in an oven or the like is applied to the transparent substrate 1 by a roll coater, and then the organic birefringent film 5 is placed. Is good.
[0107]
Example 7
Example 7 will be described with reference to FIG.
[0108]
As shown in FIGS. 7A and 7B, a disc-shaped transparent substrate 1 made of shot optical glass BK7 having a diameter of 100 mm and a thickness of 1.0 mm is set on a roll coater 14, and a roll without grooves. An acrylic ultraviolet curable adhesive 3 (same as that used in Example 1) 3 having a refractive index of 1.52 and a viscosity of 500 cp is applied uniformly on the entire surface of the transparent substrate 1. The coating thickness of the ultraviolet curable adhesive 3 is 40 to 80 μm.
[0109]
Next, as shown in FIG. 7 (c), an organic birefringent film (diameter: 100 mm, thickness: 50 μm, circular shape) 5 provided with a protective film 4 made of an organic polymer via an adhesive 2 on one side is provided. Then, it is placed on the ultraviolet curable adhesive 3 by using a placing device (not shown) so that the center thereof is substantially aligned with the center of the transparent substrate 1 and the protective film 4 side is a free surface.
[0110]
As shown in FIG. 7D, the transparent substrate 1 on which the organic birefringent film 5 covered with the post-protective film 4 is placed is placed on the spin table 10 and fixed by vacuum suction, and then the spin table 10 is set to 1000 to 1000. Rotate at 3000 rpm (fourth rotation) to flatten the surface of the protective film. The rotation of the spin table 10 is stopped, the ultraviolet ray UV is irradiated using a high-pressure mercury lamp (not shown), and the ultraviolet curable adhesive is cured (FIG. 7E). The protective film 4 is peeled from the organic birefringent film 5 using a method such as The intensity of ultraviolet UV is 1.2 times the intensity in Example 6 in consideration of absorption by the protective film.
[0111]
When the transparent substrate 1 to which the organic birefringent film 5 is bonded is removed from the spin table 10 and a diffraction grating is formed by lithography / etching in the same manner as in the first embodiment, a state as shown in FIG.
[0112]
Next, as shown in FIG. 7 (h), the λ / 4 wavelength plate 7 is pasted by the adhesive 8 using the acrylic ultraviolet curable adhesive (isotropic adhesive) 6 as in Example 1. An intermediate finished product 1A is obtained by bonding a disk-shaped counter transparent substrate (shot optical glass BK7, diameter: 100 mm, thickness: 1 mm) 9.
[0113]
Finally, the intermediate finished product 1A is cut into a 5 mm square with a dicing saw to obtain a plurality of polarized light separating elements 100 (FIG. 7 (i)).
[0114]
According to the manufacturing method of Example 7, since the ultraviolet curable adhesive 3 is applied to the entire surface of the transparent substrate 1 by the roll coater 14, the organic birefringent film 5 is placed on the transparent substrate 1 to which the adhesive 3 has been applied. Then, since the organic birefringent film 5 is in contact with the surface of the transparent substrate 1 through the adhesive layer 3 over the entire surface, the entire surface can be bonded by ultraviolet irradiation.
[0115]
Further, by applying a centrifugal force to the organic birefringent film 5 and the UV curable adhesive 3 by the fourth rotation, the surplus adhesive is shaken off while improving the unevenness of the surface of the organic birefringent film 5 such as waviness and undulation. Since the ultraviolet curable adhesive 3 is cured by performing ultraviolet irradiation after the fourth rotation, an organic birefringent film / adhesive layer / transparent substrate having a flat surface can be obtained.
[0116]
Further, as in Example 3, the bonding step of bonding the transparent substrate 1 and the organic birefringent film 5 can be performed in a state where the diffraction grating forming surface of the organic birefringent film 5 is covered with a protective film. Pattern defects caused by foreign matter and scratches can be reduced, and the manufacturing yield of the polarization separation element can be improved.
[0117]
Even in Example 7, since the UV curable adhesive is applied to the transparent substrate with a roll having no groove, a coating layer having a relatively good flatness of the UV curable adhesive 3 can be obtained. Streaky unevenness occurs on the surface of the adhesive layer. In that case, it is preferable to improve the flatness of the surface of the adhesive layer by heating the transparent substrate coated with the ultraviolet curable adhesive in an oven to reduce the viscosity of the ultraviolet curable adhesive 3.
[0118]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 8 shows an embodiment of the optical pickup device.
This optical pickup device is for a CD, and light having a wavelength of 780 nm emitted from a laser diode 81 is irradiated to a CD-RW 90, which is an optical disc, through a polarization separation element 83, a collimator lens 85, and an objective lens 87, and a recording surface. The reflected light at is converted into a return light beam, diffracted by the polarization separation element 83, guided to the light detection element 89, and focus detection, track detection, and signal detection are performed.
[0119]
The optical pickup device of FIG. 8 is configured using the polarization separation element 83 manufactured by the manufacturing method of Example 1, and a signal is recorded on the CD-RW using this, and then the same optical pickup device is used. When the signal is reproduced, a reproduction signal output equivalent to the case of using the “conventional polarization separation element combining a beam splitter with a prism attached and a λ / 4 wavelength plate” can be obtained. It was confirmed that the optical pickup device has the same recording / reproducing characteristics as the “conventional one”.
[0120]
In the optical pickup device of the embodiment shown in FIG. 8, the polarization separation element 83 is smaller than the conventional “beam splitter with a prism attached”, and a λ / 4 wavelength plate is also incorporated in the polarization separation element. Therefore, it is possible to realize a reduction in size as compared with a conventional optical pickup.
[0121]
FIG. 9 shows another embodiment of the optical pickup device.
This optical pickup device is for a DVD. Light having a wavelength of 680 nm emitted from a laser diode 81 passes through a polarization separation element 83, a collimator lens 85, a λ / 4 wavelength plate 86, an objective lens 87, and then an optical disc. The return light beam irradiated by the DVD 91 and reflected by the recording surface of the DVD 91 is linearly polarized by the λ / 4 wave plate 86, then diffracted by the polarization separation element 83 and guided to the light detection element 89, and focused. Detection, track detection, and signal detection are performed.
[0122]
As the polarization separation element 83, the one produced by the production method of Example 3 was used to construct the optical pickup device of FIG. 9, and the information signal was reproduced from the DVD-ROM. A signal output equivalent to that of a conventional DVD optical pickup device used in combination with a λ / 4 wavelength plate can be obtained, and the optical pickup device of this embodiment has the same reproduction characteristics as the conventional optical pickup device. I was able to confirm that
[0123]
Further, in the optical pickup device of FIG. 9, the polarization separation element 83 is smaller than the “beam splitter with a prism attached”, and thus is smaller than the conventional optical pickup device.
[0124]
FIG. 10 shows an embodiment of an “adhesion apparatus” for adhering an organic birefringent film. This bonding apparatus includes a spin table 10 that holds a transparent substrate 1, a rotation mechanism (not shown) including a stepping motor that rotates the spin table 10, and a dispenser that applies an ultraviolet curable adhesive to the transparent substrate 1. A layer of UV curable adhesive applied on the transparent substrate 1 with both ends of the organic birefringent film 5 held by a coating mechanism consisting of 12 (controlled by a robot arm 12A) and two adsorption arms 50 It comprises a mounting mechanism 55 for mounting the organic birefringent film 5 thereon, and an ultraviolet irradiation mechanism 60 comprising a high-pressure mercury lamp, a metal halide lamp, or the like that irradiates the ultraviolet curable adhesive with ultraviolet rays.
[0125]
The procedure for adhering the organic birefringent film 5 to the transparent substrate 1 is as follows.
[0126]
A transparent substrate 1 made of shot optical glass BK7 having a diameter of 100 mm and a thickness of 1.0 mm (with a circular portion cut out to form an “orientation flat”) is placed on a spin table 10. Then, it is fixed to the spin table 10 by vacuum suction. Next, the dispenser 12 is moved above the central portion of the transparent substrate 1 by the robot arm 12A, and the spin table 10 is rotated at 10 rpm by a rotating mechanism, while the refractive index: 1.52 and the viscosity: 500 cp, an acrylic ultraviolet curing type. 4 g of adhesive is dropped.
[0127]
Thereafter, the dispenser 12 is returned to the original position, the spin table 10 is rotated at 300 rpm (first rotation), the ultraviolet curable adhesive is spread on the entire surface of the transparent substrate, and then the rotation of the spin table 10 is stopped.
[0128]
Subsequently, the two adsorption mechanisms of the mounting mechanism are attached to both ends of the organic birefringent film 5 having a diameter: 100 mm, a thickness: 100 μm, and circular (partially cut away to form an “orientation flat”). The organic birefringent film 5 is moved onto the transparent substrate 1 and held on the arm 50 by vacuum suction, and the center of the organic birefringent film 5 is substantially aligned with the rotation center of the spin table 10. Vacuum adsorption is gradually released, and an organic birefringent film is placed on the ultraviolet curable adhesive.
[0129]
After returning the mounting device to the original position, the spin table 10 is rotated at 1800 rpm (second rotation), the UV curable adhesive is shaken off, and the surface of the organic birefringent film 5 is flattened. Is stopped, the ultraviolet irradiation mechanism 60 is moved above the transparent substrate, and the ultraviolet curable adhesive is cured by irradiating ultraviolet rays from the organic birefringent film 5 side. After the ultraviolet irradiation is completed, the ultraviolet irradiation mechanism 60 is returned to the original position, the vacuum adsorption of the spin table 10 is released, and the transparent substrate 1 to which the organic birefringent film 5 is bonded is taken out.
[0130]
As described above, when this bonding apparatus is used, the bonding step in the manufacturing method of Example 1 can be realized, and the flatness of the surface of the organic birefringent film bonded to the transparent substrate can be improved.
[0131]
In the embodiment of FIG. 10, the ultraviolet irradiation mechanism 60 irradiates ultraviolet rays after the second rotation is stopped. However, during the second rotation, the ultraviolet irradiation mechanism 60 is moved onto the transparent substrate 1 and the organic birefringence film 5 is moved. When the ultraviolet rays are irradiated from the side, the bonding step in the manufacturing method of Example 3 can be realized. Furthermore, in the said embodiment, although the dispenser 12 is used for application | coating of an ultraviolet curable adhesive, the adhesion process in the preparation methods of Examples 4 and 5 can be implement | achieved by using a spray, and an ultraviolet curable adhesive is used. When a roll coater is used for coating, the fixing step in the production methods of Examples 6 and 7 can be realized.
[0132]
In these embodiments, when an organic birefringent film having a protective film made of an organic polymer on one side with an adhesive is used, the fixing step in the production methods of Examples 2, 5, and 7 can be realized. .
[0133]
【The invention's effect】
As described above, according to the present invention, a novel polarization separation element, a method for producing the same, an optical pickup device, and a fixing device can be realized.
According to the manufacturing method of the present invention, the surface of the organic birefringent film can be planarized with extremely high accuracy in the bonding step. In the polarization separation element manufactured by this manufacturing method, the optical path length with respect to the transmitted light is substantially uniform in the diffraction grating formation region, and the disturbance of the wavefront in the diffracted light can be effectively reduced. Therefore, the optical pickup device using this polarization separation element can satisfactorily perform one or more of recording / reproducing / erasing information with respect to the optical disc, and can be configured more compactly than the conventional one. Further, according to the bonding apparatus of the present invention, the bonding process in the manufacturing method of the present invention can be realized satisfactorily.
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams for explaining a manufacturing method of Example 1. FIGS.
FIGS. 2A and 2B are diagrams for explaining a manufacturing method of Example 2. FIGS.
3 is a diagram for explaining a manufacturing method of Example 3. FIG.
4 is a diagram for explaining a manufacturing method of Example 4. FIG.
5 is a diagram for explaining a manufacturing method of Example 5. FIG.
6 is a diagram for describing a manufacturing method of Example 6. FIG.
7 is a diagram for explaining a manufacturing method of Example 7. FIG.
FIG. 8 is a diagram showing an embodiment of an optical pickup device.
FIG. 9 is a diagram showing another embodiment of the optical pickup device.
FIG. 10 is a diagram for explaining one embodiment of a bonding apparatus.
[Explanation of symbols]
1 Transparent substrate
3 UV curable adhesive
5 Organic birefringent film
100 Polarization separation element

Claims (11)

An adhesion process for adhering organic birefringent films having different refractive indexes to the vibration surfaces of different incident light on a transparent substrate, and forming a periodic mask pattern on the organic birefringent film, and using this mask pattern Etching the organic birefringent film to form a large number of diffraction gratings with periodic irregularities,
The bonding step applies a first rotation to the transparent substrate to apply an ultraviolet curable adhesive to the entire surface of the transparent substrate. On the applied ultraviolet curable adhesive, a circular shape with a diameter of 100 mm and a thickness of 50 μm or more. The organic birefringent film is placed with the film center and the rotation center aligned, and a second rotation of 1000 to 3000 rpm is applied to the transparent substrate, and the surface of the organic birefringent film is applied by the action of centrifugal force. A method for producing a polarization separation element, comprising the step of curing the ultraviolet curable adhesive by irradiating the ultraviolet curable adhesive with ultraviolet rays after planarization. An adhesion process for adhering organic birefringent films having different refractive indexes to the vibration surfaces of different incident light on a transparent substrate, and forming a periodic mask pattern on the organic birefringent film, and using this mask pattern Etching the organic birefringent film to form a large number of diffraction gratings with periodic irregularities,
The bonding step applies a first rotation to the transparent substrate to apply an ultraviolet curable adhesive to the entire surface of the transparent substrate. On the applied ultraviolet curable adhesive, a circular shape with a diameter of 100 mm and a thickness of 50 μm or more. The organic birefringent film is placed with the film center and the rotation center aligned, and a second rotation of 1000 to 3000 rpm is applied to the transparent substrate, and the surface of the organic birefringent film is applied by the action of centrifugal force. A method for producing a polarization separation element, comprising the step of curing the ultraviolet curable adhesive by irradiating the ultraviolet curable adhesive with ultraviolet rays during the second rotation while being flattened. An adhesion process for adhering organic birefringent films having different refractive indexes to the vibration surfaces of different incident light on a transparent substrate, and forming a periodic mask pattern on the organic birefringent film, and using this mask pattern Etching the organic birefringent film to form a large number of diffraction gratings with periodic irregularities,
Bonding process, spraying an ultraviolet curable adhesive is applied to the transparent substrate over the entire surface by, on the applied ultraviolet-curable adhesive, diameter at 100mm circular, thickness: a 50μm or more organic birefringent film, The film center and the rotation center are placed together, and a third rotation of 1000 to 3000 rpm is applied to the transparent substrate to flatten the surface of the organic birefringent film by the action of centrifugal force , and then the ultraviolet light is applied. A method for producing a polarization separation element, comprising a step of irradiating an ultraviolet ray onto a curable adhesive to cure the ultraviolet curable adhesive. An adhesion process for adhering organic birefringent films having different refractive indexes to the vibration surfaces of different incident light on a transparent substrate, and forming a periodic mask pattern on the organic birefringent film, and using this mask pattern in the method for manufacturing a polarization separating element and a step of plurality forming a diffraction grating by periodic roughness organic birefringent film is etched Te,
In the bonding step, an ultraviolet curable adhesive is applied to the entire surface of the transparent substrate by a spray method , and an organic birefringent film having a diameter of 100 mm and a thickness of 50 μm or more is formed on the applied ultraviolet curable adhesive . The film center and the rotation center are placed together, and the third rotation of 1000 to 3000 rpm is applied to the transparent substrate, and the surface of the organic birefringence film is flattened by the action of centrifugal force . A method for producing a polarization separation element, comprising the step of irradiating the ultraviolet curable adhesive with ultraviolet rays during rotation to cure the ultraviolet curable adhesive. An adhesion process for adhering an organic birefringent film having a different refractive index to a vibration surface with different incident light on a transparent substrate, and a periodic mask pattern is formed on the adhered organic birefringent film. And a method of forming a plurality of diffraction gratings having periodic irregularities by etching an organic birefringent film using
In the bonding process, an ultraviolet curable adhesive is applied to the entire surface of the transparent substrate with a roll coater , and an organic birefringent film having a diameter of 100 mm and a thickness of 50 μm or more is formed on the applied ultraviolet curable adhesive . After placing the film center and the rotation center together , the transparent substrate is subjected to a fourth rotation of 1000 to 3000 rpm, and the surface of the organic birefringent film is flattened by the action of centrifugal force. A method for producing a polarization separation element, comprising a step of irradiating an ultraviolet ray onto a curable adhesive to cure the ultraviolet curable adhesive. An adhesion process for adhering an organic birefringent film having a different refractive index to a vibration surface with different incident light on a transparent substrate, and a periodic mask pattern is formed on the adhered organic birefringent film. And a method of forming a plurality of diffraction gratings having periodic irregularities by etching an organic birefringent film using
In the bonding process, an ultraviolet curable adhesive is applied to the entire surface of the transparent substrate with a roll coater , and an organic birefringent film having a diameter of 100 mm and a thickness of 50 μm or more is formed on the applied ultraviolet curable adhesive . The film center and the rotation center are placed together, and a fourth rotation at 1000 to 3000 rpm is applied to the transparent substrate to flatten the surface of the organic birefringent film by the action of centrifugal force . A method for producing a polarization separation element, comprising: a step of irradiating the ultraviolet curable adhesive with ultraviolet rays during the rotation of the ultraviolet curable adhesive to cure the ultraviolet curable adhesive. In the manufacturing method of the polarization separation element according to any one of claims 1 to 6,
Layer thickness after application of UV curable adhesive: Tc, Layer thickness of the UV curable adhesive after curing by UV irradiation: Tad: Tc> Tad . In the manufacturing method of the polarization separation element according to any one of claims 1 to 7,
  An organic birefringent film provided with a protective film via an adhesive on the surface opposite to the surface to be bonded to the transparent substrate is placed on the ultraviolet curable adhesive layer,
  A method for producing a polarization separation element, wherein the protective film is peeled off from the organic birefringent film after the ultraviolet curable adhesive is cured by ultraviolet irradiation. A polarization beam splitting element manufactured by the manufacturing method according to claim 1. An optical pickup device using the polarization separation element according to claim 9. A spin table holding a transparent substrate;
  A rotation mechanism for rotating the spin table;
  An application mechanism for applying an ultraviolet curable adhesive to the transparent substrate held by the spin table;
  A mounting mechanism for mounting an organic birefringent film on the ultraviolet curable adhesive applied on the transparent substrate;
  An ultraviolet irradiation mechanism for irradiating the ultraviolet curable adhesive with ultraviolet rays through the organic birefringent film,
  An organic birefringent film bonding apparatus for performing a bonding step in the production method according to any one of claims 1 to 8.

Images