JP2004079979A

JP2004079979A - Aligner

Info

Publication number: JP2004079979A
Application number: JP2002269209A
Authority: JP
Inventors: Shigehiko Komatsu; 小松　重彦; Toshihide Ito; 伊藤　利秀; Tetsuya Matsuyama; 松山　哲也; Takeshi Kashiwagi; 柏木　剛; Kenji Ueda; 植田　健治
Original assignee: Dai Nippon Printing Co Ltd
Current assignee: Dai Nippon Printing Co Ltd
Priority date: 2002-08-11
Filing date: 2002-08-11
Publication date: 2004-03-11
Anticipated expiration: 2022-08-11
Also published as: JP4050116B2

Abstract

<P>PROBLEM TO BE SOLVED: To stably keep optical beam by automatically adjusting when collimation fluctuates. <P>SOLUTION: Polarized beam splitters 81X and 83X are disposed on a reference optical path S that runs from an incident point Qin to an ejection point Qout, and the polarized beam penetrating them enter the incident point Qin. The positional information (position of incident point Q10 on a light receiving element 85) and directional information (position of condensing point Q20 on a light receiving element 87) for a slight detection light reflected on a light distribution surface ξ2x are stored in a storage device 91 as reference information. The exposure beam in which a polarization plane of incident light is turned by 90° is made to detour for an optical path D1, and it is guided to the light distribution surface ξ2x from an optical path D3 by a corner reflector 82 to be reflected toward the ejection point Qout. Here, the positional and directional information for the slight detection light having penetrated the light distribution surface ξ2x is detected, and the angle of an optical element 81X and the position of an optical element 82 are so controlled that they approach the reference information in the storage device 91. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は露光装置に関し、特に、感光性材料層上にホログラム像を露光するような場合に用いられる高精度な光軸調節が必要な露光装置に関する。
【０００２】
【従来の技術】
微細なパターンを形成する手法として、所定の露光面に光を照射し、この露光面上に置かれた感光性材料層を部分的に感光させる方法は、半導体装置の製造プロセスや、ホログラム像の形成プロセスなどで広く利用されている。このような露光作業に利用される露光装置は、通常、ビーム源で発生した光ビームを露光面へと誘導し、ビーム径を必要な大きさに拡張した上で、露光面へと照射する構造を有している。光ビームを正しい位置へ導くためには、光ビームを誘導する光学系において、光軸の正しい位置調節が重要である。一般に、光ビームの光軸調節は、反射鏡やプリズムなどの光学素子を組み合わせた装置によって行われ、作業者が目視手作業によって調節を行う場合もあれば、光ビームの位置センサからの出力信号に基く自動制御によって調節が行われる場合もある。
【０００３】
【発明が解決しようとする課題】
通常、ビーム源で発生させた光ビームの断面強度は、ガウシアン分布をとることが多く、ビーム断面の中央部分ほど強度が高くなる。このため、露光面への照射光にも強度分布が生じ、このような強度分布の存在を考慮した上で露光作業が行われている。したがって、露光面へと誘導される光ビームの光軸位置にずれが生じると、露光面上での照射光強度分布に予期せぬずれが発生することになり好ましくない。特に、ホログラム像を露光するような場合、照射光強度分布にわずかな変動が生じても、再生像が不鮮明になるおそれがあり、かなり高精度な光軸調節が必要になる。
【０００４】
このような光軸調節を行うために、これまでに様々な光軸調節装置が用いられている。しかしながら、従来利用されている光軸調節装置は、ビーム源から発せられた光ビームを、露光面上の所定位置に導くための調節を正確に行うことはできるが、ビーム源自体の動作の不安定要素や経年変化などに起因して光軸にずれが生じる現象を防止することはできない。たとえば、ビーム源としてレーザ光源を用いた場合、電源投入後、しばらくの間はレーザ光の出力が安定せず、光軸が不安定な状態が続くことが少なくない。このため、厳密な光軸調節を施しておいたとしても、レーザ光源の出力が安定するまでは、正しい露光を行うことができない。また、レーザ光源の特性は経年変化するため、過去に厳密な光軸調節が施されていたとしても、長期間使用しているうちに、光軸が徐々にずれてくることになる。このような場合、その都度、光軸調節作業を行う必要が生じ、作業者に多大な作業負担を強いることになる。
【０００５】
そこで本発明は、光ビームの光軸調節作業を軽減することができる露光装置を提供することを目的とする。
【０００６】
【課題を解決するための手段】
本発明の要旨は、所定の露光面に対して光を照射することにより、この露光面上に配置された感光材料を露光させるための露光装置を、平面偏光波からなる光ビームを発生させるビーム源と、このビーム源で発生した光ビームを所定の基準光路に沿って露光面へと誘導するビーム誘導手段と、このビーム誘導手段によって誘導される光ビームの径を、露光面の大きさに応じて拡張するビーム径拡張装置と、基準光路上に配置され、光ビームの光軸が前記基準光路上に維持されるように調節する光軸調節装置と、によって構成するようにした点にある。
【０００７】
ここで、光軸調節装置は、本発明に係る露光装置を実現するために開発された新規な光軸調節装置であり、予め、所定の基準光路に沿って光ビームが進行するように光軸調節が行われているときに、入射光がこの基準光路を外れた場合にも、射出光が基準光路に沿った状態を維持できるような自動光軸調節機能を有する装置である。このような光軸調節装置には、後述するように、いくつかの態様が考えられ、どの態様の光軸調節装置を用いるかによって、本発明をいくつかの態様として把握することができる。以下、これら光軸調節装置の各態様を述べる。
【０００８】
（１）　本発明に係る露光装置に用いる光軸調節装置の第１の態様は、図１〜図８を参照して、後述する§１で説明する検出原理に基く光軸調節装置に、§４で説明する改良点を盛り込んだものである。
すなわち、入射点と射出点とを通る基準光路に沿って光ビームが存在するときに、入射点と射出点との間に配置することにより、入射光が基準光路を外れた場合にも、射出光が基準光路に沿った状態を維持するように光軸調節を行う機能をもった光軸調節装置において、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を透過して残りを反射し、第１の偏光面に対して直交する第２の偏光面を有する平面偏光波が照射された場合には、その大部分を反射して残りを透過する光分配面をもち、基準光路の入射点側に配置された入射側ビーム分配手段と、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を透過して残りを反射し、第２の偏光面を有する平面偏光波が照射された場合には、その大部分を反射して残りを透過する光分配面をもち、基準光路の射出点側に配置された射出側ビーム分配手段と、
基準光路に沿って入射した第１の偏光面を有する平面偏光波のうち、入射側ビーム分配手段の光分配面を透過して、射出側ビーム分配手段の光分配面で反射することにより得られる反射光について、射出側ビーム分配手段の光分配面上での位置および向きを測定し、この測定結果を基準情報として取得する基準情報取得手段と、
基準光路に沿って入射した第２の偏光面を有する平面偏光波のうち、入射側ビーム分配手段の光分配面で反射することにより得られる反射光を、基準光路とは異なる迂回光路へ誘導し、この誘導された光ビームの位置および向きを調節して射出側ビーム分配手段の光分配面の射出点側に照射する光路迂回調節手段と、
迂回光路を経由した光ビームに基いて射出側ビーム分配手段の光分配面から得られる透過光について、射出側ビーム分配手段の光分配面上での位置および向きを測定し、この測定結果が基準情報に近付くように、光路迂回調節手段を制御する制御手段と、
を設けるようにしたものである。
【０００９】
（２）　本発明に係る露光装置に用いる光軸調節装置の第２の態様は、図９を参照して、後述する§２で説明する実施形態Ａに係る光軸調節装置に、§４で説明する改良点を盛り込んだものであり、光ビームを迂回光路へ導いた後、まず、角度調節を行い、続いて位置調節を行うような構成をもった光軸調節装置に関するものである。
すなわち、入射点と射出点とを通る基準光路に沿って光ビームが存在するときに、入射点と射出点との間に配置することにより、入射光が基準光路を外れた場合にも、射出光が基準光路に沿った状態を維持するように光軸調節を行う機能をもった光軸調節装置において、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を透過して、残りを所定の迂回光路に向けて反射し、第１の偏光面に対して直交する第２の偏光面を有する平面偏光波が照射された場合には、その大部分を迂回光路に向けた迂回光として反射して、残りを透過する光分配面をもち、基準光路の入射点側に配置された入射側ビーム分配手段と、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を入射光透過光として透過して、残りを入射光反射光として反射し、第２の偏光面を有する平面偏光波が照射された場合には、その大部分を調節光反射光として反射して、残りを調節光透過光として透過する光分配面をもち、基準光路の射出点側に配置された射出側ビーム分配手段と、
迂回光の向きを所定の設定角度だけ変化させて角度調節光として射出する角度調節手段と、
角度調節光を入射し、この角度調節光に対して平行で、所定の設定変位量だけずれた位置を通る位置角度調節光を、射出側ビーム分配手段の光分配面の射出点側に向けて射出することにより、位置角度調節光が、反射した大部分からなる調節光反射光と、透過した残りの部分からなる調節光透過光と、に分配されるようにする位置調節手段と、
入射点に第１の偏光面を有する平面偏光波が照射されているときには、射出側ビーム分配手段の光分配面における入射光反射光の位置および向きを検出し、入射点に第２の偏光面を有する平面偏光波が照射されているときには、射出側ビーム分配手段の光分配面における調節光透過光の位置および向きを検出する検出手段と、
入射点に第１の偏光面を有する平面偏光波が照射されているときに、検出手段によって検出された位置および向きを基準情報として記憶する記憶手段と、
入射点に第２の偏光面を有する平面偏光波が照射されているときに、検出手段によって検出される位置および向きが、記憶手段に記憶されている基準情報の位置および向きに近付くように、角度調節手段による設定角度および位置調節手段による設定変位量を制御する機能をもった制御手段と、
を設けたものである。
【００１０】
（３）　本発明に係る露光装置に用いる光軸調節装置の第３の態様は、図１０を参照して、後述する§２で説明する実施形態Ｂに係る光軸調節装置に、§４で説明する改良点を盛り込んだものであり、光ビームを迂回光路へ導いた後、上述の第２の態様とは逆に、まず、位置調節を行い、続いて角度調節を行うような構成をもった光軸調節装置に関するものである。
すなわち、入射点と射出点とを通る基準光路に沿って光ビームが存在するときに、入射点と射出点との間に配置することにより、入射光が基準光路を外れた場合にも、射出光が基準光路に沿った状態を維持するように光軸調節を行う機能をもった光軸調節装置において、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を透過して、残りを所定の迂回光路に向けて反射し、第１の偏光面に対して直交する第２の偏光面を有する平面偏光波が照射された場合には、その大部分を迂回光路に向けた迂回光として反射して、残りを透過する光分配面をもち、基準光路の入射点側に配置された入射側ビーム分配手段と、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を入射光透過光として透過して、残りを入射光反射光として反射し、第２の偏光面を有する平面偏光波が照射された場合には、その大部分を調節光反射光として反射して、残りを調節光透過光として透過する光分配面をもち、基準光路の射出点側に配置された射出側ビーム分配手段と、
迂回光を入射し、この迂回光に対して平行で、所定の設定変位量だけずれた位置を通る位置調節光を射出する位置調節手段と、
位置調節光の向きを所定の設定角度だけ変化させることにより得られる位置角度調節光を、射出側ビーム分配手段の光分配面の射出点側に向けて射出することにより、位置角度調節光が、反射した大部分からなる調節光反射光と、透過した残りの部分からなる調節光透過光と、に分配されるようにする角度調節手段と、
入射点に第１の偏光面を有する平面偏光波が照射されているときには、射出側ビーム分配手段の光分配面における入射光反射光の位置および向きを検出し、入射点に第２の偏光面を有する平面偏光波が照射されているときには、射出側ビーム分配手段の光分配面における調節光透過光の位置および向きを検出する検出手段と、
入射点に第１の偏光面を有する平面偏光波が照射されているときに、検出手段によって検出された位置および向きを基準情報として記憶する記憶手段と、
入射点に第２の偏光面を有する平面偏光波が照射されているときに、検出手段によって検出される位置および向きが、記憶手段に記憶されている基準情報の位置および向きに近付くように、角度調節手段による設定角度および位置調節手段による設定変位量を制御する機能をもった制御手段と、
を設けたものである。
【００１１】
（４）　本発明に係る露光装置に用いる光軸調節装置の第４の態様は、図１１を参照して、後述する§２で説明する実施形態Ｃに係る光軸調節装置に、§４で説明する改良点を盛り込んだものであり、上述の第２の態様に係る光軸調節装置において、入射側ビーム分配手段に角度調節手段を兼ねさせるようにした点に特徴がある。
すなわち、入射点と射出点とを通る基準光路に沿って光ビームが存在するときに、入射点と射出点との間に配置することにより、入射光が基準光路を外れた場合にも、射出光が基準光路に沿った状態を維持するように光軸調節を行う機能をもった光軸調節装置において、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を透過して、残りを所定の迂回光路に向けて反射し、第１の偏光面に対して直交する第２の偏光面を有する平面偏光波が照射された場合には、その大部分を迂回光路に向けた迂回光として反射して、残りを透過する光分配面をもち、基準光路の入射点側に配置され、かつ、迂回光の向きを所定の設定角度だけ変化させて角度調節光として射出する角度調節機能をもった入射側ビーム分配手段と、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を入射光透過光として透過して、残りを入射光反射光として反射し、第２の偏光面を有する平面偏光波が照射された場合には、その大部分を調節光反射光として反射して、残りを調節光透過光として透過する光分配面をもち、基準光路の射出点側に配置された射出側ビーム分配手段と、
角度調節光を入射し、この角度調節光に対して平行で、所定の設定変位量だけずれた位置を通る位置角度調節光を、射出側ビーム分配手段の光分配面の射出点側に向けて射出することにより、位置角度調節光が、反射した大部分からなる調節光反射光と、透過した残りの部分からなる調節光透過光と、に分配されるようにする位置調節手段と、
入射点に第１の偏光面を有する平面偏光波が照射されているときには、射出側ビーム分配手段の光分配面における入射光反射光の位置および向きを検出し、入射点に第２の偏光面を有する平面偏光波が照射されているときには、射出側ビーム分配手段の光分配面における調節光透過光の位置および向きを検出する検出手段と、
入射点に第１の偏光面を有する平面偏光波が照射されているときに、検出手段によって検出された位置および向きを基準情報として記憶する記憶手段と、
入射点に第２の偏光面を有する平面偏光波が照射されているときに、検出手段によって検出される位置および向きが、記憶手段に記憶されている基準情報の位置および向きに近付くように、入射側ビーム分配手段による設定角度および位置調節手段による設定変位量を制御する機能をもった制御手段と、
を設けたものである。
【００１２】
（５）　本発明に係る露光装置に用いる光軸調節装置の第５の態様は、図１２を参照して、後述する§２で説明する実施形態Ｄに係る光軸調節装置に、§４で説明する改良点を盛り込んだものであり、上述の第３の態様に係る光軸調節装置において、入射側ビーム分配手段に位置調節手段を兼ねさせるようにした点に特徴がある。
すなわち、入射点と射出点とを通る基準光路に沿って光ビームが存在するときに、入射点と射出点との間に配置することにより、入射光が基準光路を外れた場合にも、射出光が基準光路に沿った状態を維持するように光軸調節を行う機能をもった光軸調節装置において、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を透過して、残りを所定の迂回光路に向けて反射し、第１の偏光面に対して直交する第２の偏光面を有する平面偏光波が照射された場合には、その大部分を迂回光路に向けた迂回光として反射して、残りを透過する光分配面をもち、基準光路の入射点側に配置され、かつ、迂回光を所定の設定変位量だけ平行移動させて位置調節光として射出する位置調節機能をもった入射側ビーム分配手段と、
第１の偏光面を有する平面偏光波が照射された場合には、その大部分を入射光透過光として透過して、残りを入射光反射光として反射し、第２の偏光面を有する平面偏光波が照射された場合には、その大部分を調節光反射光として反射して、残りを調節光透過光として透過する光分配面をもち、基準光路の射出点側に配置された射出側ビーム分配手段と、
位置調節光の向きを所定の設定角度だけ変化させることにより得られる位置角度調節光を、射出側ビーム分配手段の光分配面の射出点側に向けて射出することにより、位置角度調節光が、反射した大部分からなる調節光反射光と、透過した残りの部分からなる調節光透過光と、に分配されるようにする角度調節手段と、
入射点に第１の偏光面を有する平面偏光波が照射されているときには、射出側ビーム分配手段の光分配面における入射光反射光の位置および向きを検出し、入射点に第２の偏光面を有する平面偏光波が照射されているときには、射出側ビーム分配手段の光分配面における調節光透過光の位置および向きを検出する検出手段と、
入射点に第１の偏光面を有する平面偏光波が照射されているときに、検出手段によって検出された位置および向きを基準情報として記憶する記憶手段と、
入射点に第２の偏光面を有する平面偏光波が照射されているときに、検出手段によって検出される位置および向きが、記憶手段に記憶されている基準情報の位置および向きに近付くように、入射側ビーム分配手段による設定変位量および角度調節手段による設定角度を制御する機能をもった制御手段と、
を設けたものである。
【００１３】
（６）　本発明の第６の態様は、上述の第１〜第５の態様に係る光軸調節装置を用いた露光装置において、
入射側ビーム分配手段の光分配面を透過して射出側ビーム分配手段の光分配面へと向かう光を、必要に応じて遮断することができる第１の遮断手段と、
入射側ビーム分配手段の光分配面で反射して迂回光路を進む光を、必要に応じて遮断することができる第２の遮断手段と、
を更に設けるようにしたものである。
【００１４】
（７）　本発明の第７の態様は、上述の第２〜第５の態様に係る光軸調節装置を用いた露光装置において、
検出手段を、射出側ビーム分配手段の光分配面からの検出用光ビームを２つのビームに分配する検出用ビーム分配器と、分配された第１のビームに基いて位置を検出する位置検出器と、分配された第２のビームに基いて向きを検出する向き検出器と、によって構成したものである。
【００１５】
（８）　本発明の第８の態様は、上述の第７の態様に係る光軸調節装置を用いた露光装置において、
位置検出器を、所定の受光面上へのビームの照射位置を検出する受光素子によって構成したものである。
【００１６】
（９）　本発明の第９の態様は、上述の第７の態様に係る光軸調節装置を用いた露光装置において、
向き検出器を、平行光線を所定の焦点に集光する集光レンズと、この集光レンズに対して焦点距離だけ離れた位置に配置された受光面を有しこの受光面上の集光位置を検出する受光素子と、によって構成したものである。
【００１７】
（１０）　本発明の第１０の態様は、上述の第１〜第９の態様に係る光軸調節装置を用いた露光装置において、
それぞれ各色成分ごとの光ビームを発生させる複数のビーム源と、
前記各色成分ごとの光ビームを露光面へと誘導する過程で、これら各光ビームを合成するビーム合成手段と、
各色成分ごとの基準光路上に配置された各色成分ごとの光軸調節装置と、
を設けるようにしたものである。
【００１８】
【発明の実施の形態】
以下、本発明を図示する実施形態に基いて説明する。
【００１９】
本発明に係る露光装置の特徴は、ビーム源から露光面へと向かう光ビームの基準光路上に、ユニークな光軸調節装置を組み込むことにより、光ビームの光軸が自動調節されるようにした点にある。このユニークな光軸調節装置の基本構成は、特願２００１−０２８３５４号明細書に開示されている。そこで、§１〜§３において、このユニークな光軸調節装置の構成および動作について詳述することにする。具体的には、まず、§１においてユニークな光軸調節装置の基本原理を説明し、§２においてこの原理に基づく基本的な実施形態を説明し、§３においてより具体的な実施形態を説明する。
【００２０】
更に、§４では、このユニークな光軸調節装置に偏光ビームスプリッターを用いることによる改良点を述べ、最後の§５において、この改良された光軸調節装置を用いた露光装置の全体構成を説明することにする。
【００２１】
＜＜＜　§１．光軸調節装置の基本原理　＞＞＞
はじめに、本発明に係る露光装置に用いられるユニークな光軸調節装置の基本原理を簡単に説明する。この光軸調節装置の主眼は、光軸調節が既に完了している光学系について、動作の不安定要素や経年変化などに起因して光軸にずれが生じる現象を防止することにあり、既存の光路を通る光ビームを安定維持させることにある。
【００２２】
いま、図１に示すように、ビーム源１００からターゲット２００の目標点Ｑに対して、光ビームを照射する場合を考える。ここで、ビーム源１００は、光ビームを発生させる光源と、この光ビームに対する光軸調節を行う光学系（光軸調節装置）とを内蔵しているものとし、光ビームに対する光軸調節は、この内蔵の光学系を調節することにより行われるものとする。このように、従来の一般的な光軸調節装置は、光ビームの照準を所定の目標点に合致させるための積極的な位置調節を行うことを目的としており、このビーム源１００に内蔵された光軸調節装置を利用した光軸調節作業により、光ビームをターゲット２００上の目標点Ｑに到達させることが可能になる。このような光軸調節作業が完了すると、ビーム源１００から発せられた光ビームは、入射点Ｑｉｎから射出点Ｑｏｕｔへ向かう基準光路Ｓ（図では、一点鎖線で示す）に沿って進行し、目標点Ｑに到達する。
【００２３】
この図１に示すように、一旦、光軸調節作業が完了してしまえば、理論的には、ビーム源１００から照射された光ビームは、常に、基準光路Ｓ上を通って目標点Ｑへと導かれることになるが、実際には、ビーム源１００自身の動作の不安定要素や経年変化などに起因して、調節済みの光軸にずれが生じる現象が発生する。たとえば、長期間にわたって使用していると、ビーム源１００に対する振動などの影響により、ビーム源１００自身の取付位置に変位が生じることがある。すると図２に示すように、ビーム源１００から発せられた光ビームＢは、入射点Ｑｉｎの位置に正しく入射しなくなり、基準光路Ｓから外れたものとなる。このため、光ビームＢは、ターゲット２００上の目標点Ｑから外れてしまう。もちろん、ビーム源１００自身の取付位置に変位が生じていなくても、ビーム源１００の内部の光学系を構成する個々の光学素子に位置変位が生じても同様の結果となる。また、光学系自身に変位が生じていなくても、光源に固有の不安定要素に基いて、光ビームＢに変動が生じる可能性もある。たとえば、レーザ光源などを用いた場合、起動直後のしばらくの間、動作が不安定になる場合も少なくない。また、電源電圧の変動などの外乱により、光ビームＢに変動が生じることもある。
【００２４】
本発明で利用される光軸調節装置の狙いは、図１に示す例のように、入射点Ｑｉｎから射出点Ｑｏｕｔへ向かう所定の基準光路Ｓが既に設定されており、この基準光路Ｓに沿って進む光ビームが存在するときに、何らかの事情で将来、入射光がこの基準光路Ｓを外れた場合にも、射出光が基準光路Ｓに沿った状態を維持することができるような自動光軸調節を行うことにある。別言すれば、図３に示すように、既に所定の基準光路Ｓが設定されている状態において、光軸調節装置３００を、入射点Ｑｉｎと射出点Ｑｏｕｔとの間に挿入して設置しておくことにより、将来、何らかの事情で光軸調節装置３００への入射光に変動が生じた場合にも、光軸調節装置３００からの射出光をもとの状態に維持することができるようにすることが目的である。すなわち、ビーム源１００からの光ビームに対して、基準光路Ｓに沿った正しい光軸調節がなされている状態において、図３に示すように、本発明に係る光軸調節装置３００を基準光路Ｓ上に挿入しておけば、図４に示すように、ビーム源１００側の光軸に変動が生じ、光ビームＢの光軸調節装置３００に対する入射条件が変化したとしても、光軸調節装置３００からの射出光は以前と同じ条件を維持するような自動的な光軸調節が行われることになる。以下、このような自動光軸調節を行うための基本原理を説明する。
【００２５】
いま、図５に示すように、入射点Ｑｉｎから射出点Ｑｏｕｔへ向けて基準光路Ｓが設定されている場合に、この基準光路Ｓ上に光分配面ξを配置したとする。この光分配面ξは、照射された光の一部を反射、一部を透過させる性質をもった面であり、ここでは、ハーフミラーなどの光分配面ξを有するビーム分配手段を、基準光路Ｓ上に配置した場合を考える。このようなビーム分配手段を基準光路Ｓ上に配置すると、入射点Ｑｉｎに、基準光路Ｓに沿って入射してきた光ビームＢは、このビーム分配手段によって２つの光ビームに分配されることになる。すなわち、一部は光分配面ξをそのまま透過して透過光Ｂｔとなり、一部は光分配面ξで反射して反射光Ｂｒとなる。このとき、透過光Ｂｔは、基準光路Ｓに沿って光分配面ξ上の位置Ｐ０を透過して射出点Ｑｏｕｔから射出する光になるが、反射光Ｂｒは、光分配面ξ上の位置Ｐ０において向きを変えて図の上方へと向かう光となる。ここで、光分配面ξ上の位置Ｐ０に立てた法線をＮとすれば、光ビームＢの入射角と反射角とは等しく、いずれも角度α０になる。
【００２６】
そこで、このときに得られる反射光Ｂｒについて、光分配面ξ上での位置Ｐ０および向き（たとえば、反射角α０）を測定し、この測定結果を基準情報として取得しておく。図示の基準情報取得手段１は、このような基準情報Ｉ（Ｐ０，α０）を取得する機能をもった構成要素（具体的な構成例については後述する）である。このような基準情報の取得作業は、光ビームＢが、基準光路Ｓに沿って正しく光軸調整されている状態（別言すれば、透過光Ｂｔが基準光路Ｓに沿って、所定の目標点にまで到達する状態）で行っておく必要がある。
【００２７】
このユニークな光軸調節装置３００を機能させる上では、図６に示すように、この系に、光路迂回調節手段２を追加する必要がある。図では便宜上、この光路迂回調節手段２を単なるブロックとして示すが、実際には、この光路迂回調節手段２は複数の光学素子によって構成される。この光路迂回調節手段２は、必要に応じて、入射光の光ビームＢを基準光路Ｓとは異なる迂回光路Ｄへ誘導し、この誘導された光ビームの位置および向きを調節して光分配面ξへ照射する機能を有する。図示の例では、この迂回光路Ｄは、光路Ｄ１，Ｄ２，Ｄ３によって構成されており、いずれも二点鎖線で示してある。迂回光路Ｄへ誘導された光ビームに対しては、光路迂回調節手段２によって、位置および向きの調節が行われる。ここで、「位置の調節」とは、光ビームの光路を所定の設定変位量だけ平行移動させる処理であり、「向きの調節」とは、光ビームの光路を所定の設定角度だけ変化させる処理である。もちろん、迂回光路Ｄ上で、このような位置および向きの調節が行われると、迂回光路Ｄ自身が変化することになる。したがって、本願における「迂回光路Ｄ」とは、ある定まった特定の経路を意味するわけではなく、位置および向きの調節処理によって様々に変化する不定形態の経路を意味している。なお、この「位置の調節」および「向きの調節」については、後に具体例を挙げて詳述する。
【００２８】
こうして、迂回光路Ｄを経由した光ビームは、光分配面ξに照射されることになるが、光分配面ξのどの位置にどのような向きで照射されるかは、迂回光路Ｄ上において施された位置および向きの調節次第である。ここでは、迂回光路Ｄにおいて行われた位置および向きの調節の結果、図６の光路Ｄ３に沿った光ビームが、光分配面ξ上の位置Ｐに照射されたものとしよう。前述したように、光分配面ξは、照射された光の一部を反射、一部を透過させる性質をもった面であり、迂回光路Ｄを経由した光ビームは、この光分配面ξによって２つの光ビームに分配されることになる。すなわち、一部は光分配面ξをそのまま透過して透過光Ｂｔとなり、一部は光分配面ξで反射して反射光Ｂｒとなる。このとき、位置Ｐに立てた法線をＮとすれば、透過光Ｂｔと法線Ｎとのなす角と、反射光Ｂｒと法線Ｎとのなす角とは、互いに等しい角度αになる（もちろん、光路Ｄ３と法線Ｎとのなす角も角度αになる）。
【００２９】
続いて、このときに得られる透過光Ｂｔについて、光分配面ξ上での位置Ｐおよび向き（たとえば、反射角α）を測定する。もちろん、この測定結果は、通常、図５に示す基準情報取得手段１によって予め取得された基準情報Ｉ（Ｐ０，α０）とは異なっている（図５と図６とを比較すればわかるように、位置Ｐと位置Ｐ０とは一致せず、角度αと角度α０とは一致しない）。そこで、この測定結果が基準情報Ｉ（Ｐ０，α０）に近付くように、光路迂回調節手段２を制御することにする。図６に示す制御手段３は、透過光Ｂｔについて、光分配面ξ上での位置および向きを測定し、この測定結果が基準情報Ｉ（Ｐ０，α０）に近付くように、光路迂回調節手段２を制御する機能をもった構成要素である。前述したように、光路迂回調節手段２は、迂回光路Ｄ上において、光ビームの位置および向きを調節する機能を有しているので、制御手段３による測定結果が基準情報Ｉ（Ｐ０，α０）に一致するようなフィードバック制御を行うことが可能である。
【００３０】
制御手段３によるフィードバック制御により、測定結果が基準情報Ｉ（Ｐ０，α０）に完全に一致するところまで到達した状態を図７に示す。光路迂回調節手段２によって導かれる迂回経路Ｄａは、光路Ｄ１ａ，Ｄ２ａ，Ｄ３ａから構成されており、図６に示す迂回光路Ｄとは異なっている。その結果、迂回光路Ｄａを経由した光ビームの光分配面ξへの照射位置Ｐは、図５に示す位置Ｐ０に一致した状態となり、透過光Ｂｔについての光分配面ξ上での位置Ｐおよび向き（たとえば、反射角α）は、基準情報Ｉ（Ｐ０，α０）に完全に一致する（Ｐ＝Ｐ０，α＝α０）。図５と図７とを比較してみれば、図５における反射光Ｂｒが図７における透過光Ｂｔと完全に一致し、図５における透過光Ｂｔが図７における反射光Ｂｒに完全に一致していることがわかる。ここで重要な点は、図５に示す反射光Ｂｒおよび透過光Ｂｔは、基準光路Ｓ上を経た光ビームを分配することによって得られた光ビームであるのに対し、図７に示す透過光Ｂｔおよび反射光Ｂｒは、迂回光路Ｄａ上を経た光ビームを分配することによって得られた光ビームである、という点である。ここで、図５に示す透過光Ｂｔが、射出点Ｑｏｕｔから基準光路Ｓに沿った光ビームとして射出されるのと全く同様に、図７に示す反射光Ｂｒが、射出点Ｑｏｕｔから基準光路Ｓに沿った光ビームとして射出されることを考えれば、光路迂回調節手段２による迂回が行われているにもかかわらず、「射出点Ｑｏｕｔから基準光路Ｓに沿った射出光が得られる」という点に関しては、図７の状態は図５の状態に比べて何ら変化がないことになる。
【００３１】
これは、図１に示すように、所定の基準光路Ｓが設定されている状態において、図３に示すように、この基準光路Ｓ上に本発明に係る光軸調節装置３００を挿入し、この光軸調節装置３００の内部において、入射してきた光ビームを光路迂回調節手段２によって迂回光路へと迂回させるようにしても、光軸調節装置３００から基準光路Ｓに沿って目標点Ｑへ向かう光ビームを射出することが可能であることを意味している。より具体的に手順を説明すれば、図３に示すように、光軸調節装置３００を基準光路Ｓ上に挿入したら、まず、光路迂回調節手段２による迂回を行わせずに、図５に示すように、入射してきた光ビームＢをそのまま光分配面ξへと導き、基準情報取得手段１によって基準情報Ｉ（Ｐ０，α０）を取得する作業を行う。続いて、光路迂回調節手段２による迂回を行わせ、入射してきた光ビームＢを迂回光路Ｄへと導く。このように、入射してきた光ビームＢの経路を迂回光路Ｄに切り換えた当初には、図６に示すように、光分配面ξからの反射光Ｂｒは基準光路Ｓに沿った光ビームにはならないため、光軸調節装置３００から射出される光ビームは、基準光路Ｓから外れた状態になる。しかしながら、上述したフィードバック制御が行われるため、やがて迂回光路Ｄは図７に示すような迂回光路Ｄａへと変遷し、光分配面ξからの反射光Ｂｒは基準光路Ｓに沿った光ビームになり、光軸調節装置３００から射出される光ビームは、基準光路Ｓに沿ったものになる。
【００３２】
結局、図３に示すように、本発明に係る光軸調節装置３００を、既存の基準光路Ｓ上に挿入すると、光ビームの経路を迂回光路Ｄへ切り換えた当初は、ビーム源１００からの光ビームがターゲット２００上の目標点Ｑから外れた状態になるが、フィードバック制御系が安定した状態になれば、光ビームはもとどおり目標点Ｑに照射された状態に戻る。したがって、本発明に係る光軸調節装置３００を、既に光軸調節が完了している既存の基準光路Ｓに挿入したとしても、一時的な光軸の変動は生じるものの、すぐにもとの状態に復帰するので、ビーム源１００からターゲット２００に至る全体の系は、そのまま使用することができる。しかも、光軸調節装置３００を挿入することにより、将来、何らかの事情で光軸調節装置３００への入射光に変動が生じた場合にも、光軸調節装置３００からの射出光をもとの状態に維持する自動光軸調節が行われることになる。すなわち、図４に示すように、ビーム源１００側の光軸に変動が生じ、光ビームＢの光軸調節装置３００に対する入射条件が変化したとしても、光軸調節装置３００からの射出光は以前と同じ条件を維持するような自動的な光軸調節が行われることになる。
【００３３】
これは、次のようなフィードバック制御が行われるためである。たとえば、本来は、図７に示すように、入射点Ｑｉｎに対して基準光路Ｓに沿った光ビームＢが与えられるべきであったのに、何らかの事情で、図８に示すように、光ビームＢの入射条件が変動してしまったとしよう。このような変動が生じると、制御手段３によって測定される透過光Ｂｔの位置Ｐおよび向きαの測定結果が、予め取得しておいた基準情報Ｉ（Ｐ０，α０）に一致しなくなるので、両者を一致させる方向にフィードバックが働くことになる。その結果、図７に示す迂回光路Ｄａは、図８に示す迂回光路Ｄｂ（光路Ｄ１ｂ，Ｄ２ｂ，Ｄ３ｂから構成されている）のように変更され、再び、透過光Ｂｔについての光分配面ξ上での位置Ｐおよび向き（たとえば、反射角α）が、基準情報Ｉ（Ｐ０，α０）に完全に一致するようになる（Ｐ＝Ｐ０，α＝α０）。かくして、光ビームＢの入射条件が変動してしまったとしても、フィードバック制御系が安定した状態になれば、光分配面ξからの反射光Ｂｒは、再び、基準光路Ｓに沿って射出される状態に戻ることになる。
【００３４】
以上が、本発明に用いられる光軸調節装置の基本原理であり、このような基本原理により、既存の光路を通る光ビームを安定維持させる機能が実現できる。
【００３５】
なお、これまでの原理説明は、二次元平面上の図面を用いた説明であったため、位置や向きの自由度を制限した説明を行ったが、実際には、光ビームの光路は三次元空間内に形成され、当然、位置や向きの自由度は、この三次元空間に応じたものになる。たとえば、図６に示す例では、光分配面ξは一次元の線分として示され、この光分配面ξ上の位置Ｐは、この線分上を移動する一次元の自由度しかもたないように描かれているが、実際には、位置Ｐは、図の紙面に垂直な方向にも移動する二次元の自由度を有していることになる。同様に、図６に示す例では、各光ビームの向きを、二次元平面上における角度αで表現しているが、実際には、各光ビームの向きはこの二次元平面上に限定されるわけではなく、三次元空間内の任意の方向を向くことができるので、角度で表現した場合には、たとえば、ＸＺ平面に対する角度αｘｙとＹＺ平面に対する角度αｙｚのような２通りの角度パラメータで表現されることになる。したがって、光路迂回調節手段２は、光ビームの位置および向きを、三次元空間内の自由度をもって調節する機能を有し、制御手段３は、このような自由度を考慮したフィードバック制御を行う機能を有する。
【００３６】
＜＜＜　§２．基本的な実施形態　＞＞＞
続いて、本発明に係る露光装置で用いられる光軸調節装置の基本的な実施形態を４通りについて述べることにする。
（Ａ）　図９は、基本的な実施形態Ａに係る光軸調節装置の構成を示すブロック図である。この光軸調節装置の特徴は、光ビームを迂回光路へ導いた後、まず、角度調節（向きの調節）を行い、続いて位置調節を行う点にある。
【００３７】
既に§１で述べたように、この光軸調節装置は、入射点Ｑｉｎと射出点Ｑｏｕｔとを通る基準光路Ｓに沿って光ビームが存在するときに、入射点Ｑｉｎと射出点Ｑｏｕｔとの間に配置することにより、入射光が基準光路を外れた場合にも、射出光が基準光路Ｓに沿った状態を維持するように光軸調節を行う機能を有する。この光軸調節装置の基本構成要素は、図示のとおり、ビーム分配手段１０、光路切換手段２０、角度調節手段３０、位置調節手段４０、検出手段５０、記憶手段６０、制御手段７０である。§１の基本原理で説明した各構成要素との関係では、ビーム分配手段１０は、いわゆるビームスプリッターによって構成され、基準光路Ｓ上に光分配面ξを配置する機能を果たし、光路切換手段２０、角度調節手段３０、位置調節手段４０は、光路迂回調節手段２としての機能を果たす。また、検出手段５０、記憶手段６０、制御手段７０は、基準情報取得手段１および制御手段３としての機能を果たす。以下、これら各手段の機能を個々に説明する。なお、図において一点鎖線は基準光路Ｓ、二点鎖線は迂回光路、破線は検出用光路、実線は電気信号の経路を示す。
【００３８】
まず、ビーム分配手段１０は、光分配面ξを基準光路Ｓ（図の一点鎖線）上に配置する役割を果たす。光分配面ξは、既に述べたように、照射された光の一部を反射、一部を透過させる機能をもった面であり、たとえば、図の右側から入射してきた入射光Ｌ１がこのビーム分配手段１０に照射されると、光分配面ξにおいて、透過光と反射光とに分けられる。ここでは、入射光Ｌ１に基いて生じた透過光（図においてビーム分配手段１０から左方向に射出される光）を入射光透過光Ｌ２と呼び、入射光Ｌ１に基いて生じた反射光（図においてビーム分配手段１０から上方向に射出される光）を入射光反射光Ｌ３と呼ぶことにする。
【００３９】
光路切換手段２０は、入射点Ｑｉｎとビーム分配手段１０との間に配置され、入射光Ｌ１の光路を切り換えるための構成要素である。すなわち、光路切換手段２０は、入射光Ｌ１をそのまま透過させてビーム分配手段１０へと導く第１の機能と、入射光Ｌ１の向きを所定の迂回光路（図の二点鎖線）に向けて変化させ、迂回光Ｌ４として射出する第２の機能と、の２つの機能を選択的に実行することができる。角度調節手段３０は、この迂回光Ｌ４の向きを所定の設定角度θだけ変化させて角度調節光Ｌ５として射出する機能を果たし、位置調節手段４０は、この角度調節光Ｌ５を入射し、この角度調節光Ｌ５に対して平行で（図示の例の場合、平行で進行方向が逆向き）、所定の設定変位量ｄだけずれた位置を通る位置角度調節光Ｌ６（任意の設定変位量ｄに基く位置調節と、任意の設定角度θに基く角度調節との双方が施された光）を、ビーム分配手段１０の光分配面ξの射出点Ｑｏｕｔ側に向けて射出する機能を果たす。
【００４０】
ビーム分配手段１０に照射された位置角度調節光Ｌ６は、光分配面ξによって透過光と反射光とに分配される。ここでは、位置角度調節光Ｌ６に基いて生じた透過光（図においてビーム分配手段１０から上方向に射出される光）を調節光透過光Ｌ７と呼び、位置角度調節光Ｌ６に基いて生じた反射光（図においてビーム分配手段１０から左方向に射出される光）を調節光反射光Ｌ８と呼ぶことにする。結局、光路切換手段２０が第１の機能を実行しているときには、ビーム分配手段１０から入射光透過光Ｌ２および入射光反射光Ｌ３が得られ、光路切換手段２０が第２の機能を実行しているときには、ビーム分配手段１０から調節光透過光Ｌ７および調節光反射光Ｌ８が得られることになる。
【００４１】
検出手段５０は、このビーム分配手段１０から図の上方へと進行する入射光反射光Ｌ３または調節光透過光Ｌ７の位置および向きを検出する機能を有する。別言すれば、検出手段５０は、光路切換手段２０が第１の機能を実行しているときには、光分配面ξにおける入射光反射光Ｌ３の位置および向きを検出し、光路切換手段２０が第２の機能を実行しているときには、光分配面ξにおける調節光透過光Ｌ７の位置および向きを検出する。
【００４２】
記憶手段６０は、§１で述べた基準情報を記憶する構成要素である。すなわち、光路切換手段２０が第１の機能を実行しているときに、検出手段５０によって検出された位置および向き（入射光反射光Ｌ３の位置および向き）を基準情報として記憶する機能を果たす。もちろん、このような基準情報を記憶する処理は、入射光Ｌ１が基準光路Ｓに沿って正しく入射してきており、ビーム分配手段１０から射出される入射光透過光Ｌ２が、ターゲット上の目標点Ｑに正しく照射されている状態で行うことになる。
【００４３】
制御手段７０は、光路切換手段２０が第２の機能を実行しているときに、検出手段５０によって検出される位置および向き（図示の例の場合、調節光透過光Ｌ７の位置および向き）が、記憶手段６０に記憶されている基準情報の位置および向きに近付くように、角度調節手段３０による設定角度θおよび位置調節手段４０による設定変位量ｄを制御する機能を果たす。§１で述べたように、このような制御はフィードバック制御となり、制御系が安定した状態になった時点で、検出手段５０によって検出される位置および向きが、基準情報の位置および向きに一致することになり、ビーム分配手段１０からターゲットに向けて射出される調節光反射光Ｌ８は、基準光路Ｓに沿った光ビームとなる。もちろん、このようなフィードバック制御は、入射光Ｌ１の入射条件に変動が生じた場合にも有効であり、入射光Ｌ１が基準光路Ｓから外れた状態で入射してくるようになったとしても、制御手段７０によるフィードバック制御により、ビーム分配手段１０から射出される調節光反射光Ｌ８は、基準光路Ｓに沿った光ビームとなるように調節される。
【００４４】
なお、このようなフィードバック制御では、制御対象となる量が、設定角度θ（向きの制御）と設定変位量ｄ（位置の制御）との２つになるので、これら２つの量を同時に制御しようとすると、制御動作が複雑になる。そこで、実用上は、設定角度θの制御と設定変位量ｄの制御とを、交互に繰り返して行うようにし、検出手段５０による測定結果が記憶手段６０に記憶されている基準情報に徐々に近付いてゆくようにするのが好ましい。
【００４５】
（Ｂ）　図１０は、基本的な実施形態Ｂに係る光軸調節装置の構成を示すブロック図である。この実施形態Ｂの特徴は、光ビームを迂回光路へ導いた後、まず、位置調節を行い、続いて角度調節（向きの調節）を行う点にある。図９に示す実施形態Ａとの相違点は、角度調節と位置調節との実施順が逆転しているだけであり、具体的な構成の相違は、角度調節手段３０と位置調節手段４０との位置関係が逆転している点だけである。
【００４６】
すなわち、光路切換手段２０の第２の機能により、入射光Ｌ１が迂回光路へと導かれ、迂回光Ｌ４として射出されたら、まず、位置調節手段４０による位置調節が行われる。この位置調節の結果、迂回光Ｌ４は、所定の設定変位量ｄだけずれた位置を通る位置調節光Ｌ９（図示の例の場合、迂回光Ｌ４と位置調節光Ｌ９とは平行で進行方向も同じ）として射出される。続いて、この位置調節光Ｌ９に対して、角度調節手段３０による設定角度θの調節が行われ、位置角度調節光Ｌ６が得られる。この位置角度調節光Ｌ６が、ビーム分配手段１０へと照射された後に関与する各構成要素については、図９に示す実施形態Ａと全く同様であり、また、この光軸調節装置の動作も、図９に示す実施形態Ａの動作と全く同様である。
【００４７】
（Ｃ）　図１１は、基本的な実施形態Ｃに係る光軸調節装置の構成を示すブロック図である。この実施形態Ｃの特徴は、図９に示す実施形態Ａに係る光軸調節装置において、光路切換手段２０と角度調節手段３０とを、その双方を兼ねる機能をもった光路切換角度調節手段３５に置き換えた点にある。光路切換角度調節手段３５は、入射点Ｑｉｎとビーム分配手段１０との間に配置され、入射光Ｌ１を透過させる第１の機能と、入射光Ｌ１の向きを所定の設定角度θだけ変化させることにより得られる角度調節光Ｌ５を、所定の迂回光路に沿って射出する第２の機能と、の２つの機能を選択的に実行することができる。この第２の機能を実行する際の設定角度θは、制御手段７０による制御対象となり、この設定角度θを制御することにより、角度調節光Ｌ５を、たとえば図に破線で示したＬ５^＊のような向きに調節することが可能である。その他の構成要素や動作については、図９に示す実施形態Ａと同様である。
【００４８】
（Ｄ）　図１２は、基本的な実施形態Ｄに係る光軸調節装置の構成を示すブロック図である。この実施形態Ｄの特徴は、図１０に示す実施形態Ｂに係る光軸調節装置において、光路切換手段２０と位置調節手段４０とを、その双方を兼ねる機能をもった光路切換位置調節手段４５に置き換えた点にある。光路切換位置調節手段４５は、入射点Ｑｉｎとビーム分配手段１０との間に配置され、入射光Ｌ１を透過させる第１の機能と、入射光Ｌ１の向きを変えることによって得られる迂回光Ｌ４の位置を所定の設定変位量ｄだけ変化させることにより得られる位置調節光Ｌ９を、所定の迂回光路に沿って射出する第２の機能と、の２つの機能を選択的に実行することができる。この第２の機能を実行する際の設定変位量ｄは、制御手段７０による制御対象となり、この設定変位量ｄを制御することにより、位置調節光Ｌ９を、たとえば図に破線で示したＬ９^＊のような位置に調節することが可能である。図１２において、光路切換位置調節手段４５を示すブロックから下方に向かう３本の二点鎖線のうち、迂回光Ｌ４が通る二点鎖線は、入射光Ｌ１の進行方向を単に曲げた光路に相当し（ｄ＝０の場合）、その左右に位置する二点鎖線は、所定の設定変位量だけ平行移動させた光路に相当する。この光軸調節装置のその他の構成要素や動作については、図１０に示す実施形態Ｂと同様である。なお、迂回光Ｌ４を所定の設定変位量ｄだけ平行移動する代わりに、入射光Ｌ１を直接、図示の設定変位量ｄｄだけ平行移動することにより、左水平方向を向いた位置調節光Ｌ９を得るようにしてもかまわない。
【００４９】
＜＜＜　§３．具体的な実施例　＞＞＞
上述の§２では、光軸調節装置の基本的な実施形態を４通り説明したが、ここでは、これら４通りのうちの実施形態Ｃについて、より具体的な実施例を説明し、更に、その問題点についての指摘を行うことにする。
【００５０】
図１３は、上述の実施形態Ｃについての一実施例を示す図（光学的要素については平面図、電気的要素および機械的要素についてはブロック図として示す）である。光反射素子８１は、入射光を反射させることができる反射面ηを有する光学素子であり、この反射面ηで反射した光ビームは、図に二点鎖線で示す光路Ｄ１を経て、コーナリフレクタ８２へと入射し、更に、光路Ｄ２，Ｄ３を経て、ビーム分配器８３へと入射する。ビーム分配器８３は、§２で述べたビーム分配手段１０として機能する光学素子であり、ハーフミラーなどからなる光分配面ξを有している。また、検出用ビーム分配器８４も、ハーフミラーなどからなる光分配面μを有しており、ビーム分配器８３の光分配面ξから図の上方に向かって進行してきた検出用光ビームを２つのビームに分配する機能を有する。光分配面μによって分配された第１のビーム（この例の場合、透過光）は、受光素子８５によって受光され、分配された第２のビーム（この例の場合、反射光）は、集光レンズ８６を経て受光素子８７によって受光される。受光素子８５および受光素子８７は、二次元平面状の受光面を有し、この受光面上への光ビームの照射位置を示す検出信号を発生させる機能を有している。具体的には、ＰＳＤ（Ｐｏｓｉｔｉｏｎ　Ｓｅｎｓｉｎｇ　Ｄｅｔｅｃｔｏｒ）素子やＣＣＤ（Ｃｈａｒｇｅ　Ｃｏｕｐｌｅｄ　Ｄｅｖｉｃｅ）素子を用いて構成すればよい。集光レンズ８６は、平行光線を所定の焦点に集光するレンズであり、受光素子８７の受光面は、この集光レンズ８６からその焦点距離だけ離れた位置に配置されている。したがって、受光素子８７は、受光面上に集光された位置を検出する機能を有する。
【００５１】
後述するように、受光素子８５は、光分配面ξからの検出用光ビームについての位置を検出する位置検出器として機能し、集光レンズ８６および受光素子８７は、光分配面ξからの検出用光ビームについての向きを検出する向き検出器として機能する。結局、検出用ビーム分配器８４、受光素子８５、集光レンズ８６、受光素子８７は、図１１に示す実施形態Ｃにおける検出手段５０に対応する構成要素ということになる。受光素子８５および受光素子８７からの検出信号は、記憶装置９１および制御装置９２に与えられる。ここで、記憶装置９１および制御装置９２は、図１１に示す実施形態Ｃにおける記憶手段６０および制御手段７０に対応する構成要素であり、実際には、メモリやマイクロプロセッサなどを備えたコンピュータにより構成することができる。
【００５２】
角度調節機構９３は、光反射素子８１の向き（反射面ηの向き）を調節する機構であり、より具体的には、この反射面η上で直交する２つの回転軸ω１（基準光路Ｓと反射面ηとの交点Ａを通り図の紙面に垂直な軸）およびω２に関して、光反射素子８１を回転させる機能をもった機構である。実際には、高精度のステッピングモータなどを用いた機構により実現されることになるが、ここではその構造についての詳細な説明は省略する。一方、位置調節機構９４は、コーナリフレクタ８２の位置を調節する機構であり、ここに示す例の場合、コーナリフレクタ８２をＸ軸方向（図において、＋Ｘおよび−Ｘと示した左右方向）およびＹ軸方向（図の紙面に垂直な方向）の二軸方向にそれぞれ独立して平行移動させる機能を有している。別言すれば、位置調節機構９４は、コーナリフレクタ８２を所定平面（ＸＹ平面）に沿って平行移動させる機能を有していることになる。このような位置調節機構９４も、実際には、高精度のステッピングモータなどを用いた機構により実現されることになるが、ここではその構造についての詳細な説明は省略する。
【００５３】
ここで、光反射素子８１についての説明を更に補足すると、この光反射素子８１は、入射点Ｑｉｎとビーム分配器８３との間の基準光路Ｓ上に着脱自在に配置することができるようになっている。すなわち、光反射素子８１は、図にハッチングを施して示した支持機構８８によって取り付けられているが、支持機構８８は、光反射素子８１を着脱自在に支持する機能を有している。この支持機構８８は、たとえば、光反射素子８１を支持するレールなどの単純な機械的構造物によって構成すればよい。この場合、作業者が光反射素子８１を抜き差しすることにより、光反射素子８１を配置したり、除去したりすることができる。もちろん、支持機構８８を電動駆動機能を備えた機構によって構成し、作業者の操作指示に基いて、自動的に基準光路Ｓ上に配置されたり、基準光路Ｓ上から除去されたりするようにしてもかまわない。要するに、光反射素子８１を、基準光路Ｓ上に配置しない第１の状態と、基準光路Ｓ上に配置した第２の状態と、を選択的に採ることができ、かつ、この光反射素子８１を基準光路Ｓ上に配置した場合に、入射光を所望の方向に反射させることができるように反射面ηの角度調節が可能な構成になっていれば、支持機構８８としてどのような機械的構造物を用いてもかまわない。
【００５４】
このように、光反射素子８１を支持機構８８で支持することにより、この光反射素子８１は、図１１に示す実施形態Ｃにおける光路切換角度調節手段３５として機能することになる。すなわち、光反射素子８１を基準光路Ｓ上から脱離させた第１の状態にすれば、入射光をそのままビーム分配器８３へと導く第１の機能が実行されることになり、光反射素子８１を基準光路Ｓ上に配置した第２の状態にすれば、入射光を所定の迂回光路へと導くとともに、所定の設定角度θに応じた角度調節を行う第２の機能が実行されることになる。
【００５５】
図１４は、このような角度調節を行う原理を示すものである。いま、図１４の実線で示されている向きに光反射素子８１が設置されており、この光反射素子８１の反射面ηに対して実線で示す入射光Ｌｉｎが図のような向きに照射され、その結果、図のような向きに実線で示す射出光Ｌｏｕｔが反射している状態を考える。この状態で、光反射素子８１を紙面上で反時計回りにθ／２だけ回転させて図の破線で示されている状態にし、反射面ηの向きを変えたとすると、射出光は図に破線で示すＬｏｕｔ^＊のように変化する。ここで、射出光ＬｏｕｔとＬｏｕｔ^＊とのなす角はθである。結局、光ビームの向きを角度θだけ変化させるような調節を行いたい場合には、光反射素子８１を角度θ／２だけ回転させるような制御を行えばよいことになる。
【００５６】
一方、コーナリフレクタ８２は、図１１に示す実施形態Ｃにおける位置調節手段４０として機能する光学素子であり、光反射素子８１からの反射光（図１３の光路Ｄ１を通って入ってくる光ビーム）を入射し、これに平行な逆向光（図１３の光路Ｄ３を通って出て行く光ビーム）を射出する機能を有している。一般に、コーナリフレクタは、立方体を構成する６面のうち、同一頂点Ｃを含む３面の内側を反射面とした光学素子であり、これら反射面内の任意の位置に、任意の向きで入射光を照射すると、必ずこの入射光に平行で逆向きの射出光が得られるという光学的な性質を有する。図１３に示す例では、光路Ｄ１に沿った入射光が反射面ρ１上の入射点Ｃｉｎに入射すると、光路Ｄ２に沿った反射光となり、更に、この光路Ｄ２に沿った反射光が反射面ρ２上の射出点Ｃｏｕｔで反射して、光路Ｄ３に沿って射出することになる。この場合、入射点Ｃｉｎの位置や入射角度にかかわらず、光路Ｄ１に沿った入射光と光路Ｄ３に沿った射出光とは、必ず平行で逆向きの光となる。なお、このような性質をもった光学素子としては、コーナリフレクタの他にも、コーナキューブプリズムが知られており、位置調節手段としては、コーナリフレクタの代わりにコーナキューブプリズムを用いてもかまわない。
【００５７】
図１５は、コーナリフレクタ８２を用いた位置調節を行う原理を示すものである。いま、図１５の実線で示されている位置にコーナリフレクタ８２が設置されており、このコーナリフレクタ８２に対して実線で示す入射光Ｌｉｎが図のような向きに照射され、その結果、図のような向きに実線で示す射出光Ｌｏｕｔが射出されている状態を考える。この状態で、コーナリフレクタ８２を紙面上で右方向（＋Ｘ方向）に距離ｄ／２だけ移動させて図の破線で示されている状態にしたとすると、射出光は図に破線で示すＬｏｕｔ^＊のように変化する。ここで、射出光ＬｏｕｔとＬｏｕｔ^＊との間の変位量はｄである。結局、光ビームの位置を変位量ｄだけ変化させるような調節を行いたい場合には、コーナリフレクタ８２を変位量ｄ／２だけ移動させるような制御を行えばよいことになる。
【００５８】
続いて、図１３に示す光軸調節装置における検出器、すなわち、検出用ビーム分配器８４、受光素子８５、集光レンズ８６、受光素子８７の機能について説明する。この検出器は、光反射素子８１を基準光路Ｓ上に配置しない第１の状態において、ビーム分配器８３の光分配面ξから反射されてきた検出用光ビームについて、光分配面ξ上での位置および向きを検出する第１の機能と、光反射素子８１を基準光路Ｓ上に配置した第２の状態において、ビーム分配器８３の光分配面ξを透過してきた検出用光ビームについて、光分配面上での位置および向きを検出する第２の機能と、を備えている。いずれの機能を実施する場合にも、検出の基本原理は同じであり、光分配面ξからの検出用光ビームについての位置Ｐと向きとを測定することができればよい。そして、第１の機能によって検出された位置および向きは、基準情報として記憶装置９１に記憶されることになり、第２の機能によって検出された位置および向きは、制御装置９２へと与えられ、この検出結果が記憶装置９１に記憶されている基準情報に近付くように、角度調節機構９３および位置調節機構９４に対するフィードバック制御が行われる。
【００５９】
既に述べたように、検出用光ビームは、検出用ビーム分配器８４によって、２つのビームに分配され、受光素子８５によって位置の検出が、受光素子８７によって向きの検出が行われることになる。図１３に示す例では、受光素子８５の受光面上では、点Ｑ１０の位置にビームが照射されており、受光素子８７の受光面上では、点Ｑ２０の位置にビームが照射されており、これら点Ｑ１０および点Ｑ２０の受光面上での位置が、それぞれ検出用光ビームの光分配面ξ上での位置Ｐおよび向きに対応する情報になる。
【００６０】
図１６は、受光素子８５によって、位置検出が行われる原理を説明する図である。いま、図に実線で示すような検出用光ビームＬ１０が、光分配面ξの位置Ｐから検出用ビーム分配器８４の光分配面μを透過して受光素子８５まで到達したとすると、受光面上での照射点は点Ｑ１０になる。このとき、光分配面μから反射して集光レンズ８６で集光され、受光素子８７まで到達した検出用光ビームの集光点は点Ｑ２０になる。ここで、もし、検出用光ビームの光分配面ξ上での位置だけが、ＰからＰ１にずれたとすると（向きは同じであったとする）、検出用光ビームＬ１１は破線に示すような光路を通って、受光素子８５および受光素子８７に照射されることになる。すなわち、受光素子８５の受光面上での照射点は点Ｑ１１となり、もとの点Ｑ１０からずれることになる。一方、受光素子８７の受光面上での集光点は点Ｑ２１となり、もとの点Ｑ２０と同一の点になる。これは、受光素子８７の受光面が集光レンズ８６の焦点位置に置かれているためである。すなわち、集光レンズ８６に入射する複数の光ビームがあったとしても、これらが互いに平行である限りは、受光素子８７の受光面上の同一点に集光することになる。かくして、光分配面ξからの検出用光ビームＬ１０に生じた位置の変化は、位置検出器として機能する受光素子８５においてのみ検出されることになり、向き検出器として機能する受光素子８７では検出されない。
【００６１】
これに対して、図１７は、受光素子８７によって、向き検出が行われる原理を説明する図である。いま、図に実線で示すような検出用光ビームＬ１０が、光分配面ξの位置Ｐから検出用ビーム分配器８４の光分配面μを透過して受光素子８５まで到達したとすると、受光面上での照射点は点Ｑ１０になる。このとき、光分配面μから反射して集光レンズ８６で集光され、受光素子８７まで到達した検出用光ビームの集光点は点Ｑ２０になる。ここで、もし、検出用光ビームＬ１０の光分配面ξに対する向きだけがずれたとすると（検出用光ビームの光分配面ξ上の位置Ｐは同じであったとする）、検出用光ビームＬ１２は破線に示すような光路を通って、受光素子８５および受光素子８７に照射されることになる。すなわち、受光素子８５の受光面上での照射点は点Ｑ１２となり、もとの点Ｑ１０からずれることになる。一方、受光素子８７の受光面上での集光点は点Ｑ２２となり、やはりもとの点Ｑ２０からずれることになる。これは、実線で示す光ビームと破線で示す光ビームとが平行ではないため、集光レンズ８６による集光点がずれるからである。かくして、光分配面ξからの検出用光ビームＬ１０に生じた向きの変化は、向き検出器として機能する受光素子８７によって検出できる。ただ、このような向きの変化は、受光素子８５においても検出されることになる。
【００６２】
結局、受光素子８７の検出結果には、向きの変化のみが含まれているのに対し、受光素子８５の検出結果には、位置の変化と向きの変化との双方の成分が含まれていることになる。このような事情から、理論的には、図１３に示す光軸調節装置では、制御装置９２によるフィードバック制御は、まず、向きを一致させるための角度制御（角度調節機構９３に対する制御）を先に行い、続いて、位置を一致させるための位置制御（位置調節機構９４に対する制御）を行うようにするのが好ましい。向きについての検出結果が基準情報に一致すれば、受光素子８５の検出結果から向きについての変化成分を除去することができ、位置についての変化成分のみを認識することができる。もっとも、実用上は、角度制御と位置制御とを交互に繰り返して実行することにより、検出結果を基準情報に徐々に近付けてゆくフィードバック制御が行われることになるので、角度制御と位置制御との順を厳密に考慮する必要はない。
【００６３】
続いて、この光軸調節装置による自動光軸調節動作の一例を示す。たとえば、図１８に示すように、入射点Ｑｉｎから射出点Ｑｏｕｔへ向かう基準光路Ｓ（一点鎖線）が形成されている状態において、この基準光路Ｓ上に、この光軸調節装置を挿入したとしよう。この場合、まず、光反射素子８１を基準光路Ｓ上から取り外し、基準光路Ｓに沿って入射してくる入射光をビーム分配器８３の光分配面ξへと導き、この光分配面ξから反射してきた検出用光ビーム（図の破線に示す光路を進む）についての位置Ｐおよび向きを検出する。具体的には、受光素子８５上の点Ｑ１０の位置が、「位置Ｐを示す情報」として検出され、受光素子８７上の点Ｑ２０の位置が、「向きを示す情報」として検出され、これらの情報が基準情報として記憶装置９１（図１８では図示省略）に記憶される。次に、基準光路Ｓ上に光反射素子８１を配置した状態にし、入射光を反射面η上の点Ａで反射させて迂回光路（二点鎖線）へと導き、光分配面ξから透過してきた検出用光ビームについての位置および向きを検出し、これらの検出結果が、記憶装置９１に記憶されている基準情報に一致するようなフィードバック制御を行う。このようなフィードバック制御により、検出用光ビームは、受光素子８５の点Ｑ１０および受光素子８７の点２０に照射された状態となり、ビーム分配器８３からは基準光路Ｓに沿った射出光が射出点Ｑｏｕｔへ向けて射出されることになる。いわば、図３に示すような状態が得られたことになる。なお、このような状態において、「迂回光路を経てターゲット方向へ射出される光ビーム強度」が、「検出用ビーム分配器８４へと導かれる検出用光ビームの強度」に比べて十分に大きくなるようにするためには、ビーム分配器８３内の光分配面ξを、反射率９９％、透過率１％程度のハーフミラーによって構成しておくようにすればよい。
【００６４】
さて、ここで、何らかの原因により、この光軸調節装置への入射光の入射条件が変動し、図１８に実線で示すような入射光Ｌ１５が与えられるようになったとしよう。すなわち、これまでは、基準光路Ｓに沿った入射光が与えられていたのに、この入射光の位置が若干変動したことになる（ここでは、入射光の向きについての変動はなかったものとしよう）。すると、迂回光路は、図の二点鎖線で示す光路から、図の実線で示す光路へと変化し、光ビームは光分配面ξにおける位置Ｐ１５に照射されることになる。その結果、ビーム分配器８３から図の左方へ射出される光ビームは、基準光路Ｓから外れることになり、その最終照射位置は、ターゲット上の目標点Ｑから外れてしまう。
【００６５】
このような光軸変動は、受光素子８５および受光素子８７によって検出される。すなわち、受光素子８５上の照射点は点Ｑ１０から点Ｑ１５へと変動し、受光素子８７上の集光点は点Ｑ２０から点Ｑ２５へと変動する。もっとも、この例では、入射光の向きについての変動はなかったので、点Ｑ２０と点Ｑ２５とは同一点となり、向きについての調節を行う必要はないことが認識される。そこで、制御手段７０（図１８では図示省略）は、位置についての変動量ｄ（点Ｑ１０と点Ｑ１５との距離）を相殺すべく、位置調節機構９４（図１８では図示省略）に対して制御信号を送り、図１９に破線で示すように、コーナリフレクタ８２を距離ｄ／２だけ図の左方向へシフトさせる。すると、入射光Ｌ１５は、図に実線で示す迂回光路を通って、光分配面ξの「変動が生じる前の位置Ｐ」へと導かれるような位置調節が行われることになり、受光素子８５上の照射点は点Ｑ１０へ戻り、受光素子８７上の集光点は点Ｑ２０となる。かくして、ビーム分配器８３から図の左方へ射出される光ビームは、基準光路Ｓ上の位置に戻され、その最終照射位置は、ターゲット上の目標点Ｑに戻される。
【００６６】
以上、入射光について位置変動が生じた場合を述べたが、向きの変動が生じた場合には、光反射素子８１の角度が調節され、同様の自動光軸調節が行われることになる。
【００６７】
実は、この図１３に示す実施例には、次のような２つの問題点がある。第１の問題点は、光反射素子８１の抜き差し操作により光路の切換えを行う構造であるため、機構上、迂回光路にずれが生じる可能性があるという問題である。前述したように、入射光をそのままビーム分配器８３へと導く第１の機能を実行するためには、光反射素子８１を基準光路Ｓ上から抜き取った状態にし、入射光を所定の迂回光路へと導く第２の機能を実行するためには、光反射素子８１を支持機構８８に装着した状態にする必要がある。したがって、迂回光路の位置精度は、光反射素子８１を支持する支持機構８８の機械的な精度に大きく左右される。ところが、光反射素子８１の抜き差し操作を繰り返すと、支持機構８８が磨耗したり、位置ずれを生じたりするため、その機械的な精度は低下せざるを得ず、迂回光路に好ましくないずれが発生するおそれがある。
【００６８】
第２の問題点は、レーザ光のような高エネルギーの光ビームの光軸調節に利用する場合に、検出手段を構成する受光素子８５，８７を損傷させるおそれがあるという問題である。すなわち、図１３に示す構成において、光反射素子８１を基準光路Ｓ上に配置しない第１の状態では、ビーム分配器８３の光分配面ξから反射されてきた検出用光ビームについて、光分配面ξ上での位置および向きの検出が行われ、光反射素子８１を基準光路Ｓ上に配置した第２の状態では、ビーム分配器８３の光分配面ξを透過してきた検出用光ビームについて、光分配面上での位置および向きの検出が行われる。したがって、たとえば、光分配面ξを透過率５０％のハーフミラーで構成した場合、検出用光ビームのパワーは、入射点Ｑｉｎに入射した光ビームの５０％にも達することになり、レーザ光などが入射した場合には、受光素子８５，８７を焼きつけてしまう可能性がある。光分配面ξの透過率を、９９％のように非常に大きく設定したり、１％のように非常に小さく設定すると、上述の第１の状態と第２の状態とのいずれか一方においては、検出用光ビームのパワーが非常に小さくなるものの、他方においては、逆に検出用光ビームのパワーが非常に大きくなってしまう。このため、図１３に示す実施例に係る装置を、レーザ光などの光軸調節に利用すると、操作中に過って受光素子８５，８７を損傷させるおそれがある。
【００６９】
＜＜＜　§４．光軸調節装置に対する改良　＞＞＞
上述の§３で述べた具体的な実施例は、特願２００１−０２８３５４号明細書に開示された実施例であり、上述したように２つの問題点がある。そこで、ここでは、この２つの問題点を解決するための改良点を述べることにする。この改良点の根本原理は、偏光を利用したビーム分配手段、すなわち、偏光ビームスプリッター（ＰＢＳ：Ｐｏｌａｒｉｚｉｎｇ　Ｂｅａｍ　Ｓｐｌｉｔｔｅｒ）を用いて、光ビームの分配を行うようにする点にある。
【００７０】
前述した§２では、４つの基本的な実施形態Ａ，Ｂ，Ｃ，Ｄを説明した。ここでは、まず、実施形態Ａに、偏光ビームスプリッターを利用した例を、実施形態Ｅとして説明する。実施形態Ａでは、図９に示すように、光路切換手段２０によって迂回させた迂回光Ｌ４に対して、角度調節手段３０による角度調節と、位置調節手段４０による位置調節とを施し、ビーム分配手段１０の光分配面ξの射出点Ｑｏｕｔ側へと導く方式が採られている。ここで述べる実施形態Ｅは、この実施形態Ａにおけるビーム分配手段１０および光路切換手段２０として、偏光ビームスプリッターを用いるようにしたものであり、その構成を図２０のブロック図に示す。
【００７１】
図２０におけるビーム分配手段１０Ｘおよび２０Ｘは、それぞれ図９に示すビーム分配手段１０および光路切換手段２０に対応する構成要素であり、いずれも偏光ビームスプリッターによって構成されている。ここでは、入射点Ｑｉｎ側に配置されたビーム分配手段２０Ｘを入射側ビーム分配手段と呼び、射出点Ｑｏｕｔ側に配置されたビーム分配手段１０Ｘを射出側ビーム分配手段と呼ぶことにする。図示のとおり、入射側ビーム分配手段２０Ｘは光分配面ξ１ｘを有しており、射出側ビーム分配手段１０Ｘは光分配面ξ２ｘを有している。これら光分配面ξ１ｘ、ξ２ｘは、第１の偏光面を有する平面偏光波が照射された場合には、その大部分を透過して残りを反射し、この第１の偏光面に対して直交する第２の偏光面を有する平面偏光波が照射された場合には、その大部分を反射して残りを透過するという基本的な特徴を有している。
【００７２】
ここでは、説明の便宜上、第１の偏光面を平面Ｘと呼び、第２の偏光面を平面Ｙと呼ぶことにする。平面Ｘと平面Ｙとは互いに直交しており、両平面が交差する直線に沿った方向が、入射光Ｌ１の進行方向ということになる。いま、光分配面ξ１ｘ、ξ２ｘのいずれもが、平面Ｘを偏光面とする平面偏光波が照射された場合には、その大部分（たとえば、９９％としよう）を透過し、残り（１％）を反射し、平面Ｙを偏光面とする平面偏光波が照射された場合には、その大部分（たとえば、９９％としよう）を反射し、残り（１％）を透過する性質をもっていたものとしよう（符号１０Ｘ、２０Ｘ、ξ１ｘ、ξ２ｘにおける英文字Ｘは、このように平面Ｘを偏光面とする光の大部分を透過する性質を示すものである）。
【００７３】
さて、上述のような前提において、図２０に示す基準光路Ｓに沿った入射光Ｌ１として、平面Ｘを偏光面とする平面偏光波を与えた場合の現象を考えてみよう。この場合、入射光Ｌ１の大部分（９９％）が光分配面ξ１ｘを透過して基準光路Ｓに沿って進み、更にその大部分（９９％）が光分配面ξ２ｘを透過して、入射光透過光Ｌ２として射出することになる。このとき、検出手段５０へ入射光反射光Ｌ３として向かう光は、光分配面ξ２ｘに照射された光のうちのわずか１％ということになる。
【００７４】
次に、上述のような前提において、図２０に示す基準光路Ｓに沿った入射光Ｌ１として、平面Ｙを偏光面とする平面偏光波を与えた場合の現象を考えてみよう。この場合、入射光Ｌ１の大部分（９９％）が光分配面ξ１ｘを反射して迂回光Ｌ４として迂回光路へと導かれ、角度調節手段３０を経て角度調節光Ｌ５となり、更に、位置調節手段４０を経て位置角度調節光Ｌ６となって、光分配面ξ２ｘの射出点Ｑｏｕｔ側に照射されることになる。そして、この光分配面ξ２ｘにおいても、照射された位置角度調節光Ｌ６の大部分（９９％）が反射し、調節光反射光Ｌ８として射出することになる。このとき、検出手段５０へ調節光透過光Ｌ７として向かう光は、光分配面ξ２ｘに照射された光のうちのわずか１％ということになる。
【００７５】
結局、図２０に示す実施例の場合、入射光Ｌ１として、平面Ｘを偏光面とする平面偏光波を与えても、平面Ｙを偏光面とする平面偏光波を与えても、その大部分は射出点Ｑｏｕｔに向けた入射光透過光Ｌ２または調節光反射光Ｌ８として射出されることになり、検出手段５０に対して入射光反射光Ｌ３または調節光透過光Ｌ７として照射される光のエネルギーは非常に小さなものになる。これは、検出手段５０を構成する受光素子を損傷させるおそれがあるという問題を解決する上では極めて有効である。すなわち、入射光Ｌ１として、レーザ光のような高エネルギー光ビームを用いた場合であっても、検出手段５０へと導かれる検出用光ビームのエネルギーはそのほんの一部になるので、上述したように、平面Ｘもしくは平面Ｙを偏光面にもつレーザ光を入射光Ｌ１として用いる限り、検出手段５０を構成する受光素子に焼きつけが生じることを防ぐことができる。
【００７６】
また、図２０に示す実施例では、前述したもうひとつの問題も解決することが可能である。すなわち、図２０に示すビーム分配手段２０Ｘによるビーム分配動作は、入射光Ｌ１の偏光面によって自動的に決定される動作になるため、物理的な抜き差し作業を行う必要は全くなくなるのである。§１で述べた基本原理によれば、ビーム分配手段２０Ｘは、入射光Ｌ１を透過させる第１の状態（検出手段５０によって基準情報を取得し、記憶手段６０に格納するための状態）と、入射光Ｌ１を迂回光路へ向けて反射させる第２の状態（検出手段５０による検出値を記憶手段６０内に格納されている基準情報に近付けるようなフィードバック制御を行うための状態）と、を切り替える光路切換手段としての機能を果たす必要がある。ところが、図２０に示す実施例では、このような切換操作を光学素子の抜き差し作業によって行う必要はなくなり、入射光Ｌ１の偏光面を変える作業によって行うことが可能になる。したがって、図２０に示す実施形態Ｅの場合、ビーム分配手段２０Ｘを、完全に固定しておくことが可能になり、迂回光路の精度にずれが生じる弊害を防止することができるようになる。
【００７７】
この図２０に示す光軸調節装置による自動光軸調節動作は次のようにして行われる。まず、入射点Ｑｉｎに、平面Ｘを偏光面とする平面偏光波からなる光ビームを、基準光路Ｓに沿って入射光Ｌ１として入射させる。すると、その大部分は、光分配面ξ１ｘを透過し、更にその大部分は、光分配面ξ２ｘを透過して入射光透過光Ｌ２として射出する。このとき、検出手段５０には、わずかな光が入射光反射光Ｌ３として得られるので、その光分配面ξ２ｘ上での位置および向きを測定し、この測定結果を基準情報として記憶手段６０に格納する。次に、平面Ｙを偏光面とする平面偏光波からなる光ビームを、入射光Ｌ１として入射させる。すると、その大部分は、光分配面ξ１ｘを反射して迂回光路を経た後、光分配面ξ２ｘを反射して調節光反射光Ｌ８として射出する。このとき、検出手段５０には、わずかな光が調節光透過光Ｌ７として得られるので、その光分配面ξ２ｘ上での位置および向きを測定し、この測定結果が、記憶手段６０に格納されている基準情報に一致するようなフィードバック制御を行えばよい。
【００７８】
結局、§３で述べた実施例において、光学素子の抜き差し作業によって行っていた光路切換操作を、図２０に示す実施例では、入射光Ｌ１の偏光面の切換作業によって行うことになる。もちろん、偏光面の切換作業を行ったときには、検出手段５０などに、現在、いずれの偏光面をもった光ビームが入射光Ｌ１として与えられているかを指示する入力を行い、検出手段５０等が適切な動作を実行できるようにする必要がある。偏光面の切換作業は、偏光面を９０°回転させる光学素子（たとえば、１／２波長板など）を用意しておき、入射点Ｑｉｎに向かう光ビームについての偏光面を回転させるようにすればよい。このような偏光面を回転させるための光学素子は、物理的な抜き差しを行ったとしても、光路精度に対する影響を及ぼすことはないので、特に問題は生じない。
【００７９】
このように、この§４で述べる改良点を実施する上では、光ビームの偏光を利用してビーム分配を行う必要があるので、光軸調節の対象となる入射光Ｌ１は、所定の偏光面をもった平面偏光波であることが前提となる。もっとも、レーザ光はコヒーレントな光であり、所定の偏光面をもった平面偏光波となるので、実用上、レーザ光の光軸調節を行う上では、本発明は非常に好都合である。もちろん、本発明に係る光軸調節は、必ずしもレーザ光を対象としたものに限定されるわけではなく、平面偏光波であれば、どのような光ビームを調節対象としてもかまわない。
【００８０】
なお、図２０におけるビーム分配手段１０Ｘ，２０Ｘとして用いる偏光ビームスプリッターは、入射光の偏光面に応じて、大部分を透過あるいは反射する性質を有しているが、「平面Ｘを偏光面とする平面偏光波を１００％透過し、平面Ｙを偏光面とする平面偏光波を１００％反射する」という公称値をもった偏光ビームスプリッターを用いても、実用上、問題はない。これは、理論的な公称値が１００％であったとしても、現実的には、１００％透過あるいは１００％反射という現象は起こらず、わずかながらの漏れ成分が必ず存在するためである。特に、光軸調節の対象となる光ビームが高出力レーザ光であった場合、わずかな漏れ成分であってもかなりのパワーがあるため、検出手段５０による位置および角度検出には十分である。
【００８１】
ここで用いるビーム分配手段１０Ｘ，２０Ｘは、「所定の偏光面を有する平面偏光波が照射された場合には、その大部分を透過して残りを反射する」という性質を有する構成要素であるが、ここでいう「大部分」と「残り」との割合は、光軸調節の対象となる光ビームのエネルギー強度、検出手段に用いられる受光素子の受光感度や受光許容エネルギー強度などを考慮して決定されるべき値ということになる。別言すれば、光軸調節の対象となる光ビームのエネルギーのうち、受光素子の適切な検出範囲に相当するエネルギーが検出手段側へと導かれるような割合、ということになる。
【００８２】
図２０に示す基本的な実施形態Ｅは、図９に示す基本的な実施形態Ａについて改良点を適用した例であるが、この改良点は、もちろん、図１０〜図１２に示す基本的な実施形態Ｂ〜Ｄにも同様に適用可能である。たとえば、図１０に示す実施形態Ｂに適用する場合であれば、ビーム分配手段１０と光路切換手段２０を、偏光ビームスプリッターからなるビーム分配手段１０Ｘ，２０Ｘに置き換えればよい。また、図１１に示す実施形態Ｃに適用する場合であれば、ビーム分配手段１０と光路切換角度調節手段３５を、偏光ビームスプリッターからなるビーム分配手段１０Ｘ，３５Ｘに置き換えればよい（この場合、ビーム分配手段３５Ｘとして利用される偏光ビームスプリッターは、角度調節機能を有している必要がある）。更に、図１２に示す実施形態Ｄに適用する場合であれば、ビーム分配手段１０と光路切換位置調節手段４５を、偏光ビームスプリッターからなるビーム分配手段１０Ｘ，４５Ｘに置き換えればよい（この場合、ビーム分配手段４５Ｘとして利用される偏光ビームスプリッターは、位置調節機能を有している必要がある）。
【００８３】
図２１に示す基本的な実施形態Ｆは、図２０に示す実施形態Ｅの変形例であり、基準光路Ｓ上に遮断手段Ｇ１を付加するとともに、迂回光路上に遮断手段Ｇ２を付加したものである。遮断手段Ｇ１，Ｇ２は、それぞれ基準光路Ｓを通る光ビームおよび迂回光路を通る光ビームを光学的に遮断する光シャッターである。このような遮断手段Ｇ１，Ｇ２を設け、必要なときに光の遮断操作を行うようにすれば、光路差に基づく干渉の影響を排除した利用形態が可能になる。以下、そのメリットについて説明する。
【００８４】
既に述べたとおり、この§４で述べる改良を施した実施例では、まず、入射光Ｌ１として、平面Ｘを偏光面にもつ光ビームを入射させ、検出手段５０によって基準情報を取得する作業が行われる。この作業では、光分配面ξ１ｘを透過し、光分配面ξ２ｘで反射した入射光反射光Ｌ３が利用される。ところが、このとき、迂回光路には、光分配面ξ１ｘを反射したわずかな光が迂回光として進行し、この迂回光の大部分は、光分配面ξ２ｘを透過して、調節光透過光Ｌ７として検出手段５０に入射することになる。また、この迂回光の一部は、光分配面ξ２ｘを反射して、調節光反射光Ｌ８として射出することになる。ここで、入射光反射光Ｌ３と調節光透過光Ｌ７とは、所定の光路差をもった光であるため、互いに干渉を生じることになり、入射光透過光Ｌ２と調節光反射光Ｌ８とは、やはり所定の光路差をもった光であるため、互いに干渉を生じることになる。このような干渉が生じると好ましくない場合には、基準情報取得段階では、遮断手段Ｇ１は機能させず（光シャッターを開いた状態にし）、遮断手段Ｇ２によって迂回光路を進む光を遮断し（光シャッターを閉じた状態にし）、入射光透過光Ｌ２および入射光反射光Ｌ３のみが得られるようにすればよい。
【００８５】
続いて、入射光Ｌ１として、平面Ｙを偏光面にもつ光ビームを入射させ、検出手段５０の検出値を基準情報に近付けるような制御段階が行われる。具体的には、光分配面ξ１ｘを反射して迂回光路を進み、光分配面ξ２ｘを透過した調節光透過光に基づく検出制御が行われる。ところが、このとき、基準光路Ｓには、光分配面ξ１ｘを透過したわずかな光が進行し、その大部分は、光分配面ξ２ｘを反射して、入射光反射光Ｌ３として検出手段５０に入射することになり、その一部は、光分配面ξ２ｘを透過して、入射光透過光Ｌ２として射出することになる。そこで、この場合も、入射光反射光Ｌ３と調節光透過光Ｌ７との干渉や、入射光透過光Ｌ２と調節光反射光Ｌ８との干渉が生じることになる。このような干渉が好ましくない場合には、制御段階では、遮断手段Ｇ１によって迂回光路を進む光を遮断し（光シャッターを閉じた状態にし）、遮断手段Ｇ２は機能させず（光シャッターを開いた状態にし）、調節光透過光Ｌ７および調節光反射光Ｌ８のみが得られるようにすればよい。
【００８６】
このように、基準情報取得段階と制御段階とでは、入射光の偏光面の切換、遮断手段の開閉切換、検出手段等の動作切換、という３つの事項についての切換操作が必要になる。そこで、実用上は、単一の切換スイッチを用意しておき、この切換スイッチを「基準情報取得動作」か「制御動作」かのいずれか一方に切り換える操作を行うことにより、上記３つの事項の切換が連動して自動的に実行されるような構成にしておくのが好ましい。すなわち、この切換スイッチを「基準情報取得動作」側に切り換えると、入射光の偏光面が平面Ｘとなるように設定され、遮断手段Ｇ１が開いて光を通す状態となり、遮断手段Ｇ２が閉じて光を遮断する状態となり、検出手段５０が、検出した位置および角度を基準情報として記憶手段６０に格納する動作を行うようにすればよい。逆に、この切換スイッチを「制御動作」側に切り換えると、入射光の偏光面が平面Ｙとなるように設定され、遮断手段Ｇ１が閉じて光を遮断する状態となり、遮断手段Ｇ２が開いて光を通す状態となり、検出手段５０が、検出した位置および角度を制御手段７０に与え、制御手段７０が、与えられた位置および角度が記憶手段６０内に格納されている基準情報に近付くようなフィードバック制御動作を行うようにすればよい。
【００８７】
上述した入射光の偏光面の切換操作は、入射光の光路上に１／２波長板などを設置し、モータなどの駆動手段でこれを９０°だけ回転させたり、元に戻したりする制御を行うようにすればよい。また、遮断手段Ｇ１，Ｇ２の開閉切換操作は、電磁式光シャッターなどを用いれば容易に行うことができ、検出手段や制御手段の動作切換操作は、マイクロプロセッサなどにより容易に制御することができる。このように、切換スイッチの操作によって、上記３つの事項の切換操作が連動して行われるような構成にしておけば、オペレータの作業負担は大幅に軽減される。すなわち、オペレータは、まず、切換スイッチを「基準情報取得動作」側に切り換える操作を行い、現在の基準光路Ｓについての基準情報の取得を行い、続いて、切換スイッチを「制御動作」側に切り換える操作を行い、光路を安定化するためのフィードバック制御を開始させればよい。
【００８８】
最後に、§３で述べた図１３の実施例に、この§４で述べた改良点を適用した実施例のブロック図を図２２に示す。この実施例は、ちょうど、図１３におけるビーム分配器８３を偏光ビームスプリッターからなる射出側ビーム分配手段８３Ｘに置き換え、光反射素子８１を偏光ビームスプリッターからなる入射側ビーム分配手段８１Ｘに置き換え、遮断手段Ｇ１，Ｇ２を付加した構成に相当する。入射側ビーム分配手段８１Ｘは、角度調節機能を有しているため、回転軸ω１，ω２に関して回転が可能になっているものの、抜き差しは不要であるため、図１３に示す支持手段８８に相当する構成要素は設けられていない。光分配面ξ１ｘ，ξ２ｘは、いずれも平面Ｘを偏光面とする平面偏光波の大部分を透過し残りを反射し、平面Ｙを偏光面とする平面偏光波の大部分を反射し残りを透過する性質をもった面である。
【００８９】
この図２２に示す実施例を用いた光軸調節の動作は、図１３の実施例とほぼ同じである。相違点は、入射光としてレーザ光などの平面偏光波の光ビームを用いるようにし、基準光路か迂回光路かの光路切換動作を、光学素子の抜き差しではなく、入射光の偏光面の切換によって行う点である。すなわち、まず、平面Ｘを偏光面にもつ光ビームを入射点Ｑｉｎに基準光路Ｓに沿って入射させる。このとき、遮断手段Ｇ１としての光シャッターは開き、遮断手段Ｇ２としての光シャッターは閉じるようにする（実際には、前述した切換スイッチによる連動操作で切り換えるのが好ましい）。これにより、光分配面ξ１ｘを透過し、光分配面ξ２ｘで反射した入射光反射光の位置および角度が検出され、基準情報として記憶装置９１に記憶されることになる。もちろん、このとき、射出点Ｑｏｕｔ側には、光分配面ξ２ｘを透過した入射光透過光が射出されることになる。続いて、入射する光ビームの偏光面を平面Ｙに切り換える。このとき、遮断手段Ｇ１としての光シャッターは閉じ、遮断手段Ｇ２としての光シャッターは開くようにする（実際には、前述した切換スイッチによる連動操作で切り換えるのが好ましい）。これにより、入射光は、光分配面ξ１ｘを反射して迂回光路を進み、光分配面ξ２ｘを透過した調節光透過光として検出される。もちろん、このとき、射出点Ｑｏｕｔ側には、光分配面ξ２ｘを反射した調節光反射光が射出されることになる。制御装置は、このときの検出値を記憶装置９１内の基準情報に近付けるように、角度調節機構９３および位置調節機構９４を制御する。その結果、入射側ビーム分配手段８１Ｘとして利用されている偏光ビームスプリッターの角度調節が行われ、コーナリフレクタ（もしくはコーナキューブプリズム）８２の位置調節が行われる。
【００９０】
このように、図２２に示す実施例は、図１３に示す実施例と全く同じ基本原理で動作するものの、光路精度に影響を与える光学素子の抜き差し操作が不要になったため、光路ずれによる誤差発生を抑制することが可能になる。また、入射光として、平面Ｘを偏光面とする光ビームを入射した場合も、平面Ｙを偏光面とする光ビームを入射した場合も、検出用の光学素子８４〜８７へと導かれる光ビームは、入射した光ビームのごく一部になるため、受光素子の焼き付きを防ぐ効果も得られる。
【００９１】
＜＜＜　§５．本発明に係る露光装置　＞＞＞
これまで、§１〜§３において、光軸の自動調節機能をもったユニークな光軸調節装置の構成および動作を説明し、§４において、その改良点を説明した。本発明の特徴は、既存の露光装置に、§４で述べた改良点を施した光軸調節装置を取り入れた点にある。以下、本発明の露光装置の全体構成を説明する。
【００９２】
はじめに、従来から利用されている一般的な露光装置の構成例を、簡単に説明しておく。図２３は、カラーホログラム像についての露光を行う一般的な露光装置の構成図である。この露光装置は、所定の露光面に対して光を照射することにより、この露光面上に配置された感光材料を露光させる作業に利用される。ビーム源１００Ｒ，１００Ｇ，１００Ｂは、それぞれ赤色、緑色、青色のレーザビーム（平面偏光波）を発生させるレーザ光源であり、それぞれ図に一点鎖線で示す光路に沿って、赤色ビームＬｒ、緑色ビームＬｇ、青色ビームＬｂを発生させる。こうして発生されたレーザビームを露光面へと誘導するために、ビーム誘導手段４０１〜４０４が設けられている。ここで、ビーム誘導手段４０１，４０２は反射鏡、ビーム誘導手段４０３，４０４はビーム合成器となっている。緑色ビームＬｇは、反射鏡４０２で図の下方へと曲げられてビーム合成器４０３へ入射し、ここで青色ビームＬｂと合成させられる。この合成ビームＬｇｂは更にビーム合成器４０４へ入射する。一方、赤色ビームＬｒは、反射鏡４０１で図の下方へと曲げられてビーム合成器４０４へ入射し、ここで合成ビームＬｇｂと更に合成させられ、三原色の合成ビームＬｒｇｂとなり、ビーム径拡張装置４０５へと入射する。ビーム径拡張装置４０５は、誘導されてきた合成ビームＬｒｇｂの径を、露光面Ｅの大きさに応じて拡張する光学素子であり、ビーム径が拡張された合成ビームＬＬｒｇｂは、そのまま露光面Ｅへと照射される。
【００９３】
露光面Ｅは、概念的に定義された平面であり、実際には、この露光面Ｅ上に配置された感光材料に対して露光が行われる。図示の例では、所定の搬送路に沿って、感光材料５０１〜５０４が図の左方向へ向かって搬送されており（搬送機構についての図示は省略）、露光面Ｅ上に搬送されてきた感光材料５０１に対して露光が行われている状態が示されている。ここでは、１枚ずつ独立した感光材料５０１〜５０４を搬送する例を示したが、もちろん、巻取状の感光フィルムを感光材料として用い、この巻取状の感光フィルムを図の水平方向に搬送するような形態の露光装置も利用されている。図示の例は、感光材料５０１〜５０４上に、いわゆるリップマン型ホログラムの像を形成させるための露光装置であり、露光面Ｅの下方に、ホログラム原版６００（たとえば、所定のモチーフを表現したレリーフ像）が配置されている。また、感光材料５０１〜５０４として、透明な感光性フィルムを使用している。このような構成によって、感光材料５０１上には、図の上方から照射された合成ビームＬＬｒｇｂと、ホログラム原版６００からの反射光と、の干渉縞が記録されることになり、カラーホログラム像の記録が行われる。
【００９４】
このような露光装置では、合成ビームＬＬｒｇｂの光軸調節が非常に重要である。各ビーム源１００Ｒ，１００Ｇ，１００Ｂから発せられたレーザビームの断面強度は、一般に、ガウシアン分布をとるため、露光面Ｅ上に照射される合成ビームＬＬｒｇｂの断面強度もガウシアン分布をとる。したがって、各色ごとのレーザビームの光軸が正確に調節されていないと、露光面上での各色ごとの強度分布にずれが生じることになり、ホログラム像の再生時に色むらが生じる原因になる。このため、ビーム源１００Ｒ，１００Ｇ，１００Ｂおよびビーム誘導手段４０１〜４０４を設置し、テスト動作を行う際には、精密な光軸調節作業が行われる。たとえば、露光面Ｅに、複数の光センサが配置された測定板を配置し、各光センサの検出出力をモニタしながら、ビーム源１００Ｒ，１００Ｇ，１００Ｂに内蔵された光軸調節機構を調節したり、ビーム誘導手段４０１〜４０４の位置や向きを調節したりする作業が行われることになる。
【００９５】
こうして、この露光装置を設置する際のテスト段階で、精密な光軸調節を行っておけば、一応、各レーザビームの光軸は所定の基準光路に合わせられることになり、正しい露光作業を行うことが可能になる。しかしながら、このような光軸調節によって、各ビームの光軸が必ずしも正確な位置に固定されるわけではない。光軸に変動が生じる要因のひとつは、ビーム源１００Ｒ，１００Ｇ，１００Ｂの不安定要因である。一般に、レーザ光源は、起動してから動作が安定な状態に達するまでに、ある程度の時間を要する。したがって、レーザ光源が完全に安定した状態になるまでは、各レーザビームの光軸に変動が生じるおそれがある。また、レーザ光源の起動後、十分な時間が経過しているにもかかわらず、電源電圧の変動などの外乱によって、光軸に変動を来す場合もある。更に、長期間の使用による経年変化という要因により、徐々に光軸にずれが生じることもある。従来は、このような光軸ずれが生じた場合、その都度、既存の光軸調節機構を利用して、再度の光軸調節作業を行っていた。
【００９６】
本発明に係る露光装置では、§１〜§３で述べたユニークな光軸調節装置に、§４で述べた改良を施した光軸調節装置を利用することにより、上述のような光軸変動が生じた場合にも、自動的な光軸調節を行うことができる。図２４は、本発明の一実施形態に係る露光装置の構成図である。この露光装置は、図２３に示す従来の露光装置に、３つの光軸調節装置３００Ｒ，３００Ｇ，３００Ｂを追加したものである。光軸調節装置３００Ｒ，３００Ｇ，３００Ｂとしては、§２で述べた種々の光軸調節装置のいずれかの実施形態のものに、§４で述べた改良を施したものを用いるようにすればよい。
【００９７】
各光軸調節装置３００Ｒ，３００Ｇ，３００Ｂの具体的な設置方法の一例を以下に述べる。まず、図２３に示す露光装置を設置し、テスト段階で正確な光軸調節が完了し、各色別レーザビームについての基準光路が確定した段階で、光軸調節装置３００Ｒ，３００Ｇ，３００Ｂを、各色別レーザビームの基準光路上に挿入する。このとき、各色別レーザビームの偏光面は、いずれも平面Ｘとなるように調整しておく（必要なら、１／２波長板などを挿入して、偏光面の調整を行っておく）。そうすれば、各色別レーザビームの大部分は、入射側ビーム分配手段の光分配面ξ１ｘを透過し、そのごく一部が射出側ビーム分配手段の光分配面ξ２ｘを反射して検出手段によって検出される。この検出結果に基づいて基準情報を取得し、これを記憶させる処理を行う。続いて、各色別レーザビームの偏光面が、いずれも平面Ｙとなるような偏光面の切換を行う。そして、迂回光路を通ったビームの一部を検出手段に導き、制御手段によるフィードバック制御を行うようにする。このような制御により、光軸の自動調節機能が働き、各光軸調節装置３００Ｒ，３００Ｇ，３００Ｂから射出される各色別レーザビームは、テスト段階で設定された基準光路に沿ったものになる。
【００９８】
このようにして、基準光路上で光軸調節装置３００Ｒ，３００Ｇ，３００Ｂを機能させておけば、ビーム源１００Ｒ，１００Ｇ，１００Ｂに、何らかの要因で光軸ずれが生じたとしても、生じた光軸ずれは、光軸調節装置３００Ｒ，３００Ｇ，３００Ｂによって自動的に補正される。なお、図２４に示す例のように、各色別レーザビームの基準光路上にだけ光軸調節装置を設けたのでは、ビーム誘導手段４０１〜４０４の位置や向きがずれた場合に生じる光軸ずれに対しては対処することができない。このような場合にも対処できるようにするためには、更に、合成ビームＬｒｇｂの基準光路上にも、光軸調節装置を挿入するようにすればよい。
【００９９】
また、上述した設置方法の例は、テスト段階で正確な光軸調節が完了し、各色別レーザビームについての基準光路が確定した後に、各光軸調節装置３００Ｒ，３００Ｇ，３００Ｂを各基準光路上に挿入していたが、逆に、各光軸調節装置３００Ｒ，３００Ｇ，３００Ｂを設置した後に、正確な光軸調節を行うことも可能である。この場合は、まず、図２３に示すような露光装置の構成要素を設置し、大まかな粗い光軸調節だけを行う。この粗い光軸調節が完了すれば、一応、各レーザビームについての大まかな経路を示す「仮の基準光路」が決定されることになる。そこで、この「仮の基準光路」上に、各光軸調節装置３００Ｒ，３００Ｇ，３００Ｂを挿入する。このとき、各色別レーザビームの偏光面は、いずれも平面Ｘとなるように調整しておく。すると、各色別レーザビームの大部分は、入射側ビーム分配手段および射出側ビーム分配手段を透過してそのまま射出することになるので、図２４に示す露光装置は、実質的に図２３に示す従来の露光装置と同じ構成となり、各色別レーザビームは露光面Ｅまで誘導されることになる。したがって、これまでどおりの手法で、正確な光軸調節を行うことが可能である。こうして正確な光軸調節を行うことにより、「真の基準光路」が確定するので、その時点でビーム分配器８３に照射されている光ビーム、すなわち「真の基準光路」を通っている光ビームについて基準情報の取得を行う。基準情報が取得できたら、各色別レーザビームの偏光面を平面Ｙに切換え、フィードバック制御を機能させればよい。
【０１００】
【発明の効果】
以上のとおり、本発明によれば、光ビームの光軸を自動的に安定維持させる機能をもった露光装置を実現することが可能になる。また、光軸調節装置による光路の精度を高め、用いている光学素子の損傷を防ぐ効果も期待できる。
【図面の簡単な説明】
【図１】本発明に係る光軸調節装置により光軸を安定させる対象となる光学系の構成を示す図である。
【図２】図１に示す光学系におけるビーム源の変動要因に基いて、光軸ずれが生じた状態を示す図である。
【図３】図１に示す光学系における基準光路Ｓ上に本発明に係る光軸調節装置を挿入した状態を示す図である。
【図４】本発明に係る光軸調節装置の機能により、光軸が安定維持される状態を示す図である。
【図５】本発明に係る光軸調節装置における基準情報取得の原理を説明する図である。
【図６】本発明に係る光軸調節装置において形成される迂回光路を示す図である。
【図７】図６に示す光軸調節装置によるフィードバック制御の結果を示す図である。
【図８】図６に示す光軸調節装置によるフィードバック制御により、光源側に変動が生じた場合にも、光軸が安定維持される状態を示す図である。
【図９】本発明の基本的な実施形態Ａに係る光軸調節装置の構成を示すブロック図である。
【図１０】本発明の基本的な実施形態Ｂに係る光軸調節装置の構成を示すブロック図である。
【図１１】本発明の基本的な実施形態Ｃに係る光軸調節装置の構成を示すブロック図である。
【図１２】本発明の基本的な実施形態Ｄに係る光軸調節装置の構成を示すブロック図である。
【図１３】図１１に示す基本的な実施形態Ｃに対応した光軸調節装置の構成例を示す図である。
【図１４】図１３に示す光軸調節装置における光反射素子による角度調節の原理を示す図である。
【図１５】図１３に示す光軸調節装置におけるコーナリフレクタによる位置調節の原理を示す図である。
【図１６】図１３に示す光軸調節装置における位置変動の検出原理を示す図である。
【図１７】図１３に示す光軸調節装置における角度変動の検出原理を示す図である。
【図１８】図１３に示す光軸調節装置において、入射光に位置変動が生じた状態を示す図である。
【図１９】図１３に示す光軸調節装置において、入射光に位置変動が生じた場合に行われる自動光軸調節を示す図である。
【図２０】本発明に係る改良を施した基本的な実施形態Ｅに係る光軸調節装置の構成を示すブロック図である。
【図２１】図２０に示す実施形態Ｅの変形例に対応する実施形態Ｆに係る光軸調節装置の構成を示すブロック図である。
【図２２】図１３に示す実施例に、本発明に係る改良を適用した実施例のブロック図である。
【図２３】カラーホログラム像についての露光を行う一般的な露光装置の構成図である。
【図２４】本発明の一実施形態に係る露光装置の構成図である。
【符号の説明】
１…基準情報取得手段
２…光路迂回調節手段
３…制御手段
１０…ビーム分配手段
１０Ｘ…射出側ビーム分配手段（偏光ビームスプリッター）
２０…光路切換手段
２０Ｘ…入射側ビーム分配手段（偏光ビームスプリッター）
３０…角度調節手段
３５…光路切換角度調節手段
４０…位置調節手段
４５…光路切換位置調節手段
５０…検出手段
６０…記憶手段
７０…制御手段
８１…光反射素子
８１Ｘ…入射側ビーム分配手段（偏光ビームスプリッター）
８２…コーナリフレクタ（コーナキューブプリズム）
８３…ビーム分配器
８３Ｘ…射出側ビーム分配手段（偏光ビームスプリッター）
８４…検出用ビーム分配器
８５…受光素子
８６…集光レンズ
８７…受光素子
８８…支持機構
９１…記憶装置
９２…制御装置
９３…角度調節機構
９４…位置調節機構
１００…ビーム源
２００…ターゲット
３００，３００Ｒ，３００Ｇ，３００Ｂ…本発明に用いられる光軸調節装置
４０１〜４０４…ビーム誘導手段（反射鏡およびビーム合成器）
４０５…ビーム径拡張装置
５０１…感光材料
６００…ホログラム原版
Ａ…光ビームの入射位置
Ｂ…光ビーム
Ｂｒ…光分配面ξからの反射光
Ｂｔ…光分配面ξからの透過光
Ｃ…コーナリフレクタの頂点
Ｃｉｎ…入射点
Ｃｏｕｔ…射出点
Ｄ，Ｄａ，Ｄ１〜Ｄ３，Ｄ１ａ〜Ｄ３ａ，Ｄ１ｂ〜Ｄ３ｂ…迂回光路
ｄ，ｄｄ…位置の変位量
Ｅ…露光面
Ｇ１，Ｇ２…遮断手段（光シャッター）
Ｉ（Ｐ０，α０）…基準情報
Ｌ１…入射光
Ｌ２…入射光透過光
Ｌ３…入射光反射光
Ｌ４…迂回光
Ｌ５，Ｌ５^＊…角度調節光
Ｌ６…位置角度調節光
Ｌ７…調節光透過光
Ｌ８…調節光反射光
Ｌ９，Ｌ９^＊…位置調節光
Ｌ１０，Ｌ１１，Ｌ１２…検出用光ビーム
Ｌ１５…変動した光ビーム
Ｌｉｎ…入射光
Ｌｏｕｔ，Ｌｏｕｔ^＊…射出光
Ｌｒ，Ｌｇ，Ｌｂ…各原色ビーム
Ｌｇｂ，Ｌｒｇｂ…合成ビーム
ＬＬｒｇｂ…径が拡大された合成ビーム
Ｎ…光分配面ξ上の法線
Ｐ，Ｐ１…検出対象となる光ビームの位置
Ｐ０…基準情報となる位置
Ｑ…目標点
Ｑｉｎ…入射点
Ｑｏｕｔ…射出点
Ｑ１０，Ｑ１１，Ｑ１２，Ｑ１５…照射点
Ｑ２０，Ｑ２１，Ｑ２２，Ｑ２５…集光点
Ｓ…基準光路
α…検出対象となる光ビームの射出角度
α０…基準情報となる角度
η…反射面
θ…調節角度
μ…反射面
ξ，ξ１ｘ，ξ２ｘ…光分配面
ρ１，ρ２…反射面
ω１〜ω２…回転軸[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exposure apparatus, and more particularly, to an exposure apparatus that is required when a hologram image is exposed on a photosensitive material layer and requires high-precision optical axis adjustment.
[0002]
[Prior art]
As a method of forming a fine pattern, a method of irradiating a predetermined exposed surface with light and partially exposing a photosensitive material layer placed on the exposed surface is a method of manufacturing a semiconductor device or a method of forming a hologram image. Widely used in the formation process. An exposure apparatus used for such an exposure operation usually has a structure in which a light beam generated by a beam source is guided to an exposure surface, the beam diameter is expanded to a required size, and then the exposure surface is irradiated. have. In order to guide the light beam to a correct position, it is important to adjust the position of the optical axis correctly in the optical system for guiding the light beam. Generally, the optical axis of a light beam is adjusted by a device combining optical elements such as a reflecting mirror and a prism. In some cases, the adjustment is performed manually by a worker. The adjustment may be performed by automatic control based on
[0003]
[Problems to be solved by the invention]
Usually, the cross-sectional intensity of a light beam generated by a beam source often has a Gaussian distribution, and the intensity is higher at the center of the beam cross-section. For this reason, an intensity distribution also occurs in the irradiation light on the exposure surface, and the exposure operation is performed in consideration of the existence of such an intensity distribution. Therefore, if the optical axis position of the light beam guided to the exposure surface shifts, an unexpected shift occurs in the irradiation light intensity distribution on the exposure surface, which is not preferable. In particular, in the case of exposing a hologram image, even if there is a slight change in the irradiation light intensity distribution, the reproduced image may be unclear, and the optical axis must be adjusted with extremely high precision.
[0004]
In order to perform such optical axis adjustment, various optical axis adjustment devices have been used so far. However, the conventionally used optical axis adjusting device can accurately adjust the light beam emitted from the beam source to a predetermined position on the exposure surface, but does not operate the beam source itself. It is not possible to prevent a phenomenon in which the optical axis shifts due to a stable element or aging. For example, when a laser light source is used as a beam source, the output of laser light is not stable for a while after the power is turned on, and the optical axis often remains unstable. For this reason, even if the optical axis is strictly adjusted, correct exposure cannot be performed until the output of the laser light source is stabilized. In addition, since the characteristics of the laser light source change over time, even if the optical axis is strictly adjusted in the past, the optical axis gradually shifts over a long period of use. In such a case, it is necessary to perform the optical axis adjustment work each time, which imposes a great workload on the operator.
[0005]
Therefore, an object of the present invention is to provide an exposure apparatus that can reduce the operation of adjusting the optical axis of a light beam.
[0006]
[Means for Solving the Problems]
The gist of the present invention is to provide an exposure apparatus for exposing a photosensitive material arranged on an exposure surface by irradiating light to a predetermined exposure surface, thereby forming a beam for generating a light beam composed of a plane polarized wave. A light source generated by the beam source, a beam guiding unit for guiding the light beam along the predetermined reference optical path to the exposure surface, and a diameter of the light beam guided by the beam guiding unit to a size of the exposure surface. A beam diameter expanding device that expands in response to the light beam, and an optical axis adjusting device that is disposed on the reference optical path and adjusts the optical axis of the light beam so as to be maintained on the reference optical path. .
[0007]
Here, the optical axis adjusting device is a novel optical axis adjusting device developed for realizing the exposure apparatus according to the present invention, and the optical axis adjusting device is configured to advance the optical axis so that the light beam travels along a predetermined reference optical path. This is an apparatus having an automatic optical axis adjustment function such that, even when incident light deviates from the reference optical path while adjustment is being performed, emitted light can maintain a state along the reference optical path. As will be described later, there are some embodiments of such an optical axis adjusting device, and the present invention can be grasped as some embodiments depending on which optical axis adjusting device is used. Hereinafter, each aspect of these optical axis adjusting devices will be described.
[0008]
(1) A first embodiment of an optical axis adjusting device used in an exposure apparatus according to the present invention is described below with reference to FIGS. It incorporates the improvements described in Section 4.
That is, when a light beam is present along the reference optical path passing through the incident point and the exit point, by disposing the light beam between the incident point and the exit point, even if the incident light deviates from the reference optical path, In an optical axis adjusting device having a function of adjusting an optical axis so that light maintains a state along a reference optical path,
When a plane-polarized wave having a first plane of polarization is irradiated, the plane-polarized wave having a second plane of polarization perpendicular to the first plane of polarization is transmitted through most of the plane and reflected the rest. When is irradiated, the incident side beam distribution means having a light distribution surface that reflects most of the light and transmits the rest, and is disposed on the incident point side of the reference optical path,
When a plane polarized wave having a first plane of polarization is irradiated, a large part of the plane is transmitted and the rest is reflected. An emission-side beam distribution unit having a light distribution surface that reflects a part and transmits the rest, and is disposed on the emission point side of the reference optical path,
Of the plane polarized wave having the first polarization plane incident along the reference optical path, the plane polarized wave is obtained by transmitting through the light distribution plane of the incident side beam distribution unit and reflecting on the light distribution plane of the exit side beam distribution unit. With respect to the reflected light, a reference information acquisition unit that measures the position and orientation of the emission side beam distribution unit on the light distribution surface, and acquires the measurement result as reference information,
In the plane polarized wave having the second polarization plane incident along the reference optical path, the reflected light obtained by being reflected by the light distribution plane of the incident side beam distribution means is guided to a detour optical path different from the reference optical path. An optical path detour adjusting means for adjusting the position and direction of the guided light beam to irradiate the exit point side of the light distribution surface of the emission side beam distribution means;
With respect to the transmitted light obtained from the light distribution surface of the emission side beam distribution means based on the light beam passing through the bypass optical path, the position and direction on the light distribution surface of the emission side beam distribution means are measured, and this measurement result is used as a reference. Control means for controlling the light path detour adjustment means so as to approach information;
Is provided.
[0009]
(2) A second mode of the optical axis adjusting device used in the exposure apparatus according to the present invention is similar to the optical axis adjusting device according to Embodiment A described in §2 described later with reference to FIG. The invention relates to an optical axis adjusting device having a configuration in which a light beam is guided to a detour optical path, an angle is adjusted first, and then a position is adjusted.
That is, when a light beam is present along the reference optical path passing through the incident point and the exit point, by disposing the light beam between the incident point and the exit point, even if the incident light deviates from the reference optical path, In an optical axis adjusting device having a function of adjusting an optical axis so that light maintains a state along a reference optical path,
When the plane polarized wave having the first plane of polarization is irradiated, most of the plane polarized wave is transmitted, the rest is reflected toward a predetermined detour optical path, and the second plane orthogonal to the first plane of polarization is reflected. When a plane-polarized wave having a polarization plane is irradiated, most of the light is reflected as detour light directed to the detour optical path, and has a light distribution surface that transmits the rest, and is disposed on the incident point side of the reference optical path. Incident side beam distribution means,
When a plane-polarized wave having a first plane of polarization is irradiated, most of the plane-polarized wave is transmitted as incident light transmitted light, and the rest is reflected as incident light reflected light, and the plane-polarized light having the second plane of polarization is reflected. When a wave is irradiated, an emission-side beam that has a light distribution surface that reflects most of the wave as adjustment light reflected light and transmits the rest as adjustment light transmission light, and is disposed on the emission point side of the reference optical path. Dispensing means;
Angle adjusting means for changing the direction of the detour light by a predetermined set angle and emitting it as angle adjusting light,
The angle adjustment light is incident, and the position angle adjustment light parallel to the angle adjustment light and passing through a position shifted by a predetermined set amount of displacement is directed toward the emission point side of the light distribution surface of the emission side beam distribution means. By emitting, the position angle adjusting light is adjusted to be distributed to the adjusting light reflected light consisting of the reflected most part and the adjusting light transmitting light consisting of the remaining part transmitted, and position adjusting means,
When a plane-polarized wave having a first plane of polarization is irradiated on the incident point, the position and direction of the reflected light on the light distribution surface of the exit-side beam distribution means are detected, and the second plane of polarization is detected on the incident point. When the plane-polarized wave having is irradiated, the detecting means for detecting the position and direction of the adjustment light transmitted light on the light distribution surface of the emission-side beam distribution means,
Storage means for storing the position and orientation detected by the detection means as reference information when the plane of polarization having the first polarization plane is applied to the incident point;
When the incident point is irradiated with the plane-polarized wave having the second plane of polarization, the position and the direction detected by the detection unit approach the position and the direction of the reference information stored in the storage unit, Control means having a function of controlling a set angle by the angle adjusting means and a set displacement amount by the position adjusting means,
Is provided.
[0010]
(3) A third mode of the optical axis adjusting device used in the exposure apparatus according to the present invention is similar to the optical axis adjusting device according to the embodiment B described later in §2 with reference to FIG. It incorporates the improvements to be described, and has a configuration in which, after guiding the light beam to the detour optical path, the position is adjusted first, and then the angle is adjusted, contrary to the second aspect described above. And an optical axis adjusting device.
That is, when a light beam is present along the reference optical path passing through the incident point and the exit point, by disposing the light beam between the incident point and the exit point, even if the incident light deviates from the reference optical path, In an optical axis adjusting device having a function of adjusting an optical axis so that light maintains a state along a reference optical path,
When the plane polarized wave having the first plane of polarization is irradiated, most of the plane polarized wave is transmitted, the rest is reflected toward a predetermined detour optical path, and the second plane orthogonal to the first plane of polarization is reflected. When a plane-polarized wave having a polarization plane is irradiated, most of the light is reflected as detour light directed to the detour optical path, and has a light distribution surface that transmits the rest, and is disposed on the incident point side of the reference optical path. Incident side beam distribution means,
When a plane-polarized wave having a first plane of polarization is irradiated, most of the plane-polarized wave is transmitted as incident light transmitted light, and the rest is reflected as incident light reflected light, and the plane-polarized light having the second plane of polarization is reflected. When a wave is irradiated, an emission-side beam that has a light distribution surface that reflects most of the wave as adjustment light reflected light and transmits the rest as adjustment light transmission light, and is disposed on the emission point side of the reference optical path. Dispensing means;
Position adjusting means for injecting detour light, emitting position adjustment light parallel to the detour light and passing through a position shifted by a predetermined set displacement amount,
By emitting the position angle adjustment light obtained by changing the direction of the position adjustment light by a predetermined set angle toward the emission point side of the light distribution surface of the emission side beam distribution means, the position angle adjustment light is Angle adjusting means for causing the adjustment light to be distributed to the adjustment light reflected light consisting of most of the reflected light, and the adjustment light transmitted light consisting of the remaining part, and
When a plane-polarized wave having a first plane of polarization is irradiated on the incident point, the position and direction of the reflected light on the light distribution surface of the exit-side beam distribution means are detected, and the second plane of polarization is detected on the incident point. When the plane-polarized wave having is irradiated, the detecting means for detecting the position and direction of the adjustment light transmitted light on the light distribution surface of the emission-side beam distribution means,
Storage means for storing the position and orientation detected by the detection means as reference information when the plane of polarization having the first polarization plane is applied to the incident point;
When the incident point is irradiated with the plane-polarized wave having the second plane of polarization, the position and the direction detected by the detection unit approach the position and the direction of the reference information stored in the storage unit, Control means having a function of controlling a set angle by the angle adjusting means and a set displacement amount by the position adjusting means,
Is provided.
[0011]
(4) A fourth mode of the optical axis adjusting device used in the exposure apparatus according to the present invention is similar to the optical axis adjusting device according to Embodiment C described in §2 described later with reference to FIG. The optical axis adjusting device according to the above-described second aspect is characterized in that the incident side beam distributing means also serves as an angle adjusting means.
That is, when a light beam is present along the reference optical path passing through the incident point and the exit point, by disposing the light beam between the incident point and the exit point, even if the incident light deviates from the reference optical path, In an optical axis adjusting device having a function of adjusting an optical axis so that light maintains a state along a reference optical path,
When the plane polarized wave having the first plane of polarization is irradiated, most of the plane polarized wave is transmitted, the rest is reflected toward a predetermined detour optical path, and the second plane orthogonal to the first plane of polarization is reflected. When a plane-polarized wave having a polarization plane is irradiated, most of the light is reflected as detour light directed to the detour optical path, and has a light distribution surface that transmits the rest, and is disposed on the incident point side of the reference optical path. And, incident side beam distribution means having an angle adjustment function of changing the direction of the detour light by a predetermined set angle and emitting the light as angle adjustment light,
When a plane-polarized wave having a first plane of polarization is irradiated, most of the plane-polarized wave is transmitted as incident light transmitted light, and the rest is reflected as incident light reflected light, and the plane-polarized light having the second plane of polarization is reflected. When a wave is irradiated, an emission-side beam that has a light distribution surface that reflects most of the wave as adjustment light reflected light and transmits the rest as adjustment light transmission light, and is disposed on the emission point side of the reference optical path. Dispensing means;
The angle adjustment light is incident, and the position angle adjustment light parallel to the angle adjustment light and passing through a position shifted by a predetermined set amount of displacement is directed toward the emission point side of the light distribution surface of the emission side beam distribution means. By emitting, the position angle adjusting light is adjusted to be distributed to the adjusting light reflected light consisting of the reflected most part and the adjusting light transmitting light consisting of the remaining part transmitted, and position adjusting means,
When a plane-polarized wave having a first plane of polarization is irradiated on the incident point, the position and direction of the reflected light on the light distribution surface of the exit-side beam distribution means are detected, and the second plane of polarization is detected on the incident point. When the plane-polarized wave having is irradiated, the detecting means for detecting the position and direction of the adjustment light transmitted light on the light distribution surface of the emission-side beam distribution means,
Storage means for storing the position and orientation detected by the detection means as reference information when the plane of polarization having the first polarization plane is applied to the incident point;
When the incident point is irradiated with the plane-polarized wave having the second plane of polarization, the position and the direction detected by the detection unit approach the position and the direction of the reference information stored in the storage unit, Control means having a function of controlling a set angle by the incident side beam distribution means and a set displacement amount by the position adjustment means,
Is provided.
[0012]
(5) A fifth mode of the optical axis adjusting apparatus used in the exposure apparatus according to the present invention is described in the optical axis adjusting apparatus according to the embodiment D described later in §2 with reference to FIG. The optical axis adjusting device according to the above-described third aspect is characterized in that the incident side beam distributing means also serves as the position adjusting means.
That is, when a light beam is present along the reference optical path passing through the incident point and the exit point, by disposing the light beam between the incident point and the exit point, even if the incident light deviates from the reference optical path, In an optical axis adjusting device having a function of adjusting an optical axis so that light maintains a state along a reference optical path,
When the plane polarized wave having the first plane of polarization is irradiated, most of the plane polarized wave is transmitted, the rest is reflected toward a predetermined detour optical path, and the second plane orthogonal to the first plane of polarization is reflected. When a plane-polarized wave having a polarization plane is irradiated, most of the light is reflected as detour light directed to the detour optical path, and has a light distribution surface that transmits the rest, and is disposed on the incident point side of the reference optical path. Incident side beam distributing means having a position adjusting function of shifting the detour light in parallel by a predetermined set displacement amount and emitting the same as position adjusting light;
When a plane-polarized wave having a first plane of polarization is irradiated, most of the plane-polarized wave is transmitted as incident light transmitted light, and the rest is reflected as incident light reflected light, and the plane-polarized light having the second plane of polarization is reflected. When a wave is irradiated, an emission-side beam that has a light distribution surface that reflects most of the wave as adjustment light reflected light and transmits the rest as adjustment light transmission light, and is disposed on the emission point side of the reference optical path. Dispensing means;
By emitting the position angle adjustment light obtained by changing the direction of the position adjustment light by a predetermined set angle toward the emission point side of the light distribution surface of the emission side beam distribution means, the position angle adjustment light is Angle adjusting means for causing the adjustment light to be distributed to the adjustment light reflected light consisting of most of the reflected light, and the adjustment light transmitted light consisting of the remaining part, and
When a plane-polarized wave having a first plane of polarization is irradiated on the incident point, the position and direction of the reflected light on the light distribution surface of the exit-side beam distribution means are detected, and the second plane of polarization is detected on the incident point. When the plane-polarized wave having is irradiated, the detecting means for detecting the position and direction of the adjustment light transmitted light on the light distribution surface of the emission-side beam distribution means,
Storage means for storing the position and orientation detected by the detection means as reference information when the plane of polarization having the first polarization plane is applied to the incident point;
When the incident point is irradiated with the plane-polarized wave having the second plane of polarization, the position and the direction detected by the detection unit approach the position and the direction of the reference information stored in the storage unit, Control means having a function of controlling the set displacement amount by the incident side beam distribution means and the set angle by the angle adjustment means,
Is provided.
[0013]
(6) A sixth aspect of the present invention is directed to an exposure apparatus using the optical axis adjusting device according to the first to fifth aspects, wherein:
A first blocking unit that can block, as necessary, light that passes through the light distribution surface of the incident-side beam distribution unit and travels toward the light distribution surface of the emission-side beam distribution unit;
A second blocking unit that can block, as necessary, light that is reflected on the light distribution surface of the incident-side beam distribution unit and travels along the bypass optical path;
Is further provided.
[0014]
(7) A seventh aspect of the present invention is an exposure apparatus using the optical axis adjusting device according to the second to fifth aspects described above,
A detecting beam splitter for splitting the detecting light beam from the light splitting surface of the emission side beam splitting device into two beams, and a position detector for detecting a position based on the split first beam And a direction detector for detecting a direction based on the distributed second beam.
[0015]
(8) An eighth aspect of the present invention is directed to an exposure apparatus using the optical axis adjusting device according to the seventh aspect, wherein:
The position detector is constituted by a light receiving element for detecting a beam irradiation position on a predetermined light receiving surface.
[0016]
(9) A ninth aspect of the present invention is directed to an exposure apparatus using the optical axis adjusting device according to the seventh aspect, wherein:
The direction detector has a condensing lens for converging parallel light rays to a predetermined focal point, and a light receiving surface disposed at a position apart from the converging lens by a focal distance, and a condensing position on the light receiving surface And a light receiving element that detects
[0017]
(10) A tenth aspect of the present invention is directed to an exposure apparatus using the optical axis adjusting device according to the first to ninth aspects,
A plurality of beam sources each generating a light beam for each color component;
In the process of guiding the light beam for each color component to the exposure surface, beam combining means for combining these light beams,
An optical axis adjustment device for each color component arranged on a reference optical path for each color component,
Is provided.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on an illustrated embodiment.
[0019]
The feature of the exposure apparatus according to the present invention is that the optical axis of the light beam is automatically adjusted by incorporating a unique optical axis adjustment device on the reference optical path of the light beam from the beam source to the exposure surface. On the point. The basic configuration of this unique optical axis adjusting device is disclosed in Japanese Patent Application No. 2001-28354. Therefore, in §1 to §3, the configuration and operation of this unique optical axis adjusting device will be described in detail. Specifically, first, §1 describes the basic principle of a unique optical axis adjusting device, §2 describes a basic embodiment based on this principle, and §3 describes a more specific embodiment. I do.
[0020]
Further, in §4, improvements made by using a polarizing beam splitter in this unique optical axis adjusting device are described, and in the last §5, the overall configuration of an exposure apparatus using the improved optical axis adjusting device is described. I will do it.
[0021]
<<<< §1. Basic principle of optical axis adjustment device >>>>>
First, the basic principle of a unique optical axis adjusting device used in the exposure apparatus according to the present invention will be briefly described. The main purpose of this optical axis adjustment device is to prevent the optical axis, whose optical axis has already been adjusted, from being deviated from the optical axis due to unstable operation elements or aging. To stably maintain a light beam passing through the optical path.
[0022]
Now, as shown in FIG. 1, a case where a light beam is irradiated from a beam source 100 to a target point Q of a target 200 is considered. Here, it is assumed that the beam source 100 incorporates a light source that generates a light beam and an optical system (optical axis adjustment device) that adjusts the optical axis of the light beam. The adjustment is performed by adjusting the built-in optical system. As described above, the conventional general optical axis adjustment device aims at performing positive position adjustment to match the aim of the light beam with a predetermined target point, and is built in the beam source 100. The optical beam can be made to reach the target point Q on the target 200 by the optical axis adjusting operation using the optical axis adjusting device. When such an optical axis adjustment operation is completed, the light beam emitted from the beam source 100 travels along a reference optical path S (indicated by a dashed line in the figure) from the incident point Qin to the emission point Qout, and reaches the target. The point Q is reached.
[0023]
As shown in FIG. 1, once the optical axis adjustment operation is completed, theoretically, the light beam emitted from the beam source 100 always passes through the reference optical path S to the target point Q. In practice, however, a phenomenon occurs in which the adjusted optical axis shifts due to unstable factors in the operation of the beam source 100 itself, aging, and the like. For example, if the beam source 100 is used for a long time, the mounting position of the beam source 100 itself may be displaced due to the influence of vibration or the like on the beam source 100. Then, as shown in FIG. 2, the light beam B emitted from the beam source 100 does not correctly enter the position of the incident point Qin, and deviates from the reference optical path S. Therefore, the light beam B deviates from the target point Q on the target 200. Of course, even if no displacement occurs in the mounting position of the beam source 100 itself, the same result will be obtained even if a position displacement occurs in each optical element constituting the optical system inside the beam source 100. Further, even if the optical system itself has not been displaced, there is a possibility that the light beam B may fluctuate based on unstable factors inherent to the light source. For example, when a laser light source or the like is used, the operation is often unstable for a while immediately after startup. Further, the light beam B may fluctuate due to disturbance such as fluctuation of the power supply voltage.
[0024]
The aim of the optical axis adjusting device used in the present invention is that, as in the example shown in FIG. 1, a predetermined reference optical path S from the incident point Qin to the emission point Qout has already been set. When an incident light beam deviates from the reference optical path S for some reason in the future when there is a light beam traveling forward, an automatic optical axis that allows the emitted light to maintain the state along the reference optical path S can be maintained. To make adjustments. In other words, as shown in FIG. 3, in a state where the predetermined reference optical path S has already been set, the optical axis adjusting device 300 is inserted and installed between the incident point Qin and the exit point Qout. By doing so, even if the light incident on the optical axis adjustment device 300 fluctuates for some reason in the future, the light emitted from the optical axis adjustment device 300 can be maintained in the original state. That is the purpose. That is, in a state where the light beam from the beam source 100 is correctly adjusted along the reference optical path S, as shown in FIG. If it is inserted above, as shown in FIG. 4, even if the optical axis on the side of the beam source 100 fluctuates and the incident condition of the light beam B to the optical axis adjusting device 300 changes, the optical axis adjusting device 300 The optical axis is automatically adjusted to maintain the same conditions as before. Hereinafter, the basic principle for performing such automatic optical axis adjustment will be described.
[0025]
Now, as shown in FIG. 5, when the reference optical path S is set from the incident point Qin to the exit point Qout, it is assumed that the light distribution surface 配置 is arranged on the reference optical path S. This light distribution surface ξ is a surface having a property of reflecting a part of the irradiated light and transmitting a part of the light. Here, a beam distribution means having a light distribution surface の such as a half mirror is connected to a reference optical path. Consider the case where they are arranged on S. When such a beam distributing unit is arranged on the reference optical path S, the light beam B incident on the incident point Qin along the reference optical path S is distributed by the beam distributing unit into two light beams. . In other words, a part of the light is transmitted through the light distribution surface そのまま as it is to become transmitted light Bt, and a part is reflected by the light distribution surface ξ and becomes reflected light Br. At this time, the transmitted light Bt passes through the position P0 on the light distribution surface ξ along the reference optical path S and becomes light emitted from the emission point Qout, while the reflected light Br is emitted at the position P0 on the light distribution surface ξ. At this time, the light changes its direction and goes upward in the figure. Here, assuming that a normal line at the position P0 on the light distribution surface ξ is N, the incident angle and the reflection angle of the light beam B are equal, and both become the angle α0.
[0026]
Therefore, the position P0 and the direction (for example, the reflection angle α0) on the light distribution surface ξ of the reflected light Br obtained at this time are measured, and the measurement result is obtained as reference information. The illustrated reference information obtaining means 1 is a component having a function of obtaining such reference information I (P0, α0) (a specific configuration example will be described later). Such a reference information obtaining operation is performed in a state where the optical axis of the light beam B is correctly adjusted along the reference optical path S (in other words, the transmitted light Bt is shifted along the reference optical path S to a predetermined target point). ).
[0027]
In order to make this unique optical axis adjusting device 300 function, it is necessary to add an optical path detour adjusting means 2 to this system as shown in FIG. In the figure, for convenience, the optical path detour adjusting means 2 is shown as a simple block, but actually, the optical path detour adjusting means 2 is constituted by a plurality of optical elements. The light path detour adjusting means 2 guides the light beam B of the incident light to a detour light path D different from the reference light path S, if necessary, and adjusts the position and direction of the guided light beam to adjust the light distribution surface. Has the function of irradiating ξ. In the illustrated example, the detour optical path D includes optical paths D1, D2, and D3, all of which are indicated by two-dot chain lines. The position and direction of the light beam guided to the detour optical path D are adjusted by the optical path detour adjusting means 2. Here, “position adjustment” is a process of translating the optical path of the light beam by a predetermined set displacement amount, and “adjustment of the direction” is a process of changing the optical path of the light beam by a predetermined set angle. It is. Of course, when such a position and orientation adjustment is performed on the detour optical path D, the detour optical path D itself changes. Therefore, the “detour light path D” in the present application does not mean a fixed specific path, but means an irregular path that changes in various ways depending on the position and orientation adjustment processing. The “position adjustment” and “direction adjustment” will be described later in detail with specific examples.
[0028]
In this way, the light beam that has passed through the detour optical path D is radiated to the light distribution surface 、. It depends on the position and orientation of the shot. Here, it is assumed that as a result of the adjustment of the position and the direction performed in the detour optical path D, the light beam along the optical path D3 in FIG. 6 is applied to the position P on the light distribution surface ξ. As described above, the light distribution surface ξ is a surface having a property of reflecting a part of the irradiated light and transmitting a part of the light, and the light beam passing through the bypass optical path D is separated by the light distribution surface ξ. It will be split into two light beams. In other words, a part of the light is transmitted through the light distribution surface そのまま as it is to become transmitted light Bt, and a part is reflected by the light distribution surface ξ and becomes reflected light Br. At this time, assuming that the normal line at the position P is N, the angle between the transmitted light Bt and the normal line N and the angle between the reflected light Br and the normal line N are equal to each other (α). Of course, the angle between the optical path D3 and the normal N is also the angle α).
[0029]
Subsequently, for the transmitted light Bt obtained at this time, the position P and the direction (for example, the reflection angle α) on the light distribution surface ξ are measured. Of course, this measurement result is usually different from the reference information I (P0, α0) previously obtained by the reference information obtaining means 1 shown in FIG. 5 (as can be seen by comparing FIG. 5 and FIG. 6). , The position P does not coincide with the position P0, and the angle α does not coincide with the angle α0). Therefore, the optical path detour adjusting means 2 is controlled so that the measurement result approaches the reference information I (P0, α0). The control means 3 shown in FIG. 6 measures the position and direction of the transmitted light Bt on the light distribution surface ξ, and adjusts the light path detour adjustment means 2 so that the measurement result approaches the reference information I (P0, α0). Is a component having a function of controlling As described above, since the optical path detour adjusting means 2 has a function of adjusting the position and the direction of the light beam on the detour optical path D, the measurement result by the control means 3 is based on the reference information I (P0, α0). It is possible to perform feedback control that matches with.
[0030]
FIG. 7 shows a state in which the feedback result by the control means 3 has reached a point where the measurement result completely matches the reference information I (P0, α0). The detour path Da guided by the light path detour adjusting means 2 is composed of light paths D1a, D2a, and D3a, and is different from the detour light path D shown in FIG. As a result, the irradiation position P of the light beam on the light distribution surface ξ via the detour light path Da coincides with the position P0 shown in FIG. 5, and the positions P and The direction (for example, the reflection angle α) completely matches the reference information I (P0, α0) (P = P0, α = α0). Comparing FIG. 5 with FIG. 7, the reflected light Br in FIG. 5 completely matches the transmitted light Bt in FIG. 7, and the transmitted light Bt in FIG. 5 completely matches the reflected light Br in FIG. You can see that it is. The important point here is that the reflected light Br and the transmitted light Bt shown in FIG. 5 are light beams obtained by distributing the light beam passing through the reference optical path S, whereas the transmitted light shown in FIG. The point is that Bt and the reflected light Br are light beams obtained by distributing the light beam that has passed on the bypass optical path Da. Here, just like the transmitted light Bt shown in FIG. 5 is emitted from the emission point Qout as a light beam along the reference optical path S, the reflected light Br shown in FIG. Considering that the light beam is emitted as a light beam along the path, the point that “the emitted light along the reference optical path S is obtained from the emission point Qout” even though the detour by the optical path detour adjusting means 2 is performed. As for the state, there is no change in the state of FIG. 7 as compared with the state of FIG.
[0031]
This is because, in a state where a predetermined reference optical path S is set as shown in FIG. 1, an optical axis adjusting device 300 according to the present invention is inserted on this reference optical path S as shown in FIG. Even if the incoming light beam is detoured to the detour optical path by the detour optical path adjusting device 2 inside the optical axis adjusting device 300, the light traveling from the optical axis adjusting device 300 to the target point Q along the reference optical path S is also possible. It means that it is possible to emit a beam. More specifically, as shown in FIG. 3, when the optical axis adjusting device 300 is inserted on the reference optical path S, as shown in FIG. In this way, the incident light beam B is guided to the light distribution surface そのまま as it is, and the reference information obtaining means 1 performs the operation of obtaining the reference information I (P0, α0). Subsequently, the detour by the optical path detour adjusting means 2 is performed, and the incident light beam B is guided to the detour optical path D. As described above, when the path of the incident light beam B is switched to the bypass light path D, the reflected light Br from the light distribution surface ξ is not reflected by the light beam along the reference light path S as shown in FIG. Therefore, the light beam emitted from the optical axis adjusting device 300 is out of the reference optical path S. However, since the above-described feedback control is performed, the detour optical path D eventually changes to the detour optical path Da as shown in FIG. 7, and the reflected light Br from the light distribution surface ξ becomes a light beam along the reference optical path S. The light beam emitted from the optical axis adjusting device 300 follows the reference optical path S.
[0032]
After all, as shown in FIG. 3, when the optical axis adjusting device 300 according to the present invention is inserted on the existing reference optical path S, the light from the beam source 100 is initially The beam deviates from the target point Q on the target 200. However, when the feedback control system becomes stable, the light beam returns to the state where the target point Q is irradiated as before. Therefore, even if the optical axis adjusting device 300 according to the present invention is inserted into the existing reference optical path S for which the optical axis adjustment has already been completed, the optical axis will temporarily fluctuate, but the original state will be immediately obtained. Therefore, the entire system from the beam source 100 to the target 200 can be used as it is. In addition, by inserting the optical axis adjusting device 300, even if the incident light to the optical axis adjusting device 300 fluctuates for some reason in the future, the light emitted from the optical axis adjusting device 300 remains in the original state. The automatic optical axis adjustment is maintained. That is, as shown in FIG. 4, even if the optical axis on the side of the beam source 100 fluctuates and the incident condition of the light beam B on the optical axis adjusting device 300 changes, the light emitted from the optical axis adjusting device 300 remains unchanged. Automatic optical axis adjustment that maintains the same conditions as described above will be performed.
[0033]
This is because the following feedback control is performed. For example, although the light beam B along the reference optical path S should originally be given to the incident point Qin as shown in FIG. 7, for some reason, as shown in FIG. Suppose the incident condition of B fluctuates. When such a change occurs, the measurement result of the position P and the direction α of the transmitted light Bt measured by the control unit 3 does not match the reference information I (P0, α0) acquired in advance, and therefore, The feedback will work in the direction to match. As a result, the detour optical path Da shown in FIG. 7 is changed to the detour optical path Db (constituted of the optical paths D1b, D2b, and D3b) shown in FIG. 8, and again on the light distribution plane 透過 for the transmitted light Bt. , The position P and the direction (for example, the reflection angle α) completely match the reference information I (P0, α0) (P = P0, α = α0). Thus, even if the incident condition of the light beam B fluctuates, if the feedback control system becomes stable, the reflected light Br from the light distribution surface ξ is emitted again along the reference light path S. You will return to the state.
[0034]
The above is the basic principle of the optical axis adjusting device used in the present invention. With such a basic principle, a function of stably maintaining a light beam passing through an existing optical path can be realized.
[0035]
Note that the principle explained so far has been described using drawings on a two-dimensional plane, and thus the description has been made with a limited degree of freedom in position and direction. However, in practice, the optical path of the light beam is three-dimensional space. And, of course, the degree of freedom in position and orientation depends on the three-dimensional space. For example, in the example shown in FIG. 6, the light distribution plane ξ is shown as a one-dimensional line segment, and the position P on this light distribution plane ξ has only one-dimensional freedom to move on this line segment. However, in practice, the position P has a two-dimensional degree of freedom to move in a direction perpendicular to the plane of the drawing. Similarly, in the example shown in FIG. 6, the direction of each light beam is represented by an angle α on a two-dimensional plane, but in reality, the direction of each light beam is limited to this two-dimensional plane. However, since it can be directed to any direction in the three-dimensional space, if it is expressed by an angle, it is expressed by two kinds of angle parameters such as an angle αxy with respect to the XZ plane and an angle αyz with respect to the YZ plane. Will be done. Therefore, the optical path detour adjusting means 2 has a function of adjusting the position and direction of the light beam with a degree of freedom in a three-dimensional space, and the control means 3 has a function of performing feedback control in consideration of such degrees of freedom. Having.
[0036]
<<<< §2. Basic embodiment >>>>>
Subsequently, four basic embodiments of the optical axis adjusting device used in the exposure apparatus according to the present invention will be described.
(A) FIG. 9 is a block diagram illustrating a configuration of an optical axis adjusting device according to a basic embodiment A. The feature of this optical axis adjusting device is that after guiding the light beam to the detour optical path, first, angle adjustment (adjustment of direction) is performed, and then position adjustment is performed.
[0037]
As already described in §1, this optical axis adjusting device is provided between the incident point Qin and the exit point Qout when the light beam exists along the reference optical path S passing through the incident point Qin and the exit point Qout. Has a function of adjusting the optical axis so that the emitted light maintains the state along the reference optical path S even when the incident light deviates from the reference optical path. As shown, the basic components of this optical axis adjustment device are a beam distribution unit 10, an optical path switching unit 20, an angle adjustment unit 30, a position adjustment unit 40, a detection unit 50, a storage unit 60, and a control unit 70. In relation to the respective components described in the basic principle of §1, the beam distribution means 10 is constituted by a so-called beam splitter and has a function of arranging the light distribution surface に on the reference optical path S. The angle adjusting unit 30 and the position adjusting unit 40 function as the optical path detour adjusting unit 2. In addition, the detection unit 50, the storage unit 60, and the control unit 70 function as the reference information acquisition unit 1 and the control unit 3. Hereinafter, the function of each of these means will be described individually. In the drawing, the one-dot chain line indicates the reference optical path S, the two-dot chain line indicates the bypass optical path, the broken line indicates the detection optical path, and the solid line indicates the path of the electric signal.
[0038]
First, the beam distribution means 10 plays a role in arranging the light distribution surface ξ on the reference optical path S (dashed line in the drawing). As described above, the light distribution surface ξ is a surface having a function of reflecting a part of the irradiated light and transmitting a part of the irradiated light. For example, the incident light L1 incident from the right side of FIG. When the light is applied to the distribution means 10, the light is divided into transmitted light and reflected light on the light distribution surface ξ. Here, the transmitted light generated based on the incident light L1 (the light emitted to the left from the beam distribution unit 10 in the figure) is referred to as incident light transmitted light L2, and the reflected light generated based on the incident light L1 (see FIG. The light emitted upward from the beam distribution means 10 in (1) is referred to as incident light reflected light L3.
[0039]
The optical path switching means 20 is disposed between the incident point Qin and the beam distribution means 10, and is a component for switching the optical path of the incident light L1. That is, the optical path switching unit 20 has a first function of transmitting the incident light L1 as it is and guiding it to the beam distribution unit 10, and changing the direction of the incident light L1 toward a predetermined detour optical path (two-dot chain line in the figure). And the second function of emitting the detour light L4 can be selectively executed. The angle adjusting means 30 has a function of changing the direction of the detour light L4 by a predetermined set angle θ and emitting the angle adjusting light L5, and the position adjusting means 40 receives the angle adjusting light L5, A position angle adjusting light L6 (based on an arbitrary set displacement d) that is parallel to the adjusting light L5 (in the illustrated example, parallel and the traveling direction is opposite) and passes through a position shifted by a predetermined set displacement d. The light that has been subjected to both the position adjustment and the angle adjustment based on the arbitrary set angle θ) emits the light toward the emission point Qout side of the light distribution surface の of the beam distribution means 10.
[0040]
The position angle adjusting light L6 applied to the beam distribution means 10 is distributed by the light distribution surface 光 into transmitted light and reflected light. Here, the transmitted light (light emitted upward from the beam distribution means 10 in the figure) generated based on the position angle adjusting light L6 is referred to as adjusting light transmitted light L7, and generated based on the position angle adjusting light L6. The reflected light (light emitted leftward from the beam distribution means 10 in the figure) is referred to as adjustment light reflected light L8. After all, when the optical path switching means 20 performs the first function, the incident light transmitted light L2 and the incident light reflected light L3 are obtained from the beam distribution means 10, and the optical path switching means 20 performs the second function. In this case, the adjusting light transmission light L7 and the adjusting light reflected light L8 are obtained from the beam distribution means 10.
[0041]
The detecting means 50 has a function of detecting the position and the direction of the incident light reflected light L3 or the adjustment light transmitted light L7 which travels upward from the beam distribution means 10 in the figure. In other words, when the optical path switching means 20 performs the first function, the detecting means 50 detects the position and the direction of the incident light reflected light L3 on the light distribution surface 、, and the optical path switching means 20 When the second function is executed, the position and the direction of the adjustment light transmitting light L7 on the light distribution surface ξ are detected.
[0042]
The storage unit 60 is a component that stores the reference information described in §1. That is, when the optical path switching means 20 is executing the first function, it has a function of storing the position and the direction (the position and the direction of the incident light reflected light L3) detected by the detecting means 50 as reference information. Of course, in the process of storing such reference information, the incident light L1 is correctly incident along the reference optical path S, and the incident light transmitted light L2 emitted from the beam distribution means 10 is transmitted to the target point Q on the target. It is performed in a state where the light is properly irradiated.
[0043]
When the optical path switching unit 20 is executing the second function, the control unit 70 controls the position and the direction (the position and the direction of the adjustment light transmitted light L7 in the illustrated example) detected by the detection unit 50. The function of controlling the set angle θ by the angle adjusting means 30 and the set displacement d by the position adjusting means 40 so as to approach the position and orientation of the reference information stored in the storage means 60. As described in §1, such control is feedback control, and when the control system is in a stable state, the position and the direction detected by the detecting unit 50 match the position and the direction of the reference information. That is, the adjustment light reflected light L8 emitted from the beam distribution means 10 toward the target becomes a light beam along the reference optical path S. Of course, such feedback control is also effective when the incident condition of the incident light L1 fluctuates, and even if the incident light L1 comes out of the reference optical path S, By the feedback control by the control means 70, the adjustment light reflected light L8 emitted from the beam distribution means 10 is adjusted to be a light beam along the reference optical path S.
[0044]
In such feedback control, two control target amounts are set angle θ (control of the direction) and set displacement amount d (control of the position), and these two amounts will be controlled simultaneously. Then, the control operation becomes complicated. Therefore, in practice, the control of the set angle θ and the control of the set displacement d are alternately and repeatedly performed, and the measurement result by the detection unit 50 gradually approaches the reference information stored in the storage unit 60. It is preferable to make it go.
[0045]
(B) FIG. 10 is a block diagram illustrating a configuration of an optical axis adjusting device according to a basic embodiment B. The feature of the embodiment B is that after guiding the light beam to the detour optical path, first, position adjustment is performed, and then angle adjustment (direction adjustment) is performed. The only difference from the embodiment A shown in FIG. 9 is that the order of execution of the angle adjustment and the position adjustment is reversed, and a specific configuration difference is that the angle adjustment means 30 and the position adjustment means 40 are different. It is only that the positional relationship is reversed.
[0046]
That is, by the second function of the optical path switching means 20, when the incident light L1 is guided to the detour light path and is emitted as the detour light L4, first, the position adjustment by the position adjustment means 40 is performed. As a result of this position adjustment, the detour light L4 becomes a position adjustment light L9 passing through a position shifted by a predetermined set displacement d (in the example shown, the detour light L4 and the position adjustment light L9 are parallel and have the same traveling direction. ). Subsequently, the set angle θ is adjusted by the angle adjusting means 30 with respect to the position adjustment light L9, and the position angle adjustment light L6 is obtained. The components involved after the position angle adjusting light L6 is irradiated onto the beam distribution means 10 are exactly the same as those in the embodiment A shown in FIG. 9, and the operation of the optical axis adjusting device is also The operation is exactly the same as that of the embodiment A shown in FIG.
[0047]
(C) FIG. 11 is a block diagram illustrating a configuration of an optical axis adjusting device according to a basic embodiment C. The feature of the embodiment C is that, in the optical axis adjusting device according to the embodiment A shown in FIG. 9, the optical path switching means 20 and the angle adjusting means 30 are replaced by an optical path switching angle adjusting means 35 having a function of both of them. The point is that it has been replaced. The optical path switching angle adjusting means 35 is disposed between the incident point Qin and the beam distribution means 10, and has a first function of transmitting the incident light L1 and changing the direction of the incident light L1 by a predetermined set angle θ. And a second function of emitting the angle adjustment light L5 obtained along with the predetermined detour optical path can be selectively executed. The set angle θ at the time of executing the second function is to be controlled by the control means 70. By controlling the set angle θ, the angle adjusting light L5 can be changed to, for example, L5 indicated by a broken line in FIG. ^* It is possible to adjust the orientation as shown in FIG. Other components and operations are the same as those of the embodiment A shown in FIG.
[0048]
(D) FIG. 12 is a block diagram illustrating a configuration of an optical axis adjustment device according to Embodiment D. The feature of the embodiment D is that, in the optical axis adjusting device according to the embodiment B shown in FIG. 10, the optical path switching unit 20 and the position adjusting unit 40 are replaced by an optical path switching position adjusting unit 45 having a function of both of them. The point is that it has been replaced. The optical path switching position adjusting means 45 is disposed between the incident point Qin and the beam distribution means 10, and has a first function of transmitting the incident light L1 and a function of the detour light L4 obtained by changing the direction of the incident light L1. The second function of emitting the position adjustment light L9 obtained by changing the position by the predetermined set amount of displacement d along the predetermined detour optical path can be selectively executed. The set displacement d at the time of executing the second function is controlled by the control means 70, and by controlling the set displacement d, the position adjusting light L9 is, for example, L9 indicated by a broken line in the figure. ^* It is possible to adjust the position as shown in FIG. In FIG. 12, the two-dot chain line through which the detour light L4 passes out of the three two-dot chain lines going downward from the block showing the optical path switching position adjusting means 45 corresponds to an optical path obtained by simply bending the traveling direction of the incident light L1. In the case of d = 0, the two-dot chain lines located on the left and right sides thereof correspond to the optical path translated in parallel by a predetermined set displacement amount. Other components and operations of the optical axis adjusting device are the same as those of the embodiment B shown in FIG. Note that, instead of parallel movement of the detour light L4 by the predetermined set displacement d, the incident light L1 is directly translated by the set displacement dd shown in the figure, thereby obtaining the position adjustment light L9 facing the left horizontal direction. It does not matter.
[0049]
<<<< §3. Specific Examples >>>>>
In the above §2, four basic embodiments of the optical axis adjusting device have been described, but here, a more specific example will be described with respect to the embodiment C of these four types, and furthermore, I will point out the problem.
[0050]
FIG. 13 is a view showing an example of the above-described embodiment C (optical elements are shown as a plan view, and electrical and mechanical elements are shown as block diagrams). The light reflecting element 81 is an optical element having a reflecting surface η capable of reflecting incident light. A light beam reflected by the reflecting surface η passes through an optical path D1 shown by a two-dot chain line in FIG. To the beam splitter 83 via the optical paths D2 and D3. The beam distributor 83 is an optical element that functions as the beam distributor 10 described in §2, and has a light distribution surface から composed of a half mirror or the like. The detection beam distributor 84 also has a light distribution surface μ composed of a half mirror or the like, and detects the detection light beam traveling upward from the light distribution surface の of the beam distributor 83 in the figure. It has the function of distributing into two beams. The first beam (transmitted light in this example) distributed by the light distribution surface μ is received by the light receiving element 85, and the distributed second beam (reflected light in this example) is collected. The light is received by the light receiving element 87 via the lens 86. Each of the light receiving element 85 and the light receiving element 87 has a two-dimensional planar light receiving surface, and has a function of generating a detection signal indicating a light beam irradiation position on the light receiving surface. Specifically, it may be configured using a PSD (Position Sensing Detector) element or a CCD (Charge Coupled Device) element. The condensing lens 86 is a lens that condenses the parallel light beam at a predetermined focal point, and the light receiving surface of the light receiving element 87 is arranged at a position separated from the condensing lens 86 by the focal length. Therefore, the light receiving element 87 has a function of detecting a position where light is condensed on the light receiving surface.
[0051]
As will be described later, the light receiving element 85 functions as a position detector for detecting the position of the detection light beam from the light distribution surface 、, and the condenser lens 86 and the light receiving element 87 detect the light from the light distribution surface ξ. It functions as a direction detector for detecting the direction of the use light beam. After all, the detection beam splitter 84, the light receiving element 85, the condenser lens 86, and the light receiving element 87 are the components corresponding to the detecting means 50 in the embodiment C shown in FIG. The detection signals from light receiving element 85 and light receiving element 87 are provided to storage device 91 and control device 92. Here, the storage device 91 and the control device 92 are components corresponding to the storage device 60 and the control device 70 in Embodiment C shown in FIG. 11, and are actually configured by a computer having a memory, a microprocessor, and the like. can do.
[0052]
The angle adjusting mechanism 93 is a mechanism that adjusts the direction of the light reflecting element 81 (the direction of the reflecting surface η), and more specifically, two rotation axes ω1 (the reference optical path S and the This is a mechanism having a function of rotating the light reflection element 81 with respect to the axis (the axis passing through the intersection A with the reflection surface η and perpendicular to the plane of the drawing) and ω2. Actually, it is realized by a mechanism using a high-precision stepping motor or the like, but a detailed description of the structure is omitted here. On the other hand, the position adjusting mechanism 94 is a mechanism for adjusting the position of the corner reflector 82. In the case of the example shown here, the corner reflector 82 is moved in the X-axis direction (the left and right directions indicated by + X and -X in the drawing) and the Y direction. It has a function of independently translating in two axial directions (perpendicular to the plane of the drawing). In other words, the position adjusting mechanism 94 has a function to translate the corner reflector 82 along a predetermined plane (XY plane). Although such a position adjusting mechanism 94 is actually realized by a mechanism using a high-precision stepping motor or the like, a detailed description of its structure is omitted here.
[0053]
Here, to further supplement the description of the light reflecting element 81, the light reflecting element 81 can be detachably disposed on the reference optical path S between the incident point Qin and the beam distributor 83. ing. That is, the light reflecting element 81 is attached by the support mechanism 88 shown by hatching in the figure, and the supporting mechanism 88 has a function of supporting the light reflecting element 81 in a detachable manner. The support mechanism 88 may be constituted by a simple mechanical structure such as a rail for supporting the light reflecting element 81. In this case, by inserting and removing the light reflecting element 81 by the operator, the light reflecting element 81 can be arranged or removed. Of course, the support mechanism 88 is constituted by a mechanism having an electric drive function, and is automatically arranged on the reference optical path S or removed from the reference optical path S based on an operation instruction of an operator. It doesn't matter. In short, the first state in which the light reflecting element 81 is not disposed on the reference optical path S and the second state in which the light reflecting element 81 is disposed on the reference optical path S can be selectively adopted. Is arranged on the reference optical path S, if the angle of the reflection surface η can be adjusted so that incident light can be reflected in a desired direction, any mechanical mechanism can be used as the support mechanism 88. A structure may be used.
[0054]
Thus, by supporting the light reflecting element 81 with the support mechanism 88, the light reflecting element 81 functions as the light path switching angle adjusting means 35 in the embodiment C shown in FIG. That is, if the light reflecting element 81 is set to the first state in which the light reflecting element 81 is detached from the reference optical path S, the first function of directly guiding the incident light to the beam distributor 83 is executed, and the light reflecting element When the second state 81 is arranged on the reference optical path S, the second function of guiding the incident light to the predetermined detour optical path and performing the angle adjustment according to the predetermined set angle θ is executed. become.
[0055]
FIG. 14 shows the principle of such angle adjustment. Now, the light reflecting element 81 is installed in the direction shown by the solid line in FIG. 14, and the reflecting surface η of the light reflecting element 81 is irradiated with incident light Lin shown by the solid line in the direction shown in the figure. As a result, consider a state in which the emitted light Lout indicated by the solid line is reflected in the direction shown in the figure. In this state, assuming that the light reflecting element 81 is rotated counterclockwise on the paper surface by θ / 2 to the state shown by the broken line in the figure and the direction of the reflecting surface η is changed, the emitted light becomes the broken line in the figure. Lout indicated by ^* It changes like Here, the emitted light Lout and Lout ^* Is an angle θ. Eventually, when it is desired to make an adjustment to change the direction of the light beam by the angle θ, it is sufficient to perform control to rotate the light reflection element 81 by the angle θ / 2.
[0056]
On the other hand, the corner reflector 82 is an optical element functioning as the position adjusting means 40 in the embodiment C shown in FIG. 11, and reflects light from the light reflecting element 81 (light beam entering through the optical path D1 in FIG. 13). And emits parallel backward light (a light beam exiting through the optical path D3 in FIG. 13). In general, a corner reflector is an optical element in which the inside of three surfaces including the same vertex C among the six surfaces constituting a cube are reflection surfaces, and the incident light is incident at an arbitrary position in these reflection surfaces in an arbitrary direction. Irradiates light that is always parallel to the incident light and is emitted in the opposite direction. In the example shown in FIG. 13, when the incident light along the optical path D1 enters the incident point Cin on the reflection surface ρ1, it becomes reflected light along the optical path D2, and further, the reflected light along this optical path D2 becomes the reflection surface ρ2 The light is reflected at the upper exit point Cout and exits along the optical path D3. In this case, regardless of the position and the incident angle of the incident point Cin, the incident light along the optical path D1 and the emitted light along the optical path D3 are always parallel and opposite directions. In addition, as an optical element having such a property, in addition to the corner reflector, a corner cube prism is known, and as the position adjusting means, a corner cube prism may be used instead of the corner reflector. .
[0057]
FIG. 15 shows the principle of performing position adjustment using the corner reflector 82. Now, a corner reflector 82 is installed at a position shown by a solid line in FIG. 15, and the incident light Lin shown by a solid line is applied to the corner reflector 82 in a direction as shown in FIG. Consider a state in which the emission light Lout indicated by a solid line is emitted in such a direction. In this state, assuming that the corner reflector 82 is moved rightward (+ X direction) on the paper surface by a distance d / 2 to the state shown by the broken line in the figure, the emitted light is represented by Lout shown by the broken line in the figure. ^* It changes like Here, the emitted light Lout and Lout ^* Is a displacement amount d. As a result, when it is desired to make an adjustment to change the position of the light beam by the displacement d, it is sufficient to perform control to move the corner reflector 82 by the displacement d / 2.
[0058]
Subsequently, the functions of the detectors in the optical axis adjusting device shown in FIG. 13, that is, the functions of the detection beam distributor 84, the light receiving element 85, the condenser lens 86, and the light receiving element 87 will be described. In the first state in which the light reflecting element 81 is not disposed on the reference optical path S, the detector detects the detection light beam reflected from the light distribution surface の of the beam distributor 83 on the light distribution surface ξ. In the second function of detecting the position and the direction and the second state in which the light reflecting element 81 is arranged on the reference optical path S, the light beam for detection transmitted through the light distribution surface の of the beam distributor 83 A second function of detecting a position and an orientation on the distribution surface. Regardless of which function is performed, the basic principle of detection is the same, as long as the position P and direction of the detection light beam from the light distribution surface ξ can be measured. Then, the position and the orientation detected by the first function are stored in the storage device 91 as reference information, and the position and the orientation detected by the second function are given to the control device 92. Feedback control is performed on the angle adjustment mechanism 93 and the position adjustment mechanism 94 so that this detection result approaches the reference information stored in the storage device 91.
[0059]
As described above, the detection light beam is split into two beams by the detection beam splitter 84, and the light receiving element 85 detects the position and the light receiving element 87 detects the direction. In the example shown in FIG. 13, on the light receiving surface of the light receiving element 85, the beam is irradiated at the position of the point Q10, and on the light receiving surface of the light receiving element 87, the beam is irradiated at the position of the point Q20. The positions of the points Q10 and Q20 on the light receiving surface are information corresponding to the position P and the direction of the detection light beam on the light distribution surface ξ, respectively.
[0060]
FIG. 16 is a diagram for explaining the principle of position detection performed by the light receiving element 85. Now, assuming that the light beam L10 for detection as shown by a solid line in FIG. 7 reaches the light receiving element 85 from the position P of the light distribution surface ξ through the light distribution surface μ of the detection beam distributor 84. The irradiation point above is point Q10. At this time, the light is reflected from the light distribution surface μ and condensed by the condensing lens 86, and the converging point of the detection light beam reaching the light receiving element 87 is the point Q20. Here, if only the position of the detection light beam on the light distribution plane ξ is shifted from P to P1 (assuming the same direction), the detection light beam L11 has an optical path indicated by a broken line. Through the light-receiving element 85 and the light-receiving element 87. That is, the irradiation point on the light receiving surface of the light receiving element 85 is the point Q11, which is shifted from the original point Q10. On the other hand, the condensing point on the light receiving surface of the light receiving element 87 is the point Q21, which is the same point as the original point Q20. This is because the light receiving surface of the light receiving element 87 is located at the focal position of the condenser lens 86. That is, even if there are a plurality of light beams incident on the condenser lens 86, they are condensed on the same point on the light receiving surface of the light receiving element 87 as long as they are parallel to each other. Thus, a change in the position of the detection light beam L10 from the light distribution surface ξ is detected only by the light receiving element 85 functioning as a position detector, and is detected by the light receiving element 87 functioning as a direction detector. Not done.
[0061]
On the other hand, FIG. 17 is a diagram for explaining the principle of detecting the direction by the light receiving element 87. Now, assuming that the light beam L10 for detection as shown by a solid line in FIG. 7 reaches the light receiving element 85 from the position P of the light distribution surface ξ through the light distribution surface μ of the detection beam distributor 84. The irradiation point above is point Q10. At this time, the light is reflected from the light distribution surface μ and condensed by the condensing lens 86, and the converging point of the detection light beam reaching the light receiving element 87 is the point Q20. Here, if only the direction of the detection light beam L10 with respect to the light distribution surface ξ is shifted (assuming that the position P of the detection light beam on the light distribution surface ξ is the same), the detection light beam L12 becomes The light is irradiated on the light receiving element 85 and the light receiving element 87 through the optical path shown by the broken line. That is, the irradiation point on the light receiving surface of the light receiving element 85 is the point Q12, which is shifted from the original point Q10. On the other hand, the condensing point on the light receiving surface of the light receiving element 87 is the point Q22, which is also shifted from the original point Q20. This is because the light beam indicated by the solid line and the light beam indicated by the dashed line are not parallel, so that the converging point by the converging lens 86 is shifted. Thus, the change in the direction of the detection light beam L10 from the light distribution surface ξ can be detected by the light receiving element 87 functioning as a direction detector. However, such a change in the direction is also detected in the light receiving element 85.
[0062]
After all, the detection result of the light receiving element 87 includes only the change in the direction, whereas the detection result of the light receiving element 85 includes both the change in the position and the change in the direction. Will be. Under such circumstances, theoretically, in the optical axis adjusting device shown in FIG. 13, the feedback control by the control device 92 firstly performs the angle control (control on the angle adjusting mechanism 93) for matching the directions. Then, it is preferable to perform position control (control on the position adjusting mechanism 94) for matching the positions. If the detection result of the orientation matches the reference information, the change component of the orientation can be removed from the detection result of the light receiving element 85, and only the change component of the position can be recognized. However, in practice, by repeatedly performing the angle control and the position control alternately, the feedback control that gradually brings the detection result closer to the reference information is performed. The order does not need to be considered strictly.
[0063]
Next, an example of an automatic optical axis adjusting operation by the optical axis adjusting device will be described. For example, as shown in FIG. 18, suppose that the optical axis adjusting device is inserted on the reference optical path S in a state where a reference optical path S (dashed-dotted line) from the incident point Qin to the emission point Qout is formed. . In this case, first, the light reflecting element 81 is removed from the reference optical path S, and the incident light incident along the reference optical path S is guided to the light distribution surface の of the beam distributor 83 and reflected from the light distribution surface ξ. The position P and the direction of the detected detection light beam (which travels along the optical path shown by the broken line in the figure) are detected. Specifically, the position of point Q10 on light receiving element 85 is detected as "information indicating position P", and the position of point Q20 on light receiving element 87 is detected as "information indicating direction". The information is stored in the storage device 91 (not shown in FIG. 18) as reference information. Next, the light reflecting element 81 is arranged on the reference optical path S, and the incident light is reflected at the point A on the reflecting surface η, guided to the bypass optical path (two-dot chain line), and transmitted from the light distribution surface ξ. The position and the orientation of the detected light beam for detection are detected, and feedback control is performed so that the detection results match the reference information stored in the storage device 91. By such feedback control, the detection light beam is applied to the point Q10 of the light receiving element 85 and the point 20 of the light receiving element 87, and the beam splitter 83 emits the emission light along the reference optical path S at the emission point. It will be ejected toward Qout. In other words, a state as shown in FIG. 3 is obtained. In such a state, “the intensity of the light beam emitted toward the target via the bypass optical path” is sufficiently larger than “the intensity of the detection light beam guided to the detection beam distributor 84”. In order to achieve this, the light distribution surface ビーム in the beam distributor 83 may be constituted by a half mirror having a reflectance of about 99% and a transmittance of about 1%.
[0064]
Now, it is assumed that the incident condition of the incident light to the optical axis adjusting device fluctuates for some reason, and the incident light L15 shown by a solid line in FIG. 18 is given. That is, although the incident light along the reference optical path S has been given so far, the position of the incident light slightly fluctuates (here, there is no change in the direction of the incident light. Try). Then, the bypass optical path changes from the optical path shown by the two-dot chain line in the figure to the optical path shown by the solid line in the figure, and the light beam is applied to the position P15 on the light distribution plane ξ. As a result, the light beam emitted from the beam distributor 83 to the left in the drawing deviates from the reference optical path S, and the final irradiation position deviates from the target point Q on the target.
[0065]
Such an optical axis fluctuation is detected by the light receiving element 85 and the light receiving element 87. That is, the irradiation point on the light receiving element 85 changes from the point Q10 to the point Q15, and the condensing point on the light receiving element 87 changes from the point Q20 to the point Q25. However, in this example, since there was no change in the direction of the incident light, the points Q20 and Q25 are the same point, and it is recognized that there is no need to adjust the direction. Therefore, the control means 70 (not shown in FIG. 18) controls the position adjusting mechanism 94 (not shown in FIG. 18) so as to cancel the variation d (distance between the points Q10 and Q15) about the position. A signal is sent to shift the corner reflector 82 leftward in the figure by a distance d / 2, as shown by the dashed line in FIG. Then, the position adjustment of the incident light L15 is performed such that the incident light L15 is guided to the “position P before the fluctuation occurs” on the light distribution surface 迂 through the detour optical path shown by the solid line in the figure. The upper irradiation point returns to the point Q10, and the condensing point on the light receiving element 87 becomes the point Q20. Thus, the light beam emitted from the beam distributor 83 to the left in the figure is returned to the position on the reference optical path S, and the final irradiation position is returned to the target point Q on the target.
[0066]
As described above, the case where the position fluctuation has occurred with respect to the incident light has been described. However, when the direction fluctuation has occurred, the angle of the light reflecting element 81 is adjusted, and the same automatic optical axis adjustment is performed.
[0067]
In fact, the embodiment shown in FIG. 13 has the following two problems. The first problem is that since the optical path is switched by the operation of inserting and removing the light reflection element 81, there is a possibility that the detour optical path may be shifted mechanically. As described above, in order to execute the first function of directly guiding the incident light to the beam splitter 83, the light reflecting element 81 is extracted from the reference optical path S, and the incident light is directed to a predetermined detour optical path. In order to execute the second function to guide the light reflection element 81, the light reflecting element 81 needs to be mounted on the support mechanism 88. Therefore, the positional accuracy of the detour optical path largely depends on the mechanical accuracy of the support mechanism 88 that supports the light reflecting element 81. However, when the operation of inserting and removing the light reflecting element 81 is repeated, the support mechanism 88 is worn out or displaced, so that the mechanical accuracy of the supporting mechanism 88 must be reduced, and an undesired one occurs in the detour optical path. There is a possibility that.
[0068]
The second problem is that when used for adjusting the optical axis of a high-energy light beam such as a laser beam, the light receiving elements 85 and 87 constituting the detection means may be damaged. That is, in the first state in which the light reflecting element 81 is not disposed on the reference optical path S in the configuration shown in FIG. 13, the detection light beam reflected from the light distribution surface In the second state in which the position and the orientation on the 反射 are detected, and the light reflecting element 81 is arranged on the reference optical path S, for the detection light beam transmitted through the light distribution surface の of the beam distributor 83, The position and the orientation on the light distribution surface are detected. Therefore, for example, when the light distribution surface ξ is constituted by a half mirror having a transmittance of 50%, the power of the detection light beam reaches as much as 50% of the light beam incident on the incident point Qin, such as a laser beam. Is incident, the light receiving elements 85 and 87 may be burned. If the transmittance of the light distribution surface ξ is set very large, such as 99%, or set very small, such as 1%, in one of the first state and the second state, Although the power of the detection light beam becomes very small, on the other hand, the power of the detection light beam becomes very large. Therefore, if the apparatus according to the embodiment shown in FIG. 13 is used for adjusting the optical axis of a laser beam or the like, the light receiving elements 85 and 87 may be damaged during operation.
[0069]
<<<< §4. Improvements to the optical axis adjustment device >>>>>
The specific embodiment described in §3 is an embodiment disclosed in Japanese Patent Application No. 2001-28354, and has two problems as described above. Therefore, here, an improved point for solving these two problems will be described. The fundamental principle of this improvement lies in that a light beam is distributed using a beam splitting means using polarized light, that is, a polarizing beam splitter (PBS: Polarizing Beam Splitter).
[0070]
In §2 described above, four basic embodiments A, B, C, and D have been described. Here, an example in which a polarizing beam splitter is used in Embodiment A will be described as Embodiment E. In the embodiment A, as shown in FIG. 9, the detour light L4 detoured by the optical path switching unit 20 is subjected to angle adjustment by the angle adjustment unit 30 and position adjustment by the position adjustment unit 40, and the beam distribution unit A method of guiding the light distribution surface の to the exit point Qout side of the ten light distribution surfaces ξ is adopted. In the embodiment E described here, a polarizing beam splitter is used as the beam distribution unit 10 and the optical path switching unit 20 in the embodiment A, and the configuration is shown in a block diagram of FIG.
[0071]
The beam distribution units 10X and 20X in FIG. 20 are components corresponding to the beam distribution unit 10 and the optical path switching unit 20 shown in FIG. 9, respectively, and are each configured by a polarization beam splitter. Here, the beam distribution unit 20X disposed on the incident point Qin side is referred to as incident side beam distribution unit, and the beam distribution unit 10X disposed on the exit point Qout side is referred to as exit side beam distribution unit. As shown, the incident side beam distribution means 20X has a light distribution surface ξ1x, and the emission side beam distribution means 10X has a light distribution surface ξ2x. When a plane polarized wave having a first polarization plane is irradiated, these light distribution planes # 1x and # 2x transmit most of the light and reflect the rest, and are orthogonal to the first polarization plane. When a plane polarized wave having the second plane of polarization is irradiated, it has a basic feature that most of the plane is reflected and the rest is transmitted.
[0072]
Here, for convenience of explanation, the first polarization plane is referred to as a plane X, and the second polarization plane is referred to as a plane Y. The plane X and the plane Y are orthogonal to each other, and a direction along a straight line intersecting the two planes is a traveling direction of the incident light L1. Now, when both of the light distribution surfaces # 1x and # 2x are irradiated with a plane-polarized wave having the plane X as the plane of polarization, most of the light (for example, 99%) is transmitted, and the rest (1%). ) Is reflected, and when irradiated with a plane-polarized wave having the plane Y as a plane of polarization, it reflects most (for example, 99%) and transmits the rest (1%). (The letter X in the reference numerals 10X, 20X, $ 1x, $ 2x indicates the property of transmitting most of the light having the plane X as the polarization plane in this way).
[0073]
Now, on the premise described above, let us consider a phenomenon in which a plane polarized wave having a plane X as a plane of polarization is given as the incident light L1 along the reference optical path S shown in FIG. In this case, most (99%) of the incident light L1 passes through the light distribution surface # 1x and travels along the reference optical path S, and most (99%) of the incident light L1 passes through the light distribution surface # 2x, and It will be emitted as transmitted light L2. At this time, the light going to the detection means 50 as the incident light reflected light L3 is only 1% of the light applied to the light distribution surface # 2x.
[0074]
Next, let us consider a phenomenon in which a plane polarized wave having the plane Y as a plane of polarization is given as the incident light L1 along the reference optical path S shown in FIG. In this case, most (99%) of the incident light L1 reflects off the light distribution surface # 1x and is guided to the detour light path as detour light L4, becomes the angle adjustment light L5 via the angle adjustment means 30, and furthermore is the position adjustment means. After passing through 40, it becomes position angle adjusting light L6, and is emitted to the exit point Qout side of the light distribution surface # 2x. Then, also on the light distribution surface # 2x, most (99%) of the irradiated position angle adjustment light L6 is reflected and emitted as adjustment light reflected light L8. At this time, the light traveling as the adjustment light transmitted light L7 to the detection means 50 is only 1% of the light applied to the light distribution surface # 2x.
[0075]
After all, in the case of the embodiment shown in FIG. 20, even if a plane polarized wave having a plane X as a plane of polarization or a plane polarized wave having a plane Y as a plane of polarization is given as the incident light L1, most of the The energy of the light emitted as the incident light transmitted light L2 or the adjustment light reflected light L8 toward the emission point Qout and emitted to the detection unit 50 as the incident light reflected light L3 or the adjustment light transmitted light L7 is It will be very small. This is extremely effective in solving the problem that the light receiving element constituting the detecting means 50 may be damaged. That is, even when a high-energy light beam such as a laser beam is used as the incident light L1, the energy of the detection light beam guided to the detection unit 50 is only a small part of the energy, and therefore, as described above. In addition, as long as the laser light having the plane X or the plane Y as the polarization plane is used as the incident light L1, it is possible to prevent the light receiving element constituting the detection unit 50 from being burned.
[0076]
Further, in the embodiment shown in FIG. 20, it is possible to solve another problem described above. That is, since the beam distribution operation by the beam distribution means 20X shown in FIG. 20 is an operation automatically determined by the polarization plane of the incident light L1, there is no need to perform a physical insertion / removal operation at all. According to the basic principle described in §1, the beam distribution unit 20X includes a first state in which the incident light L1 is transmitted (a state in which the detection unit 50 acquires the reference information and stores the reference information in the storage unit 60), Switching between a second state in which the incident light L1 is reflected toward the detour optical path (a state for performing feedback control such that a detection value of the detection unit 50 approaches reference information stored in the storage unit 60). It is necessary to function as an optical path switching means. However, in the embodiment shown in FIG. 20, such a switching operation does not need to be performed by inserting and removing the optical element, and can be performed by changing the polarization plane of the incident light L1. Therefore, in the case of the embodiment E shown in FIG. 20, it is possible to completely fix the beam distribution unit 20X, and it is possible to prevent a problem that the accuracy of the bypass optical path is shifted.
[0077]
The automatic optical axis adjusting operation by the optical axis adjusting device shown in FIG. 20 is performed as follows. First, a light beam composed of a plane-polarized wave having the plane X as a plane of polarization is made incident on the incident point Qin along the reference optical path S as incident light L1. Then, most of the light passes through the light distribution surface # 1x, and most of the light passes through the light distribution surface # 2x and exits as the incident light transmitted light L2. At this time, since a small amount of light is obtained as the incident light reflected light L3 in the detection means 50, its position and orientation on the light distribution surface ξ2x are measured, and this measurement result is stored in the storage means 60 as reference information. I do. Next, a light beam composed of a plane-polarized wave having the plane Y as a polarization plane is incident as incident light L1. Then, most of the light is reflected on the light distribution surface # 1x and passes through the bypass light path, and then reflected on the light distribution surface # 2x and emitted as the adjusted light reflected light L8. At this time, since a small amount of light is obtained as the adjustment light transmitted light L7 in the detection means 50, its position and orientation on the light distribution surface # 2x are measured, and this measurement result is stored in the storage means 60. What is necessary is just to perform feedback control that matches the reference information.
[0078]
Eventually, the optical path switching operation performed by inserting and removing the optical element in the embodiment described in §3 is performed by switching the polarization plane of the incident light L1 in the embodiment shown in FIG. Of course, when the switching operation of the polarization plane is performed, the detection unit 50 or the like is input to indicate which light beam having the polarization plane is currently given as the incident light L1. You need to be able to perform the appropriate actions. To switch the polarization plane, an optical element (for example, a half-wave plate or the like) that rotates the polarization plane by 90 ° is prepared, and the polarization plane of the light beam traveling toward the incident point Qin is rotated. Good. Such an optical element for rotating the plane of polarization does not affect the accuracy of the optical path even if the optical element is physically inserted and removed, so that there is no particular problem.
[0079]
As described above, in order to implement the improvements described in §4, it is necessary to perform beam distribution using the polarization of the light beam. Therefore, the incident light L1 to be adjusted for the optical axis has a predetermined polarization plane. It is assumed that the plane polarized wave has However, since the laser light is coherent light and becomes a plane-polarized wave having a predetermined polarization plane, the present invention is very convenient for practically adjusting the optical axis of the laser light. Of course, the optical axis adjustment according to the present invention is not necessarily limited to a laser beam, and any light beam may be used as the adjustment target as long as it is a plane polarized wave.
[0080]
The polarization beam splitter used as the beam distribution means 10X and 20X in FIG. 20 has a property of transmitting or reflecting most of the light depending on the polarization plane of the incident light. Even if a polarizing beam splitter having a nominal value of "transmitting 100% of a plane-polarized wave and reflecting 100% of a plane-polarized wave having the plane Y as a plane of polarization" is used, there is no practical problem. This is because even if the theoretical nominal value is 100%, the phenomenon of 100% transmission or 100% reflection does not actually occur, and a slight leakage component always exists. In particular, when the light beam to be adjusted is a high-power laser beam, even a slight leakage component has considerable power, and is sufficient for the position and angle detection by the detection means 50.
[0081]
The beam distributing means 10X and 20X used here are components having the property that "when a plane polarized wave having a predetermined polarization plane is irradiated, most of it is transmitted and the rest is reflected". However, the ratio of “most” and “remaining” here is determined in consideration of the energy intensity of the light beam to be adjusted for the optical axis, the light receiving sensitivity of the light receiving element used for the detecting means, the light receiving allowable energy intensity, and the like. That is the value to be determined. In other words, of the energy of the light beam to be adjusted, the ratio is such that the energy corresponding to an appropriate detection range of the light receiving element is guided to the detection means side.
[0082]
The basic embodiment E shown in FIG. 20 is an example in which improvements are applied to the basic embodiment A shown in FIG. 9. The present invention is similarly applicable to Embodiments B to D. For example, if the present invention is applied to the embodiment B shown in FIG. 10, the beam distribution means 10 and the optical path switching means 20 may be replaced with beam distribution means 10X and 20X comprising polarization beam splitters. In the case where the present invention is applied to the embodiment C shown in FIG. 11, the beam distribution means 10 and the optical path switching angle adjustment means 35 may be replaced with beam distribution means 10X and 35X comprising polarization beam splitters (in this case, beam The polarizing beam splitter used as the distribution unit 35X needs to have an angle adjusting function). Further, in the case where the present invention is applied to the embodiment D shown in FIG. 12, the beam distribution means 10 and the optical path switching position adjusting means 45 may be replaced with beam distribution means 10X and 45X comprising polarization beam splitters (in this case, beam The polarizing beam splitter used as the distribution unit 45X needs to have a position adjusting function).
[0083]
The basic embodiment F shown in FIG. 21 is a modified example of the embodiment E shown in FIG. 20, in which a blocking unit G1 is added on the reference optical path S and a blocking unit G2 is added on the bypass optical path. is there. The blocking means G1 and G2 are optical shutters for optically blocking the light beam passing through the reference light path S and the light beam passing through the bypass light path, respectively. If such blocking means G1 and G2 are provided and a light blocking operation is performed when necessary, a usage mode in which the influence of interference based on the optical path difference is eliminated is possible. Hereinafter, the merits will be described.
[0084]
As described above, in the embodiment in which the improvement described in §4 is applied, first, a light beam having a plane X as a polarization plane is made incident as the incident light L1, and the detection unit 50 acquires reference information. Will be In this operation, the incident light reflected light L3 transmitted through the light distribution surface # 1x and reflected by the light distribution surface # 2x is used. However, at this time, on the detour optical path, a small amount of light reflected on the light distribution surface # 1x travels as detour light, and most of this detour light passes through the light distribution surface # 2x and becomes the adjustment light transmitted light L7. The light enters the detection means 50. In addition, a part of the bypass light is reflected by the light distribution surface # 2x, and is emitted as the adjustment light reflected light L8. Here, since the incident light reflected light L3 and the adjustment light transmission light L7 are lights having a predetermined optical path difference, they interfere with each other, and the incident light transmission light L2 and the adjustment light reflection light L8 are different from each other. Also, since the lights have a predetermined optical path difference, they interfere with each other. When it is not preferable that such interference occurs, in the reference information acquisition stage, the blocking unit G1 is not operated (the optical shutter is opened), and the light traveling on the bypass optical path is blocked by the blocking unit G2 (light). The shutter may be closed) so that only the incident light transmitted light L2 and the incident light reflected light L3 may be obtained.
[0085]
Subsequently, a control step is performed in which a light beam having a plane Y as a polarization plane is incident as the incident light L1, and the detection value of the detection means 50 is brought closer to the reference information. Specifically, detection control is performed based on the adjusted light transmitted light that is reflected on the light distribution surface # 1x, travels on the detour optical path, and transmits through the light distribution surface # 2x. However, at this time, a small amount of light transmitted through the light distribution surface # 1x travels along the reference optical path S, and most of the light is reflected by the light distribution surface # 2x and enters the detection unit 50 as incident light reflected light L3. Part of the light is transmitted through the light distribution surface ξ2x, and is emitted as incident light transmitted light L2. Therefore, also in this case, interference between the incident light reflected light L3 and the adjustment light transmission light L7 and interference between the incident light transmission light L2 and the adjustment light reflection light L8 occur. When such interference is not preferable, in the control stage, the light traveling in the bypass optical path is blocked by the blocking unit G1 (the optical shutter is closed), and the blocking unit G2 is not operated (the optical shutter is opened). State) to obtain only the adjustment light transmitted light L7 and the adjustment light reflected light L8.
[0086]
As described above, in the reference information acquisition step and the control step, switching operations for three items, ie, switching of the polarization plane of the incident light, switching of the opening and closing of the blocking unit, and switching of the operation of the detecting unit are required. Therefore, in practice, a single changeover switch is prepared, and an operation of switching the changeover switch to one of the “reference information acquisition operation” and the “control operation” is performed. It is preferable that the switching is automatically performed in conjunction with the switching. That is, when the changeover switch is switched to the "reference information acquisition operation" side, the polarization plane of the incident light is set to be the plane X, the blocking means G1 is opened to pass light, and the blocking means G2 is closed. The light may be blocked, and the detection unit 50 may perform an operation of storing the detected position and angle in the storage unit 60 as reference information. Conversely, when the changeover switch is switched to the “control operation” side, the polarization plane of the incident light is set to be the plane Y, the blocking means G1 is closed and the light is blocked, and the blocking means G2 is opened. In a state where light is transmitted, the detection means 50 gives the detected position and angle to the control means 70, and the control means 70 makes the given position and angle approach the reference information stored in the storage means 60. What is necessary is just to perform a feedback control operation.
[0087]
The above-described switching operation of the polarization plane of the incident light is performed by installing a half-wave plate or the like on the optical path of the incident light and rotating the mirror 90 degrees by a driving means such as a motor, or returning it to the original position. What should be done is. The switching operation of the blocking means G1 and G2 can be easily performed by using an electromagnetic optical shutter or the like, and the operation switching operation of the detection means and the control means can be easily controlled by a microprocessor or the like. . As described above, if the switching operation of the above three items is performed in conjunction with the operation of the changeover switch, the operator's work load is greatly reduced. That is, the operator first performs an operation of switching the changeover switch to the “reference information acquisition operation” side, acquires the reference information about the current reference optical path S, and then switches the changeover switch to the “control operation” side. An operation may be performed to start feedback control for stabilizing the optical path.
[0088]
Finally, FIG. 22 shows a block diagram of an embodiment in which the improvements described in §4 are applied to the embodiment of FIG. 13 described in §3. In this embodiment, the beam splitter 83 in FIG. 13 is replaced with an exit-side beam splitter 83X composed of a polarizing beam splitter, the light reflecting element 81 is replaced with an incident-side beam distributor 81X composed of a polarizing beam splitter, This corresponds to a configuration in which G1 and G2 are added. The incident-side beam distribution unit 81X has an angle adjusting function, and thus can rotate about the rotation axes ω1 and ω2, but does not need to be inserted and removed, and thus corresponds to the support unit 88 shown in FIG. No components are provided. Each of the light distribution surfaces # 1x and # 2x transmits most of the plane-polarized wave having the plane X as the polarization plane and reflects the remainder, and reflects most of the plane-polarized wave having the plane Y as the polarization plane and transmits the rest. This is a surface with the property of
[0089]
The operation of adjusting the optical axis using the embodiment shown in FIG. 22 is almost the same as the embodiment shown in FIG. The difference is that a plane-polarized light beam such as a laser beam is used as the incident light, and the optical path switching operation between the reference optical path and the detour optical path is performed by switching the polarization plane of the incident light instead of inserting and removing the optical element. Is a point. That is, first, a light beam having the plane X as a polarization plane is incident on the incident point Qin along the reference optical path S. At this time, the optical shutter serving as the blocking unit G1 is opened, and the optical shutter serving as the blocking unit G2 is closed (in practice, switching is preferably performed by the above-described interlocking operation using the switch). Thus, the position and angle of the incident light reflected by the light distribution surface # 1x and reflected by the light distribution surface # 2x are detected and stored in the storage device 91 as reference information. Of course, at this time, the incident light transmitted through the light distribution surface # 2x is emitted toward the emission point Qout. Subsequently, the plane of polarization of the incident light beam is switched to the plane Y. At this time, the optical shutter as the blocking unit G1 is closed, and the optical shutter as the blocking unit G2 is opened (in practice, it is preferable to switch by the above-described interlocking operation using the switch). As a result, the incident light is reflected on the light distribution surface # 1x, travels on the bypass optical path, and is detected as the adjusted light transmitted light transmitted through the light distribution surface # 2x. Of course, at this time, the adjustment light reflected by the light distribution surface # 2x is emitted toward the emission point Qout. The control device controls the angle adjustment mechanism 93 and the position adjustment mechanism 94 so that the detected value at this time approaches the reference information in the storage device 91. As a result, the angle of the polarization beam splitter used as the incident side beam distribution means 81X is adjusted, and the position of the corner reflector (or corner cube prism) 82 is adjusted.
[0090]
As described above, the embodiment shown in FIG. 22 operates on the same basic principle as the embodiment shown in FIG. Can be suppressed. In addition, even when a light beam having a plane of polarization as the plane X and a light beam having a plane of polarization as the plane Y are incident as the incident light, the light beam guided to the optical elements 84 to 87 for detection can be obtained. Is a very small part of the incident light beam, and therefore has the effect of preventing burn-in of the light receiving element.
[0091]
<<<< §5. Exposure apparatus according to the present invention >>>
Up to now, §1 to §3 have described the configuration and operation of a unique optical axis adjusting device having an automatic optical axis adjustment function, and §4 has described its improvements. A feature of the present invention resides in that an optical axis adjusting device having the improvements described in §4 is incorporated in an existing exposure apparatus. Hereinafter, the overall configuration of the exposure apparatus of the present invention will be described.
[0092]
First, a configuration example of a conventional exposure apparatus that has been conventionally used will be briefly described. FIG. 23 is a configuration diagram of a general exposure apparatus that performs exposure for a color hologram image. The exposure apparatus is used for irradiating a predetermined exposure surface with light, thereby exposing a photosensitive material disposed on the exposure surface. The beam sources 100R, 100G, and 100B are laser light sources that generate red, green, and blue laser beams (plane-polarized waves), respectively. A red beam Lr and a green beam Lg are respectively provided along the optical paths indicated by dashed lines in FIG. , A blue beam Lb. Beam guiding means 401 to 404 are provided to guide the laser beam generated in this way to the exposure surface. Here, the beam guiding means 401 and 402 are reflecting mirrors, and the beam guiding means 403 and 404 are beam combiners. The green beam Lg is bent downward in the drawing by the reflecting mirror 402 and enters the beam combiner 403, where it is combined with the blue beam Lb. The combined beam Lgb further enters the beam combiner 404. On the other hand, the red beam Lr is bent downward by the reflecting mirror 401 and enters the beam combiner 404, where it is further combined with the combined beam Lgb to become a combined beam Lrgb of three primary colors, and the beam diameter expanding device 405 Incident on. The beam diameter expanding device 405 is an optical element that expands the diameter of the guided combined beam Lrgb in accordance with the size of the exposure surface E. The combined beam LLrgb whose beam diameter has been expanded is transferred to the exposure surface E as it is. Is irradiated.
[0093]
The exposure surface E is a conceptually defined plane, and in actuality, the photosensitive material disposed on the exposure surface E is exposed. In the illustrated example, the photosensitive materials 501 to 504 are transported leftward in the figure along a predetermined transport path (the transport mechanism is not shown), and the photosensitive material that has been transported onto the exposure surface E is exposed. The state where the material 501 is being exposed is shown. Here, an example in which independent photosensitive materials 501 to 504 are transported one by one has been described. However, it is needless to say that a wound photosensitive film is used as the photosensitive material, and the wound photosensitive film is transported in the horizontal direction in the drawing. Exposure apparatuses having the following configuration are also used. The illustrated example is an exposure apparatus for forming an image of a so-called Lippmann type hologram on the photosensitive materials 501 to 504, and a hologram master 600 (for example, a relief image expressing a predetermined motif) is provided below the exposure surface E. ) Is arranged. In addition, transparent photosensitive films are used as the photosensitive materials 501 to 504. With such a configuration, interference fringes of the combined beam LLrgb irradiated from above in the figure and the reflected light from the hologram master 600 are recorded on the photosensitive material 501, and a color hologram image is recorded. Is performed.
[0094]
In such an exposure apparatus, it is very important to adjust the optical axis of the combined beam LLrgb. Since the cross-sectional intensity of the laser beam emitted from each of the beam sources 100R, 100G, and 100B generally has a Gaussian distribution, the cross-sectional intensity of the combined beam LLrgb irradiated onto the exposure surface E also has a Gaussian distribution. Therefore, if the optical axis of the laser beam for each color is not accurately adjusted, a deviation occurs in the intensity distribution for each color on the exposure surface, causing color unevenness when reproducing the hologram image. Therefore, when the beam sources 100R, 100G, and 100B and the beam guiding means 401 to 404 are installed and a test operation is performed, a precise optical axis adjustment operation is performed. For example, a measurement plate on which a plurality of optical sensors are arranged is arranged on the exposure surface E, and the optical axis adjustment mechanism built in the beam sources 100R, 100G, 100B is adjusted while monitoring the detection output of each optical sensor. In addition, an operation of adjusting the positions and directions of the beam guiding means 401 to 404 is performed.
[0095]
In this way, if the optical axis is precisely adjusted at the test stage when installing this exposure apparatus, the optical axis of each laser beam will be adjusted to the predetermined reference optical path, and the correct exposure operation will be performed. It becomes possible. However, such optical axis adjustment does not always fix the optical axis of each beam at an accurate position. One of the causes of the fluctuation of the optical axis is an unstable cause of the beam sources 100R, 100G, and 100B. Generally, a laser light source requires a certain amount of time from when it is started to when the operation reaches a stable state. Therefore, the optical axis of each laser beam may fluctuate until the laser light source is completely stabilized. In addition, even if a sufficient time has elapsed after the activation of the laser light source, the optical axis may fluctuate due to disturbance such as fluctuation in power supply voltage. Further, the optical axis may gradually shift due to aging due to long-term use. Conventionally, every time such an optical axis shift occurs, the optical axis adjustment operation is performed again using the existing optical axis adjustment mechanism.
[0096]
In the exposure apparatus according to the present invention, the optical axis fluctuation described above is used by using the optical axis adjustment apparatus improved in section 4 in the unique optical axis adjustment apparatus described in sections 1 to 3. Automatically occurs, the optical axis can be automatically adjusted. FIG. 24 is a configuration diagram of an exposure apparatus according to an embodiment of the present invention. This exposure apparatus is obtained by adding three optical axis adjusting apparatuses 300R, 300G, and 300B to the conventional exposure apparatus shown in FIG. As the optical axis adjusting devices 300R, 300G, and 300B, any of various embodiments of the optical axis adjusting devices described in §2 may be used in which the improvements described in §4 are applied. .
[0097]
An example of a specific method of installing each of the optical axis adjusting devices 300R, 300G, and 300B will be described below. First, the exposure apparatus shown in FIG. 23 is installed. At the stage where accurate optical axis adjustment is completed in the test stage and the reference optical path for each color laser beam is determined, the optical axis adjustment devices 300R, 300G and 300B are set to the respective colors. It is inserted on the reference optical path of another laser beam. At this time, the polarization plane of the laser beam for each color is adjusted so as to be all in the plane X (if necessary, the polarization plane is adjusted by inserting a half-wave plate or the like). Then, most of the laser beam for each color passes through the light distribution surface ξ1x of the incident-side beam distribution means, and only a small part thereof reflects off the light distribution surface ξ2x of the emission-side beam distribution means and is detected by the detection means. Is done. The reference information is acquired based on the detection result, and a process of storing the reference information is performed. Subsequently, the polarization planes of the laser beams for each color are switched such that the planes of polarization are all Y planes. Then, a part of the beam that has passed through the detour optical path is guided to the detection unit, and feedback control is performed by the control unit. By such control, the automatic adjustment function of the optical axis works, and the laser beam for each color emitted from each of the optical axis adjusting devices 300R, 300G, 300B follows the reference optical path set in the test stage.
[0098]
By operating the optical axis adjusting devices 300R, 300G, and 300B on the reference optical path in this manner, even if the optical axes are shifted by any factor in the beam sources 100R, 100G, and 100B, the generated optical axis is generated. The displacement is automatically corrected by the optical axis adjusting devices 300R, 300G, and 300B. If the optical axis adjusting device is provided only on the reference optical path of the laser beam for each color as in the example shown in FIG. 24, the optical axis shift that occurs when the positions and directions of the beam guiding means 401 to 404 are shifted. Cannot be dealt with. In order to cope with such a case, an optical axis adjusting device may be further inserted on the reference optical path of the combined beam Lrgb.
[0099]
Further, in the above-described example of the installation method, after the accurate optical axis adjustment is completed in the test stage and the reference optical path for each color laser beam is determined, each optical axis adjustment device 300R, 300G, 300B is placed on each reference optical path. However, conversely, it is also possible to perform accurate optical axis adjustment after installing each of the optical axis adjusting devices 300R, 300G, and 300B. In this case, first, the components of the exposure apparatus as shown in FIG. 23 are installed, and only rough and coarse optical axis adjustment is performed. When the coarse optical axis adjustment is completed, a “temporary reference optical path” indicating a rough path for each laser beam is determined. Therefore, the optical axis adjusting devices 300R, 300G, and 300B are inserted on the “temporary reference optical path”. At this time, the polarization plane of the laser beam for each color is adjusted so as to be a plane X. Then, most of the laser beam for each color passes through the incident-side beam distribution means and the emission-side beam distribution means and is emitted as it is. Therefore, the exposure apparatus shown in FIG. , And the laser beam for each color is guided to the exposure surface E. Therefore, accurate optical axis adjustment can be performed by the same method as before. By performing the accurate optical axis adjustment in this manner, the “true reference optical path” is determined, so that the light beam that is being irradiated on the beam distributor 83 at that time, that is, the light beam that is passing through the “true reference optical path” Acquisition of reference information for. When the reference information has been obtained, the polarization plane of the laser beam for each color may be switched to the plane Y to perform the feedback control.
[0100]
【The invention's effect】
As described above, according to the present invention, it is possible to realize an exposure apparatus having a function of automatically and stably maintaining the optical axis of a light beam. Further, the effect of improving the accuracy of the optical path by the optical axis adjusting device and preventing damage to the optical element used can be expected.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an optical system to be stabilized with an optical axis by an optical axis adjusting device according to the present invention.
FIG. 2 is a diagram illustrating a state in which an optical axis shift has occurred based on a fluctuation factor of a beam source in the optical system illustrated in FIG. 1;
3 is a diagram showing a state where an optical axis adjusting device according to the present invention is inserted on a reference optical path S in the optical system shown in FIG. 1;
FIG. 4 is a diagram showing a state in which the optical axis is stably maintained by the function of the optical axis adjusting device according to the present invention.
FIG. 5 is a diagram illustrating the principle of acquiring reference information in the optical axis adjusting device according to the present invention.
FIG. 6 is a view showing a detour optical path formed in the optical axis adjusting device according to the present invention.
FIG. 7 is a diagram showing a result of feedback control by the optical axis adjusting device shown in FIG. 6;
8 is a diagram showing a state in which the optical axis is stably maintained even when the light source side fluctuates due to feedback control by the optical axis adjusting device shown in FIG.
FIG. 9 is a block diagram illustrating a configuration of an optical axis adjusting device according to a basic embodiment A of the present invention.
FIG. 10 is a block diagram showing a configuration of an optical axis adjusting device according to a basic embodiment B of the present invention.
FIG. 11 is a block diagram illustrating a configuration of an optical axis adjusting device according to a basic embodiment C of the present invention.
FIG. 12 is a block diagram illustrating a configuration of an optical axis adjusting device according to a basic embodiment D of the present invention.
FIG. 13 is a diagram illustrating a configuration example of an optical axis adjusting device corresponding to the basic embodiment C illustrated in FIG. 11;
FIG. 14 is a diagram showing a principle of angle adjustment by a light reflecting element in the optical axis adjusting device shown in FIG.
FIG. 15 is a diagram showing the principle of position adjustment by a corner reflector in the optical axis adjusting device shown in FIG.
FIG. 16 is a diagram showing a principle of detecting position fluctuation in the optical axis adjusting device shown in FIG.
FIG. 17 is a diagram showing a principle of detecting angle fluctuation in the optical axis adjusting device shown in FIG.
FIG. 18 is a diagram showing a state where a position change has occurred in incident light in the optical axis adjusting device shown in FIG.
FIG. 19 is a diagram illustrating automatic optical axis adjustment performed when a position change occurs in incident light in the optical axis adjustment device illustrated in FIG. 13;
FIG. 20 is a block diagram illustrating a configuration of an optical axis adjusting device according to a basic embodiment E in which an improvement according to the present invention is performed.
FIG. 21 is a block diagram illustrating a configuration of an optical axis adjusting device according to Embodiment F corresponding to a modification of Embodiment E illustrated in FIG. 20;
FIG. 22 is a block diagram of an embodiment in which the improvement according to the present invention is applied to the embodiment shown in FIG.
FIG. 23 is a configuration diagram of a general exposure apparatus that performs exposure on a color hologram image.
FIG. 24 is a configuration diagram of an exposure apparatus according to an embodiment of the present invention.
[Explanation of symbols]
1. Reference information acquisition means
2. Optical path detour adjustment means
3. Control means
10 ... Beam distribution means
10X ... Emission side beam distribution means (polarization beam splitter)
20. Optical path switching means
20X: Incident-side beam distribution means (polarizing beam splitter)
30 ... Angle adjusting means
35 ... Optical path switching angle adjusting means
40 ... Position adjusting means
45 ... Optical path switching position adjusting means
50 ... Detection means
60 storage means
70 ... Control means
81 ... Light reflection element
81X: Incident-side beam distribution means (polarizing beam splitter)
82: Corner reflector (Corner cube prism)
83 ... Beam distributor
83X ... Emission side beam distribution means (polarization beam splitter)
84 ... Beam splitter for detection
85 ... Light receiving element
86 ... Condensing lens
87 ... Light receiving element
88 ... Support mechanism
91 ... Storage device
92 ... Control device
93 ... Angle adjustment mechanism
94 ... Position adjustment mechanism
100 ... Beam source
200 ... Target
300, 300R, 300G, 300B ... Optical axis adjusting device used in the present invention
401 to 404... Beam guiding means (reflecting mirror and beam combiner)
405 ... Beam diameter expansion device
501: photosensitive material
600 hologram master
A: Light beam incident position
B: Light beam
Br: reflected light from the light distribution surface ξ
Bt: transmitted light from the light distribution surface ξ
C: the top of the corner reflector
Cin: incidence point
Cout: injection point
D, Da, D1 to D3, D1a to D3a, D1b to D3b...
d, dd ... displacement of position
E: Exposure surface
G1, G2: blocking means (optical shutter)
I (P0, α0) ... Reference information
L1… incident light
L2: incident light transmitted light
L3: Incident light reflected light
L4: detour light
L5, L5 ^* … Angle adjustment light
L6: Position angle adjustment light
L7: Adjustable light transmitted light
L8: adjustment light reflected light
L9, L9 ^* … Position adjustment light
L10, L11, L12 ... Light beam for detection
L15: fluctuated light beam
Lin: incident light
Lout, Lout ^* … Emission light
Lr, Lg, Lb ... each primary color beam
Lgb, Lrgb ... composite beam
LLrgb: Synthetic beam with enlarged diameter
N: Normal line on the light distribution surface ξ
P, P1 ... Position of light beam to be detected
P0: Position serving as reference information
Q: Target point
Qin: Point of incidence
Qout: injection point
Q10, Q11, Q12, Q15 ... Irradiation point
Q20, Q21, Q22, Q25 ... Focus point
S: Reference optical path
α: Emission angle of light beam to be detected
α0: angle used as reference information
η ... Reflective surface
θ ... adjustment angle
μ ... Reflective surface
ξ, ξ1x, ξ2x ... light distribution surface
ρ1, ρ2 ... reflective surface
ω1-ω2 ... Rotation axis

Claims

By irradiating a predetermined exposure surface with light, a device for exposing a photosensitive material disposed on the exposure surface,
A beam source for generating a light beam composed of a plane polarized wave,
Beam guiding means for guiding a light beam generated by the beam source to an exposure surface along a predetermined reference optical path,
A beam diameter expanding device that expands the diameter of the light beam guided by the beam guiding means according to the size of the exposure surface,
An optical axis adjustment device that is arranged on the reference optical path and adjusts an optical axis of a light beam to be maintained on the reference optical path;
Comprising, the optical axis adjusting device,
When a plane-polarized wave having a first plane of polarization is irradiated, the plane-polarized light having a second plane of polarization that is transmitted through most of the plane and reflects the rest, and is orthogonal to the first plane of polarization. When the wave is irradiated, the light has a light distribution surface that reflects most of the light and transmits the remainder, and an incident-side beam distribution means disposed on the incident point side of the reference optical path,
When the plane-polarized wave having the first plane of polarization is irradiated, when the plane-polarized wave having the second plane of polarization is irradiated, it transmits most of the plane and reflects the rest, An emission-side beam distribution unit having a light distribution surface that reflects most of the light and transmits the remainder, and is disposed on the emission point side of the reference optical path,
Of the plane polarized wave having the first polarization plane incident along the reference optical path, the plane polarized wave transmits through the light distribution plane of the incident side beam distribution unit and is reflected by the light distribution plane of the exit side beam distribution unit. With respect to the reflected light obtained thereby, a position and an orientation on the light distribution surface of the emission-side beam distribution means are measured, and reference information acquisition means for acquiring the measurement result as reference information,
Among the plane-polarized waves having the second polarization plane incident along the reference optical path, reflected light obtained by being reflected by the light distribution surface of the incident-side beam distribution means is detoured differently from the reference optical path. Light path detour adjusting means for guiding to the optical path, adjusting the position and direction of the guided light beam, and irradiating the light emitting surface of the light emitting surface of the light emitting surface of the light emitting surface on the side of the light emitting point;
With respect to the transmitted light obtained from the light distribution surface of the emission side beam distribution means based on the light beam passing through the bypass light path, the position and the direction on the light distribution surface of the emission side beam distribution means are measured. Control means for controlling the light path detour adjustment means so that a result approaches the reference information,
An exposure apparatus comprising:

By irradiating a predetermined exposure surface with light, a device for exposing a photosensitive material disposed on the exposure surface,
A beam source for generating a light beam composed of a plane polarized wave,
Beam guiding means for guiding a light beam generated by the beam source to an exposure surface along a predetermined reference optical path,
A beam diameter expanding device that expands the diameter of the light beam guided by the beam guiding means according to the size of the exposure surface,
An optical axis adjustment device that is arranged on the reference optical path and adjusts an optical axis of a light beam to be maintained on the reference optical path;
Comprising, the optical axis adjusting device,
When a plane polarized wave having a first plane of polarization is irradiated, most of the plane polarized wave is transmitted, and the rest is reflected toward a predetermined bypass optical path, and the second plane orthogonal to the first plane of polarized light is reflected. When a plane-polarized wave having two polarization planes is irradiated, most of the plane-polarized wave is reflected as detour light directed to the detour optical path, and has a light distribution surface that transmits the rest. Incident side beam distribution means arranged on the point side,
When the plane polarized wave having the first polarization plane is irradiated, most of the plane light is transmitted as incident light transmitted light, and the rest is reflected as incident light reflected light, and has the second polarization plane. When the plane-polarized wave is irradiated, the plane has a light distribution surface that reflects most of the light as adjustment light reflected light and transmits the rest as adjustment light transmission light, and is disposed on the exit point side of the reference light path. Exit-side beam distribution means;
Angle adjusting means for changing the direction of the detour light by a predetermined set angle and emitting the light as angle adjusting light,
The angle adjusting light is incident, and a position angle adjusting light which is parallel to the angle adjusting light and passes through a position shifted by a predetermined set amount of displacement is transmitted to the light emitting surface side of the light emitting surface of the light emitting side of the light emitting surface at the light emitting point side. Position adjusting means for causing the position angle adjusting light to be distributed to the adjusting light reflected light composed of a large part of the reflected light and the adjusted light transmitting light composed of the remaining transmitted part. When,
When the plane of polarized light having the first polarization plane is irradiated on the incident point, the position and direction of the incident light reflected light on the light distribution surface of the emission side beam distribution means are detected, and the incident point is detected. Detecting means for detecting the position and direction of the adjustment light transmitted light on the light distribution surface of the emission side beam distribution means when the plane polarized wave having the second polarization plane is irradiated;
Storage means for storing the position and orientation detected by the detection means as reference information when the incident point is irradiated with a plane polarized wave having the first polarization plane;
When the plane of incidence is irradiated with the plane-polarized wave having the second plane of polarization, the position and orientation detected by the detection unit are the positions and orientations of the reference information stored in the storage unit. Control means having a function of controlling a set angle by the angle adjustment means and a set displacement amount by the position adjustment means so as to approach;
An exposure apparatus comprising:

By irradiating a predetermined exposure surface with light, a device for exposing a photosensitive material disposed on the exposure surface,
A beam source for generating a light beam composed of a plane polarized wave,
Beam guiding means for guiding a light beam generated by the beam source to an exposure surface along a predetermined reference optical path,
A beam diameter expanding device that expands the diameter of the light beam guided by the beam guiding means according to the size of the exposure surface,
An optical axis adjustment device that is arranged on the reference optical path and adjusts an optical axis of a light beam to be maintained on the reference optical path;
Comprising, the optical axis adjusting device,
When a plane polarized wave having a first plane of polarization is irradiated, most of the plane polarized wave is transmitted, and the rest is reflected toward a predetermined bypass optical path, and the second plane orthogonal to the first plane of polarized light is reflected. When a plane-polarized wave having two polarization planes is irradiated, most of the plane-polarized wave is reflected as detour light directed to the detour optical path, and has a light distribution surface that transmits the rest. Incident side beam distribution means arranged on the point side,
When the plane polarized wave having the first polarization plane is irradiated, most of the plane light is transmitted as incident light transmitted light, and the rest is reflected as incident light reflected light, and has the second polarization plane. When the plane-polarized wave is irradiated, the plane has a light distribution surface that reflects most of the light as adjustment light reflected light and transmits the rest as adjustment light transmission light, and is disposed on the exit point side of the reference light path. Exit-side beam distribution means;
Position adjusting means for entering the detour light, emitting position adjustment light parallel to the detour light and passing through a position shifted by a predetermined set displacement amount,
By emitting the position angle adjustment light obtained by changing the direction of the position adjustment light by a predetermined set angle toward the emission point side of the light distribution surface of the emission side beam distribution means, the position angle adjustment light is emitted. Angle adjusting means for adjusting light to be distributed to adjusting light reflected light consisting of a large part of reflected light, and adjusting light transmitting light consisting of the remaining transmitted part,
When the plane of polarized light having the first polarization plane is irradiated on the incident point, the position and direction of the incident light reflected light on the light distribution surface of the emission side beam distribution means are detected, and the incident point is detected. Detecting means for detecting the position and direction of the adjustment light transmitted light on the light distribution surface of the emission side beam distribution means when the plane polarized wave having the second polarization plane is irradiated;
Storage means for storing the position and orientation detected by the detection means as reference information when the incident point is irradiated with a plane polarized wave having the first polarization plane;
When the plane of incidence is irradiated with the plane-polarized wave having the second plane of polarization, the position and orientation detected by the detection unit are the positions and orientations of the reference information stored in the storage unit. Control means having a function of controlling a set angle by the angle adjustment means and a set displacement amount by the position adjustment means so as to approach;
An exposure apparatus comprising:

By irradiating a predetermined exposure surface with light, a device for exposing a photosensitive material disposed on the exposure surface,
A beam source for generating a light beam composed of a plane polarized wave,
Beam guiding means for guiding a light beam generated by the beam source to an exposure surface along a predetermined reference optical path,
A beam diameter expanding device that expands the diameter of the light beam guided by the beam guiding means according to the size of the exposure surface,
An optical axis adjustment device that is arranged on the reference optical path and adjusts an optical axis of a light beam to be maintained on the reference optical path;
Comprising, the optical axis adjusting device,
When the plane polarized wave having the first plane of polarization is irradiated, most of the plane polarized wave is transmitted, and the rest is reflected toward a predetermined detour optical path, and the second plane orthogonal to the first plane of polarization is reflected. When a plane-polarized wave having two polarization planes is irradiated, most of the light is reflected as detour light directed to the detour optical path, and has a light distribution surface that transmits the rest. Incident-side beam distribution means having an angle adjustment function that is arranged on the point side, and changes the direction of the detour light by a predetermined set angle and emits it as angle adjustment light;
When the plane polarized wave having the first polarization plane is irradiated, most of the plane light is transmitted as incident light transmitted light, and the rest is reflected as incident light reflected light, and has the second polarization plane. When the plane-polarized wave is irradiated, the plane has a light distribution surface that reflects most of the light as adjustment light reflected light and transmits the rest as adjustment light transmission light, and is disposed on the exit point side of the reference light path. Exit-side beam distribution means;
The angle adjusting light is incident, and a position angle adjusting light which is parallel to the angle adjusting light and passes through a position shifted by a predetermined set amount of displacement is transmitted to the light emitting surface side of the light emitting surface of the light emitting side of the light emitting surface at the light emitting point side. Position adjusting means for causing the position angle adjusting light to be distributed to the adjusting light reflected light composed of a large part of the reflected light and the adjusted light transmitting light composed of the remaining transmitted part. When,
When the plane of polarized light having the first polarization plane is irradiated on the incident point, the position and direction of the incident light reflected light on the light distribution surface of the emission side beam distribution means are detected, and the incident point is detected. Detecting means for detecting the position and direction of the adjustment light transmitted light on the light distribution surface of the emission side beam distribution means when the plane polarized wave having the second polarization plane is irradiated;
Storage means for storing the position and orientation detected by the detection means as reference information when the incident point is irradiated with a plane polarized wave having the first polarization plane;
When the plane of polarization having the second plane of polarization is irradiated on the incident point, the position and orientation detected by the detection unit are set to the positions and orientations of the reference information stored in the storage unit. Control means having a function of controlling a set angle by the incident-side beam distribution means and a set displacement amount by the position adjustment means,
An exposure apparatus comprising:

By irradiating a predetermined exposure surface with light, a device for exposing a photosensitive material disposed on the exposure surface,
A beam source for generating a light beam composed of a plane polarized wave,
Beam guiding means for guiding a light beam generated by the beam source to an exposure surface along a predetermined reference optical path,
A beam diameter expanding device that expands the diameter of the light beam guided by the beam guiding means according to the size of the exposure surface,
An optical axis adjustment device that is arranged on the reference optical path and adjusts an optical axis of a light beam to be maintained on the reference optical path;
Comprising, the optical axis adjusting device,
When the plane polarized wave having the first plane of polarization is irradiated, most of the plane polarized wave is transmitted, and the rest is reflected toward a predetermined detour optical path, and the second plane orthogonal to the first plane of polarization is reflected. When a plane-polarized wave having two polarization planes is irradiated, most of the plane-polarized wave is reflected as detour light directed to the detour optical path, and has a light distribution surface that transmits the rest. An incident-side beam distribution unit having a position adjustment function that is disposed on the point side, and has a position adjustment function of emitting the detour light as a position adjustment light by performing parallel movement by a predetermined set displacement amount,
When the plane polarized wave having the first polarization plane is irradiated, most of the plane light is transmitted as incident light transmitted light, and the rest is reflected as incident light reflected light, and has the second polarization plane. When the plane-polarized wave is irradiated, the plane has a light distribution surface that reflects most of the light as adjustment light reflected light and transmits the rest as adjustment light transmission light, and is disposed on the exit point side of the reference light path. Exit-side beam distribution means;
By emitting the position angle adjustment light obtained by changing the direction of the position adjustment light by a predetermined set angle toward the emission point side of the light distribution surface of the emission side beam distribution means, the position angle adjustment light is emitted. Angle adjusting means for adjusting light to be distributed to adjusting light reflected light consisting of a large part of reflected light, and adjusting light transmitting light consisting of the remaining transmitted part,
When the plane of polarized light having the first polarization plane is irradiated on the incident point, the position and direction of the incident light reflected light on the light distribution surface of the emission side beam distribution means are detected, and the incident point is detected. Detecting means for detecting the position and direction of the adjustment light transmitted light on the light distribution surface of the emission side beam distribution means when the plane polarized wave having the second polarization plane is irradiated;
Storage means for storing the position and orientation detected by the detection means as reference information when the incident point is irradiated with a plane polarized wave having the first polarization plane;
When the plane of polarization having the second plane of polarization is irradiated on the incident point, the position and orientation detected by the detection unit are set to the positions and orientations of the reference information stored in the storage unit. Control means having a function of controlling a set displacement amount by the incident side beam distribution means and a set angle by the angle adjustment means so as to approach;
An exposure apparatus comprising:

The exposure apparatus according to any one of claims 1 to 5,
A first blocking unit that can block, as necessary, light that passes through the light distribution surface of the incident-side beam distribution unit and travels toward the light distribution surface of the emission-side beam distribution unit;
A second blocking unit that can block, as necessary, light that is reflected on the light distribution surface of the incident-side beam distribution unit and travels along the bypass optical path;
An exposure apparatus, further comprising:

The exposure apparatus according to any one of claims 2 to 5,
A detecting beam splitter for splitting the detecting light beam from the light splitting surface of the emission side beam splitting device into two beams, and a position detector for detecting a position based on the split first beam And an orientation detector for detecting an orientation based on the distributed second beam.

The exposure apparatus according to claim 7,
An exposure apparatus, wherein the position detector comprises a light receiving element for detecting a beam irradiation position on a predetermined light receiving surface.

The exposure apparatus according to claim 7,
The direction detector has a condensing lens for converging parallel light rays to a predetermined focal point, and a light receiving surface disposed at a position apart from the condensing lens by a focal length, and a condensing position on the light receiving surface. An exposure apparatus, comprising: a light-receiving element that detects the light.

The exposure apparatus according to any one of claims 1 to 9,
A plurality of beam sources each generating a light beam for each color component;
In the process of guiding the light beam for each color component to the exposure surface, beam combining means for combining these light beams,
An optical axis adjustment device for each color component arranged on a reference optical path for each color component,
An exposure apparatus comprising: