JP4137410B2 - Scanning exposure equipment - Google Patents

Description

【００４６】
一方、走査位置ｘに関する荷重関数Ｗ（ｘ）を用いると、レーザ強度分布Ｉ（ｘ）は式（２）のように記述することもできる。
【００４７】
【数２】

【００４８】
さて、図２（ａ）に示す目標照射強度分布において、ｘ＜０の走査区間ではレーザ強度分布Ｉ（ｘ）は単調増加関数であり、ｘ＞０の走査区間ではレーザ強度分布Ｉ（ｘ）は単調減少関数となっている。したがって、走査区間毎に式（１）を変形すると、式（３），式（４）がそれぞれ得られる。
【００４９】
【数３】

【００５０】
【数４】

【００５１】
また同様に、式（２）のレーザ強度分布Ｉ（ｘ）も走査区間毎のレーザ強度分布Ｉ₁ （ｘ），Ｉ₂（ｘ）に分離することができる。この結果を次の式（５）に示す。
【００５２】
【数５】

【００５３】
ここで、Ｗ₁（ｘ），Ｗ₂（ｘ）はそれぞれ走査区間ｘ＜０，０＜ｘにおける荷重関数Ｗ（ｘ）である。式（３），式（４）と式（５）とを比較すると、走査位置ｘで時間ｔを微分した滞在時間（∂ｔ／∂ｘ）は荷重関数Ｗ（ｘ）に比例することが分かる。滞在時間（∂ｔ／∂ｘ）は走査速度の逆数なので、上の考察結果は走査速度（∂ｘ／∂ｔ）が荷重関数Ｗ（ｔ）に逆比例することを意味している。
【００５４】
以上の式（３），式（４）と式（５）との比較・考察によって、走査位置ｘを独立変数とする時間の関数ｔ（ｘ）を次の式（６ａ），式（６ｂ）のように表すことができる。
【００５５】
【数６】

【００５６】
この式（６ａ）および式（６ｂ）を用いて、目標照射強度分布を表す荷重関数Ｗ（ｘ），つまりＷ₁（ｘ）とＷ₂（ｘ）とから時間ｔ（ｘ）のダイヤグラムを求めることができる。
【００５７】
図２（ａ）のアポダイゼーションの目標照射強度分布を実現するための走査位置−時間ダイヤグラムを式（６ａ），式（６ｂ）で算出すると図２（ｂ）のようになる。図２（ｂ）を見ると分かるように、走査位置の両端に対応する部分では、ダイヤグラムの微分係数の大きさが急激に増大しており、アポダイゼーションを実現するには走査位置の両端で走査速度を大きく増大させる必要のあることが理解できる。理論的には、照射強度をゼロとするために走査速度を無限大にする必要がある。
【００５８】
繰り返し走査を行なう場合についても考察する。
図３は繰り返し走査を行なう場合の走査位置−時間ダイヤグラムの例を示す図であり、図３（ａ）は時間に対して走査位置が常に単調増加する場合、図３（ｂ）は時間に対して走査位置が単調増加と単調減少とを繰り返す場合である。
【００５９】
図３（ａ），図３（ｂ）いずれの場合も、走査位置の両端で走査方向（または走査速度）を反転する必要のあることが分かる。この反転を行なうときに走査速度はゼロとなるのだが、上で述べたように、走査位置の両端ではアポダイゼーション実現のために走査速度は増大して最大速度となっているので、最大速度のまま走査方向を反転することは困難である。
【００６０】
この困難を解決するために、この発明では、位相マスク７の直前に遮光手段９を設けるようにしている。遮光手段９は中央に矩形の開口部を持っており、この開口部は偏向角補償手段３からのレーザ光を通過し（通光領域）、開口部以外の部分はレーザ光を遮蔽するようになっている（遮光領域）。この遮光手段９の働きについて次に説明する。
【００６１】
図４はこの発明の実施の形態１による走査型露光装置による繰り返し走査を説明するための図である。
図４（ａ）は図１の偏向角補償手段３，遮光手段９，位相マスク７および光ファイバ８を拡大した図、図４（ｂ）はアポダイゼーションの目標照射強度分布であり、遮光手段９の開口部が通光領域、開口部以外が遮光領域にそれぞれ対応している。図４（ｃ）はこの実施の形態１による繰り返し走査の走査位置−時間ダイヤグラムである。
【００６２】
この実施の形態１では、図４（ａ）に示すように、遮光手段９の大きさ以下の範囲で、遮光手段９の開口部よりもレーザ光の走査区間を大きく設定しており、走査区間の両端には遮光手段９によってレーザ光が遮られる２つの遮光領域が存在する。このことによって、レーザ光の１走査周期の間には、レーザ光が開口部を通過し、位相マスク７を介して光ファイバ８を照射する期間（照射期間）と、開口部以外の部分でレーザ光が遮られ、光ファイバ８を照射しない期間（非照射期間）とが作り出される。
【００６３】
そして、図４（ｃ）に示すように、アポダイゼーションの目標照射強度分布を実現するダイヤグラムを照射期間中に行なうようにし、レーザ光の走査速度を大きく増大させる動作や走査速度の減速・反転、次の走査に要する初期走査速度までの加速（助走）を行なうダイヤグラムを非照射期間に割り当てるようにしている。
【００６４】
これにより、走査速度を無限大とする必要があるとともに、走査方向を反転しなければならない走査位置の両端部は図４（ｂ）の遮光領域に相当することになり、遮光手段９によって遮光されるため光ファイバ８へレーザ光が照射されることはなく、このときの照射強度をゼロにすることができる。したがって、レーザ光が開口部を通過して光ファイバ８を照射する図４（ｂ）の通光領域において、目標照射強度分布を実現させつつ、レーザ光走査を繰り返すことができるようになる。
【００６５】
なお、以上の説明では、レーザ光源１として連続発振レーザ（ＣＷレーザ）の光源を想定している。この場合、どのような走査周期で走査しても目標照射強度分布を実現できる。
【００６６】
一方、レーザ光源１からパルスレーザ光を出射する場合には、繰り返しの走査周期とパルスレーザ光のパルス周期との整数比の最小公倍数を大きくするように、各周期の組み合わせを決定するようにする。このことにより、走査を多数回繰り返した場合に照射強度分布内に意図しない周期的な強度分布（リップル）の発生を防ぐことができる。次の計算例によってこれを説明する。
【００６７】
図５はパルスレーザ光によって繰り返し走査を行なった場合の照射強度分布の計算例を示す図であり、走査周期を２０ｍｓｅｃとし、パルスレーザ光のパルス周期をそれぞれ図５（ａ）０．９０ｍｓｅｃ，図５（ｂ）１．００ｍｓｅｃとした場合に、１０２４回のＧａｕｓｓｉａｎビーム（ビーム半値幅１ｍｍ）をパルス照射した場合の計算値である。走査周期とパルス周期との整数比は、図５（ａ）が２００：９，図５（ｂ）が２０：１であり、各周期比の最小公倍数はそれぞれ、図５（ａ）が１８００，図５（ｂ）が２０に対応する。
【００６８】
これを見ると、各周期の整数比の最小公倍数が小さい図５（ｂ）の計算例では、照射強度分布に周期的な強度分布が生じている。この強度分布は照射パルス数を増加させた場合でも残存してしまい、光ファイバグレーティングの性能を劣化させる要因になる。
【００６９】
一方、各周期の整数比の最小公倍数が大きい図５（ａ）の計算例では、照射強度分布に周期的な強度分布は現れておらず、理想に近いアポダイゼーションが実現できている。図５（ｂ）で若干存在しているリップルは、パルス照射回数を増加させることにより、さらに減少させることができる。
【００７０】
以上のように、この実施の形態１によれば、レーザ光を出射するレーザ光源１と、レーザ光源１が出射したレーザ光を所定の偏向角で偏向して出射する偏向手段２と、偏向角を補償して偏向手段２が出射したレーザ光を出射する偏向角補償手段３と、偏向角を制御し、偏向角補償手段３が出射したレーザ光を走査方向へ走査する信号記憶手段４・信号発生手段５・駆動手段６と、走査方向に沿ってその下面に設置された光ファイバ８に対して位相変調型の透過型回折格子を介してレーザ光を照射する位相マスク７とを備えるようにしたので、レーザ光を高速走査することができるようになり、レーザの強度ドリフトの影響と、低速照射によって発生してしまう局所加熱の影響とを最小化することができるという効果が得られる。
【００７１】
また、この実施の形態１によれば、時系列制御信号にしたがって偏向角を駆動手段６が制御し、信号発生手段５が所定の走査周期で時系列制御信号を繰り返すようにしたので、レーザ光を高速繰り返し走査することができるという効果が得られる。
【００７２】
さらに、この実施の形態１によれば、時系列制御信号にしたがって偏向角を駆動手段６が制御し、偏向角補償手段３が出射したレーザ光の走査速度（∂ｘ／∂ｔ）と目標照射強度分布Ｗ（ｘ）とを逆比例の関係にして計算した走査位置−時間ダイヤグラムを信号記憶手段４が時系列制御信号とするようにしたので、アポダイゼーションなどの目標照射強度分布Ｗ（ｘ）を実現することができるという効果が得られる。
【００７３】
さらに、この実施の形態１によれば、偏向角補償手段３と位相マスク７との間に設けられ、偏向角補償手段３が出射したレーザ光が通過する開口部を有する遮光手段９を備え、偏向角補償手段３が出射したレーザ光の走査区間が遮光手段９に収まる範囲で、信号記憶手段４・信号発生手段５・駆動手段６がレーザ光を開口部よりも大きく走査して走査区間の両端に遮光領域を存在させるとともに、レーザ光が遮光領域を走査する期間に、信号記憶手段４・信号発生手段５・駆動手段６がレーザ光の走査速度の助走または反転を行なうようにしたので、レーザ光の走査区間の両端では、遮光手段９によってレーザ光が遮光されてこのときの照射強度をゼロにすることができるようになり、レーザ光が開口部を通過して光ファイバ８を照射するときに目標照射強度分布を実現することができるという効果が得られる。
【００７４】
さらに、この実施の形態１によれば、連続発振するレーザ光をレーザ光源１が出射するようにしたので、走査周期に依存することなく、目標照射強度分布を実現することができるという効果が得られる。
【００７５】
さらに、この実施の形態１によれば、所定のパルス周期で発振するパルスレーザ光をレーザ光源１が出射するとともに、時系列制御信号の走査周期とパルス周期との整数比の最小公倍数が大きくなるように、信号発生手段５が走査周期を定めるようにしたので、パルスレーザ光によって繰り返し走査を行う際に、周期的な照射強度分布の発生を抑制することができるという効果が得られる。
【００７６】
さらに、この実施の形態１によれば、信号記憶手段４・信号発生手段５・駆動手段６によって走査方向の揺動角度が制御される第１反射鏡を偏向手段２とするとともに、第１反射鏡の揺動角度と絶対値が等しく逆方向に、信号記憶手段４・信号発生手段５・駆動手段６によって走査方向の揺動角度が制御される第２反射鏡を偏向角補償手段３とし、第１反射鏡および第２反射鏡を順次反射させて、レーザ光源１が出射したレーザ光を遮光手段９へ出射するようにしたので、レーザ光源１に波長広がりがある場合に色収差の影響による走査位置誤差を防ぐことができるという効果が得られる。
【００７７】
なお、この発明の走査型露光装置は高速繰り返し走査に限定されるわけではなく、信号発生手段５が１走査周期分だけ時系列制御信号を発生するようにしても良い。
【００７８】
また、時系列制御信号は式（６）を用いて計算した走査位置−時間ダイヤグラムに限定されるものではなく、この他にも任意に定めることができる。
【００７９】
実施の形態２．
図６はこの発明の実施の形態２による走査型露光装置の構成を示す図である。図１と同一符号は相当する構成要素である。
図６の偏向手段２において、符号１０および１１はそれぞれ同一の回転軸周りの回転角速度が駆動手段６によって制御される第１ウェッジおよび第２ウェッジである。また、図６の偏向角補償手段３において、符号１２および１３はそれぞれ同一の回転軸周りの回転角速度が駆動手段６によって制御される第３ウェッジおよび第４ウェッジである。レーザ光源１から出射したレーザ光は、第１〜第４ウェッジ１０〜１３を順次透過して遮光手段９へ入射する。
【００８０】
図６では、第１ウェッジ１０の回転方向と第２ウェッジ１１の回転方向、第３ウェッジ１２の回転方向と第４ウェッジ１３の回転方向はそれぞれ互いに逆方向になるように駆動手段６によって駆動されている。第１〜第４ウェッジ１０〜１３の形状は特に限定されるものではないが、これらのうち少なくとも１つの入射面または出射面を回転軸と直交する平面形状にすることで、レーザ光の光路追跡が容易になり、また入射するレーザ光の入射角の誤差に対する偏向動作精度の劣化を抑制することができ、走査制御の精度に対するレーザ光の入射角依存性を軽減することができるようになる。
【００８１】
まず、偏向手段２の第１ウェッジ１０，第２ウェッジ１１について、走査機能を説明する。ｘ軸方向を光ファイバ８の長手方向、レーザ光源１の光軸およびｘ方向と垂直にｙ軸方向をとり、レーザ光源１の光軸上に原点に取る。第１，第２ウェッジ１０，１１によって生じるレーザ光の偏向角を偏向手段２から出射するレーザ光とレーザ光源１の光軸とのなす角で定義し、ｘ軸方向の偏向角をθ_x ，ｙ軸方向の偏向角をθ_yとすると、偏向角θ_x，θ_yは式（７ａ），式（７ｂ）でそれぞれ表される。
【００８２】
【数７】

【００８３】
ここでδ₁，δ₂は第１，第２ウェッジ１０，１１による光線の偏角、φ₁，φ₂は第１，第２ウェッジ１０，１１の回転角速度、ψは第１，第２ウェッジ１０，１１間の位相差である。
いま、同一材料、同一形状で作られた第１，第２ウェッジ１０，１１を用いると、偏角δ₁，δ₂の関係はδ₁＝δ₂＝δとなり、第１，第２ウェッジ１０，１１の回転角速度φ₁，φ₂を同じ速さで逆方向に回転（φ₁＝−φ₂＝φ）させて位相差ψ＝０とすれば、次の式（８ａ），式（８ｂ）がそれぞれ得られ、ｘ方向、つまり光ファイバ８の長手方向にのみレーザ光を走査できることがわかる。
【００８４】
【数８】

【００８５】
一方、偏向角補償手段３の第３，第４ウェッジ１２，１３については、第３ウェッジ１２の初期位相を第１ウェッジ１０に対して１８０°だけ進め、第４ウェッジ１３の初期位相を第２ウェッジ１１に対して１８０°だけ進めると、第３，第４ウェッジ１２，１３間の位相差ψ＝０°となる。
【００８６】
そして第１，第２ウェッジ１０，１１と同様に、同一材料、同一形状で作られた第３，第４ウェッジ１２，１３を用いると偏角δ₁＝δ₂＝δとなり、回転角速度φ₁＝−φ₂＝φなので（第３ウェッジ１２の回転角速度φ₃＝φ₁，第４ウェッジ１３の回転角速度φ₄＝φ₂）、式（７ａ），（７ｂ）はそれぞれδｃｏｓ［φ＋１８０°］＋δｃｏｓ［−（φ＋１８０°）］，δｓｉｎ［φ＋１８０°］＋δｓｉｎ［−（φ＋１８０°）］となって式（９ａ），式（９ｂ）が得られ、偏向角が補償されることが分かる。
【００８７】
【数９】

【００８８】
したがって、第４ウェッジ１３から距離Ｌの位置に第３ウェッジ１２を置き、かつθ＝−θ_xの偏向を与える場合、第１ウェッジ１０へ入射して第４ウェッジ１３から出射するレーザ光のレーザ光源１の光軸からの走査位置ｘは式（１０）により求めることができる。
【００８９】
【数１０】

【００９０】
式（１０）を見ると、第１〜第４ウェッジ１０〜１３の回転角速度φに応じて走査位置を往復制御できることが分かる。走査位置ｘは回転角速度φに対して一般的に線形変化しないが、回転角速度φの角度範囲を限定し、偏角δを最適に選ぶことで線形近似が可能である。走査位置ｘが回転角速度φに近似的に線形となる例を次の図７に示す。
【００９１】
図７はウェッジの回転角速度φと走査位置絶対誤差（線形性からのズレ）との関係を示す図であり、偏角δと距離Ｌとをパラメータとして、式（１０）の線形性からのズレを計算している。図７の横軸は回転角速度φ［ｄｅｇ．］，縦軸は走査位置ｘの絶対誤差［ｍｍ］である。この図７に示すように、回転角速度φの範囲を±３０°に制限した場合において、φ＝±３０°間の範囲で常に誤差をゼロとする偏角δ，距離Ｌの組が存在し、図７の例ではδ＝２１．２ｄｅｇ．，Ｌ＝５１．６ｍｍが最適値と分かる。
【００９２】
いま、この回転角速度φに対して走査位置ｘが近似的に線形変化する線形近似回転角範囲を実施の形態１で説明した照射期間に割り当て、この線形近似回転角範囲以外の角度範囲を非照射期間に割り当てることを考える。図８は照射期間および非照射期間に対するウェッジ回転角度の割り当てを示す図であり、ウェッジの上面から見た回転角度範囲を示している。なお説明を簡単にするため、４枚の第１〜第４ウェッジ１０〜１３全てを９０°回転させた位置を回転角度の基準に取り直している。
【００９３】
それでは、繰り返し走査について説明する。
図９はこの発明の実施の形態２による走査型露光装置による繰り返し走査を説明するための図である。図９（ａ）は目標照射強度分布、図９（ｂ）はこの実施の形態２による走査位置−時間ダイヤグラム、図９（ｃ）はこの実施の形態２によるウェッジの回転角速度―時間ダイヤグラム、図９（ｄ）はこの実施の形態２によるウェッジの回転角度―時間ダイヤグラムをそれぞれ示している。
【００９４】
実施の形態１と同様に、照射期間内で走査速度を目標照射強度分布に逆比例させて時系列制御信号を計算している。また、図９（ａ），図９（ｂ）に示すように、走査位置両端には遮光手段９によって２つの遮光領域を設け、レーザ光の走査速度を大きく増大させる動作や走査速度の減速、次の走査に要する初期走査速度までの加速をこの遮光領域中の非照射期間に行なう。
【００９５】
特に限定されるものではないが、さらに前述したように、各ウェッジの回転角速度φに対して走査位置ｘが近似的に線形変化する線形近似回転角範囲を照射期間に割り当てようにすれば、各ウェッジの回転角速度φを等間隔で変化させたときに走査位置ｘも等間隔に制御できるので、制御性を向上することができる。
【００９６】
以上により、図９（ｄ）の各ウェッジの回転角度―時間ダイヤグラムで示すように、第１〜第４ウェッジ１０〜１３を０から３６０°まで１回転させる間に２回分の照射期間が割り当てられ、１往復の走査が完了する。このウェッジ回転角制御を連続的に行うことで、位置走査を高速に繰り返すことができる。
【００９７】
特に実施の形態１と比較すると、この実施の形態２では、図９（ｃ）の回転角速度―時間ダイヤグラムに示すように、第１〜第４ウェッジ１０〜１３の回転方向を非照射期間内で反転させる必要がなく、回転角速度の高低変化だけで済むようになっている。これにより、駆動手段６に加わる電気的・機械的負荷を軽減することができる。
【００９８】
さて、ここまでの説明では、第１〜第４ウェッジ１０〜１３の回転だけでレーザ光の走査を実現したが、偏向角補償手段３の第３，第４ウェッジ１２，１３を光ファイバ８の長手方向へ並進走査するようにしても良い。
【００９９】
図１０はこの発明の実施の形態２による走査型露光装置の構成を示す図であり、図１，図６と同一符号は相当する構成要素である。
図１０において、符号１４は第３，第４ウェッジ１２，１３を備えた偏向角補償手段であり、この偏向角補償手段１４の第３，第４ウェッジ１２，１３は、第３，第４ウェッジ１２，１３の回転運動に同期して光ファイバ８の長手方向へ駆動手段６によって並進走査されるようになっている。
【０１００】
この図１０における位置走査に位置精度は必要なく、偏向手段２の第１，第２ウェッジ１０，１１によって偏向したレーザ光が偏向角補償手段１４の第３，第４ウェッジ１２，１３のウェッジ内へ蹴られることなく入射しさえすれば良い。位置走査を併用することで、第３，４ウェッジ１２，１３の有効径を小さくできるため、第３，第４ウェッジ１２，１３の面精度の向上、駆動手段６の小型化、コスト軽減などの効果がある。
【０１０１】
さらに図１１に示すように、シリンドリカルレンズを設置することで、ウェッジ走査によって第４ウェッジ１３の回転軸方向および走査方向と直交する方向に走査位置誤差が発生した場合でもこれを補償することができる。
【０１０２】
図１１はこの発明の実施の形態２による走査型露光装置の構成を示す図であり、図１，図６と同一符号は相当する構成要素である。また、図１１では、レーザ光源１〜第３ウェッジ１２の図示を省略している。
図１１において、符号１５は第４ウェッジ１３と遮光手段９との間に設けられたシリンドリカルレンズである。
【０１０３】
シリンドリカルレンズ１５は、第４ウェッジ１３の回転軸方向および走査方向と直交する方向にのみレンズ作用を有しており、図１１中の第４ウェッジ１３の出射側で走査位置誤差が生じた走査軌跡１６を補償して、走査位置誤差の抑制された走査軌跡１７にレンズ作用で変換する。
【０１０４】
このシリンドリカルレンズ１５は全走査区間をカバーするように、光ファイバ８の長手方向（走査方向）へ全走査区間以上に長くなった形状を採用しても良いが、偏向角補償手段１４の第３，第４ウェッジ１２，１３と同時に並進走査を行うようにしても良い。これによりシリンドリカルレンズ１５も小型化することが可能になり、またコスト低減できる。
【０１０５】
一方、シリンドリカルレンズ１５による副次的な作用として、第４ウェッジ１３の回転軸方向および走査方向と直交する方向へビーム形状を引き伸ばすことがあげられる。これにより、第４ウェッジ１３の回転軸方向・走査方向と直交する方向へのビーム変位の影響を低減できるだけでなく、シリンドリカルレンズ１５のレンズ作用の方向へ光ファイバ８と位相マスク７とを複数本平行に並べた場合、複数本の光ファイバ８に対する同時露光が可能となる。複数本の光ファイバ８への同時露光は、生産効率を向上させるだけではなく、同一のロットで照射条件や温度条件を等しくできるため、作製する光ファイバグレーティングのフィルタ特性に高い均質性を確保することができる。
なお、図９から図１１で説明した第１〜第４ウェッジ１０〜１３を偏向手段２，偏向角補償手段３としてそれぞれ用いる手法は、遮光手段９を備えていない場合の走査型露光装置に適用しても良い。
【０１０６】
以上のように、この実施の形態２によれば、回転軸周りの回転角速度が信号記憶手段４・信号発生手段５・駆動手段６によって制御される第１ウェッジ１０と、第１ウェッジ１０と共有する回転軸周りの回転角速度が信号記憶手段４・信号発生手段５・駆動手段６によって制御される第２ウェッジ１１とから偏向手段２が構成されるとともに、回転軸周りの回転角速度が信号記憶手段４・信号発生手段５・駆動手段６によって制御される第３ウェッジ１２と、第３ウェッジ１２と共有する回転軸周りの回転角速度が信号記憶手段４・信号発生手段５・駆動手段６によって制御される第４ウェッジ１３とから偏向角補償手段３が構成され、第１ウェッジ１０，第２ウェッジ１１，第３ウェッジ１２および第４ウェッジ１３を順次透過させて、レーザ光源１が出射したレーザ光を遮光手段９へ出射するようにしたので、偏向手段２および偏向角補償手段３に対して揺動による走査が必要なくなり、走査の速度変化を小さくすることができるという効果が得られ、また偏角の制御精度を向上することができるという効果が得られ、さらに光学系の光軸調整を容易に行なうことができるという効果が得られる。
【０１０７】
また、この実施の形態２によれば、第１ウェッジ１０，第２ウェッジ１１，第３ウェッジ１２および第４ウェッジ１３が同一形状で同一材料によってそれぞれ構成され、第１ウェッジ１０と位相差を有することなく、第１ウェッジ１０の回転角速度と絶対値が等しく逆方向の回転角速度で第２ウェッジ１１が制御され、第１ウェッジ１０と１８０°の位相差を有し、第１ウェッジ１０の回転角速度で第３ウェッジ１２が制御され、第２ウェッジ１１と１８０°の位相差を有し、第１ウェッジ１０の回転角速度と絶対値が等しく逆方向の回転角速度で第４ウェッジ１３が制御されるようにしたので、各ウェッジの回転角速度の制御が容易になり、駆動手段６の負荷を軽減することができるという効果が得られる。
【０１０８】
さらに、この実施の形態２によれば、第１ウェッジ１０，第２ウェッジ１１，第３ウェッジ１２または第４ウェッジ１３の少なくともいずれか１つがその回転軸と直交する平面形状の入射面または出射面を有するようにしたので、走査制御の精度に対するレーザ光の入射角依存性を軽減することができるという効果が得られる。
【０１０９】
さらに、この実施の形態２によれば、第３ウェッジ１２および第４ウェッジ１３の回転走査に同期して、第３ウェッジ１２および第４ウェッジ１３を信号記憶手段４・信号発生手段５・駆動手段６が走査方向へ並進走査するようにしたので、並進走査させる分だけ第３ウェッジ１２および第４ウェッジ１３の小型化が可能になって、第３ウェッジ１２および第４ウェッジ１３の高速回転を行なうことができるようになり、走査速度を高速化できるという効果が得られ、また小型化の分だけ第３ウェッジ１２および第４ウェッジ１３の面精度を向上することができるという効果が得られ、さらにコスト低減が可能になるという効果が得られる。
【０１１０】
さらに、この実施の形態２によれば、第４ウェッジ１３と遮光手段９との間に設けられ、第４ウェッジ１３の回転軸および走査方向と直交する方向にのみレンズ作用を有し、レーザ光の走査区間以上の長さを走査方向に有するシリンドリカルレンズ１５を備えるようにしたので、第４ウェッジ１３の回転軸およびレーザ光の走査方向と直交する方向へビーム形状を伸ばすことができるようになり、複数の光ファイバ８への同時露光が可能になって生産効率を向上することができるという効果が得られ、また同一のロットで照射条件や温度条件を等しくできるため作製する光ファイバグレーティングのフィルタ特性に高い均質性を確保することができるという効果が得られ、さらに第４ウェッジ１３の回転軸および走査方向と直交する方向へのビーム変位の影響を低減できるという効果が得られる。
【０１１１】
さらに、この実施の形態２によれば、第４ウェッジ１３と遮光手段９との間に設けられ、第４ウェッジ１３の回転軸および走査方向と直交する方向にのみレンズ作用を有し、レーザ光の走査区間以上の長さを走査方向に有するシリンドリカルレンズ１５を備えるとともに、第３ウェッジ１２および第４ウェッジ１３の並進走査とともに、信号記憶手段４・信号発生手段５・駆動手段６がシリンドリカルレンズ１５を走査方向へ並進走査するようにしたので、第４ウェッジ１３の回転軸およびレーザ光の走査方向と直交する方向へビーム形状を伸ばすことができるようになり、複数の光ファイバ８への同時露光が可能になって生産効率を向上することができるという効果が得られ、また同一のロットで照射条件や温度条件を等しくできるため作製する光ファイバグレーティングのフィルタ特性に高い均質性を確保することができるという効果が得られ、さらに第４ウェッジ１３の回転軸および走査方向と直交する方向へのビーム変位の影響を低減することができるという効果が得られるとともに、並進走査させる分だけ第３ウェッジ１２および第４ウェッジ１３の小型化が可能になって、第３ウェッジ１２および第４ウェッジ１３の高速回転を行なうことができるようになり、走査速度を高速化できるという効果が得られ、また小型化の分だけ第３ウェッジ１２および第４ウェッジ１３の面精度を向上することができるという効果が得られ、さらにコスト低減が可能になるという効果が得られる。
【０１１２】
実施の形態３．
図１２はこの発明の実施の形態３による走査型露光装置の構成を示す図である。図１と同一符号は相当する構成要素である。
図１２において、１８はレーザ光源１からのレーザ光の光路を折り曲げる反射鏡、１９は反射鏡１８からのレーザ光を反射する偏向手段２としての多面体反射鏡（ポリゴンミラー）、２０は多面体反射鏡１９からのレーザ光にレンズ作用を与えて遮光手段９へ出射する偏向角補償手段３としてのＦθ光学系である。
【０１１３】
多面体反射鏡１９は、図１２の紙面垂直方向に回転軸を有し、回転軸の周りの回転角速度が駆動手段６によって制御されており、側面に複数の反射面（平面鏡）を回転軸と平行に備えた多面体柱である。多面体反射鏡１９の形状は特に限定されるものではないが、回転軸と直交する平面によって切断した多面体反射鏡１９の断面形状が正多角形（図１２では正８角形）となるように複数の反射面を等分割に形成すれば、走査制御の精度を向上することができ、また多面体反射鏡１９の製造が容易になって製造性を向上することができる。このとき、多面体反射鏡１９によって走査可能な偏向角範囲は、反射面の等分割数をＮとすれば±１８０°／Ｎとなる。
【０１１４】
一方、Ｆθ光学系２０は入射レーザ光の入射角を出射レーザ光の光軸からの距離に変換するレンズ作用を有する光学系で、Ｆθ光学系２０自身の光軸と入射角θをなしてレーザ光が入射するものとし、Ｆθ光学系２０固有の焦点距離をＦとすると、Ｆθ光学系２０から出射するレーザ光の走査位置ｘは式（１１）のようになる。
【０１１５】
【数１１】

【０１１６】
式（１１）にしたがって、Ｆθ光学系２０から出射するレーザ光の走査区間を目標照射強度分布の照射範囲よりも大きくなるように、Ｆθ光学系２０へ入射するレーザ光の入射角θの範囲を選び、これに合わせてＦθ光学系２０の光学的特性を設計し、かつ遮光手段９の開口幅を照射範囲と一致させるようにする。このことにより、偏向角補償手段３をパッシブに構成することができ、偏向角補償手段３に対する駆動系を不要にすることができる。なお、このＦθ光学系２０は、実施の形態１や実施の形態２の偏向手段２に適用しても良い。
【０１１７】
それでは、多面体反射鏡１９を用いた走査型露光装置の繰り返し走査について説明する。
図１３はこの発明の実施の形態３による走査型露光装置による繰り返し走査を説明するための図である。図１３（ａ）はアポダイゼーションの目標照射強度分布、図１３（ｂ）は実施の形態３による繰り返し走査の走査位置−時間ダイヤグラム、図１３（ｃ）は実施の形態３による繰り返し走査の多面体反射鏡１９の回転角速度−時間ダイヤグラムである。なお、図１３（ｂ）の走査位置−時間ダイヤグラムは実施の形態１や実施の形態２と同様に考えることができる。
【０１１８】
上述のように、Ｆθ光学系２０から出射するレーザ光の走査区間の両端部は、遮光手段９の開口部以外の部分によって遮光されるため、照射強度に寄与しない２つの遮光領域ができ、その遮光領域に対応する非照射期間が存在する。
【０１１９】
実施の形態２と同様に、照射に寄与しない時間を助走期間に割り当て、この助走期間において多面体反射鏡１９の回転角速度を高速に維持させる。図１３（ｃ）に示す回転角速度―時間ダイヤグラムを見ると、照射期間の開始時と終了時とにおいて走査速度を最大とすることができる。以上の回転角速度制御を連続的に繰り返すことで偏向動作・繰り返し走査が可能になる。
【０１２０】
また、図１３（ｃ）の回転角速度―時間ダイヤグラムを見ると、実施の形態２と同様に、多面体反射鏡１９の回転方向を時間的に反転させる必要のないことが分かり、回転角速度の高低変化だけで済むようになっている。これにより、駆動手段６に対する電気的・機械的負荷を軽減することができ、駆動手段６を小型化できる。
【０１２１】
さらに、実施の形態１，２と異なり、駆動手段６による多面体反射鏡１９の駆動系統は１つだけ有れば良く、多面体反射鏡１９の回転駆動の方向も１方向で済むので、駆動系統数や駆動方向が低減されて信頼性を向上できるとともに、コスト低減が可能になる。
【０１２２】
以上のように、この実施の形態３によれば、その光軸に対して所定の入射角で偏向手段２からレーザ光が入射すると、入射角を光軸からの距離に変換してレーザ光を出射するＦθ光学系２０を偏向角補償手段３とするようにしたので、信号記憶手段４・信号発生手段５・駆動手段６による制御を必要とすることなく偏向角補償手段３を実現することができ、駆動手段６の負荷を軽減することができるという効果が得られ、また走査型露光装置の信頼性を向上することができるという効果が得られる。
【０１２３】
また、この実施の形態３によれば、回転軸周りの回転角速度が信号記憶手段４・信号発生手段５・駆動手段６によって制御され、回転軸と平行に設けられた複数の平面鏡によってレーザ光源１が出射したレーザ光をＦθ光学系２０へ反射する多面体反射鏡１９を偏向手段２とするようにしたので、駆動系統数や駆動方向数が低減されて、駆動手段６に要する電気的・機械的負荷を軽減することができるという効果が得られ、また駆動手段６を小型化することができるという効果が得られ、さらに走査型露光装置の信頼性を向上することができるという効果が得られ、さらにコスト低減が可能になるという効果が得られる。
【０１２４】
さらに、この実施の形態３によれば、その回転軸と直交する平面によって切断された切断面形状が正多角形となるように、複数の平面鏡を多面体反射鏡１９が備えるようにしたので、走査制御の精度を向上することができるという効果が得られ、また多面体反射鏡１９の製造が容易になって製造性を向上することができるという効果が得られる。
【０１２５】
【発明の効果】
以上のように、この発明によれば、レーザ光を出射するレーザ光源と、レーザ光源が出射したレーザ光を所定の偏向角で偏向して出射する偏向手段と、偏向角を補償して偏向手段が出射したレーザ光を出射する偏向角補償手段と、偏向角を制御し、偏向角補償手段が出射したレーザ光を走査方向へ走査する走査制御手段と、偏向角補償手段が出射したレーザ光を回折させ、光ファイバに照射する位相変調型の透過型回折格子を有する位相マスクと、偏向角補償手段と位相マスクとの間に設けられ、偏向角補償手段が出射したレーザ光を位相マスクへ通過する開口部を有する遮光手段とを備え、走査制御手段は、偏向角補償手段が出射したレーザ光の走査区間が遮光手段に収まる範囲で、レーザ光を開口部よりも大きく走査して走査区間の両端に遮光領域を存在させるとともに、レーザ光が遮光領域を走査する期間に、レーザ光の走査速度の助走または反転を行ない、光ファイバにグレーティングを形成する際にアポダイゼーションを行うように構成したので、レーザ光を高速走査することができるようになり、レーザの強度ドリフトの影響と、低速照射によって発生してしまう局所加熱の影響とを最小化することができるという効果がある。
また、レーザ光の走査区間の両端では、遮光手段によってレーザ光が遮光されてこのときの照射強度をゼロにすることができるようになり、レーザ光が開口部を通過して光ファイバを照射するときに目標照射強度分布を実現することができるという効果がある。
【０１２６】
この発明によれば、時系列制御信号にしたがって偏向角を走査制御手段が制御し、走査制御手段が所定の走査周期で時系列制御信号を繰り返すようにしたので、レーザ光を高速繰り返し走査することができるという効果がある。
【０１２７】
この発明によれば、時系列制御信号にしたがって偏向角を走査制御手段が制御し、偏向角補償手段が出射したレーザ光の走査速度とアポダイゼーションの目標照射強度分布とを逆比例の関係にして計算した走査位置−時間ダイヤグラムを走査制御手段が時系列制御信号とするようにしたので、アポダイゼーションなどの目標照射強度分布を実現することができるという効果がある。
【０１２８】
この発明によれば、連続発振するレーザ光をレーザ光源が出射するようにしたので、走査周期に依存することなく、目標照射強度分布を実現することができるという効果がある。
【０１２９】
この発明によれば、所定のパルス周期で発振するパルスレーザ光をレーザ光源が出射するとともに、時系列制御信号の走査周期とパルス周期との整数比の最小公倍数が大きくなるように、走査制御手段が走査周期を定めるようにしたので、パルスレーザ光によって繰り返し走査を行う際に、周期的な照射強度分布の発生を抑制することができるという効果がある。
【０１３０】
この発明によれば、走査制御手段によって走査方向の揺動角度が制御される第１反射鏡を偏向手段とするとともに、第１反射鏡の揺動角度と絶対値が等しく逆方向に、走査制御手段によって走査方向の揺動角度が制御される第２反射鏡を偏向角補償手段とし、第１反射鏡および第２反射鏡を順次反射させて、レーザ光源が出射したレーザ光を遮光手段へ出射するようにしたので、レーザ光源に波長広がりがある場合に色収差の影響による走査位置誤差を防ぐことができるという効果がある。
【０１３１】
この発明によれば、回転軸周りの回転角速度が走査制御手段によって制御される第１ウェッジと、第１ウェッジと共有する回転軸周りの回転角速度が走査制御手段によって制御される第２ウェッジとから偏向手段が構成されるとともに、回転軸周りの回転角速度が走査制御手段によって制御される第３ウェッジと、第３ウェッジと共有する回転軸周りの回転角速度が走査制御手段によって制御される第４ウェッジとから偏向角補償手段が構成され、第１ウェッジ、第２ウェッジ、第３ウェッジおよび第４ウェッジを順次透過させて、レーザ光源が出射したレーザ光を遮光手段へ出射するようにしたので、偏向手段および偏向角補償手段に対して揺動による走査が必要なくなり、走査の速度変化を小さくすることができるという効果が得られ、また偏角の制御精度を向上することができるという効果が得られ、さらに光学系の光軸調整を容易に行なうことができるという効果がある。
【０１３２】
この発明によれば、第１ウェッジ、第２ウェッジ、第３ウェッジおよび第４ウェッジが同一形状で同一材料によってそれぞれ構成され、第１ウェッジと位相差を有することなく、第１ウェッジの回転角速度と絶対値が等しく逆方向の回転角速度で第２ウェッジが制御され、第１ウェッジと１８０°の位相差を有し、第１ウェッジの回転角速度で第３ウェッジが制御され、第２ウェッジと１８０°の位相差を有し、第１ウェッジの回転角速度と絶対値が等しく逆方向の回転角速度で第４ウェッジが制御されるようにしたので、各ウェッジの回転角速度の制御が容易になり、走査制御手段の負荷を軽減することができるという効果がある。
【０１３３】
この発明によれば、第１ウェッジ、第２ウェッジ、第３ウェッジまたは第４ウェッジの少なくともいずれか１つがその回転軸と直交する平面形状の入射面または出射面を有するようにしたので、走査制御の精度に対するレーザ光の入射角依存性を軽減することができるという効果がある。
【０１３４】
この発明によれば、第３ウェッジおよび第４ウェッジの回転走査に同期して、第３ウェッジおよび第４ウェッジを走査制御手段が走査方向へ並進走査するようにしたので、並進走査させる分だけ第３ウェッジおよび第４ウェッジの小型化が可能になって、第３ウェッジおよび第４ウェッジの高速回転を行なうことができるようになり、走査速度を高速化できるという効果が得られ、また小型化の分だけ第３ウェッジおよび第４ウェッジの面精度を向上することができるという効果が得られ、さらにコスト低減が可能になるという効果がある。
【０１３５】
この発明によれば、第４ウェッジと遮光手段との間に設けられ、第４ウェッジの回転軸および走査方向と直交する方向にのみレンズ作用を有し、レーザ光の走査区間以上の長さを走査方向に有するシリンドリカルレンズを備えるようにしたので、第４ウェッジの回転軸およびレーザ光の走査方向と直交する方向へビーム形状を伸ばすことができるようになり、複数の光ファイバへの同時露光が可能になって生産効率を向上することができるという効果が得られ、また同一のロットで照射条件や温度条件を等しくできるため作製する光ファイバグレーティングのフィルタ特性に高い均質性を確保することができるという効果が得られ、さらに第４ウェッジの回転軸および走査方向と直交する方向へのビーム変位の影響を低減できるという効果がある。
【０１３６】
この発明によれば、第４ウェッジと遮光手段との間に設けられ、第４ウェッジの回転軸および走査方向と直交する方向にのみレンズ作用を有し、レーザ光の走査区間以上の長さを走査方向に有するシリンドリカルレンズを備えるとともに、第３ウェッジおよび第４ウェッジの並進走査とともに、走査制御手段がシリンドリカルレンズを走査方向へ並進走査するようにしたので、第４ウェッジの回転軸およびレーザ光の走査方向と直交する方向へビーム形状を伸ばすことができるようになり、複数の光ファイバへの同時露光が可能になって生産効率を向上することができるという効果が得られ、また同一のロットで照射条件や温度条件を等しくできるため作製する光ファイバグレーティングのフィルタ特性に高い均質性を確保することができるという効果が得られ、さらに第４ウェッジの回転軸および走査方向と直交する方向へのビーム変位の影響を低減することができるという効果が得られるとともに、並進走査させる分だけ第３ウェッジおよび第４ウェッジの小型化が可能になって、第３ウェッジおよび第４ウェッジの高速回転を行なうことができるようになり、走査速度を高速化できるという効果が得られ、また小型化の分だけ第３ウェッジおよび第４ウェッジの面精度を向上することができるという効果が得られ、さらにコスト低減が可能になるという効果がある。
【０１３７】
この発明によれば、その光軸に対して所定の入射角で偏向手段からレーザ光が入射すると、入射角を光軸からの距離に変換してレーザ光を出射するＦθ光学系を偏向角補償手段とするようにしたので、走査制御手段による制御を必要とすることなく偏向角補償手段を実現することができ、走査制御手段の負荷を軽減することができるという効果が得られ、また走査型露光装置の信頼性を向上することができるという効果がある。
【０１３８】
この発明によれば、回転軸周りの回転角速度が走査制御手段によって制御され、回転軸と平行に設けられた複数の平面鏡によってレーザ光源が出射したレーザ光をＦθ光学系へ反射する多面体反射鏡を偏向手段とするようにしたので、駆動系統数や駆動方向数が低減されて、走査制御手段に要する電気的・機械的負荷を軽減することができるという効果が得られ、また走査制御手段を小型化することができるという効果が得られ、さらに走査型露光装置の信頼性を向上することができるという効果が得られ、さらにコスト低減が可能になるという効果がある。
【０１３９】
この発明によれば、その回転軸と直交する平面によって切断された切断面形状が正多角形となるように、複数の平面鏡を多面体反射鏡が備えるようにしたので、走査制御の精度を向上することができるという効果が得られ、また多面体反射鏡の製造が容易になって製造性を向上することができるという効果がある。
【図面の簡単な説明】
【図１】 この発明の実施の形態１による走査型露光装置の構成を示す図である。
【図２】 目標照射強度分布とこの目標照射強度分布を実現するための走査位置−時間ダイヤグラムとを示す図である。
【図３】 繰り返し走査を行なう場合の走査位置−時間ダイヤグラムの例を示す図である。
【図４】 この発明の実施の形態１による走査型露光装置による繰り返し走査を説明するための図である。
【図５】 パルスレーザ光によって繰り返し走査を行なった場合の照射強度分布の計算例を示す図である。
【図６】 この発明の実施の形態２による走査型露光装置の構成を示す図である。
【図７】 ウェッジの回転角速度と走査位置絶対誤差との関係を示す図である。
【図８】 照射期間および加減速・助走期間に対するウェッジ回転角の割り当てを示す図である。
【図９】 この発明の実施の形態２による走査型露光装置による繰り返し走査を説明するための図である。
【図１０】 この発明の実施の形態２による走査型露光装置の構成を示す図である。
【図１１】 この発明の実施の形態２による走査型露光装置の構成を示す図である。
【図１２】 この発明の実施の形態３による走査型露光装置の構成を示す図である。
【図１３】 この発明の実施の形態３による走査型露光装置による繰り返し走査を説明するための図である。
【図１４】 光ファイバの長手方向の位置に対するアポダイゼーションの実効的屈折率分布形状を説明するための図である。
【符号の説明】
１ レーザ光源、２ 偏向手段、３ 偏向角補償手段、４ 信号記憶手段（走査制御手段）、５ 信号発生手段（走査制御手段）、６ 駆動手段（走査制御手段）、７ 位相マスク、８ 光ファイバ、９ 遮光手段、１０ 第１ウェッジ、１１ 第２ウェッジ、１２ 第３ウェッジ、１３ 第４ウェッジ、１４ 偏向角補償手段、１５ シリンドリカルレンズ、１６，１７ 走査軌跡、１８ 反射鏡、１９ 多面体反射鏡、２０ Ｆθ光学系。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a scanning exposure apparatus for producing an optical fiber grating, and more particularly to a scanning exposure apparatus that realizes apodization by high-speed repetitive scanning.
[0002]
[Prior art]
  The optical fiber grating is obtained by giving a constant periodic refractive index change in the longitudinal direction of the optical fiber core, and is a device that reflects only light of a specific wavelength according to the period of the refractive index change. As a method for manufacturing this optical fiber grating, a phase mask method (for example, US Pat. No. 5,367,588) is well known in addition to the so-called two-beam interference method. The outline of manufacturing an optical fiber grating by this phase mask method is described in detail, for example, in JP-A-11-326669.
[0003]
  In a method for manufacturing an optical fiber grating using a phase mask, a phenomenon in which the refractive index increases in accordance with the amount of irradiation when quartz glass doped with germanium is irradiated with ultraviolet light is used. A phase mask in which a plurality of slits are formed at regular intervals is placed on the upper surface of an optical fiber whose main component is this material, and ultraviolet light is irradiated perpendicularly to the upper surface of the phase mask. Then, on the lower surface of the phase mask, the 0th-order light traveling straight is suppressed, and interference fringes are formed by ± 1st-order diffracted light, and the intensity of ultraviolet light periodically changes due to the interference fringes. It can be formed on the core of an optical fiber.
[0004]
  An important point as a manufacturing method is to change the effective refractive index into a trapezoidal shape with respect to the longitudinal direction of the optical fiber, as shown in FIG. This method of suppressing refractive index modulation on both sides is called apodization, and can suppress side modes (side lobes on both sides of the reflection spectrum main lobe) in the filter characteristics of the optical fiber grating. It is known that ripples in the reflection band and the flat top can be suppressed.
[0005]
  The following (A) to (C) can be cited as a method of performing apodization when producing an optical fiber grating.
[0006]
(A) Movement of optical fiber and phase mask
    The optical fiber and the phase mask are moved in the longitudinal direction of the optical fiber with respect to the ultraviolet light with the scanning position fixed and the irradiation intensity changed.
(B) Movement of ultraviolet light
    The ultraviolet light is moved along the optical fiber while changing the irradiation intensity.
(C) Movement of shielding plate
    Move the shielding plate placed in front of ultraviolet light or phase mask.
[0007]
  However, in the case of (A), since the optical fiber and the phase mask are moved, there is a drawback that the optical fiber and the phase mask are easily affected by relative positional deviation due to vibration of the drive mechanism. In addition, it is necessary to move the optical fiber / phase mask at a relatively low speed in order to avoid misalignment. Expansion due to local heating due to low-speed laser light irradiation occurs on the optical fiber or phase mask. There is also a problem that an error occurs in the width of the diffraction grating to be written. Furthermore, it is a problem that the laser beam used is susceptible to long-term intensity fluctuations (drift).
[0008]
  (C) is disclosed in JP-A-9-304638. The movement of the shielding plate can be expected to be performed at high speed because the reflecting mirror is lighter than when the optical fiber / phase mask of (A) is moved. In addition, since the phase mask and the optical fiber are fixed, there is an advantage that positional displacement due to vibration of the drive mechanism is unlikely to occur. However, there are drawbacks such as that the scanning width is limited to be less than or equal to the beam diameter of the laser beam, that it is affected by diffraction due to the aperture, and that the irradiation power per unit area is reduced, so that it is necessary to take a long irradiation time. is there.
[0009]
  When apodization is performed by moving the ultraviolet light of (B), for example, as disclosed in JP-A-11-326669, the reflecting mirror is moved in the scanning direction and the moving speed is increased in the apodization region. The velocity intensity is modulated so as to reduce the irradiation intensity distribution. Alternatively, there is a method of realizing the targeted target irradiation intensity distribution by changing the laser light intensity while moving the reflecting mirror at a constant speed.
[0010]
  These methods can be expected to perform high-speed scanning because the reflecting mirror is lighter than the movement of the optical fiber / phase mask in (A). In addition, since the optical fiber and the phase mask are fixed, positional displacement due to vibration of the drive mechanism hardly occurs. Furthermore, since it is not necessary to widen the beam diameter, the irradiation time can be shortened as compared with the movement of the shielding plate in (C).
[0011]
  However, with respect to the scanning speed modulation, the speed distribution is only qualitatively described as an example, and details of the method for calculating the scanning speed are not specified in JP-A-11-326669. In order to avoid the influence of laser beam intensity drift and local overheating due to low-speed irradiation, it is desirable not only to complete one scan at a high speed but also to repeat a high-speed scan further. Is inappropriate for high-speed repetitive scanning from the following points.
[0012]
  That is, in the example in which velocity modulation is applied, a high speed of movement is necessary at both ends of the scanning position, and a low speed of movement is necessary at the center of the scanning position. This is because the speed change becomes infinite. Also, when scanning at a constant speed, it is necessary to reverse the scanning direction at both ends of the scanning position, and the change in the scanning speed is similarly infinite.
[0013]
  The change in the scanning speed that can be realized is finite, and the speed becomes zero particularly during reversal. Therefore, when performing repeated scanning, there is a problem that an error occurs in the irradiation intensity that should be zero at both ends of the scanning position. As described above, in this conventional example, the change in speed at both ends of the scanning position is not taken into consideration.
[0014]
  As another conventional example of repeated scanning, a method of performing repeated exposure by fixing a light source and reciprocating an optical fiber and a phase mask is disclosed in JP-A-10-319255. However, this is a method of moving the optical fiber / phase mask, and as described above, it is weak against vibration caused by the movement, and it is necessary to reduce the scanning speed (1 Hz or less), which causes a problem of local heating. End up.
[0015]
  On the other hand, when scanning using pulsed laser light, if there is an integer multiple relationship between the scanning period and the pulse period, a periodic intensity distribution is generated in the irradiation intensity distribution. This periodic intensity distribution remains even when scanning is repeated, and becomes an obstacle to accurately realizing the targeted irradiation intensity distribution. This document only describes the pulse period when using a pulse laser as a rate higher than 100 Hz, and no consideration was given to this periodicity.
[0016]
[Problems to be solved by the invention]
  Since the conventional scanning exposure apparatus is configured as described above, the high-speed scanning of the laser beam cannot be repeated, and the influence of the laser intensity drift and the influence of the local heating that occurs due to low-speed irradiation. There was a problem that it could not be minimized.
[0017]
  Further, the conventional scanning exposure apparatus has a problem that the scanning control for realizing the target irradiation intensity distribution such as apodization is not clarified.
[0018]
  Furthermore, the conventional scanning exposure apparatus has a problem in that it cannot suppress the periodic intensity distribution that occurs when irradiation is performed with pulsed laser light.
[0019]
  The present invention has been made to solve the above-described problems, and can repeat high-speed scanning of laser light. The effects of laser intensity drift and the effects of local heating caused by low-speed irradiation. It is an object of the present invention to construct a scanning exposure apparatus that can be minimized.
[0020]
  Another object of the present invention is to constitute a scanning type exposure apparatus in which scanning control for realizing a target irradiation intensity distribution such as apodization is clarified.
[0021]
  A further object of the present invention is to provide a scanning exposure apparatus capable of suppressing a periodic intensity distribution that occurs when irradiation is performed with pulsed laser light.
[0022]
[Means for Solving the Problems]
  The scanning exposure apparatus according to the present invention comprises a laser light source that emits laser light, a deflection means that deflects and emits the laser light emitted from the laser light source at a predetermined deflection angle, and a deflection means that compensates the deflection angle. Deflection angle compensation means for emitting the emitted laser light, scanning control means for controlling the deflection angle and scanning the laser light emitted by the deflection angle compensation means in the scanning direction, and diffracting the laser light emitted by the deflection angle compensation means A phase mask having a phase modulation type transmission diffraction gratingA light shielding means provided between the deflection angle compensation means and the phase mask and having an opening through which the laser beam emitted from the deflection angle compensation means passes to the phase mask, and the scanning control means includes the deflection angle compensation means. The laser beam is scanned larger than the opening so that the laser beam is scanned larger than the opening so that the light shielding region exists at both ends of the scanning region and the laser beam scans the light shielding region. Advancing or reversing the scanning speed of the light to apodize when forming the grating in the optical fiberIt is what.
[0023]
  In the scanning type exposure apparatus according to the present invention, the scanning control means controls the deflection angle in accordance with the time series control signal, and the scanning control means repeats the time series control signal at a predetermined scanning cycle.
[0024]
  In the scanning exposure apparatus according to the present invention, the scanning angle is controlled by the scanning control means in accordance with the time series control signal, and the scanning speed of the laser beam emitted by the deflection angle compensating means is determined.ApodizationThe scanning position-time diagram calculated with an inversely proportional relationship with the target irradiation intensity distribution is used as the time-series control signal by the scanning control means.
[0025]
  In the scanning exposure apparatus according to the present invention, a laser light source emits continuously oscillating laser light.
[0026]
  In the scanning exposure apparatus according to the present invention, the laser light source emits pulsed laser light that oscillates at a predetermined pulse period, and the least common multiple of the integer ratio between the scanning period and the pulse period of the time-series control signal is increased. The scanning control means determines the scanning cycle.
[0027]
  In the scanning type exposure apparatus according to the present invention, the first reflecting mirror whose scanning direction swing angle is controlled by the scanning control means is used as the deflecting means, and the swing angle of the first reflecting mirror is equal to the absolute value in the opposite direction. In addition, the second reflecting mirror whose swing angle in the scanning direction is controlled by the scanning control means is used as a deflection angle compensating means, and the first reflecting mirror and the second reflecting mirror are sequentially reflected so that the laser light emitted from the laser light source is reflected. The light is emitted to the light shielding means.
[0028]
  In the scanning type exposure apparatus according to the present invention, the first wedge whose rotation angular velocity around the rotation axis is controlled by the scanning control means, and the rotation angular velocity around the rotation axis shared with the first wedge are controlled by the scanning control means. The deflection means is composed of the two wedges, the rotation angular velocity around the rotation axis is controlled by the scanning control means, and the rotation angular velocity around the rotation axis shared with the third wedge is controlled by the scanning control means. The deflection angle compensating means is constituted by the fourth wedge, and the first wedge, the second wedge, the third wedge and the fourth wedge are sequentially transmitted so that the laser light emitted from the laser light source is emitted to the light shielding means. It is a thing.
[0029]
  In the scanning exposure apparatus according to the present invention, the first wedge, the second wedge, the third wedge, and the fourth wedge are formed of the same material with the same shape, and have no phase difference with the first wedge. The second wedge is controlled with a rotational angular velocity that is equal in absolute value and opposite to the rotational angular velocity of the first wedge, has a phase difference of 180 ° with respect to the first wedge, the third wedge is controlled with the rotational angular velocity of the first wedge, and the second The fourth wedge has a phase difference of 180 ° with respect to the wedge, and the fourth wedge is controlled with the rotational angular velocity of the first wedge that is equal in absolute value and in the opposite direction.
[0030]
  In the scanning exposure apparatus according to the present invention, at least one of the first wedge, the second wedge, the third wedge, or the fourth wedge has a plane-shaped entrance surface or exit surface orthogonal to the rotation axis thereof. Is.
[0031]
  In the scanning type exposure apparatus according to the present invention, the scanning control means translates the third wedge and the fourth wedge in the scanning direction in synchronization with the rotational scanning of the third wedge and the fourth wedge.
[0032]
  The scanning exposure apparatus according to the present invention is provided between the fourth wedge and the light shielding means, has a lens action only in a direction orthogonal to the rotation axis of the fourth wedge and the scanning direction, and is longer than the scanning section of the laser beam. A cylindrical lens having a length of 1 in the scanning direction is provided.
[0033]
  The scanning exposure apparatus according to the present invention is provided between the fourth wedge and the light shielding means, has a lens action only in a direction orthogonal to the rotation axis of the fourth wedge and the scanning direction, and is longer than the scanning section of the laser beam. And a cylindrical lens having a length of 3 mm in the scanning direction, and along with the translational scanning of the third wedge and the fourth wedge, the scanning control means translates the cylindrical lens in the scanning direction.
[0034]
  The scanning exposure apparatus according to the present invention is an Fθ optical system that emits laser light by converting the incident angle into a distance from the optical axis when the laser light is incident from the deflecting means at a predetermined incident angle with respect to the optical axis. Is used as a deflection angle compensation means.
[0035]
  In the scanning exposure apparatus according to the present invention, the rotational angular velocity around the rotation axis is controlled by the scanning control means, and the laser beam emitted from the laser light source is reflected to the Fθ optical system by a plurality of plane mirrors provided in parallel with the rotation axis. A polyhedral reflecting mirror is used as the deflecting means.
[0036]
  In the scanning exposure apparatus according to the present invention, the polyhedral reflecting mirror is provided with a plurality of plane mirrors so that a cut surface shape cut by a plane orthogonal to the rotation axis thereof is a regular polygon.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
  An embodiment of the present invention will be described below.
Embodiment 1 FIG.
  FIG. 1 is a diagram showing the configuration of a scanning exposure apparatus according to Embodiment 1 of the present invention.
  In FIG. 1, 1 is a laser light source that emits a single wavelength laser beam (ultraviolet light), 2 is a deflection unit that changes (deflects) the deflection angle of the laser beam emitted from the laser light source 1, and 3 is a deflection unit 2. This is a deflection angle compensation means for emitting a laser beam by compensating and canceling the deflection angle of the deflected laser beam.
[0038]
  In FIG. 1, 4 is a signal storage means (scanning control means) for storing a time series control signal, and 5 is a signal generating means for repeatedly generating the time series control signal stored in the signal storage means 4 at a constant scanning cycle. (Scanning control means), 6 is a driving means (scanning control means) for driving the deflection operation of the deflecting means 2 in accordance with a time-series control signal from the signal generating means 5, and 7 is adjacent by a phase modulation type transmission diffraction grating. A phase mask that causes a difference in the optical path length (phase change amount) of the transmitted laser light, 8 is an optical fiber as an exposure target installed on the lower surface of the phase mask 7, and 9 is the deflection angle compensation means 3 and the phase mask 7 Is a light shielding means having an opening at the center thereof. In FIG. 1, the optical fiber 8 is installed in parallel with the paper surface, and the vertical direction in FIG. 1 corresponds to the longitudinal direction of the optical fiber 8.
[0039]
  Next, the operation will be described.
  The traveling direction of the laser light emitted from the laser light source 1 is deflected by the deflecting means 2. The deflection angle of the laser beam deflected by the deflecting unit 2 is driven by a driving unit 6 that receives a time-series control signal from the signal generating unit 5. The signal generation means 5 reads the time series control signal stored in the signal storage means 4 and repeatedly generates this time series control signal at a constant scanning cycle.
[0040]
  The laser beam deflected by the deflecting unit 2 is compensated for the deflection angle by the deflection angle compensating unit 3 located away from the deflecting unit 2, and reaches a position determined by the distance between the deflecting unit 2 and the deflection angle compensating unit 3. Scanned. One-dimensional scanning can be performed by continuously changing the deflection angle in one axial direction. In the present invention, the one-dimensional scanning direction coincides with the longitudinal direction of the optical fiber 8.
[0041]
  As the deflecting means 2 and the deflection angle compensating means 3, for example, one reflecting mirror (each of the first reflecting mirror and the second reflecting mirror, respectively) is used, and these reflecting mirrors are swung in the scanning direction. By controlling the swing angles of the two so that the values are equal and the signs are reversed, the deflection operation of the deflection means 2 and the deflection angle compensation operation of the deflection angle compensation means 3 can be realized. In this case, the first reflecting mirror and the second reflecting mirror are sequentially reflected so that the laser light from the laser light source 1 is emitted to the light shielding means 9, and only the light reflection phenomenon is used. There is an advantage that a scanning position error due to the influence of chromatic aberration does not occur when there is a wavelength broadening.
[0042]
  Of the laser light emitted from the deflection angle compensation means 3, only the laser light that has passed through the opening of the light shielding means 9 installed immediately before the phase mask 7 is incident on the upper surface of the phase mask 7, and the phase modulation of the phase mask 7 is performed. Interference between ± 1st order diffracted lights is generated by the transmissive diffraction grating of the mold, and an intensity distribution is formed on the optical fiber 8 on the lower surface.
[0043]
  Next, a method for realizing apodization by velocity modulation is described.
  FIG. 2 is a diagram showing a target irradiation intensity distribution and a scanning position-time diagram for realizing the target irradiation intensity distribution.
  FIG. 2A shows an example of the target irradiation intensity distribution, in which the central portion is flat and both end portions have bell-shaped apodization distribution shapes. The vertical axis represents the scanning position, and the horizontal axis represents the laser irradiation intensity. FIG. 2B shows a scanning position-time diagram for one scanning period. The vertical axis represents the scanning position corresponding to FIG. 2A, and the horizontal axis represents time.
[0044]
  Now, assuming that the laser irradiation intensity per unit time is i (x, t), the scanning position (modulation parameter) is x, the time is t, and the scanning period is τ, the laser intensity distribution I (x) per scanning period τ. Is represented by the following equation (1).
[0045]
[Expression 1]

[0046]
  On the other hand, when the load function W (x) relating to the scanning position x is used, the laser intensity distribution I (x) can also be described as in Expression (2).
[0047]
[Expression 2]

[0048]
  In the target irradiation intensity distribution shown in FIG. 2A, the laser intensity distribution I (x) is a monotonically increasing function in the scanning section where x <0, and the laser intensity distribution I (x) in the scanning section where x> 0. Is a monotonically decreasing function. Therefore, when Expression (1) is modified for each scanning section, Expression (3) and Expression (4) are obtained, respectively.
[0049]
[Equation 3]

[0050]
[Expression 4]

[0051]
  Similarly, the laser intensity distribution I (x) in Expression (2) is also the laser intensity distribution I for each scanning section.₁ (X), I₂It can be separated into (x). The result is shown in the following formula (5).
[0052]
[Equation 5]

[0053]
  Where W₁(X), W₂(X) is the load function W (x) in the scanning interval x <0, 0 <x, respectively. Comparing Equation (3), Equation (4), and Equation (5), it can be seen that the stay time (∂t / ∂x) obtained by differentiating the time t at the scanning position x is proportional to the load function W (x). . Since the dwell time (∂t / ∂x) is the reciprocal of the scanning speed, the above consideration results mean that the scanning speed (∂x / ∂t) is inversely proportional to the load function W (t).
[0054]
  By comparing and considering the above formulas (3), (4), and (5), the time function t (x) with the scanning position x as an independent variable is expressed by the following formulas (6a) and (6b). It can be expressed as
[0055]
[Formula 6]

[0056]
  Using this equation (6a) and equation (6b), a load function W (x) representing the target irradiation intensity distribution, that is, W₁(X) and W₂From (x), a diagram of time t (x) can be obtained.
[0057]
  When the scanning position-time diagram for realizing the target irradiation intensity distribution of the apodization in FIG. 2A is calculated by the equations (6a) and (6b), it is as shown in FIG. 2 (b). As can be seen from FIG. 2B, in the portions corresponding to both ends of the scanning position, the magnitude of the differential coefficient of the diagram increases rapidly, and in order to realize apodization, the scanning speed is measured at both ends of the scanning position. It can be understood that there is a need to greatly increase. Theoretically, it is necessary to make the scanning speed infinite in order to make the irradiation intensity zero.
[0058]
  Consider the case of repeated scanning.
  FIG. 3 is a diagram showing an example of a scanning position-time diagram in the case of performing repetitive scanning. FIG. 3A shows a case where the scanning position always monotonously increases with respect to time, and FIG. This is a case where the scanning position repeats monotonous increase and monotonous decrease.
[0059]
  3A and 3B, it is understood that the scanning direction (or scanning speed) needs to be reversed at both ends of the scanning position. When this reversal is performed, the scanning speed becomes zero. However, as described above, the scanning speed increases at the both ends of the scanning position to increase the maximum speed to realize apodization. It is difficult to reverse the scanning direction.
[0060]
  In order to solve this difficulty, in the present invention, the light shielding means 9 is provided immediately before the phase mask 7. The light shielding means 9 has a rectangular opening at the center, and this opening passes the laser light from the deflection angle compensation means 3 (light transmission region), and the portions other than the opening shield the laser light. (Shading area). Next, the function of the light shielding means 9 will be described.
[0061]
  FIG. 4 is a view for explaining repeated scanning by the scanning exposure apparatus according to the first embodiment of the present invention.
  4A is an enlarged view of the deflection angle compensation unit 3, the light shielding unit 9, the phase mask 7 and the optical fiber 8 of FIG. 1, and FIG. 4B is a target irradiation intensity distribution of apodization. The opening corresponds to the light transmission region, and the portions other than the opening correspond to the light shielding region. FIG. 4C is a scanning position-time diagram of repeated scanning according to the first embodiment.
[0062]
  In the first embodiment, as shown in FIG. 4A, the scanning section of the laser beam is set larger than the opening of the light shielding means 9 within the range of the size of the light shielding means 9. There are two light-shielding areas where the laser light is shielded by the light-shielding means 9 at both ends. As a result, during one scanning period of the laser light, the laser light passes through the opening and the optical fiber 8 is irradiated through the phase mask 7 (irradiation period), and the laser is emitted in a portion other than the opening. A period in which light is blocked and the optical fiber 8 is not irradiated (non-irradiation period) is created.
[0063]
  Then, as shown in FIG. 4C, a diagram for realizing the target irradiation intensity distribution of the apodization is performed during the irradiation period, and the operation of greatly increasing the scanning speed of the laser beam, the reduction / inversion of the scanning speed, A diagram for accelerating (running) up to the initial scanning speed required for scanning is assigned to the non-irradiation period.
[0064]
  As a result, the scanning speed needs to be infinite, and both ends of the scanning position where the scanning direction must be reversed correspond to the light-shielding region in FIG. Therefore, the optical fiber 8 is not irradiated with laser light, and the irradiation intensity at this time can be made zero. Therefore, the laser beam scanning can be repeated while realizing the target irradiation intensity distribution in the light transmission region of FIG. 4B in which the laser beam passes through the opening and irradiates the optical fiber 8.
[0065]
  In the above description, a continuous wave laser (CW laser) light source is assumed as the laser light source 1. In this case, the target irradiation intensity distribution can be realized regardless of the scanning cycle.
[0066]
  On the other hand, when the pulse laser beam is emitted from the laser light source 1, the combination of each cycle is determined so as to increase the least common multiple of the integer ratio between the repeated scanning cycle and the pulse cycle of the pulse laser beam. . This can prevent the occurrence of unintended periodic intensity distribution (ripple) in the irradiation intensity distribution when scanning is repeated many times. This is illustrated by the following calculation example.
[0067]
  FIG. 5 is a diagram showing a calculation example of the irradiation intensity distribution when the scanning is repeatedly performed by the pulse laser beam. The scanning cycle is 20 msec, the pulse cycle of the pulse laser beam is 0.90 msec, and FIG. 5 (b) When 1.00 msec is set, this is a calculated value when 1024 times of Gaussian beams (beam half width 1 mm) are irradiated with pulses. The integer ratio between the scanning period and the pulse period is 200: 9 in FIG. 5A and 20: 1 in FIG. 5B, and the least common multiple of each period ratio is 1800 in FIG. FIG. 5B corresponds to 20.
[0068]
  Looking at this, in the calculation example of FIG. 5B in which the least common multiple of the integer ratio of each period is small, a periodic intensity distribution is generated in the irradiation intensity distribution. This intensity distribution remains even when the number of irradiation pulses is increased, and becomes a factor that degrades the performance of the optical fiber grating.
[0069]
  On the other hand, in the calculation example of FIG. 5A in which the least common multiple of the integer ratio of each period is large, a periodic intensity distribution does not appear in the irradiation intensity distribution, and an ideal apodization can be realized. The ripple that is slightly present in FIG. 5B can be further reduced by increasing the number of pulse irradiations.
[0070]
  As described above, according to the first embodiment, the laser light source 1 that emits laser light, the deflection unit 2 that deflects and emits the laser light emitted from the laser light source 1 with a predetermined deflection angle, and the deflection angle. And a deflection angle compensation means 3 for emitting laser light emitted from the deflection means 2 and a signal storage means 4 for controlling the deflection angle and scanning the laser light emitted by the deflection angle compensation means 3 in the scanning direction. The generating means 5 and the driving means 6 and a phase mask 7 for irradiating the optical fiber 8 installed on the lower surface thereof along the scanning direction with a laser beam via a phase modulation type transmission diffraction grating are provided. Therefore, the laser beam can be scanned at high speed, and the effect of minimizing the influence of the laser intensity drift and the influence of local heating caused by the low-speed irradiation can be obtained.
[0071]
  Further, according to the first embodiment, the driving means 6 controls the deflection angle according to the time series control signal, and the signal generating means 5 repeats the time series control signal at a predetermined scanning period. Can be repeatedly scanned at high speed.
[0072]
  Furthermore, according to the first embodiment, the driving means 6 controls the deflection angle according to the time-series control signal, the scanning speed (∂x / ∂t) of the laser beam emitted from the deflection angle compensation means 3 and the target irradiation. Since the signal storage means 4 uses the scanning position-time diagram calculated with an inversely proportional relationship with the intensity distribution W (x) as a time-series control signal, the target irradiation intensity distribution W (x) such as apodization is obtained. The effect that it is realizable is acquired.
[0073]
  Furthermore, according to the first embodiment, the light shielding means 9 is provided between the deflection angle compensation means 3 and the phase mask 7 and has an opening through which the laser beam emitted from the deflection angle compensation means 3 passes. The signal storage means 4, the signal generation means 5, and the drive means 6 scan the laser light larger than the opening so that the scanning section of the laser light emitted from the deflection angle compensation means 3 is within the light shielding means 9. Since the light shielding regions exist at both ends, and the signal storage means 4, the signal generation means 5, and the driving means 6 perform the run-up or inversion of the scanning speed of the laser light during the period in which the laser light scans the light shielding area, At both ends of the scanning section of the laser light, the laser light is shielded by the light shielding means 9 so that the irradiation intensity at this time can be made zero, and when the laser light passes through the opening and irradiates the optical fiber 8 There is an advantage that it is possible to realize a target irradiation intensity distribution.
[0074]
  Further, according to the first embodiment, since the laser light source 1 emits the continuously oscillating laser beam, the effect of realizing the target irradiation intensity distribution can be realized without depending on the scanning cycle. It is done.
[0075]
  Furthermore, according to the first embodiment, the laser light source 1 emits pulsed laser light that oscillates at a predetermined pulse period, and the least common multiple of the integer ratio between the scanning period and the pulse period of the time-series control signal increases. As described above, since the signal generating means 5 determines the scanning cycle, it is possible to suppress the generation of a periodic irradiation intensity distribution when the scanning is repeatedly performed by the pulse laser beam.
[0076]
  Further, according to the first embodiment, the first reflecting mirror whose swing angle in the scanning direction is controlled by the signal storing means 4, the signal generating means 5, and the driving means 6 is the deflecting means 2, and the first reflecting The second reflecting mirror in which the swing angle in the scanning direction is controlled by the signal storage means 4, the signal generation means 5, and the drive means 6 in the opposite direction in which the absolute value of the mirror is equal to the absolute value is the deflection angle compensation means 3. Since the first reflecting mirror and the second reflecting mirror are sequentially reflected so that the laser light emitted from the laser light source 1 is emitted to the light shielding means 9, scanning due to the influence of chromatic aberration occurs when the laser light source 1 has a wavelength broadening. An effect that a position error can be prevented is obtained.
[0077]
  The scanning exposure apparatus according to the present invention is not limited to high-speed repetitive scanning, and the signal generating means 5 may generate a time-series control signal for one scanning period.
[0078]
  Further, the time series control signal is not limited to the scanning position-time diagram calculated using the equation (6), and can be arbitrarily determined.
[0079]
Embodiment 2. FIG.
  FIG. 6 is a view showing the arrangement of a scanning exposure apparatus according to Embodiment 2 of the present invention. The same reference numerals as those in FIG. 1 denote corresponding components.
  In the deflecting means 2 in FIG. 6, reference numerals 10 and 11 denote a first wedge and a second wedge, respectively, whose rotational angular velocities around the same rotational axis are controlled by the driving means 6. In the deflection angle compensating means 3 of FIG. 6, reference numerals 12 and 13 denote a third wedge and a fourth wedge, respectively, whose rotational angular velocities around the same rotational axis are controlled by the driving means 6. Laser light emitted from the laser light source 1 sequentially passes through the first to fourth wedges 10 to 13 and enters the light shielding means 9.
[0080]
  In FIG. 6, the rotation direction of the first wedge 10 and the rotation direction of the second wedge 11 are driven by the driving means 6 so that the rotation direction of the third wedge 12 and the rotation direction of the fourth wedge 13 are opposite to each other. ing. The shapes of the first to fourth wedges 10 to 13 are not particularly limited, but at least one of the entrance surface or the exit surface is a planar shape orthogonal to the rotation axis, thereby tracking the optical path of the laser light. In addition, it is possible to suppress the deterioration of the deflection operation accuracy due to the incident angle error of the incident laser beam, and to reduce the dependency of the laser beam on the incident angle on the scanning control accuracy.
[0081]
  First, the scanning function of the first wedge 10 and the second wedge 11 of the deflection unit 2 will be described. The x-axis direction is the longitudinal direction of the optical fiber 8, the optical axis of the laser light source 1 and the y-axis direction perpendicular to the x direction, and the origin is on the optical axis of the laser light source 1. The deflection angle of the laser beam generated by the first and second wedges 10 and 11 is defined by the angle between the laser beam emitted from the deflecting means 2 and the optical axis of the laser light source 1, and the deflection angle in the x-axis direction is defined as θ_x , The deflection angle in the y-axis direction is θ_yThen the deflection angle θ_x, Θ_yAre represented by the equations (7a) and (7b), respectively.
[0082]
[Expression 7]

[0083]
  Where δ₁, Δ₂Is the deflection angle of the light beam by the first and second wedges 10 and 11, φ₁, Φ₂Is the rotational angular velocity of the first and second wedges 10 and 11, and ψ is the phase difference between the first and second wedges 10 and 11.
  If the first and second wedges 10 and 11 made of the same material and the same shape are used, the deflection angle δ₁, Δ₂The relationship is δ₁= Δ₂= Δ, and the rotational angular velocity φ of the first and second wedges 10 and 11₁, Φ₂Rotate in the opposite direction at the same speed (φ₁= -Φ₂= Φ) and the phase difference ψ = 0, the following equations (8a) and (8b) are obtained respectively, and it can be seen that the laser beam can be scanned only in the x direction, that is, in the longitudinal direction of the optical fiber 8.
[0084]
[Equation 8]

[0085]
  On the other hand, for the third and fourth wedges 12 and 13 of the deflection angle compensation means 3, the initial phase of the third wedge 12 is advanced by 180 ° with respect to the first wedge 10, and the initial phase of the fourth wedge 13 is set to the second phase. When the wedge 11 is advanced by 180 °, the phase difference ψ = 0 ° between the third and fourth wedges 12 and 13 is obtained.
[0086]
  Similarly to the first and second wedges 10 and 11, when the third and fourth wedges 12 and 13 made of the same material and the same shape are used, the deflection angle δ₁= Δ₂= Δ, rotation angular velocity φ₁= -Φ₂= Φ (the rotational angular velocity φ of the third wedge 12_Three= Φ₁, Angular velocity φ of the fourth wedge 13_Four= Φ₂), Formulas (7a) and (7b) become δcos [φ + 180 °] + δcos [− (φ + 180 °)], δsin [φ + 180 °] + δsin [− (φ + 180 °)], respectively, and formulas (9a) and (9b) It can be seen that the deflection angle is compensated.
[0087]
[Equation 9]

[0088]
  Accordingly, the third wedge 12 is placed at a distance L from the fourth wedge 13, and θ = −θ._xWhen the above-described deflection is applied, the scanning position x from the optical axis of the laser light source 1 of the laser light incident on the first wedge 10 and emitted from the fourth wedge 13 can be obtained by Expression (10).
[0089]
[Expression 10]

[0090]
  From the expression (10), it can be seen that the scanning position can be reciprocated in accordance with the rotational angular velocity φ of the first to fourth wedges 10-13. The scanning position x generally does not change linearly with respect to the rotational angular velocity φ, but linear approximation is possible by limiting the angular range of the rotational angular velocity φ and optimally selecting the deflection angle δ. An example in which the scanning position x is approximately linear with the rotational angular velocity φ is shown in FIG.
[0091]
  FIG. 7 is a diagram showing the relationship between the rotational angular velocity φ of the wedge and the scanning position absolute error (deviation from linearity). Deviation from the linearity of equation (10) using the deviation angle δ and the distance L as parameters. Is calculated. The horizontal axis in FIG. 7 represents the rotational angular velocity φ [deg. The vertical axis represents the absolute error [mm] of the scanning position x. As shown in FIG. 7, when the range of the rotational angular velocity φ is limited to ± 30 °, there is a set of a deviation angle δ and a distance L in which the error is always zero in the range between φ = ± 30 °, In the example of FIG. 7, δ = 21.2 deg. , L = 51.6 mm is found to be the optimum value.
[0092]
  Now, a linear approximate rotation angle range in which the scanning position x approximately linearly changes with respect to this rotation angular velocity φ is assigned to the irradiation period described in the first embodiment, and an angle range other than this linear approximate rotation angle range is not irradiated. Consider assigning to a period. FIG. 8 is a diagram showing assignment of the wedge rotation angle with respect to the irradiation period and the non-irradiation period, and shows the rotation angle range viewed from the upper surface of the wedge. For simplicity of explanation, the position where all the four first to fourth wedges 10 to 13 are rotated by 90 ° is read again with reference to the rotation angle.
[0093]
  Now, repeated scanning will be described.
  FIG. 9 is a diagram for explaining repeated scanning by the scanning exposure apparatus according to the second embodiment of the present invention. 9A is a target irradiation intensity distribution, FIG. 9B is a scanning position-time diagram according to the second embodiment, and FIG. 9C is a rotational angular velocity-time diagram of a wedge according to the second embodiment. 9 (d) shows a wedge rotation angle-time diagram according to the second embodiment.
[0094]
  Similar to the first embodiment, the time series control signal is calculated by making the scanning speed in inverse proportion to the target irradiation intensity distribution within the irradiation period. Further, as shown in FIGS. 9A and 9B, two light shielding regions are provided at both ends of the scanning position by the light shielding means 9, and the operation of greatly increasing the scanning speed of the laser beam, the reduction of the scanning speed, The acceleration up to the initial scanning speed required for the next scanning is performed during the non-irradiation period in the light shielding region.
[0095]
  Although not particularly limited, as described above, if a linear approximate rotation angle range in which the scanning position x changes approximately linearly with respect to the rotation angular velocity φ of each wedge is assigned to the irradiation period, Since the scanning position x can be controlled at equal intervals when the wedge rotational angular velocity φ is changed at equal intervals, the controllability can be improved.
[0096]
  As described above, as shown in the rotation angle-time diagram of each wedge in FIG. 9D, two irradiation periods are allocated while the first to fourth wedges 10 to 13 are rotated once from 0 to 360 °. One round-trip scanning is completed. By performing this wedge rotation angle control continuously, position scanning can be repeated at high speed.
[0097]
  Particularly in comparison with the first embodiment, in the second embodiment, as shown in the rotational angular velocity-time diagram of FIG. 9C, the rotational directions of the first to fourth wedges 10-13 are within the non-irradiation period. There is no need to invert, and only a change in the rotational angular velocity is required. Thereby, the electrical and mechanical load applied to the driving means 6 can be reduced.
[0098]
  In the description so far, the scanning of the laser beam is realized only by the rotation of the first to fourth wedges 10 to 13. However, the third and fourth wedges 12 and 13 of the deflection angle compensating means 3 are connected to the optical fiber 8. Translational scanning may be performed in the longitudinal direction.
[0099]
  FIG. 10 is a view showing the structure of a scanning exposure apparatus according to Embodiment 2 of the present invention, and the same reference numerals as those in FIGS. 1 and 6 denote corresponding components.
  In FIG. 10, reference numeral 14 denotes a deflection angle compensator having third and fourth wedges 12 and 13. The third and fourth wedges 12 and 13 of the deflection angle compensator 14 are third and fourth wedges. In synchronism with the rotational movements 12 and 13, translational scanning is performed by the driving means 6 in the longitudinal direction of the optical fiber 8.
[0100]
  The position scanning in FIG. 10 does not require positional accuracy, and the laser beams deflected by the first and second wedges 10 and 11 of the deflection unit 2 are within the wedges of the third and fourth wedges 12 and 13 of the deflection angle compensation unit 14. It is only necessary to enter without being kicked. Since the effective diameter of the third and fourth wedges 12 and 13 can be reduced by using the position scanning together, the surface accuracy of the third and fourth wedges 12 and 13 can be improved, the driving means 6 can be downsized, the cost can be reduced, etc. effective.
[0101]
  Further, as shown in FIG. 11, by installing a cylindrical lens, even when a scanning position error occurs in the direction of the rotation axis of the fourth wedge 13 and the direction orthogonal to the scanning direction by the wedge scanning, this can be compensated. .
[0102]
  FIG. 11 is a view showing the structure of a scanning exposure apparatus according to Embodiment 2 of the present invention, and the same reference numerals as those in FIGS. 1 and 6 denote corresponding components. In FIG. 11, the laser light source 1 to the third wedge 12 are not shown.
  In FIG. 11, reference numeral 15 denotes a cylindrical lens provided between the fourth wedge 13 and the light shielding means 9.
[0103]
  The cylindrical lens 15 has a lens action only in the direction of the rotation axis of the fourth wedge 13 and the direction orthogonal to the scanning direction, and the scanning locus in which the scanning position error has occurred on the emission side of the fourth wedge 13 in FIG. 16 is compensated and converted into a scanning locus 17 in which a scanning position error is suppressed by a lens action.
[0104]
  The cylindrical lens 15 may adopt a shape that is longer than the entire scanning section in the longitudinal direction (scanning direction) of the optical fiber 8 so as to cover the entire scanning section. , Translational scanning may be performed simultaneously with the fourth wedges 12 and 13. As a result, the cylindrical lens 15 can also be reduced in size and the cost can be reduced.
[0105]
  On the other hand, as a secondary action by the cylindrical lens 15, the beam shape is stretched in the direction perpendicular to the rotation axis direction and the scanning direction of the fourth wedge 13. Thereby, not only can the influence of the beam displacement in the direction perpendicular to the rotation axis direction / scanning direction of the fourth wedge 13 be reduced, but a plurality of optical fibers 8 and phase masks 7 are arranged in the direction of the lens action of the cylindrical lens 15. When arranged in parallel, simultaneous exposure to a plurality of optical fibers 8 is possible. Simultaneous exposure to a plurality of optical fibers 8 not only improves the production efficiency, but also makes it possible to equalize irradiation conditions and temperature conditions in the same lot, thus ensuring high homogeneity in the filter characteristics of the optical fiber grating to be manufactured. be able to.
  The method using the first to fourth wedges 10 to 13 described with reference to FIGS. 9 to 11 as the deflecting means 2 and the deflection angle compensating means 3 is applied to a scanning exposure apparatus in the case where the light shielding means 9 is not provided. You may do it.
[0106]
  As described above, according to the second embodiment, the first wedge 10 whose rotation angular velocity around the rotation axis is controlled by the signal storage means 4, the signal generation means 5, and the driving means 6 is shared with the first wedge 10. The deflection means 2 is composed of the second wedge 11 whose rotational angular velocity around the rotating shaft is controlled by the signal storage means 4, the signal generating means 5 and the driving means 6, and the rotational angular velocity around the rotational axis is the signal storage means. 4. The third wedge 12 controlled by the signal generating means 5 and the driving means 6 and the rotational angular velocity around the rotation axis shared with the third wedge 12 are controlled by the signal storing means 4, the signal generating means 5 and the driving means 6. The fourth wedge 13 constitutes the deflection angle compensating means 3, and the first wedge 10, the second wedge 11, the third wedge 12 and the fourth wedge 13 are sequentially transmitted through the lever. Since the laser light emitted from the light source 1 is emitted to the light shielding means 9, the deflection means 2 and the deflection angle compensation means 3 do not require scanning by swinging, and the change in scanning speed can be reduced. The effect that the control accuracy of the deflection angle can be improved is obtained, and the effect that the optical axis of the optical system can be easily adjusted is obtained.
[0107]
  Further, according to the second embodiment, the first wedge 10, the second wedge 11, the third wedge 12, and the fourth wedge 13 are respectively formed of the same shape and the same material, and have a phase difference with the first wedge 10. The second wedge 11 is controlled at a rotational angular velocity that is equal in absolute value and opposite to the rotational angular velocity of the first wedge 10, has a phase difference of 180 ° from the first wedge 10, and has a rotational angular velocity of the first wedge 10. Thus, the third wedge 12 is controlled to have a phase difference of 180 ° with respect to the second wedge 11, and the fourth wedge 13 is controlled with the rotational angular velocity of the first wedge 10 that is equal in absolute value and in the opposite direction. As a result, the rotation angular velocity of each wedge can be easily controlled, and the load on the driving means 6 can be reduced.
[0108]
  Furthermore, according to the second embodiment, at least one of the first wedge 10, the second wedge 11, the third wedge 12, or the fourth wedge 13 has a planar incident surface or output surface orthogonal to the rotation axis thereof. Thus, the effect that the dependency of the laser beam on the incident angle with respect to the accuracy of the scanning control can be reduced can be obtained.
[0109]
  Further, according to the second embodiment, in synchronization with the rotational scanning of the third wedge 12 and the fourth wedge 13, the third wedge 12 and the fourth wedge 13 are connected to the signal storing means 4, the signal generating means 5, and the driving means. Since 6 is translationally scanned in the scanning direction, the third wedge 12 and the fourth wedge 13 can be reduced in size by the amount of translation scanning, and the third wedge 12 and the fourth wedge 13 are rotated at high speed. Thus, the effect that the scanning speed can be increased is obtained, and the surface accuracy of the third wedge 12 and the fourth wedge 13 can be improved by the size reduction, and further The effect that the cost can be reduced is obtained.
[0110]
  Further, according to the second embodiment, the laser beam is provided only between the fourth wedge 13 and the light shielding means 9 and has a lens function only in the direction orthogonal to the rotation axis of the fourth wedge 13 and the scanning direction. Since the cylindrical lens 15 having a length equal to or longer than the scanning section in the scanning direction is provided, the beam shape can be extended in a direction orthogonal to the rotation axis of the fourth wedge 13 and the scanning direction of the laser beam. An optical fiber grating filter to be manufactured because it is possible to improve the production efficiency by enabling simultaneous exposure to a plurality of optical fibers 8, and the irradiation conditions and temperature conditions can be made equal in the same lot. The effect that high homogeneity can be ensured in the characteristics is obtained, and further, the rotation direction of the fourth wedge 13 and the direction orthogonal to the scanning direction are obtained. The effect is obtained that it is possible to reduce the influence of over-time displacement.
[0111]
  Further, according to the second embodiment, the laser beam is provided only between the fourth wedge 13 and the light shielding means 9 and has a lens function only in the direction orthogonal to the rotation axis of the fourth wedge 13 and the scanning direction. The cylindrical lens 15 having a length equal to or longer than the scanning section in the scanning direction is provided, and the signal storage means 4, the signal generation means 5, and the driving means 6 are provided with the cylindrical lens 15 along with the translational scanning of the third wedge 12 and the fourth wedge 13. , The beam shape can be extended in a direction perpendicular to the rotation axis of the fourth wedge 13 and the scanning direction of the laser beam, and simultaneous exposure to a plurality of optical fibers 8 is performed. The production efficiency can be improved and the irradiation conditions and temperature conditions can be made equal in the same lot. The effect of ensuring high homogeneity in the filter characteristics of the optical fiber grating to be obtained is obtained, and the influence of beam displacement in the direction perpendicular to the rotation axis of the fourth wedge 13 and the scanning direction can be reduced. The third wedge 12 and the fourth wedge 13 can be downsized by the amount of translation scanning, and the third wedge 12 and the fourth wedge 13 can be rotated at high speed. The effect that the scanning speed can be increased is obtained, and the surface accuracy of the third wedge 12 and the fourth wedge 13 can be improved by the size reduction, and the cost can be further reduced. The effect is obtained.
[0112]
Embodiment 3 FIG.
  FIG. 12 is a view showing the structure of a scanning exposure apparatus according to Embodiment 3 of the present invention. The same reference numerals as those in FIG. 1 denote corresponding components.
  In FIG. 12, 18 is a reflecting mirror that bends the optical path of the laser light from the laser light source 1, 19 is a polyhedral reflecting mirror (polygon mirror) as the deflecting means 2 that reflects the laser light from the reflecting mirror 18, and 20 is a polyhedral reflecting mirror. Reference numeral 19 denotes an Fθ optical system serving as a deflection angle compensation unit 3 that applies a lens action to the laser beam from the beam 19 and emits the laser beam to the light shielding unit 9.
[0113]
  The polyhedral reflecting mirror 19 has a rotation axis in the direction perpendicular to the paper surface of FIG. 12, the rotational angular velocity around the rotation axis is controlled by the driving means 6, and a plurality of reflecting surfaces (plane mirrors) on the side are parallel to the rotation axis. It is a polyhedral column prepared for. The shape of the polyhedral reflecting mirror 19 is not particularly limited. However, the polyhedral reflecting mirror 19 cut by a plane orthogonal to the rotation axis has a plurality of shapes such that the cross-sectional shape of the polyhedral reflecting mirror 19 is a regular polygon (a regular octagon in FIG. 12). If the reflecting surface is formed in equal divisions, the accuracy of scanning control can be improved, and the polyhedral reflecting mirror 19 can be easily manufactured and the productivity can be improved. At this time, the deflection angle range that can be scanned by the polyhedral reflecting mirror 19 is ± 180 ° / N, where N is the number of equally divided reflecting surfaces.
[0114]
  On the other hand, the Fθ optical system 20 is an optical system having a lens function for converting the incident angle of the incident laser light into a distance from the optical axis of the outgoing laser light. The Fθ optical system 20 forms an incident angle θ with the optical axis of the Fθ optical system 20 itself. Assuming that light is incident and the focal length peculiar to the Fθ optical system 20 is F, the scanning position x of the laser light emitted from the Fθ optical system 20 is as shown in Expression (11).
[0115]
[Expression 11]

[0116]
  According to the equation (11), the range of the incident angle θ of the laser light incident on the Fθ optical system 20 is set so that the scanning section of the laser light emitted from the Fθ optical system 20 is larger than the irradiation range of the target irradiation intensity distribution. According to this, the optical characteristics of the Fθ optical system 20 are designed, and the opening width of the light shielding means 9 is made to coincide with the irradiation range. As a result, the deflection angle compensation means 3 can be passively configured, and a drive system for the deflection angle compensation means 3 can be eliminated. The Fθ optical system 20 may be applied to the deflecting unit 2 of the first embodiment or the second embodiment.
[0117]
  Now, repeated scanning of the scanning exposure apparatus using the polyhedral reflecting mirror 19 will be described.
  FIG. 13 is a diagram for explaining repetitive scanning by the scanning exposure apparatus according to the third embodiment of the present invention. 13A is a target irradiation intensity distribution of apodization, FIG. 13B is a scanning position-time diagram of repetitive scanning according to the third embodiment, and FIG. 13C is a polyhedral reflecting mirror of repetitive scanning according to the third embodiment. 19 is a rotational angular velocity-time diagram of nineteen. Note that the scanning position-time diagram in FIG. 13B can be considered in the same manner as in the first and second embodiments.
[0118]
  As described above, since both ends of the scanning section of the laser light emitted from the Fθ optical system 20 are shielded by the portions other than the opening of the light shielding means 9, two light shielding regions that do not contribute to the irradiation intensity are formed. There is a non-irradiation period corresponding to the light shielding region.
[0119]
  As in the second embodiment, a time that does not contribute to irradiation is assigned to the run-up period, and the rotational angular velocity of the polyhedral reflector 19 is maintained at a high speed during this run-up period. Looking at the rotational angular velocity-time diagram shown in FIG. 13C, the scanning speed can be maximized at the start and end of the irradiation period. By repeating the above rotational angular velocity control continuously, deflection operation and repeated scanning are possible.
[0120]
  Also, the rotational angular velocity-time diagram of FIG. 13C shows that, as in the second embodiment, it is not necessary to reverse the rotational direction of the polyhedral reflecting mirror 19 in time. It ’s just that. Thereby, the electrical and mechanical load on the driving means 6 can be reduced, and the driving means 6 can be reduced in size.
[0121]
  Further, unlike the first and second embodiments, only one driving system for the polyhedral reflecting mirror 19 by the driving means 6 is required, and only one direction of rotational driving of the polyhedral reflecting mirror 19 is required. In addition, the driving direction can be reduced and the reliability can be improved, and the cost can be reduced.
[0122]
  As described above, according to the third embodiment, when the laser light is incident from the deflecting unit 2 at a predetermined incident angle with respect to the optical axis, the incident angle is converted into a distance from the optical axis, and the laser light is converted. Since the outgoing Fθ optical system 20 is the deflection angle compensation means 3, the deflection angle compensation means 3 can be realized without requiring control by the signal storage means 4, signal generation means 5, and drive means 6. Thus, the effect that the load on the driving means 6 can be reduced is obtained, and the reliability of the scanning exposure apparatus can be improved.
[0123]
  Further, according to the third embodiment, the rotational angular velocity around the rotation axis is controlled by the signal storage means 4, the signal generation means 5, and the drive means 6, and the laser light source 1 is provided by the plurality of plane mirrors provided in parallel with the rotation axis. The polyhedral reflecting mirror 19 that reflects the laser light emitted from the Fθ optical system 20 is used as the deflecting means 2, so that the number of driving systems and the number of driving directions is reduced, and the electrical and mechanical characteristics required for the driving means 6 are reduced. The effect that the load can be reduced is obtained, the effect that the drive means 6 can be reduced is obtained, and the reliability that the scanning exposure apparatus can be improved is obtained. Furthermore, the effect that cost reduction becomes possible is acquired.
[0124]
  Further, according to the third embodiment, since the polyhedral reflecting mirror 19 is provided with a plurality of plane mirrors so that the cut surface shape cut by the plane orthogonal to the rotation axis is a regular polygon, scanning is performed. The effect that the accuracy of control can be improved is obtained, and the effect that the production of the polyhedral reflecting mirror 19 is facilitated and the productivity can be improved is obtained.
[0125]
【The invention's effect】
  As described above, according to the present invention, the laser light source that emits the laser light, the deflecting means that deflects and emits the laser light emitted from the laser light source at a predetermined deflection angle, and the deflection means that compensates the deflection angle. The deflection angle compensation means for emitting the laser beam emitted from the laser beam, the scanning control means for controlling the deflection angle and scanning the laser beam emitted by the deflection angle compensation means in the scanning direction, and the laser beam emitted by the deflection angle compensation means DiffractIrradiate the optical fiberA phase mask having a phase modulation type transmissive diffraction grating; andA light shielding means provided between the deflection angle compensation means and the phase mask and having an opening through which the laser beam emitted from the deflection angle compensation means passes to the phase mask, and the scanning control means includes the deflection angle compensation means. The laser beam is scanned larger than the opening so that the laser beam is scanned larger than the opening so that the light shielding region exists at both ends of the scanning region and the laser beam scans the light shielding region. Since the scanning speed of the light is accelerated or reversed, and apodization is performed when forming a grating in an optical fiber.The laser beam can be scanned at a high speed, and there is an effect that the influence of the laser intensity drift and the influence of the local heating generated by the low-speed irradiation can be minimized.
  Further, at both ends of the scanning section of the laser light, the laser light is shielded by the light shielding means so that the irradiation intensity at this time can be made zero, and the laser light irradiates the optical fiber through the opening. There is an effect that sometimes the target irradiation intensity distribution can be realized.
[0126]
  According to the present invention, since the scanning control means controls the deflection angle according to the time series control signal, and the scanning control means repeats the time series control signal at a predetermined scanning cycle, the laser light can be repeatedly scanned at high speed. There is an effect that can be.
[0127]
  According to this invention, the scanning control means controls the deflection angle according to the time-series control signal, and the scanning speed of the laser beam emitted from the deflection angle compensation meansApodizationSince the scanning control means uses the time-series control signal as the scanning position-time diagram calculated with an inversely proportional relationship with the target irradiation intensity distribution, the effect of realizing the target irradiation intensity distribution such as apodization can be realized. There is.
[0128]
  According to the present invention, since the laser light source emits continuously oscillating laser light, the target irradiation intensity distribution can be realized without depending on the scanning period.
[0129]
  According to this invention, the laser light source emits a pulsed laser beam that oscillates at a predetermined pulse period, and the scanning control means so that the least common multiple of the integer ratio between the scanning period and the pulse period of the time-series control signal is increased. Since the scanning period is determined, there is an effect that it is possible to suppress the generation of a periodic irradiation intensity distribution when the scanning is repeatedly performed by the pulse laser beam.
[0130]
  According to the present invention, the first reflecting mirror whose scanning direction swing angle is controlled by the scanning control means is used as the deflecting means, and the first reflecting mirror swing angle and the absolute value are equal and in the opposite direction. The second reflecting mirror whose swing angle in the scanning direction is controlled by the means is used as the deflection angle compensation means, and the first reflecting mirror and the second reflecting mirror are sequentially reflected to emit the laser light emitted from the laser light source to the light shielding means. Thus, when the laser light source has a wavelength broadening, there is an effect that it is possible to prevent a scanning position error due to the influence of chromatic aberration.
[0131]
  According to the present invention, the first wedge whose rotation angular velocity around the rotation axis is controlled by the scanning control means, and the second wedge whose rotation angular velocity around the rotation axis shared with the first wedge is controlled by the scanning control means. A third wedge in which the deflection means is configured and the rotation angular velocity around the rotation axis is controlled by the scanning control means, and a fourth wedge in which the rotation angular velocity around the rotation axis shared with the third wedge is controlled by the scanning control means The deflection angle compensator is composed of the first wedge, the second wedge, the third wedge, and the fourth wedge so that the laser light emitted from the laser light source is emitted to the light shielding means. Scanning is not required for the means and the deflection angle compensation means, and the effect that the change in scanning speed can be reduced is obtained. Effect is obtained that it is possible to improve the control accuracy of the deflection angle, there is an effect that it is possible to more easily perform the optical axis adjustment of the optical system.
[0132]
  According to the present invention, the first wedge, the second wedge, the third wedge, and the fourth wedge are formed of the same material with the same shape, and the rotational angular velocity of the first wedge without having a phase difference with the first wedge. The second wedge is controlled with a rotation angular velocity of equal and opposite absolute value, having a phase difference of 180 ° with the first wedge, the third wedge is controlled with the rotation angular velocity of the first wedge, and 180 ° with the second wedge. Since the fourth wedge is controlled with the rotational angular velocity of the first wedge having the same absolute value as that of the first wedge and in the opposite direction, the rotational angular velocity of each wedge is easily controlled, and the scanning control is performed. There is an effect that the load of the means can be reduced.
[0133]
  According to this invention, since at least one of the first wedge, the second wedge, the third wedge, or the fourth wedge has a plane-shaped entrance surface or exit surface orthogonal to the rotation axis thereof, scanning control is performed. It is possible to reduce the dependency of the laser beam on the incident angle with respect to the accuracy.
[0134]
  According to the present invention, the scanning control means performs translational scanning of the third wedge and the fourth wedge in the scanning direction in synchronization with the rotational scanning of the third wedge and the fourth wedge. The size of the third wedge and the fourth wedge can be reduced, and the third wedge and the fourth wedge can be rotated at a high speed, so that the effect of increasing the scanning speed can be obtained. As a result, the surface accuracy of the third wedge and the fourth wedge can be improved, and the cost can be further reduced.
[0135]
  According to this invention, it is provided between the fourth wedge and the light shielding means, has a lens action only in the direction orthogonal to the rotation axis of the fourth wedge and the scanning direction, and has a length longer than the scanning interval of the laser beam. Since the cylindrical lens is provided in the scanning direction, the beam shape can be extended in the direction perpendicular to the rotation axis of the fourth wedge and the scanning direction of the laser beam, and simultaneous exposure to a plurality of optical fibers can be performed. It is possible to improve the production efficiency and to obtain the effect that the irradiation conditions and the temperature conditions can be made equal in the same lot, so that high homogeneity can be ensured in the filter characteristics of the optical fiber grating to be manufactured. The effect that the influence of the beam displacement in the direction perpendicular to the rotation axis of the fourth wedge and the scanning direction can be reduced can be obtained. That.
[0136]
  According to this invention, it is provided between the fourth wedge and the light shielding means, has a lens action only in the direction orthogonal to the rotation axis of the fourth wedge and the scanning direction, and has a length longer than the scanning interval of the laser beam. Since the cylindrical lens having the scanning direction is provided, and the scanning control means is configured to translate the cylindrical lens in the scanning direction along with the translational scanning of the third wedge and the fourth wedge, the rotation axis of the fourth wedge and the laser beam The beam shape can be extended in the direction orthogonal to the scanning direction, and it is possible to improve the production efficiency by enabling simultaneous exposure to a plurality of optical fibers. High uniformity of the filter characteristics of the optical fiber grating produced because the irradiation and temperature conditions can be made equal In addition, it is possible to reduce the influence of the beam displacement in the direction perpendicular to the rotation axis of the fourth wedge and the scanning direction, and the third wedge and the fourth wedge are equivalent to the amount of translational scanning. The size of the wedge can be reduced, and the third wedge and the fourth wedge can be rotated at a high speed, so that the effect of increasing the scanning speed can be obtained. And the effect that the surface precision of a 4th wedge can be improved is acquired, and also there exists an effect that cost reduction becomes possible.
[0137]
  According to the present invention, when the laser beam is incident from the deflecting means at a predetermined incident angle with respect to the optical axis, the Fθ optical system that converts the incident angle into a distance from the optical axis and emits the laser beam is compensated for the deflection angle. Therefore, the deflection angle compensation means can be realized without requiring control by the scanning control means, and the load of the scanning control means can be reduced. There is an effect that the reliability of the exposure apparatus can be improved.
[0138]
  According to the present invention, the polyhedral reflecting mirror that reflects the laser beam emitted from the laser light source to the Fθ optical system by the plurality of plane mirrors provided in parallel with the rotation axis is controlled by the scanning control means around the rotation axis. Since the deflecting means is used, the number of drive systems and the number of driving directions can be reduced, and the electrical and mechanical load required for the scan control means can be reduced, and the scan control means can be reduced in size. The effect that the reliability of the scanning exposure apparatus can be improved is obtained, and the cost can be further reduced.
[0139]
  According to the present invention, since the polyhedral reflecting mirror is provided with the plurality of plane mirrors so that the cut surface shape cut by the plane orthogonal to the rotation axis is a regular polygon, the accuracy of scanning control is improved. The effect that it can be obtained is obtained, and the production of the polyhedral reflecting mirror is facilitated and the productivity can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing the configuration of a scanning exposure apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing a target irradiation intensity distribution and a scanning position-time diagram for realizing the target irradiation intensity distribution.
FIG. 3 is a diagram showing an example of a scanning position-time diagram when performing repeated scanning.
FIG. 4 is a view for explaining repeated scanning by the scanning exposure apparatus according to the first embodiment of the present invention;
FIG. 5 is a diagram showing an example of calculation of an irradiation intensity distribution when repeated scanning is performed with a pulsed laser beam.
FIG. 6 is a diagram showing a configuration of a scanning exposure apparatus according to a second embodiment of the present invention.
FIG. 7 is a diagram showing the relationship between the rotational angular velocity of the wedge and the scanning position absolute error.
FIG. 8 is a diagram showing assignment of wedge rotation angles to irradiation periods and acceleration / deceleration / running periods.
FIG. 9 is a view for explaining repetitive scanning by the scanning exposure apparatus according to the second embodiment of the present invention.
FIG. 10 is a diagram showing a configuration of a scanning exposure apparatus according to a second embodiment of the present invention.
FIG. 11 is a diagram showing a configuration of a scanning exposure apparatus according to a second embodiment of the present invention.
FIG. 12 is a view showing a configuration of a scanning exposure apparatus according to a third embodiment of the present invention.
FIG. 13 is a diagram for explaining repetitive scanning by a scanning exposure apparatus according to Embodiment 3 of the present invention.
FIG. 14 is a diagram for explaining an effective refractive index distribution shape of apodization with respect to a position in the longitudinal direction of an optical fiber.
[Explanation of symbols]
  1 laser light source, 2 deflection means, 3 deflection angle compensation means, 4 signal storage means (scanning control means), 5 signal generation means (scanning control means), 6 driving means (scanning control means), 7 phase mask, 8 optical fiber , 9 Shielding means, 10 1st wedge, 11 2nd wedge, 12 3rd wedge, 13 4th wedge, 14 Deflection angle compensation means, 15 Cylindrical lens, 16, 17 Scanning locus, 18 Reflecting mirror, 19 Polyhedral reflecting mirror, 20 Fθ optical system.

Claims (15)

A laser light source for emitting laser light;
Deflection means for deflecting and emitting the laser beam emitted from the laser light source at a predetermined deflection angle;
Deflection angle compensation means for compensating for the deflection angle and emitting the laser beam emitted by the deflection means;
Scanning control means for controlling the deflection angle and scanning the laser beam emitted from the deflection angle compensation means in a scanning direction;
A phase mask having a phase modulation type transmissive diffraction grating that diffracts the laser beam emitted from the deflection angle compensation unit and irradiates the optical fiber ;
A light shielding means provided between the deflection angle compensating means and the phase mask, and having an opening through which the laser beam emitted from the deflection angle compensating means passes to the phase mask;
The scanning control means includes
The laser beam is scanned larger than the opening so that the laser beam emitted from the deflection angle compensation unit is within the light shielding unit, so that the light shielding regions exist at both ends of the scanning segment, and the laser beam is present. In the scanning period of the light shielding region, the scanning speed of the laser beam is run up or reversed, and apodization is performed when a grating is formed on the optical fiber . The scanning control means
Control deflection angle according to time series control signal,
2. The scanning exposure apparatus according to claim 1, wherein the time-series control signal is repeated at a predetermined scanning cycle. The scanning control means
Control deflection angle according to time series control signal,
2. A scanning position-time diagram calculated by making an inversely proportional relationship between a scanning speed of a laser beam emitted from a deflection angle compensation means and a target irradiation intensity distribution of apodization is used as the time series control signal. The scanning exposure apparatus described. Laser light source
2. A scanning exposure apparatus according to claim 1, wherein a laser beam that oscillates continuously is emitted. Laser light source
While emitting pulsed laser light that oscillates at a predetermined pulse period,
The scanning control means
3. The scanning exposure apparatus according to claim 2, wherein the scanning period is determined so that a least common multiple of an integer ratio between a scanning period of a time-series control signal and the pulse period is increased. The deflection means is
A first reflecting mirror whose scanning direction swing angle is controlled by the scanning control means;
The deflection angle compensation means is
The second reflecting mirror whose swing angle in the scanning direction is controlled by the scanning control means in the opposite direction in which the swing angle of the first reflecting mirror is equal and in the opposite direction,
2. The scanning exposure apparatus according to claim 1, wherein the first reflecting mirror and the second reflecting mirror are sequentially reflected so that the laser light emitted from the laser light source is emitted to the light shielding means. The deflection means is
A first wedge in which the rotational angular velocity about the rotation axis is controlled by the scanning control means;
The rotation angular velocity around the rotation axis shared with the first wedge is composed of a second wedge controlled by the scanning control means,
The deflection angle compensation means is
A third wedge in which the rotational angular velocity around the rotation axis is controlled by the scanning control means;
A rotation angle velocity around a rotation axis shared with the third wedge is configured by a fourth wedge controlled by the scanning control means;
2. The scanning type according to claim 1, wherein the first wedge, the second wedge, the third wedge, and the fourth wedge are sequentially transmitted, and the laser beam emitted from the laser light source is emitted to the light shielding means. Exposure device. The first wedge, the second wedge, the third wedge and the fourth wedge are:
Each composed of the same material with the same shape,
The second wedge is
Without having a phase difference with the first wedge, the rotational angular velocity and absolute value of the first wedge are equal and controlled with the rotational angular velocity in the opposite direction,
The third wedge is
Having a phase difference of 180 ° with the first wedge, controlled by the rotational angular velocity of the first wedge,
The fourth wedge is
8. The scanning exposure apparatus according to claim 7 , wherein the scanning wedge exposure apparatus has a phase difference of 180 [deg.] With respect to the second wedge, and the rotation angular velocity and absolute value of the first wedge are equal and controlled with a rotation angular velocity in the opposite direction. At least one of the first wedge, the second wedge, the third wedge, or the fourth wedge is:
8. The scanning exposure apparatus according to claim 7, further comprising a plane-shaped entrance surface or exit surface orthogonal to the rotation axis. The scanning control means
8. The scanning exposure apparatus according to claim 7 , wherein the third wedge and the fourth wedge are translationally scanned in the scanning direction in synchronization with the rotational scanning of the third wedge and the fourth wedge. Provided between the fourth wedge and the light shielding means, has a lens action only in the direction orthogonal to the rotation axis of the fourth wedge and the scanning direction, and has a length longer than the scanning section of the laser beam in the scanning direction. scanning exposure apparatus according to claim 7, further comprising a cylindrical lens. Provided between the fourth wedge and the light shielding means, has a lens action only in the direction orthogonal to the rotation axis of the fourth wedge and the scanning direction, and has a length longer than the scanning section of the laser beam in the scanning direction. With a cylindrical lens,
The scanning control means
11. The scanning exposure apparatus according to claim 10 , wherein the cylindrical lens is translationally scanned in the scanning direction together with translational scanning of the third wedge and the fourth wedge. The deflection angle compensation means is
An Fθ optical system that emits the laser beam by converting the incident angle into a distance from the optical axis when the laser beam is incident on the optical axis at a predetermined incident angle from the deflecting unit. The scanning exposure apparatus according to claim 1. The deflection means is
The rotation angular velocity around the rotation axis is controlled by a scanning control means, and a polyhedral reflecting mirror that reflects the laser beam emitted from the laser light source to the Fθ optical system by a plurality of plane mirrors provided in parallel with the rotation axis is provided. The scanning exposure apparatus according to claim 13 . The polyhedral reflector is
15. The scanning exposure apparatus according to claim 14 , further comprising a plurality of plane mirrors such that a cut surface shape cut by a plane orthogonal to the rotation axis is a regular polygon.

Images