JP3660253B2 - Method for aligning hologram information recording medium, program thereof, recording medium, and hologram information recording medium - Google Patents

Description

となる。したがって、光源をｙ軸方向に動かしたとき、導波光強度分布のピーク位置がどちらにどれだけ動くかを測定できれば、次式により、光源の傾きφを逆算することができる。
【数２】

以上より、φの補正ができることが分かる。
φの位置合わせが完了すれば、後のｙ軸方向の位置合わせは簡単である。導波光の全パワーは、例えば図２、３、４の導波光強度分布を位置で定積分して得られるが、この全パワーが最大となるのが最適なｙ方向の相対位置である。
【００２２】
また、これまでの説明ではｚ軸方向の位置合わせが完了していることを前提としたが、粗いｚ軸方向の位置決めには、φとｙ軸方向の位置は固定したまま、光源のｚ軸方向の位置調整により、最大の導波光全パワーが得られるようにすればよい。この方法では導波光全パワーがｚ軸方向位置にあまり敏感でない場合があり、この時は位置合わせ精度もあまり上がらない。より精度の高いｚ軸方向位置決めには、ｙ軸方向の移動を併用する。導波光全パワーの変化を観測しながら光源をｙ軸方向に移動させていくと、光源が目的とする導波路のコア層付近を通過するときのみ導波光が発生するため、導波光全パワーを光源のｙ軸方向移動量（または位置）の関数としてプロットすると、図５に示すような曲線が描かれる。
【００２３】
しかし、適切な結合が得られる状態からｚ軸方向に光源がずれていると、図５の曲線において導波光が観測される幅が広がる。従って、図５に示す曲線で導波光強度分布のピークの幅が最小になる位置が、ｚ軸方向に関する最適な位置である。これより、ｚ軸方向の移動を行ってはｙ軸方向の移動による図５に示す曲線を観測する、という作業の繰り返しにより、ｚ軸方向の位置決めを行うことができる。
なお、ここまででは入射光を移動させて行う位置合わせについて説明してきたが、これは本発明を限定するものではなく、当然、ホログラムカードの方を移動させたり、また入射光とカードの双方を移動させても全く同様なことができる。
【００２４】
本発明の位置合わせ方法を実施するためには、図２、３、４に示したようなｘ軸方向の導波光強度分布を観測することが必須である。これを最も簡便に行うためには、ホログラムカード１０における光入射端と反対側の出射端で導波光を観測すればよい。導波光強度分布１１のピークの位置のみ、コア層１が光るのが観測できる。ただし、位置合わせ前には理想的な結合ができていないため、大部分の光がクラッド層２に漏れる。この光はホログラムカード１０外に出ることはなく、そのままカード内に閉じ込められて伝搬してホログラムカード１０の出射端から放射されるため、前述の導波光強度分布を観測する上でノイズとなり、最悪の場合はピークを観測することができない。
【００２５】
このノイズを低減する方法の一つとして、光吸収性の材料をクラッド層２に使う方法がある。入射端でクラッドに光が漏れることがあっても、クラッド層２で光が大きく吸収される場合は、このクラッド伝搬光は出射端では殆ど観測されず、ノイズの少ない導波光強度分布の観測が可能となる。
しかし、このような方策を取っても、導波光を出射端から観測する方法では、なお困難が残る。これまでの説明では、簡単のために導波路が１層のみの場合に限定したが、実際には、ホログラムカード１０には多数の導波路が積層されている。積層導波路に図３に示すようにφに関してのホログラムカード１０と入射光との間に角度ずれがある状態で光を入射すると、集光部８は複数の導波路と、それぞれ異なる位置で交わり、したがって出射端では各導波路毎にｘ軸方向に関して異なる位置で光る。
【００２６】
しかし、実際の導波路の間隔は１０μｍオーダーという狭い間隔であるのが通常であり、各導波路毎に異なる位置で光るのを観測するためには、倍率の高い顕微鏡などが必要とされる。倍率が低かったり、あるいは全くレンズを使わずに観測しようとしても、層毎の分離ができないので１１のような導波光強度分布のピークは観測されずに、全体が光って観測されてしまう。
また、高倍率顕微鏡の使用を許すとしても、自動化するには画像処理技術が必要で、煩雑な処理になる。
【００２７】
この導波光強度分布を観測するためにホログラムを用いる方法が有効である。この導波路にｘ軸方向に十分に広いホログラムが備わっていれば、導波光が伝搬する領域のみから回折光が発生する。したがって回折光のｘ軸方向の分布を観測することにより、導波光強度分布とほぼ同様のものが得られる。ホログラムは高い自由度で回折光の波面を設計することができ、観測の便宜を考慮して適切なホログラムを作製すれば、前記の導波路出射端を観測するときのような困難はなくなる。図６はその一例を示すものであり、ホログラムカード１０の上面を見た図である。この例では、通常の情報を記録するための情報記録用ホログラム１３とは別に導波光強度分布を観測するための導波光強度分布観測用ホログラム１４を用意する。
【００２８】
この導波光強度分布観測用ホログラム１４は、多数の導波路層のうちの１つだけに作り込み、さらに、この図に示したようにホログラムカード１０の上面から見て、情報記録記録用ホログラム１３とは重ならないように配置する。この例のホログラムカード１０は、位置合わせをするときには導波光強度分布観測用ホログラム１４のみを観測する。図６のホログラムの大きさはｍｍ（ミリメートル）のオーダーであるので、導波光強度分布観測用ホログラム１４を情報記録記録用ホログラム１３と分離して観測することは簡単であり、例えばＣＣＤ撮像素子を用いればレンズなしでも可能である。導波光強度分布観測用ホログラム１４の領域には１層のみしかホログラムがないので、導波路層における出射端を観測する場合のように複数の導波路の光強度分布が同時に見えることはなく、特別な顕微鏡なしで傾き角φの同定が可能となる。
【００２９】
なお、この方法では１層のみの傾き角補正しかできないが、通常のホログラムカードでは各層間での傾き角φのばらつきは非常に小さく、全ての層につき個別に傾き角補正をしなければならないということは殆どない。
導波光強度分布観測用ホログラム１４には、いろいろな形態がありうるが、データ処理の便宜を考慮すると、ｘ軸方向には大きく変化しない関数で表されるものが好ましい。例えば、複素フェイザー表示で
【数３】

なる関数で表されるようなホログラムが代表である。Ａ１は任意複素定数、ｊは虚数単位、βは導波路の伝搬定数である。このホログラムはｘ軸方向には全く変化しない。
【００３０】
図７（ａ）、（ｂ）は共に、導波光強度分布観測用ホログラムの導波層に光を入れたときの同折光の様子を示すもので、白い破線内部がホログラム領域である。図７（ａ）は、図２のように入射光が適切に位置合わせされた場合の様子を示し、入射光の幅より内側ではほぼ均一に光る。図７（ｂ）は図３のようにφについて傾きがある場合で、光が伝搬する領域のみが光るのが観測できる。
なお、図７のような回折光強度パターンが観測されるのは、ホログラムカードに近接した平面内で観測を行った場合である。回折光は、ホログラムカードから伝搬してゆくうちに自由空間での回折現象により、少しずつ強度パターンを変えてゆく。特に、図７（ｂ）のような細い線状のパターンは、次第に線の幅が広がってゆく傾向にある。このためにあまり離れた平面内で観測を行うと、レンズを使わない限り分解能が下がり、したがって傾き角φを推測する精度も落ちる。
【００３１】
しかし、数ｍｍ程度ならばホログラムカードから離れた場所で観測を行っても十分な精度が得られることが多い。離れた平面内での観測を前提とした導波光強度分布観測用ホログラム１４の例として、関数
【数４】

で表されるホログラムがある。Ａ２は任意複素定数、λ0は空気中での光の波長、ｚ0とｆは実定数である。このホログラムは、
【数５】

なるスカラー光電磁場で表される回折光を発生させる。ここでｙ0は導波路面のｙ座標である。この光は、ｚ＝ｚ0、ｙ＝ｙ0＋ｆの直線上に集光する円筒面波である。
【００３２】
位置合わせの初期には入射光が効率よく導波路に結合していないため、回折光は通常よりも暗いために検出が困難な場合がある。しかしこのホログラムでは、導波路面と平行で距離ｆだけ離れた平面内で回折光が直線状に集光されることから、光強度が非常に強く、検出することが容易であるという特長がある。
また、ｆを調整すれば、情報記録用ホログラムの再生像と同時に、同じ平面内で、１個のＣＣＤ撮像素子で観測することも可能である。さらにこの場合、観測する平面内で導波光強度分布観測用ホログラムの回折光と情報記録用ホログラムからの回折光が重ならないようにさえ設計してあれば、図６とは違ってホログラム同士は部分的あるいは全体が重なっていても良い。これは、高密度に情報を集積するときに有利な特長である。
【００３３】
次に、平面導波路を内部構造として有し、該平面導波路内に予め情報記録用ホログラムが作製され、かつ前記平面導波路の少なくとも一つに、前記導波路内を伝搬する導波光の強度分布を観測するための導波光強度分布観測用ホログラムが予め記録されたホログラム情報記録媒体の位置合わせ方法について図８乃至図１０を参照して説明する。なお、ホログラムカード１０と、光源（図示せず）からホログラムカードへの入射光４との位置関係を示すｘｙｚ直交座標系のｘ、ｙ、ｚ軸、及びｚ軸回りの回転角Φは、図２と同様である。すなわち、導波光の進行方向をｘｙｚ直交座標系のｚ軸とし、前記平面導波路の法線方向をｙ軸とし、ｚ軸とｙ軸との双方に垂直な方向をｘ軸としたとする。本実施の形態では、ホログラム情報記録媒体１０を固定し、入射光４を移動させることにより両者の位置合わせを行うものとする。
【００３４】
図８において、まず、ステップ１００及びステップ１０１で、図１２に示すようにホログラム情報記録媒体１０における平面導波路に予め作製された導波光強度分布観測用ホログラム１４を含む導波路を探索する。ステップ１００において、
コンピュータのメモリに導波光強度のｙ軸方向の測定開始位置ｙ0と、前記情報記録媒体１０と前記入射光４とのうち一方のｙ軸方向への単位移動量である移動ステップΔｙとを初期設定する。次いで、ステップ１０１における処理Ａを実行する。この処理Ａは、導波光強度分布観測用ホログラム１４による回折光の結像面１５におけるパワーのピーク（ピークの中心位置ｙp、ピーク幅２ｗ）を検出する処理であり、そのフローを図９に示す。
【００３５】
図９において、まず、コンピュータのメモリより前記初期設定値を読み出し、入射光４を前記測定開始位置ｙ0に移動させる（ステップ２００）。
次いで、測定開始位置ｙ0からｙ軸方向に移動ステップΔｙだけ移動する毎に導波光強度分布観測用ホログラムから得られる結像面上での回折光のパワーＰを次式（６）により演算する（ステップ２０１、２０２）。
【数６】

ステップ２０１、２０２の処理を（Ｌ＋１）回、繰り返し実行する。このステップ２０１、２０１の処理を（Ｌ＋１）回、繰り返し実行することによりｙ軸上の測定位置ｙ0、ｙ＋Δｙ、ｙ＋２Δｙ、…、ｙ＋ＬΔｙに対する回折光パワーのデータＰ0、Ｐ1、Ｐ2、…、ＰLを得る。
【００３６】
次いで、ステップ２０１、２０２の処理を（Ｌ＋１）回、繰り返し実行することにより得た測定位置のデータｙ0、ｙ＋Δｙ、ｙ＋２Δｙ、…、ｙ＋ＬΔｙと、回折光パワーのデータＰ0、Ｐ1、Ｐ2、…、ＰLとの関係からこれらのデータを次式に示す誤差関数にフィッティングさせる。
【数７】

式（７）より導波光強度分布観測用ホログラムから得られる結像面上での回折光のパワーの変化曲線Ｐにおけるピークの大きさＡ，ピークの中心位置ｙp、ピーク幅２ｗを得る。
次に、図８に戻り、ステップ１０２で、測定開始位置ｙ0と移動ステップΔｙの再設定を行う。
【００３７】
さらに、ステップ１０３では、ホログラム情報記録媒体１０と前記入射光４とのうちいずれか一方（本実施の形態では入射光４）のｚ軸方向への移動と、ステップ１０１の処理（処理Ａ）とを繰り返し行うことによりｗが最小となるように前記ｚ軸方向に移動させたホログラム情報記録媒体１０、または前記入射光４のｚ軸方向への移動調整を行う。
このようにして、ステップ１０２とステップ１０３の処理によりホログラム情報記録媒体１０、または前記入射光４のｚ軸方向の大まかな位置合わせを行う。ステップ１０３の処理により導波光強度分布観測用ホログラムから得られる結像面上での回折光のパワーの変化曲線Ｐにおけるピークの大きさＡ，ピークの中心位置ｙp、ピーク幅２ｗを得て、測定開始位置ｙ0と移動ステップΔｙの再設定を行う（ステップ１０４）。
【００３８】
次に、ステップ１０５では、入射光４の傾きΦの推定処理（処理Ｂ）を行う。ステップ１０５の具体的処理内容を図１０に示す。図１０において、まず、コンピュータのメモリより前記初期設定値を読み出し、入射光４を前記測定開始位置ｙ0に移動させる（ステップ３００）。
次いで、測定開始位置ｙ0からｙ軸方向に移動ステップΔｙだけ移動する毎に導波光強度分布観測用ホログラム１４からの回折光の結像面内でのx軸方向の強度分布Ｊ（ｘ）を次式（８）により演算する（ステップ３０１、３０２）。
【数８】

【００３９】
このとき、得られたx軸方向の強度Ｊ（ｘ）に測定開始位置ｘ0を含むｘ軸方向における測定位置ｘ0、ｘ＋Δｘ、ｘ＋２Δｘ、…、ｘ＋ＮΔｘに対するＪ（ｘ）の演算データＪ0、Ｊ1、Ｊ2、…、ＪNを得る。
次に、ｘ軸上の測定位置ｘ0、ｘ0＋Δｘ、ｘ0＋２Δｘ、…、ｘ0＋ＮΔｘに対するのデータＪ0、Ｊ1、Ｊ2、…、ＪNとの関係からこれらのデータを次式に示す誤差関数にフィッティングさせ、導波光強度分布観測用ホログラム１４からの回折光の結像面内でのx軸方向の強度分布Ｊ（ｘ）のピークが得られるｘ軸方向の測定位置ｘpを得る（ステップ３０３）。
【数９】

上述したステップ３０２、３０３の処理を（Ｍ＋１）回、繰り返し実行した後、最終的にｙ軸方向の各測定位置ｙ0、ｙ0＋Δｙ、ｙ0＋２Δｙ、…、ｙ0＋ＭΔｙに対する導波光強度分布観測用ホログラム１４からの回折光の結像面内でのx軸方向の強度Ｊ（ｘ）のピーク値ｘp,0、ｘp,1、ｘp,2、…、ｘp,Mを得る。
【００４０】
次に、軸方向の各測定位置ｙ0、ｙ＋Δｙ、ｙ＋２Δｙ、…、ｙ＋ＭΔｙとＪ（ｘ）のピーク値が得られるｘ軸方向の測定位置ｘp,0、ｘp,1 、ｘp,2、…、ｘp,Mとの関係からこれらのデータを次式（１０）に示す演算式にフィッティングさせる（ステップ３０４）。すなわち、誤差関数から得られる前記回折光のｘ軸方向の強度分布Ｊ（ｘ）のピーク値が得られるｘ軸上の測定位置ｘpと、対応するy軸方向の測定値との関係を示す式（１０）の特性曲線を求め、式（１０）よりホログラム情報記録媒体１０に対する光源からの入射光４の傾き、すなわち傾斜角φを求める。
【数１０】

【００４１】
上式（１０）において、ｘpは導波光強度分布観測用ホログラム１４からの回折光の結像面内でのx軸方向の強度Ｊ（ｘ）のピーク値、ｙはｙ軸方向の測定位置、φはホログラム情報記録媒体１０に対する光源からの入射光の傾斜角、ａは定数である。
再度、図８に戻り、傾斜角φが零となるように入射光４の傾斜角φが零となるようにホログラム情報記録媒体１０、または入射光４の角度調整を行う角度調整を行う（ステップ１０６）。
【００４２】
次に、本発明に係る位置合わせ方法の実施例について説明する。本実施例では、導波光強度分布観測用のホログラムには、次式で表されるものを用いた。
【数１１】

このホログラムは、入射光が適切に位置合わせされているときには、式（４）のホログラムと同様に導波路面から距離ｆだけ離れた平面内でｚ＝ｚ0の位置に直線状の再生像を生成する。式（４）とは指数関数の前の係数が異なるが、この部分はｚに関して殆ど変化しない関数であるので無視した。
【００４３】
また、式（１１）における指数関数内の第一項はノイズ除去に有効である。σは０．４ｍｍ、ｆは４ｍｍ、λ0は６８０ｎｍとした。また、ホログラムサイズはｘ軸方向にもｚ軸方向にも１ｍｍで、ｚ0はｚ軸方向の幅の中央に置いた。その他の定数はホログラムカードの製作条件に依存し、厳密には測定していない。図１１に示す写真は、位置合わせ後のこのホログラムによる再生像の観測例である。このホログラムを、図１２に示すようにホログラムカード１０の最上層の導波路に設置した。ホログラムカード１０のその他の層には、情報記録用のホログラムを設置し、その再生像は全て、式（１１）のホログラムが結像する面と同じ結像面１５で結像するように設計した。
さらに、全ての情報記録用ホログラムの再生像は、式（１１）により表されるホログラムが像を結ぶｚ0付近の領域から少し離れた場所で結像するようにした。また、各導波路の間隔は約２０μｍとした。
【００４４】
次に、このホログラムカード１０の位置合わせを、本発明の方法を用いて行った例について説明する。ホログラムカード１０を情報読み出し装置に取り付けた直後に光を入射すると、どの層からの回折も非常に弱く、再生像を観測することはできなかった。そこで、図１２の結像面１５内でｚ＝ｚ0付近の光パワーを観測しながら、＋ｙ軸方向に１０μｍ単位で入射光を移動していった。このときのｙ軸方向における移動量に対する光パワーをプロットしたグラフが図１３である。このグラフを誤差関数（Ｇａｕｓｓｉａｎ）にフィッティングさせることにより、光パワーのピークが約１７０μｍの位置にあり、したがってその付近で入射光が最上層の導波路によく結合することが分かった。
【００４５】
そこで、この付近にｙ座標の原点を移して、図１３と同様な移動量に対する光パワー変化をもう少し詳細に測定した。この結果が図１４である。このグラフについて誤差関数フィッティングを行うと、１／ｅ全幅は約３０μｍであった。
次に、入射光を＋ｚ方向に５００μｍ移動した後、同様な作業を繰り返して図１４と同様なグラフを得、フィッティングすると１／ｅ全幅は約２５μｍであった。引き続いて、入射光を−ｚ軸方向に２５０μｍ移動したところ、１／ｅ全幅は約１５μｍであった。さらに、この付近でｚ軸方向に移動させては１／ｅ全幅を測定したが、最小が約１５μｍであったため、当初の位置から入射光を＋ｚ軸方向に２５０μｍ移動させた場所がｚ軸方向に関しては適切であると仮定できた。ここでのｙ軸方向移動量に対する光パワーの変化を図１５に示す。以上で、入射光ｙ軸方向とｚ軸方向の大まかな位置合わせが完了した。
【００４６】
この時点での、導波光強度分布観測用のホログラムの再生像の例を図１６に示す。この図では、図１２の例のようにホログラム領域全体が光っておらず、一部のみ明るいが、これは、まだ傾斜角φが補正されていないため、図３に示したように導波路中には狭い幅でしか光が伝搬していないことを表す。図１７には、図１６の光強度分布をｚ軸方向に積分した値がプロットされている。曲線はフィッティングした誤差関数で、この場合は０．６７ｍｍの位置にピークがある。ここでｙ軸方向に入射光を移動させると、導波光強度のピークが（１）式に従って移動するため、図１７のような再生像の強度のピーク位置も移動するのが観測された。
【００４７】
図１８は、入射光のｙ軸方向の移動に伴うピーク位置の移動を示す。傾斜角φが非常に小さいとき、式（２）より、
【数１２】

と、傾斜角φは、ほぼ図１８の直線の傾きで近似される。これより、４３分の傾きがあることが推測されたため、これに従って入射光の角度補正を行った。
図１９は、角度補正後に図１４や図１５と同様にｙ軸方向の移動量に対する光パワー変化を観測した結果である。１／ｅ全幅は５．６μｍと、角度補正によって図１５よりも大幅に改善されていることが分かった。図２０は、図１９のピーク中心位置で観測した導波光強度分布観測用ホログラムの再生像で、こちらも角度補正前の再生像である図１６と比較して改善され、ｘ軸方向のホログラムの幅いっぱいまで明るい領域が拡がっている。
【００４８】
以上でホログラムカード１０に対する入射光の傾斜角φの位置決めが完了した。この後、ｚ軸方向の位置決めをさらに精度良く行っても良いが、本実施例では特に必要ではなかった。引き続き、ホログラムカード１０における上から２番目の導波路のホログラム情報を読み出すため、入射光４を−ｙ軸方向へ２０ｍｍ移動させた。この付近でｙ軸方向に移動させながら、図１２における画像表示領域１６の内部の光パワーを観測したところ、図１９と全く同様な振る舞いをした。光パワーのピークが得られる位置では、ほぼ設計通りの再生像が観測され、ホログラムカード１０と入射光４との適切な位置合わせができていることが確認された。 以下、同様な作業をホログラムカード１０における他の導波路層についても行ったが、予め用意された１０層全てについて同様なことが確認された。
【００４９】
なお、上述した本発明の実施の形態に係るホログラム情報記録媒体と該情報記録媒体に対するホログラム再生用の入射光との位置合わせ方法を、プログラムとして記述し、これをコンピュータにより実行させることにより上記位置合わせ方法を実施してもよい。
【００５０】
すなわち、平面導波路を内部構造として有し、該平面導波路内に予め情報記録用ホログラムが作製され、かつ前記平面導波路の少なくとも一つに、前記導波路内を伝搬する導波光の強度分布を観測するための導波光強度分布観測用ホログラムが予め記録されたホログラム情報記録媒体に、光源からの出射光を入射し、該平面導波路に伝搬する導波光が前記平面導波路内における前記情報記録用ホログラムによって回折され、回折された光を観測することによって前記情報記録用ホログラムに含まれる情報を読み出し可能に構成されたホログラム情報記録媒体の再生時におけるホログラム情報記録媒体と前記光源からホログラム情報記録媒体への入射光との位置決めを行うための、コンピュータにより実行されるホログラム情報記録媒体の位置合わせプログラムであって、該プログラムは、前記導波光の進行方向をｘｙｚ直交座標系のｚ軸とし、前記平面導波路の法線方向をｙ軸とし、ｚ軸とｙ軸との双方に垂直な方向をｘ軸としたときに、コンピュータのメモリに導波光強度のｙ軸方向の測定開始位置ｙ0と、前記情報記録媒体と前記入射光とのうち一方のｙ軸方向への移動ステップΔｙとを初期設定する第１の処理と、
前記メモリより前記初期設定値を読み出し、前記情報記録媒体と前記入射光とのうちいずれか一方を前記測定開始位置ｙ0に移動させ、該測定開始位置ｙ0からｙ軸方向に移動ステップΔｙだけ移動する毎に導波光強度分布観測用ホログラムから得られる結像面上での回折光のパワーＰを演算する第２の処理と、第２の処理により得られたy軸方向の各測定位置と前記回折光のパワーＰの値との関係から前記回折光のパワーの変化曲線におけるピークの中心位置ｙp、ピーク幅２ｗ及び高さＡを求める第３の処理と、前記情報記録媒体と前記入射光とのうちいずれか一方のｚ軸方向への移動と、前記第２、第３の処理とを繰り返し行うことによりｗが最小となるように前記ｚ軸方向に移動させた前記情報記録媒体、または前記入射光のｚ軸方向への移動調整を行う第４の処理と、前記ｚ軸方向への移動調整を行った前記情報記録媒体、または前記入射光について測定開始位置ｙ0よりy軸方向にΔｙだけ移動する毎に前記導波光強度分布観測用ホログラムからの回折光の結像面内でのx軸方向の強度分布Ｊ（ｘ）を求め、次いでｘ軸方向の各測定位置に対する前記強度分布Ｊ（ｘ）との関係を求め、これを誤差関数にフィッティングさせ、強度分布Ｊ（ｘ）のピーク値ｘp,0、ｘp,1、…、ｘp,Mを得る第５の処理と、前記ｚ軸方向への移動調整を行った前記情報記録媒体、または前記入射光を、ｙ軸方向にΔｙだけ移動する毎に第５の処理で得られた誤差関数から得られる前記回折光のｘ軸方向の強度分布Ｊ（ｘ）のピーク値が得られるｘ軸上の位置ｘp,0、ｘp,1、…、ｘpx,Mと、対応するy軸方向の測定位置ｙ0,ｙ0＋Δｙ、…、ｙ0＋ＭΔｙとの関係を示す特性曲線を求める第６の処理と、第６の処理により得られた特性曲線の傾きから前記情報記録媒体と、前記入射光との傾きであるｚ軸を中心とする回転角φを求め、該回転角φが零になるように前記情報記録媒体、または前記入射光の角度調整を行う第７の処理とからなることを特徴とするプログラムをコンピュータ読み取り可能な記録媒体に記録し、この記録媒体に記録されたホログラム情報記録媒体の位置合わせプログラムをコンピュータシステムに読み込ませ、実行することによりホログラム情報記録媒体の位置合わせ方法を実施するようにしてもよい。
【００５１】
また、面導波路を内部構造として有し、該平面導波路内に予めホログラムが作製されたホログラム情報記録媒体に、光源からの出射光を入射し、該平面導波路に伝搬する導波光が前記平面導波路内における前記ホログラムによって回折され、回折された光を観測することによって前記ホログラムに含まれる情報を読み出し可能に構成されたホログラム情報記録媒体の再生時におけるホログラム情報記録媒体と前記光源からホログラム情報記録媒体への入射光との位置決めを行うための、コンピュータにより実行されるホログラム情報記録媒体の位置合わせプログラムであって、前記導波光の進行方向をｘｙｚ直交座標系のｚ軸とし、前記平面導波路の法線方向をｙ軸とし、ｚ軸とｙ軸との双方に垂直な方向をｘ軸としたときに、該プログラムは、前記情報記録媒体、または前記入射光のうち一方をｙ軸方向に移動させ、このときの該情報記録媒体、または前記入射光のｙ軸方向の移動量、前記導波光または回折光の強度分布におけるピーク位置のｘ軸上における移動方向及び移動量に基づいて前記情報記録媒体と、前記入射光との傾きであるｚ軸を中心とする回転角φを求め、該回転角φが零となるように前記情報記録媒体、または前記入射光の角度調整を行う機能をコンピュータに実行させることを特徴とするプログラムをコンピュータ読み取り可能な記録媒体に記録し、この記録媒体に記録されたホログラム情報記録媒体の位置合わせプログラムをコンピュータシステムに読み込ませ、実行することによりホログラム情報記録媒体の位置合わせ方法を実施するようにしてもよい。
【００５２】
なお、ここでいう「コンピュータシステム」とは、ＯＳや周辺機器等のハードウェアを含むものとする。また、「コンピュータ読み取り可能な記録媒体」とは、フロッピーディスク、光磁気ディスク、ＲＯＭ、ＣＤ−ＲＯＭ等の可般媒体、コンピュータシステムに内蔵されるハードディスク等の記憶装置のことをいう。
【００５３】
さらに、「コンピュータ読み取り可能な記録媒体」とは、インターネット等のネットワークや電話回線等の通信回線を介してプログラムを送信する場合の通信線のように、短時間の間、動的にプログラムを保持するもの(伝送媒体ないしは伝送波)、その場合のサーバやクライアントとなるコンピュータシステム内部の揮発性メモリのように、一定時間プログラムを保持しているものも含むものとする。
【００５４】
また、上記プログラムは、前述した機能の一部を実現するためのものであっても良く、さらに前述した機能をコンピュータシステムにすでに記録されているプログラムとの組み合わせで実現できるもの、いわゆる差分ファイル（差分プログラム）であっても良い。
【００５５】
【発明の効果】
以上述べたように、本発明によれば、平面導波路を内部構造として有し、該平面導波路内に予めホログラムが作製されたホログラム情報記録媒体に、光源からの出射光を入射し、該平面導波路に伝搬する導波光が前記平面導波路内における前記ホログラムによって回折され、回折された光を観測することによって前記ホログラムに含まれる情報を読み出し可能に構成されたホログラム情報記録媒体の再生時におけるホログラム情報記録媒体と前記光源からホログラム情報記録媒体への入射光との位置決めを行うに際し、前記導波光の進行方向をｘｙｚ直交座標系のｚ軸とし、前記平面導波路の法線方向をｙ軸とし、ｚ軸とｙ軸との双方に垂直な方向をｘ軸としたときに、前記情報記録媒体、または前記入射光のうち一方をｙ軸方向に移動させ、このときの該情報記録媒体、または前記入射光のｙ軸方向の移動量、前記導波光または回折光の強度分布におけるピーク位置のｘ軸上における移動方向及び移動量に基づいて前記情報記録媒体と、前記入射光との傾きであるｚ軸を中心とする回転角φを求め、該回転角φが零となるように前記情報記録媒体、または前記入射光の角度調整を行うようにしたので、ホログラム情報記録媒体と、光源からホログラムの導波路に入射される光との位置合わせを自動的に、かつ精密に行うことができ、それゆえ再生画像の劣化が防止され、またはディジタル情報の誤り発生を著しく抑制することができる。
【図面の簡単な説明】
【図１】 再生専用多重ホログラムカードの構造と情報再生時の状態を示す説明図。
【図２】 ホログラムカードの入射光に対する導波光強度分布をｘｙｚ直交座標系と共に示す説明図。
【図３】 ホログラムカードに対する入射光が傾いたときのホログラムカードの導波光強度分布を示す説明図。
【図４】 ホログラムカードへの入射光の移動によって導波光強度分布のピークがずれる様子を示す説明図。
【図５】 入射光またはホログラムカードのｙ軸方向への移動に伴う導波光全パワーの変化状態を示す特性図。
【図６】 ホログラムカードにおける、情報記録用ホログラムと導波光強度分布観測用ホログラムとの配置例を示す説明図。
【図７】 ホログラムによる導波光強度分布観測例を示す説明図。
【図８】 本発明の実施の形態に係るホログラム情報記録媒体の位置合わせ方法の手順を示すフローチャート。
【図９】 図９に示すフローチャートにおける処理Ａの具体的内容を示すフローチャート。
【図１０】 図９に示すフローチャートにおける処理Ｂの具体的内容を示すフローチャート。
【図１１】 本発明の実施例におけるホログラム情報記録媒体における導波光強度分布観測用ホログラムによる回折光の結像面内での観測例を示す図。
【図１２】 本発明の実施例におけるホログラムカードの再生時の結像状態を示す説明図。
【図１３】 本発明の実施例でのホログラムカードに対する入射光のｙ軸方向の移動に伴う導波光全パワーの変化状態を示す特性図。
【図１４】 本発明の実施例においてホログラムカードに対する入射光のｙ軸方向の移動に伴う導波光全パワーの変化状態を詳細に調べた結果を示す特性図。
【図１５】 本発明の実施例においてホログラムカードに対する入射光のｚ軸方向の位置合わせを行った後に、入射光のｙ軸方向の移動に伴う導波光全パワーの変化を詳細に調べた結果を示す特性図。
【図１６】 本発明の実施例においてホログラムカードに対する入射光のｚ軸方向における位置合わせ直後の導波光強度分布観測用ホログラムの回折像観測例を示す図。
【図１７】 本発明の実施例においてホログラム観測による導波光強度分布の観測例を示す図。
【図１８】 本発明の実施例においてｙ軸方向の移動量と導波光強度分布のｘ軸方向のピーク位置の移動量との関係を示す特性図。
【図１９】 本発明の実施例においてホログラムカードに対する入射光の傾斜角φの補正後に、射光のｙ軸方向の移動に伴う導波光全パワーの変化状態を詳細に調べた結果を示す特性図。
【図２０】 本発明の実施例においてホログラムカードに対する入射光の傾斜角φの補正後の導波光強度分布観測用ホログラムの回折像の観測例を示す図。
【符号の説明】
１ コア層
２ クラッド層
３、３Ａ レンズ
４ レーザ光
５ 導波光
６ 散乱要因（ホログラム）
７ 回折光
８ 再生像（ホログラム像）
９ 集光部
１０ ホログラムカード
１１ 導波光強度分布
１２：コア層端面
１３：情報記録用ホログラム
１４：導波光強度分布観測用ホログラム
１５：結像面
１６：情報記録用ホログラムの再生画像表示領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reproduction-only hologram information recording medium, and in particular, a reproduction-only hologram information recording medium alignment method suitable for use as a portable memory card such as a magnetic card or an IC card, and a program therefor And a recording medium and a hologram information recording medium.
[0002]
[Prior art]
Conventionally, a reproduction-only multiplex hologram card (hereinafter abbreviated as “hologram card”) 10 has been devised as an information recording medium that is portable and inexpensive and has a low risk of counterfeiting. FIG. 1 is a diagram for explaining the sectional structure of a hologram card and the principle of information reproduction. The hologram card 10 is characterized by a structure in which layers having a high refractive index (referred to as core layer 1) and layers having a low refractive index (referred to as cladding layer 2) are alternately stacked. As shown in FIG. 1, when the laser beam 4 focused by the lens 3 is irradiated onto the side end face of the hologram card 10, the light is confined in the vicinity of the core layer 1 and travels through the hologram card 10. This light is referred to as guided light 5, and a region near the core layer 1 where the light energy of the guided light 5 is concentrated is referred to as a slab waveguide or simply as a waveguide. One waveguide includes one core layer 1 and a part of the cladding layer 2 adjacent thereto.
[0003]
The hologram card 10 has another feature that each waveguide includes a hologram. The guided light 5 propagating in the waveguide is scattered outside the waveguide by a scattering factor 6 that is created in advance, and the scattering factor 6 is designed to function as a hologram as a whole. Interfere with each other and travel upward or downward on the hologram card 10 as a whole, and become light that forms an image in a single plane outside the hologram card 10. This light is referred to as diffracted light 7, an image is referred to as a reproduced image (hologram image) 8, and a plane on which the image is reproduced is referred to as an imaging plane. The hologram image 8 contains information on the hologram in the waveguide, and information is read by observing this image with an image pickup device such as a CCD.
Furthermore, if the laser beam 4 is appropriately narrowed by the lens 3, the guided light can be propagated to only one of the waveguides, so that hologram information created in each waveguide can be read out independently. Can do.
[0004]
[Problems to be solved by the invention]
As described above, the hologram card 10 can independently read hologram information associated with each laminated waveguide. However, for this purpose, it is indispensable to precisely align the hologram card 10 and the light incident on the hologram card 10 from the light source. If this alignment is not appropriate, light leaks out of the waveguide or light is guided to the adjacent waveguide, so that the hologram image 8 becomes dark and the images of other layers overlap. There has been a problem that the signal / noise ratio is deteriorated, or when digital information is used on a hologram image, the frequency of error occurrence increases. An increase in the frequency of error occurrence means a reduction in information capacity.
[0005]
The present invention has been made in view of such circumstances, and can automatically and precisely align the hologram information recording medium and the light incident on the hologram waveguide from the light source. An object of the present invention is to provide a hologram information recording medium alignment method, a program thereof, a program recording medium, and a hologram information recording medium.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is directed to a hologram information recording medium having a planar waveguide as an internal structure and a hologram previously produced in the planar waveguide. Hologram information recording configured to be able to read information contained in the hologram by observing the diffracted light by diffracting the guided light that is incident and propagates in the planar waveguide by the hologram in the planar waveguide A hologram information recording medium positioning method for positioning a hologram information recording medium and incident light from the light source to the hologram information recording medium at the time of reproducing the medium, wherein the traveling direction of the guided light is expressed in an xyz orthogonal coordinate system When the z-axis is the normal direction of the planar waveguide is the y-axis, and the direction perpendicular to both the z-axis and the y-axis is the x-axis, the information recording One of the medium and the incident light is moved in the y-axis direction, the amount of movement of the information recording medium or the incident light in the y-axis direction at this time, and the peak position in the intensity distribution of the waveguide light or diffracted light Based on the moving direction and moving amount on the x-axis, a rotation angle φ centered on the z-axis, which is an inclination between the information recording medium and the incident light, is obtained, and the information is set so that the rotation angle φ becomes zero. The angle adjustment of the recording medium or the incident light is performed.
[0007]
The invention according to claim 2 has a planar waveguide as an internal structure, and light emitted from a light source is incident on a hologram information recording medium in which a hologram is produced in advance in the planar waveguide. Hologram information at the time of reproduction of a hologram information recording medium configured to be able to read out information contained in the hologram by observing the diffracted light by diffracting the guided light propagating to the hologram in the planar waveguide A hologram information recording medium positioning method for positioning a recording medium and light incident on the hologram information recording medium from the light source, wherein the traveling direction of the guided light is a z-axis in an xyz orthogonal coordinate system, When the normal direction of the waveguide is the y-axis and the direction perpendicular to both the z-axis and the y-axis is the x-axis, the information recording medium and the light source One of the incident light to the ram information recording medium is moved in the y-axis direction to obtain the total power of the waveguide light, and the position in the y-axis direction where the total power of the waveguide light is maximized is determined in the y-axis direction. A first step of adjusting the position in the y-axis direction as a relative position in the y-axis direction of the moved information recording medium or the incident light, and a movement in the y-axis direction in the first step Further, a change curve of the total power of the information recording medium or guided light accompanying the movement of one of the incident lights in the y-axis direction is measured, and the center position, width, and height of the peak of the curve are fitted to an error function. And the change curve obtained by fitting the error function by performing the processing of the second step every time the information recording medium or the incident light is moved by a predetermined amount in the z-axis direction. No pea The width is compared, and the position on the z-axis where the peak width is minimized is the information recording medium moved in the z-axis direction or the relative position of the incident light in the z-axis direction. A third step of adjusting the position, and moving one of the information recording medium or the incident light in the y-axis direction, and the amount of movement of the information recording medium or the incident light in the y-axis direction at this time; Based on the moving direction and moving amount on the x-axis of the peak position in the intensity distribution of the guided light, a rotation angle φ centered on the z-axis that is the inclination between the information recording medium and the incident light is obtained, and the rotation And a fourth step of adjusting the angle of the incident light so that the angle φ becomes zero.
[0008]
According to a third aspect of the present invention, a planar waveguide is provided as an internal structure, and light emitted from a light source is incident on a hologram information recording medium in which a hologram is produced in advance in the planar waveguide. Hologram information at the time of reproduction of a hologram information recording medium configured to be able to read out information contained in the hologram by observing the diffracted light by diffracting the guided light propagating to the hologram in the planar waveguide A method for aligning a recording medium and a hologram information recording medium for positioning light incident on the hologram information recording medium from the light source, wherein at least one of the waveguides in the hologram information recording medium includes the inside of the waveguide. A waveguide light intensity distribution observation hologram for observing the intensity distribution of propagating guided light is recorded in advance, and When the traveling direction of wave light is the z-axis of the xyz orthogonal coordinate system, the normal direction of the planar waveguide is the y-axis, and the direction perpendicular to both the z-axis and the y-axis is the x-axis, the information recording One of the medium and the incident light from the light source to the hologram information recording medium is moved in the y-axis direction, and a reproduced image of the guided light intensity distribution observation hologram is formed with respect to the amount of movement in the y-axis direction. Among the information recording medium or the incident light obtained by obtaining the total power of the diffracted light observed on the imaging plane and moving the position in the y-axis direction where the total power of the diffracted light is maximum in the y-axis direction A first step of adjusting the position in the y-axis direction as a relative position in any y-axis direction, and the information recording medium moved in the y-axis direction in the first step, or one of the incident light y Of the total power of the diffracted light as it moves in the axial direction A second step of measuring a curve, and fitting the center position, width, and height of the peak of the curve to an error function, and a predetermined amount of the information recording medium or the incident light in the z-axis direction, Each time it is moved, the processing of the second step is performed, the peak widths of the change curves obtained by fitting the error function are compared, and the position on the z-axis where the peak width is minimum is determined as the z-axis. The information recording medium moved in the axial direction, or a third step of adjusting the position in the z-axis direction as a relative position in the z-axis direction of the incident light, and one of the information recording medium and the incident light Based on the information recording medium or the amount of movement of the incident light in the y-axis direction, the movement direction and the amount of movement on the x-axis of the peak position in the change curve of the diffracted light. The rotation angle φ about the z axis that is the inclination between the information recording medium and the incident light is obtained, and the angle of the information recording medium or the incident light is adjusted so that the rotation angle φ becomes zero. And a fourth step to be performed.
[0009]
According to a fourth aspect of the present invention, a planar waveguide is provided as an internal structure, an information recording hologram is prepared in advance in the planar waveguide, and at least one of the planar waveguides includes the inside of the waveguide. The emitted light from the light source is incident on the hologram information recording medium in which the guided light intensity distribution observation hologram for observing the intensity distribution of the propagating guided light is recorded in advance, and the guided light propagating to the planar waveguide is Hologram information recording at the time of reproduction of a hologram information recording medium configured to be able to read information contained in the information recording hologram by observing the diffracted light diffracted by the information recording hologram in a planar waveguide Hologram information executed by a computer for positioning a medium and incident light from the light source to the hologram information recording medium A recording medium alignment program, wherein the traveling direction of the guided light is the z-axis of the xyz orthogonal coordinate system, the normal direction of the planar waveguide is the y-axis, and the z-axis and the y-axis When the direction perpendicular to both is the x-axis, the measurement start position y0 of the guided light intensity in the y-axis direction and the movement of one of the information recording medium and the incident light in the y-axis direction are stored in the computer memory. A first process for initial setting of step Δy, the initial setting value is read from the memory, and one of the information recording medium and the incident light is moved to the measurement start position y0, and the measurement start is started. A second process for calculating the power P of the diffracted light on the imaging plane obtained from the guided light intensity distribution observation hologram every time it moves from the position y0 in the y-axis direction by a movement step Δy, and a second process Each measurement in the y-axis direction A third process for obtaining a peak center position yp, a peak width 2w and a height A in the change curve of the power of the diffracted light from the relationship between the fixed position and the value of the power P of the diffracted light; The information recording moved in the z-axis direction so that w is minimized by repeatedly performing the movement of one of the incident light in the z-axis direction and the second and third processes. Fourth processing for adjusting movement of the medium or the incident light in the z-axis direction, and the information recording medium adjusted for movement in the z-axis direction, or the incident light from the measurement start position y0 to the y-axis The intensity distribution J (x) in the x-axis direction in the imaging plane of the diffracted light from the guided light intensity distribution observation hologram is obtained every time Δy moves in the direction, and then the measurement position for each measurement position in the x-axis direction is obtained. Find the relationship with the intensity distribution J (x). To the error function to obtain the peak value xp, 0, xp, 1,..., Xp, M of the intensity distribution J (x), and the information obtained by adjusting the movement in the z-axis direction. The peak value of the intensity distribution J (x) in the x-axis direction of the diffracted light obtained from the error function obtained in the fifth process each time the recording medium or the incident light is moved by Δy in the y-axis direction is Sixth processing for obtaining a characteristic curve indicating the relationship between the obtained positions xp, 0, xp, 1,..., Xpx, M on the x axis and the corresponding measurement positions y0, y0 + Δy,..., Y0 + MΔy in the y-axis direction. Then, a rotation angle φ centered on the z-axis, which is the inclination between the information recording medium and the incident light, is obtained from the inclination of the characteristic curve obtained by the sixth process so that the rotation angle φ becomes zero. A seventh process for adjusting the angle of the information recording medium or the incident light;
It is characterized by comprising.
[0010]
The invention according to claim 5 has a planar waveguide as an internal structure, an information recording hologram is produced in advance in the planar waveguide, and at least one of the planar waveguides includes the inside of the waveguide. The emitted light from the light source is incident on the hologram information recording medium in which the guided light intensity distribution observation hologram for observing the intensity distribution of the propagating guided light is recorded in advance, and the guided light propagating to the planar waveguide is Hologram information recording at the time of reproduction of a hologram information recording medium configured to be able to read information contained in the information recording hologram by observing the diffracted light diffracted by the information recording hologram in a planar waveguide Alignment program for hologram information recording medium for positioning medium and incident light from light source to hologram information recording medium In the recorded computer-readable recording medium, the program uses the traveling direction of the guided light as the z-axis of the xyz orthogonal coordinate system, the normal direction of the planar waveguide as the y-axis, and the z-axis and y-axis. When the direction perpendicular to both is the x-axis, the measurement start position y0 of the guided light intensity in the y-axis direction and the movement of one of the information recording medium and the incident light in the y-axis direction are stored in the computer memory. A first process for initial setting of step Δy, the initial setting value is read from the memory, and one of the information recording medium and the incident light is moved to the measurement start position y0, and the measurement start is started. A second process for calculating the power P of the diffracted light on the imaging plane obtained from the guided light intensity distribution observation hologram every time it moves from the position y0 in the y-axis direction by a movement step Δy, and a second process Obtained A third process for obtaining the peak center position yp, peak width 2w and height A in the diffracted light power change curve from the relationship between each measurement position in the y-axis direction and the value of the power P of the diffracted light; In the z-axis direction, w is minimized by repeatedly performing the movement of one of the information recording medium and the incident light in the z-axis direction and the second and third processes. Measurement is performed on the moved information recording medium or the fourth process for adjusting the movement of the incident light in the z-axis direction and the information recording medium adjusted for movement in the z-axis direction or the incident light. Every time Δy moves from the start position y0 in the y-axis direction, the intensity J (x) in the x-axis direction in the imaging plane of the diffracted light from the guided light intensity distribution observation hologram is obtained, and then in the x-axis direction Find the relationship with the intensity J (x) for each measurement position. Therefore, by fitting this to an error function, the fifth processing for obtaining the peak values xp, 0, xp, 1,..., Xp, M of the intensity distribution J (x) and the movement adjustment in the z-axis direction are performed. Further, every time the information recording medium or the incident light is moved by Δy in the y-axis direction, the intensity distribution J (x) of the diffracted light in the x-axis direction obtained from the error function obtained in the fifth process A characteristic curve indicating the relationship between the position xp, 0, xp, 1,..., Xpx, M on the x axis where the peak value is obtained and the corresponding measurement position y0, y0 + Δy,..., Y0 + MΔy in the y-axis direction is obtained. 6 and the inclination of the characteristic curve obtained by the sixth process, a rotation angle φ centered on the z-axis, which is the inclination between the information recording medium and the incident light, is obtained, and the rotation angle φ is zero. A seventh process for adjusting the angle of the information recording medium or the incident light so that And characterized by recording a positioning program that holographic information recording medium.
[0011]
According to a sixth aspect of the present invention, in a hologram information recording medium in which planar waveguides are laminated in multiple layers, an intensity distribution of guided light propagating in the planar waveguide is measured on at least one of the planar waveguides. Have a hologram for The traveling direction of the guided light propagating through the planar waveguide is the z-axis of the xyz orthogonal coordinate system, the normal direction of the planar waveguide is the y-axis, and the direction perpendicular to both the z-axis and the y-axis is When the x-axis is used, the hologram has a constant intensity distribution in the x-axis direction of the diffracted light of the hologram when the intensity distribution of the guided light in the x-axis direction is constant. It is characterized by.
[0013]
Claim 7 The invention described in claim 6 In the hologram information recording medium described in 1), the hologram generates a linear reproduction image parallel to the x-axis direction on the imaging plane when light emitted from the light source enters the planar waveguide to which the hologram belongs. It is characterized by doing.
[0014]
Claim 8 The invention described in (1) has a planar waveguide as an internal structure, and light emitted from a light source is incident on a hologram information recording medium in which a hologram is previously produced in the planar waveguide, and propagates to the planar waveguide. A hologram information recording medium at the time of reproduction of a hologram information recording medium configured such that guided light is diffracted by the hologram in the planar waveguide and information included in the hologram can be read by observing the diffracted light; A positioning program for a hologram information recording medium executed by a computer for positioning the incident light from the light source to the hologram information recording medium, wherein the traveling direction of the guided light is expressed by a z-axis of an xyz orthogonal coordinate system When the normal direction of the planar waveguide is the y-axis and the direction perpendicular to both the z-axis and the y-axis is the x-axis, The program moves one of the information recording medium or the incident light in the y-axis direction, the amount of movement of the information recording medium or the incident light in the y-axis direction, the guided light or the diffracted light. Based on the moving direction and moving amount of the peak position in the intensity distribution on the x-axis, a rotation angle φ centered on the z-axis that is the inclination between the information recording medium and the incident light is obtained, and the rotation angle φ is zero. The information recording medium or the function of adjusting the angle of the incident light is caused to be executed by a computer.
[0015]
Claim 9 The invention described in (1) has a planar waveguide as an internal structure, and light emitted from a light source is incident on a hologram information recording medium in which a hologram has been prepared in the planar waveguide, and propagates to the planar waveguide. A hologram information recording medium at the time of reproduction of a hologram information recording medium configured such that guided light is diffracted by the hologram in the planar waveguide and information included in the hologram can be read by observing the diffracted light; In a computer-readable recording medium on which a positioning program of a hologram information recording medium for positioning with incident light from the light source to the hologram information recording medium is recorded, the traveling direction of the guided light is z in the xyz orthogonal coordinate system. The normal direction of the planar waveguide is the y-axis, and the direction perpendicular to both the z-axis and the y-axis is the x-axis. Then, the program moves one of the information recording medium and the incident light in the y-axis direction, and the amount of movement of the information recording medium or the incident light in the y-axis direction at this time Based on the moving direction and moving amount of the peak position in the intensity distribution of wave light or diffracted light on the x-axis, a rotation angle φ centered on the z-axis that is the inclination between the information recording medium and the incident light is obtained, The information recording medium or an alignment program for causing a computer to execute a function of adjusting the angle of the incident light is recorded so that the rotation angle φ is zero.
[0016]
According to the present invention, light emitted from a light source is incident on a hologram information recording medium having a planar waveguide as an internal structure, and a hologram is previously produced in the planar waveguide, and propagates to the planar waveguide. A hologram information recording medium at the time of reproduction of a hologram information recording medium configured such that guided light is diffracted by the hologram in the planar waveguide and information included in the hologram can be read by observing the diffracted light; When positioning the incident light from the light source to the hologram information recording medium, the traveling direction of the guided light is the z-axis of the xyz orthogonal coordinate system, the normal direction of the planar waveguide is the y-axis, When the direction perpendicular to both the y-axis and the x-axis is the x-axis, one of the information recording medium and the incident light is moved in the y-axis direction. The recording medium, or the amount of movement of the incident light in the y-axis direction, the information recording medium based on the movement direction and the amount of movement of the peak position in the intensity distribution of the guided light or diffracted light on the x-axis, and the incident light The rotation angle φ centered on the z-axis, which is the inclination of the information recording medium, or the angle of the incident light is adjusted so that the rotation angle φ becomes zero. Alignment with the light incident on the hologram waveguide from the light source can be performed automatically and precisely, thus preventing degradation of the reproduced image or significantly reducing the occurrence of digital information errors Can do.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the hologram card described in FIG. 1, the method for introducing light into the waveguide is not particularly defined. However, in practice, a method using a laser beam having a cylindrical wavefront generated by using a cylindrical lens or the like is convenient in terms of creating a hologram and aligning the incident light from the hologram card and the light source to the hologram card. Because it is often used. FIG. 2 is a diagram for explaining this method. In this figure, it is assumed that laser light is converted into parallel rays using a collimator made up of a combination lens and the like in advance. Therefore, the laser beam 4 is a plane wave. When the laser light 4 is incident on the convex cylindrical lens 3A, the wavefront of this light is converted into a cylindrical shape, and is converged linearly at a position (condenser 8) separated by a certain focal distance as shown in FIG.
[0018]
If the linear condensing part 8 at this time is closely matched with the part where the core layer on the end face of the hologram card 10 is exposed, the light energy can be successfully introduced into the waveguide. In other words, light can be efficiently coupled to the waveguide. (Note that FIG. 2 is exaggerated for convenience of understanding. Actually, the core layer has a thickness on the order of μm, and the line width of the condensing portion 8 is about the same. Only one core layer is left out and the others are omitted.) In order to perform such ideal coupling, it is necessary to adjust the relative position by moving the hologram card 10 or the light source. Necessary parameters for alignment are parallel rotation in the x, y, and z directions as shown, rotation angle ψ about the x axis, rotation angle θ about the y axis, and z axis. There are six rotation angles φ. However, since the x direction, the ψ direction, and the θ direction have little influence on the hologram image generation, dynamic position control is often not required, and only the three axes y, z, and φ are considered in the following. Then, consider an alignment method for proper coupling.
[0019]
First, assuming that the alignment in the z-axis direction has been completed, the alignment method according to the present invention will be described for the most complicated φ direction among the three axes y, z, and φ. Here, when ideal coupling is performed, the guided light propagates with a width substantially equal to the length of the line segment of the condensing unit 9, and therefore, the intensity distribution of the guided light becomes 11, for example.
On the other hand, it is assumed that the line segment of the light collector 9 and the core layer 1 are inclined with respect to each other as in the example shown in FIG. At this time, guided light is generated only at the portion where the line segment of the light collecting portion 8 and the core layer 1 intersect. Therefore, the guided light is narrower than that in FIG. 2, and the intensity distribution of the guided light is as shown in FIG.
[0020]
Here, when the light source or the hologram card 10 is moved in the y-axis direction, the peak position in the intensity distribution of the guided light is shifted in the left-right direction (x direction). FIG. 4 shows a state in which the peak position of the guided light intensity distribution 11 is shifted. FIG. 4 shows four schematic diagrams when the diagram shown in FIG. 3 is viewed in the light traveling direction, and these schematic diagrams. 4 are shown side by side showing the waveguide light intensity distributions corresponding to. In FIG. 4, the upper and lower two diagrams on the left side show a case where the light source is inclined in the positive direction by an angle φ. In the state where the upper figure is the original state, coupling occurs only at the portion where the light converging part 8 and the core layer end face 12 intersect due to the tilt of the light source, and the width of the guided light is limited as shown in the graph. Show. Here, the light source is moved upward (in the positive direction of y) as indicated by an arrow. Then, as shown in the lower figure, the condensing part 9 intersects the core layer end face 12 on the left side of the original position, so that the peak position of the guided light intensity distribution is shifted in the negative direction of the x axis.
[0021]
On the other hand, the upper and lower two diagrams on the right side in FIG. 4 show the case where the light source is tilted in the negative direction of φ, and even if the light source is moved in the positive direction of the y-axis, Conversely, the peak position shifts in the positive direction of the x-axis. If the peak position shift at this time is Δx,
[Expression 1]

It becomes. Therefore, if it can be measured how much the peak position of the guided light intensity distribution moves when the light source is moved in the y-axis direction, the inclination φ of the light source can be calculated backward by the following equation.
[Expression 2]

From the above, it can be seen that φ can be corrected.
If the alignment of φ is completed, the subsequent alignment in the y-axis direction is simple. The total power of the guided light is obtained by, for example, definite integration of the guided light intensity distributions of FIGS. 2, 3 and 4 at the position. The optimum relative position in the y direction is the maximum of the total power.
[0022]
In the description so far, it has been assumed that the alignment in the z-axis direction has been completed. However, for rough positioning in the z-axis direction, the position of φ and the y-axis direction are fixed and the z-axis of the light source is fixed. By adjusting the position in the direction, the maximum total guided light power may be obtained. In this method, the total power of the guided light may not be very sensitive to the position in the z-axis direction. At this time, the alignment accuracy does not increase so much. For more accurate positioning in the z-axis direction, movement in the y-axis direction is used in combination. If the light source is moved in the y-axis direction while observing the change in the total power of the guided light, the guided light is generated only when the light source passes near the core layer of the target waveguide. When plotted as a function of the amount of movement (or position) of the light source in the y-axis direction, a curve as shown in FIG. 5 is drawn.
[0023]
However, if the light source is deviated in the z-axis direction from a state where appropriate coupling is obtained, the width in which guided light is observed in the curve of FIG. 5 increases. Therefore, the position where the peak width of the guided light intensity distribution is minimized in the curve shown in FIG. 5 is the optimum position in the z-axis direction. Thus, the positioning in the z-axis direction can be performed by repeating the operation of moving in the z-axis direction and observing the curve shown in FIG. 5 due to the movement in the y-axis direction.
In the above description, the alignment performed by moving the incident light has been described. However, this does not limit the present invention. Naturally, the hologram card is moved or both the incident light and the card are moved. The same thing can be done even if moved.
[0024]
In order to carry out the alignment method of the present invention, it is essential to observe the guided light intensity distribution in the x-axis direction as shown in FIGS. In order to perform this most simply, the guided light may be observed at the exit end of the hologram card 10 opposite to the light entrance end. It can be observed that the core layer 1 shines only at the peak position of the guided light intensity distribution 11. However, most of the light leaks into the cladding layer 2 because ideal coupling is not achieved before alignment. Since this light does not go out of the hologram card 10, it is confined in the card as it is, propagates and is emitted from the exit end of the hologram card 10. In the case of, no peak can be observed.
[0025]
One method for reducing this noise is to use a light-absorbing material for the cladding layer 2. Even if light may leak into the clad at the incident end, if the clad layer 2 absorbs a large amount of light, the clad propagation light is hardly observed at the outgoing end, and the guided light intensity distribution with little noise is observed. It becomes possible.
However, even if such measures are taken, difficulties still remain with the method of observing the guided light from the exit end. In the description so far, for the sake of simplicity, the waveguide is limited to a single layer, but in reality, a large number of waveguides are stacked on the hologram card 10. As shown in FIG. 3, when light is incident on the laminated waveguide with an angle deviation between the hologram card 10 and the incident light with respect to φ, the condensing unit 8 intersects with the plurality of waveguides at different positions. Therefore, at the exit end, light is emitted at different positions in the x-axis direction for each waveguide.
[0026]
However, the actual interval between the waveguides is usually a narrow interval of the order of 10 μm, and a microscope with a high magnification or the like is required in order to observe the light shining at different positions for each waveguide. Even if the magnification is low or an attempt is made to observe without using a lens at all, separation cannot be made for each layer, so that the peak of the guided light intensity distribution as shown in FIG.
Even if the use of a high-magnification microscope is permitted, image processing technology is required for automation, which is a complicated process.
[0027]
A method using a hologram is effective for observing the guided light intensity distribution. If this waveguide has a sufficiently wide hologram in the x-axis direction, diffracted light is generated only from the region where the guided light propagates. Accordingly, by observing the distribution of the diffracted light in the x-axis direction, the same distribution as the guided light intensity distribution can be obtained. The hologram can design the wavefront of the diffracted light with a high degree of freedom, and if an appropriate hologram is produced in consideration of the convenience of observation, there will be no difficulty as in observing the waveguide exit end. FIG. 6 shows an example of this, and is a view of the top surface of the hologram card 10. In this example, a guided light intensity distribution observation hologram 14 for observing the guided light intensity distribution is prepared separately from the information recording hologram 13 for recording normal information.
[0028]
This guided light intensity distribution observation hologram 14 is formed in only one of a number of waveguide layers. Further, as shown in FIG. Arrange them so that they do not overlap. The hologram card 10 of this example observes only the guided light intensity distribution observation hologram 14 when positioning. Since the size of the hologram in FIG. 6 is on the order of mm (millimeters), it is easy to observe the guided light intensity distribution observation hologram 14 separately from the information recording / recording hologram 13. If used, it is possible even without a lens. Since there is only one layer in the region of the guided light intensity distribution observation hologram 14, the light intensity distributions of a plurality of waveguides are not seen at the same time as in the case of observing the emission end in the waveguide layer. The tilt angle φ can be identified without a simple microscope.
[0029]
Note that this method can only correct the tilt angle of one layer, but in a normal hologram card, the variation of the tilt angle φ between layers is very small, and the tilt angle must be corrected individually for all layers. There is almost nothing.
The guided light intensity distribution observation hologram 14 may have various forms, but considering the convenience of data processing, it is preferable that the guided light intensity distribution observation hologram 14 is represented by a function that does not change significantly in the x-axis direction. For example, in complex phaser display
[Equation 3]

A hologram as represented by the following function is representative. A1 is an arbitrary complex constant, j is an imaginary unit, and β is a propagation constant of the waveguide. This hologram does not change at all in the x-axis direction.
[0030]
FIGS. 7A and 7B both show the state of the same folding light when light enters the waveguide layer of the guided light intensity distribution observation hologram, and the inside of the white broken line is the hologram region. FIG. 7A shows a state where the incident light is properly aligned as shown in FIG. 2, and the light is emitted almost uniformly inside the width of the incident light. FIG. 7B shows a case where there is an inclination with respect to φ as shown in FIG. 3, and it can be observed that only the region where the light propagates shines.
Note that the diffracted light intensity pattern as shown in FIG. 7 is observed when observation is performed in a plane close to the hologram card. As the diffracted light propagates from the hologram card, the intensity pattern gradually changes due to the diffraction phenomenon in free space. In particular, a thin linear pattern as shown in FIG. 7B tends to gradually increase the line width. For this reason, if observation is performed in a plane far away, the resolution is lowered unless a lens is used, and therefore the accuracy of estimating the tilt angle φ is also lowered.
[0031]
However, if it is about several millimeters, sufficient accuracy is often obtained even if observation is performed at a location away from the hologram card. As an example of the guided light intensity distribution observation hologram 14 on the premise of observation in a distant plane,
[Expression 4]

There is a hologram represented by A2 is an arbitrary complex constant, λ0 is the wavelength of light in air, and z0 and f are real constants. This hologram
[Equation 5]

A diffracted light represented by a scalar photoelectric magnetic field is generated. Here, y0 is the y coordinate of the waveguide surface. This light is a cylindrical surface wave condensed on a straight line of z = z0 and y = y0 + f.
[0032]
Since the incident light is not efficiently coupled to the waveguide at the initial stage of alignment, the diffracted light may be difficult to detect because it is darker than usual. However, this hologram has the feature that the light intensity is very strong and easy to detect because the diffracted light is collected linearly in a plane parallel to the waveguide surface and separated by a distance f. .
If f is adjusted, it is also possible to observe with one CCD image sensor in the same plane simultaneously with the reproduction image of the information recording hologram. Further, in this case, unlike in FIG. 6, the holograms are partially separated as long as the diffracted light of the guided light intensity distribution observation hologram and the diffracted light from the information recording hologram do not overlap in the observation plane. The target or the whole may overlap. This is an advantageous feature when collecting information at high density.
[0033]
Next, the planar waveguide has an internal structure, an information recording hologram is prepared in advance in the planar waveguide, and the intensity of the guided light propagating in the waveguide in at least one of the planar waveguides A method for aligning a hologram information recording medium on which a waveguide intensity distribution observation hologram for observing the distribution is recorded in advance will be described with reference to FIGS. Note that the x, y, z axes and the rotation angle Φ around the z axis in the xyz orthogonal coordinate system indicating the positional relationship between the hologram card 10 and the incident light 4 from the light source (not shown) to the hologram card are shown in FIG. Same as 2. That is, it is assumed that the traveling direction of the guided light is the z-axis of the xyz orthogonal coordinate system, the normal direction of the planar waveguide is the y-axis, and the direction perpendicular to both the z-axis and the y-axis is the x-axis. In the present embodiment, it is assumed that the hologram information recording medium 10 is fixed and the incident light 4 is moved to align the both.
[0034]
In FIG. 8, first, in step 100 and step 101, a waveguide including the guided light intensity distribution observation hologram 14 prepared in advance in the planar waveguide in the hologram information recording medium 10 is searched as shown in FIG. In step 100,
Initial setting of the measurement start position y0 of the guided light intensity in the y-axis direction and the movement step Δy, which is a unit movement amount in one y-axis direction of the information recording medium 10 and the incident light 4, in the memory of the computer To do. Next, process A in step 101 is executed. This process A is a process for detecting the power peak (peak center position yp, peak width 2w) on the imaging surface 15 of the diffracted light by the guided light intensity distribution observation hologram 14, and its flow is shown in FIG. .
[0035]
In FIG. 9, first, the initial set value is read from the memory of the computer, and the incident light 4 is moved to the measurement start position y0 (step 200).
Next, every time the measurement start position y0 moves in the y-axis direction by the movement step Δy, the power P of the diffracted light on the imaging plane obtained from the guided light intensity distribution observation hologram is calculated by the following equation (6) ( Steps 201 and 202).
[Formula 6]

Steps 201 and 202 are repeatedly executed (L + 1) times. By repeatedly executing the processing of steps 201 and 201 (L + 1) times, diffracted light power data P0, P1, P2,..., PL for the measurement positions y0, y + Δy, y + 2Δy,. .
[0036]
Next, measurement position data y0, y + Δy, y + 2Δy,..., Y + LΔy obtained by repeatedly executing the processing of steps 201 and 202 (L + 1) times, and diffracted light power data P0, P1, P2,. Therefore, these data are fitted to the error function shown in the following equation.
[Expression 7]

From equation (7), the peak size A, peak center position yp, and peak width 2w in the power change curve P of the diffracted light on the imaging plane obtained from the guided light intensity distribution observation hologram are obtained.
Next, returning to FIG. 8, in step 102, the measurement start position y0 and the movement step Δy are reset.
[0037]
Further, in step 103, the movement of either one of the hologram information recording medium 10 and the incident light 4 (incident light 4 in the present embodiment) in the z-axis direction, the processing in step 101 (processing A), The hologram information recording medium 10 moved in the z-axis direction so that w is minimized by repeating the above, or the movement adjustment of the incident light 4 in the z-axis direction is performed.
In this manner, the hologram information recording medium 10 or the incident light 4 is roughly aligned in the z-axis direction by the processes in steps 102 and 103. In step 103, the peak size A, the peak center position yp, and the peak width 2w in the power change curve P of the diffracted light on the imaging plane obtained from the guided light intensity distribution observation hologram are obtained and measured. The start position y0 and the movement step Δy are reset (step 104).
[0038]
Next, in step 105, an estimation process (process B) of the inclination Φ of the incident light 4 is performed. The specific processing content of step 105 is shown in FIG. In FIG. 10, first, the initial set value is read from the memory of the computer, and the incident light 4 is moved to the measurement start position y0 (step 300).
Next, the intensity distribution J (x) in the x-axis direction in the imaging plane of the diffracted light from the guided light intensity distribution observation hologram 14 is next calculated every time the measurement start position y0 moves in the y-axis direction by a movement step Δy. Calculation is performed according to equation (8) (steps 301 and 302).
[Equation 8]

[0039]
At this time, calculation data J0, J1, J2 of J (x) with respect to measurement positions x0, x + Δx, x + 2Δx,..., X + NΔx in the x-axis direction including the measurement start position x0 in the obtained intensity J (x) in the x-axis direction. ... and get JN.
Next, these data are fitted to the error function shown in the following equation from the relationship with the data J0, J1, J2,..., JN with respect to the measurement positions x0, x0 + Δx, x0 + 2Δx,. A measurement position xp in the x-axis direction from which the peak of the intensity distribution J (x) in the x-axis direction within the imaging plane of the diffracted light from the intensity distribution observation hologram 14 is obtained (step 303).
[Equation 9]

After repeatedly executing the processing of steps 302 and 303 described above (M + 1) times, finally diffraction from the guided light intensity distribution observation hologram 14 for each measurement position y0, y0 + Δy, y0 + 2Δy,..., Y0 + MΔy in the y-axis direction. The peak values xp, 0, xp, 1, xp, 2,..., Xp, M of the intensity J (x) in the x-axis direction in the light imaging plane are obtained.
[0040]
Next, each measurement position y0, y + Δy, y + 2Δy,..., Y + MΔy and the peak value of J (x) are obtained in the x-axis direction measurement positions xp, 0, xp, 1, xp, 2,. , M is fitted to the arithmetic expression shown in the following equation (10) from the relationship with M (step 304). That is, an expression showing the relationship between the measurement position xp on the x-axis where the peak value of the intensity distribution J (x) in the x-axis direction of the diffracted light obtained from the error function is obtained and the corresponding measurement value in the y-axis direction. The characteristic curve (10) is obtained, and the inclination of the incident light 4 from the light source with respect to the hologram information recording medium 10, that is, the inclination angle φ is obtained from the expression (10).
[Expression 10]

[0041]
In the above equation (10), xp is the peak value of the intensity J (x) in the x-axis direction in the imaging plane of the diffracted light from the guided light intensity distribution observation hologram 14, y is the measurement position in the y-axis direction, φ is the inclination angle of the incident light from the light source with respect to the hologram information recording medium 10, and a is a constant.
8 again, the hologram information recording medium 10 or the angle adjustment for adjusting the angle of the incident light 4 is performed so that the tilt angle φ of the incident light 4 becomes zero so that the tilt angle φ becomes zero (step 106).
[0042]
Next, an embodiment of the alignment method according to the present invention will be described. In the present embodiment, a hologram represented by the following formula was used as the hologram for observation of the guided light intensity distribution.
[Expression 11]

When the incident light is properly aligned, this hologram generates a linear reconstructed image at the position z = z0 in a plane separated from the waveguide surface by a distance f, as in the hologram of equation (4). To do. Although the coefficient before the exponential function is different from Equation (4), this part is a function that hardly changes with respect to z, and is ignored.
[0043]
In addition, the first term in the exponential function in Equation (11) is effective for noise removal. σ was 0.4 mm, f was 4 mm, and λ 0 was 680 nm. The hologram size was 1 mm in both the x-axis direction and the z-axis direction, and z0 was placed at the center of the width in the z-axis direction. Other constants depend on the hologram card manufacturing conditions and are not measured strictly. The photograph shown in FIG. 11 is an example of observation of a reproduced image by this hologram after alignment. This hologram was placed in the uppermost waveguide of the hologram card 10 as shown in FIG. On the other layer of the hologram card 10, information recording holograms are installed, and all the reproduced images are designed to form an image on the same imaging plane 15 as the plane on which the hologram of the formula (11) is formed. .
Furthermore, the reproduced images of all the information recording holograms were formed at a location slightly apart from the region near z0 where the hologram represented by the equation (11) connects the images. The interval between the waveguides was about 20 μm.
[0044]
Next, an example in which the alignment of the hologram card 10 is performed using the method of the present invention will be described. When light was incident immediately after the hologram card 10 was attached to the information reading device, diffraction from any layer was very weak, and a reproduced image could not be observed. Therefore, the incident light was moved in units of 10 μm in the + y-axis direction while observing the optical power in the vicinity of z = z 0 within the imaging plane 15 in FIG. FIG. 13 is a graph plotting the optical power against the amount of movement in the y-axis direction at this time. By fitting this graph to an error function (Gaussian), it was found that the peak of the optical power is at a position of about 170 μm, and therefore the incident light is well coupled to the uppermost waveguide in the vicinity thereof.
[0045]
Therefore, the origin of the y coordinate is moved to this vicinity, and the change in optical power with respect to the amount of movement similar to that in FIG. 13 was measured in a little more detail. The result is shown in FIG. When error function fitting was performed on this graph, the full width of 1 / e was about 30 μm.
Next, after the incident light was moved in the + z direction by 500 μm, the same operation was repeated to obtain a graph similar to FIG. 14, and when fitted, the 1 / e full width was about 25 μm. Subsequently, when the incident light was moved 250 μm in the −z-axis direction, the 1 / e full width was about 15 μm. Further, the full width of 1 / e was measured when moved in the z-axis direction in the vicinity, but the minimum was about 15 μm, so the place where the incident light was moved 250 μm in the + z-axis direction from the initial position is the z-axis direction. It can be assumed that is appropriate. The change of the optical power with respect to the amount of movement in the y-axis direction here is shown in FIG. This completes the rough alignment of the incident light in the y-axis direction and the z-axis direction.
[0046]
FIG. 16 shows an example of a reproduced image of a hologram for observing the guided light intensity distribution at this point. In this figure, the entire hologram area is not illuminated as in the example of FIG. 12, and only a part of the hologram area is bright. However, since the inclination angle φ has not yet been corrected, as shown in FIG. Indicates that light propagates only in a narrow width. In FIG. 17, values obtained by integrating the light intensity distribution of FIG. 16 in the z-axis direction are plotted. The curve is a fitted error function. In this case, there is a peak at a position of 0.67 mm. Here, when the incident light is moved in the y-axis direction, the peak of the guided light intensity is moved according to the equation (1), so that the peak position of the intensity of the reproduced image as shown in FIG. 17 is also observed.
[0047]
FIG. 18 shows the movement of the peak position accompanying the movement of the incident light in the y-axis direction. When the tilt angle φ is very small, from equation (2):
[Expression 12]

The inclination angle φ is approximately approximated by the inclination of the straight line in FIG. From this, it was estimated that there was an inclination of 43 minutes, so the angle of incident light was corrected accordingly.
FIG. 19 shows the result of observing the change in optical power with respect to the amount of movement in the y-axis direction after angle correction, as in FIGS. It was found that the 1 / e full width was 5.6 μm, which was significantly improved from FIG. 15 by the angle correction. FIG. 20 is a reproduced image of the guided light intensity distribution observation hologram observed at the peak center position in FIG. 19, which is also improved compared to FIG. 16, which is a reproduced image before angle correction. The bright area extends to the full width.
[0048]
This completes the positioning of the tilt angle φ of the incident light with respect to the hologram card 10. Thereafter, positioning in the z-axis direction may be performed with higher accuracy, but this is not particularly necessary in this embodiment. Subsequently, in order to read the hologram information of the second waveguide from the top in the hologram card 10, the incident light 4 was moved 20 mm in the -y axis direction. When the optical power inside the image display area 16 in FIG. 12 was observed while moving in the y-axis direction in the vicinity, the behavior was exactly the same as in FIG. At the position where the peak of the optical power is obtained, a reproduced image almost as designed was observed, and it was confirmed that the hologram card 10 and the incident light 4 were properly aligned. Hereinafter, the same operation was performed for the other waveguide layers in the hologram card 10, but the same thing was confirmed for all 10 layers prepared in advance.
[0049]
Note that a method for aligning the hologram information recording medium according to the above-described embodiment of the present invention and the incident light for reproducing the hologram with respect to the information recording medium is described as a program, and the position is obtained by causing the computer to execute the method. A combination method may be implemented.
[0050]
That is, having a planar waveguide as an internal structure, an information recording hologram is produced in advance in the planar waveguide, and the intensity distribution of the guided light propagating in the waveguide in at least one of the planar waveguides The light emitted from the light source is incident on a hologram information recording medium in which a hologram for observing the intensity distribution of the guided light for observing the light is recorded in advance, and the guided light propagating to the planar waveguide is the information in the planar waveguide. Hologram information recording medium and hologram information from the light source at the time of reproduction of the hologram information recording medium configured to be able to read the information contained in the information recording hologram by diffracting by the recording hologram and observing the diffracted light The position of the hologram information recording medium executed by the computer for positioning with the incident light on the recording medium The traveling direction of the guided light is the z-axis of the xyz orthogonal coordinate system, the normal direction of the planar waveguide is the y-axis, and is perpendicular to both the z-axis and the y-axis. When the direction is the x-axis, the measurement start position y0 of the guided light intensity in the y-axis direction and the movement step Δy in one y-axis direction of the information recording medium and the incident light are stored in the memory of the computer. A first process to initialize;
The initial set value is read from the memory, and one of the information recording medium and the incident light is moved to the measurement start position y0, and moved from the measurement start position y0 by the movement step Δy in the y-axis direction. A second process for calculating the power P of the diffracted light on the imaging plane obtained from the guided light intensity distribution observation hologram every time, the respective measurement positions in the y-axis direction obtained by the second process, and the diffraction A third process for determining the peak center position yp, peak width 2w and height A in the change curve of the power of the diffracted light from the relationship with the value of the power P of the light, and the information recording medium and the incident light. The information recording medium moved in the z-axis direction so that w is minimized by repeatedly performing one of the movements in the z-axis direction and the second and third processes, or the input medium In the z-axis direction A fourth process for performing dynamic adjustment, and the information recording medium that has been adjusted for movement in the z-axis direction, or the guided light intensity every time the incident light moves by Δy in the y-axis direction from the measurement start position y0. Obtain the intensity distribution J (x) in the x-axis direction within the imaging plane of the diffracted light from the distribution observation hologram, and then obtain the relationship with the intensity distribution J (x) for each measurement position in the x-axis direction; This is fitted to an error function, and the fifth processing for obtaining the peak values xp, 0, xp, 1,..., Xp, M of the intensity distribution J (x) and the movement adjustment in the z-axis direction are performed. The peak value of the intensity distribution J (x) in the x-axis direction of the diffracted light obtained from the error function obtained in the fifth process each time the information recording medium or the incident light is moved by Δy in the y-axis direction , Xp, 0, xp, 1, ..., xpx, M and the corresponding measurement in the y-axis direction A sixth process for obtaining a characteristic curve indicating the relationship between the positions y0, y0 + Δy,. A program comprising: a seventh process for obtaining a rotation angle φ centered on the z axis and adjusting the angle of the incident light so that the rotation angle φ is zero. A hologram information recording medium is recorded on a computer-readable recording medium, and a hologram information recording medium alignment program recorded on the recording medium is read into a computer system and executed to execute a hologram information recording medium alignment method. Also good.
[0051]
The waveguide light propagating in the planar waveguide is incident on the light emitted from the light source to the hologram information recording medium having a planar waveguide as an internal structure, and a hologram is previously produced in the planar waveguide. A hologram information recording medium and a hologram from the light source at the time of reproduction of the hologram information recording medium configured to be able to read information contained in the hologram by observing the diffracted light diffracted by the hologram in a planar waveguide A hologram information recording medium positioning program executed by a computer for positioning with incident light on an information recording medium, wherein the traveling direction of the guided light is a z-axis of an xyz orthogonal coordinate system, and the plane When the normal direction of the waveguide is the y-axis and the direction perpendicular to both the z-axis and the y-axis is the x-axis, the program , One of the information recording medium and the incident light is moved in the y-axis direction, the amount of movement of the information recording medium or the incident light in the y-axis direction, the intensity distribution of the waveguide light or diffracted light Based on the movement direction and amount of movement of the peak position on the x-axis, a rotation angle φ centered on the z-axis, which is an inclination between the information recording medium and the incident light, is obtained, and the rotation angle φ becomes zero. As described above, the information recording medium or the hologram information recording medium recorded on the recording medium is recorded on the computer-readable recording medium, and the program for causing the computer to execute the function of adjusting the angle of the incident light. The alignment method of the hologram information recording medium may be performed by causing the computer system to read and execute the alignment program.
[0052]
Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage medium such as a floppy disk, a magneto-optical disk, a general medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system.
[0053]
Furthermore, the “computer-readable recording medium” means that a program is dynamically held for a short time, like a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. It is also assumed that what holds a program for a certain period of time, such as a volatile memory inside a computer system that becomes a server or client in that case (transmission medium or transmission wave).
[0054]
Further, the program may be for realizing a part of the above-described functions, and further, a program that can realize the above-described functions in combination with a program already recorded in a computer system, a so-called difference file ( Difference program).
[0055]
【The invention's effect】
As described above, according to the present invention, light emitted from a light source is incident on a hologram information recording medium having a planar waveguide as an internal structure, and a hologram is produced in advance in the planar waveguide. During reproduction of a hologram information recording medium configured such that guided light propagating to a planar waveguide is diffracted by the hologram in the planar waveguide and information included in the hologram can be read by observing the diffracted light When positioning the hologram information recording medium in FIG. 5 and the light incident on the hologram information recording medium from the light source, the traveling direction of the guided light is the z-axis of the xyz orthogonal coordinate system, and the normal direction of the planar waveguide is y When the x-axis is a direction perpendicular to both the z-axis and the y-axis, one of the information recording medium and the incident light is moved in the y-axis direction. The information recording medium at this time, or the information recording medium based on the amount of movement of the incident light in the y-axis direction, the direction of movement and the amount of movement of the peak position in the intensity distribution of the guided light or diffracted light on the x-axis Since the rotation angle φ centered on the z-axis, which is the tilt with respect to the incident light, is obtained, the angle of the information recording medium or the incident light is adjusted so that the rotation angle φ is zero. Automatic and precise alignment of the hologram information recording medium and the light incident on the hologram waveguide from the light source can be performed, thus preventing the reproduction image from being deteriorated or generating an error in digital information. Can be remarkably suppressed.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a structure of a reproduction-only multiplex hologram card and a state during information reproduction.
FIG. 2 is an explanatory diagram showing a guided light intensity distribution with respect to incident light of a hologram card together with an xyz orthogonal coordinate system.
FIG. 3 is an explanatory diagram showing a waveguide light intensity distribution of a hologram card when incident light on the hologram card is tilted.
FIG. 4 is an explanatory diagram showing a state in which the peak of the guided light intensity distribution is shifted due to the movement of incident light to the hologram card.
FIG. 5 is a characteristic diagram showing a change state of total power of guided light accompanying movement of incident light or a hologram card in the y-axis direction.
FIG. 6 is an explanatory view showing an arrangement example of an information recording hologram and a guided light intensity distribution observation hologram in a hologram card.
FIG. 7 is an explanatory diagram showing an example of observation of a guided light intensity distribution using a hologram.
FIG. 8 is a flowchart showing a procedure of a hologram information recording medium alignment method according to an embodiment of the present invention.
FIG. 9 is a flowchart showing specific contents of process A in the flowchart shown in FIG. 9;
FIG. 10 is a flowchart showing specific contents of process B in the flowchart shown in FIG. 9;
FIG. 11 is a diagram showing an example of observation in the imaging plane of diffracted light by a guided light intensity distribution observation hologram in the hologram information recording medium in the embodiment of the present invention.
FIG. 12 is an explanatory diagram showing an image formation state at the time of reproduction of the hologram card in the embodiment of the present invention.
FIG. 13 is a characteristic diagram showing a change state of the total guided light power accompanying the movement of incident light in the y-axis direction with respect to the hologram card in the embodiment of the present invention.
FIG. 14 is a characteristic diagram showing a result of examining in detail the change state of the total guided light power accompanying the movement of the incident light in the y-axis direction with respect to the hologram card in the embodiment of the present invention.
FIG. 15 shows the result of examining in detail the change in the total power of the guided light accompanying the movement of the incident light in the y-axis direction after positioning the incident light in the z-axis direction with respect to the hologram card in the embodiment of the present invention. FIG.
FIG. 16 is a diagram showing an example of diffracted image observation of a waveguide light intensity distribution observation hologram immediately after alignment of incident light in the z-axis direction with respect to the hologram card in the embodiment of the present invention.
FIG. 17 is a diagram showing an example of observation of a guided light intensity distribution by hologram observation in the embodiment of the present invention.
FIG. 18 is a characteristic diagram showing the relationship between the amount of movement in the y-axis direction and the amount of movement of the peak position in the x-axis direction of the guided light intensity distribution in the embodiment of the present invention.
FIG. 19 is a characteristic diagram showing the result of examining in detail the change state of the total guided light power accompanying the movement of the incident light in the y-axis direction after correcting the inclination angle φ of the incident light with respect to the hologram card in the embodiment of the present invention.
FIG. 20 is a diagram showing an example of observation of a diffraction image of a guided light intensity distribution observation hologram after correcting the inclination angle φ of incident light with respect to the hologram card in the embodiment of the present invention.
[Explanation of symbols]
1 Core layer
2 Clad layer
3, 3A lens
4 Laser light
5 Waveguide light
6 Scattering factor (hologram)
7 Diffracted light
8 Reconstructed image (hologram image)
9 Condensing part
10 Hologram card
11 Waveguide intensity distribution
12: Core layer end face
13: Information recording hologram
14: Hologram for observation of guided light intensity distribution
15: Imaging plane
16: Reproduction image display area of information recording hologram

Claims (9)

 A planar waveguide is used as an internal structure, and light emitted from a light source is incident on a hologram information recording medium in which a hologram is previously produced in the planar waveguide, and the guided light propagating to the planar waveguide is guided by the planar waveguide. Hologram information recording medium and hologram information recording from light source during reproduction of hologram information recording medium configured to be able to read information contained in hologram by observing diffracted light diffracted by hologram in waveguide A hologram information recording medium positioning method for positioning with incident light on a medium, wherein a traveling direction of the guided light is a z-axis in an xyz orthogonal coordinate system, and a normal direction of the planar waveguide is a y-axis When the direction perpendicular to both the z axis and the y axis is the x axis, one of the information recording medium and the incident light is moved in the y axis direction. The information recording medium or the amount of movement of the incident light in the y-axis direction and the direction and amount of movement of the peak position in the intensity distribution of the guided light or diffracted light on the x-axis. A rotation angle φ centered on the z-axis, which is an inclination between the medium and the incident light, is obtained, and the angle of the information recording medium or the incident light is adjusted so that the rotation angle φ becomes zero. A method for aligning a hologram information recording medium.  A planar waveguide is used as an internal structure, and light emitted from a light source is incident on a hologram information recording medium in which a hologram is previously produced in the planar waveguide, and the guided light propagating to the planar waveguide is guided by the planar waveguide. Hologram information recording medium and hologram source recording light source at the time of reproduction of hologram information recording medium configured to be able to read out information contained in hologram by observing diffracted light diffracted by hologram in waveguide A hologram information recording medium positioning method for positioning with incident light on a medium, wherein a traveling direction of the guided light is a z-axis in an xyz orthogonal coordinate system, and a normal direction of the planar waveguide is a y-axis , When the direction perpendicular to both the z-axis and the y-axis is the x-axis, the information recording medium and the light source enter the hologram information recording medium. The information recording medium in which one of the light is moved in the y-axis direction, the total power of the guided light is obtained, and the position in the y-axis direction where the total power of the guided light is maximum is moved in the y-axis direction Or a first step of adjusting a position in the y-axis direction as a relative position in the y-axis direction of the incident light, and the information recording medium moved in the y-axis direction in the first step, or A second step of measuring a change curve of the total power of the guided light accompanying the movement of one of the incident lights in the y-axis direction and fitting the center position, width, and height of the peak of the curve to an error function; Each time the information recording medium or the incident light is moved by a predetermined amount in the z-axis direction, the process of the second step is performed to compare the peak widths of the change curves obtained by fitting the error function. Done before The third step of adjusting the position in the z-axis direction as the relative position in the z-axis direction of the information recording medium moved in the z-axis direction or the incident light in the position on the z-axis where the peak width is minimum And one of the information recording medium and the incident light is moved in the y-axis direction, the amount of movement of the information recording medium or the incident light in the y-axis direction at this time, and the peak in the intensity distribution of the guided light Based on the moving direction and moving amount of the position on the x-axis, a rotation angle φ centered on the z-axis, which is an inclination between the information recording medium and the incident light, is obtained, so that the rotation angle φ becomes zero. And a fourth step of adjusting an angle of the incident light, or a method of aligning a hologram information recording medium, characterized by comprising:  A planar waveguide is used as an internal structure, and light emitted from a light source is incident on a hologram information recording medium in which a hologram is previously produced in the planar waveguide, and the guided light propagating to the planar waveguide is guided by the planar waveguide. Hologram information recording medium and hologram source recording light source at the time of reproduction of hologram information recording medium configured to be able to read out information contained in hologram by observing diffracted light diffracted by hologram in waveguide An alignment method of a hologram information recording medium for positioning with incident light on a medium, wherein an intensity distribution of the guided light propagating in the waveguide is observed in at least one of the waveguides in the hologram information recording medium Recording a hologram for observing the intensity distribution of the guided light in advance, and the traveling direction of the guided light is directly Hologram information from the information recording medium and the light source when the z-axis of the coordinate system is set, the normal direction of the planar waveguide is the y-axis, and the direction perpendicular to both the z-axis and the y-axis is the x-axis. One of the incident light to the recording medium is moved in the y-axis direction, and is observed on the image plane on which the reproduced image of the guided light intensity distribution observation hologram is formed with respect to the amount of movement in the y-axis direction. The total power of the diffracted light is obtained, and the y-axis direction position at which the total power of the diffracted light is maximum is moved in the y-axis direction, or any of the incident light in the y-axis direction. A first step of adjusting the position in the y-axis direction as a relative position; and the information recording medium moved in the y-axis direction in the first step, or the movement of one of the incident light in the y-axis direction Measure the change curve of the total power of the diffracted light. A second step of fitting the peak center position, width, and height to an error function, and the second time each time the information recording medium or the incident light is moved by a predetermined amount in the z-axis direction. The information obtained by performing step processing, comparing the peak widths of the change curves obtained by fitting the error function, and moving the position on the z-axis where the peak width is minimum in the z-axis direction. A third step of adjusting the position in the z-axis direction as a relative position in the z-axis direction of the recording medium or the incident light, and moving one of the information recording medium and the incident light in the y-axis direction, And the information recording medium based on the amount of movement of the incident light in the y-axis direction, the direction of movement of the peak position in the change curve of the diffracted light, and the amount of movement on the x-axis. A rotation angle φ centered on the z-axis, which is an inclination with respect to the incident light, and a fourth step of adjusting the angle of the information recording medium or the incident light so that the rotation angle φ is zero, and A method for aligning a hologram information recording medium, comprising:  It has a planar waveguide as its internal structure, an information recording hologram is prepared in advance in the planar waveguide, and the intensity distribution of the guided light propagating in the waveguide is observed in at least one of the planar waveguides. The light emitted from the light source is incident on a hologram information recording medium in which a hologram for observing the distribution of the guided light intensity distribution is recorded in advance, and the guided light propagating to the planar waveguide is used for the information recording in the planar waveguide. Hologram information recording medium at the time of reproduction of hologram information recording medium configured to be able to read information contained in the information recording hologram by observing the light diffracted by the hologram and hologram information recording medium from the light source Computer-executed hologram information recording medium alignment program for positioning with incident light on The program is a direction perpendicular to both the z-axis and the y-axis, wherein the traveling direction of the guided light is the z-axis of the xyz orthogonal coordinate system, the normal direction of the planar waveguide is the y-axis Is the measurement start position y0 of the guided light intensity in the y-axis direction and the movement step Δy in the y-axis direction of one of the information recording medium and the incident light in the computer memory. A first process to be set and the initial setting value are read from the memory, and one of the information recording medium and the incident light is moved to the measurement start position y0, and the measurement start position y0 to the y-axis A second process for calculating the power P of the diffracted light on the imaging plane obtained from the guided light intensity distribution observing hologram every time it moves by a movement step Δy in the direction, and the y-axis obtained by the second process Each measurement position and the power of the diffracted light A third process for determining the peak center position yp, peak width 2w, and height A in the power change curve of the diffracted light from the relationship with the value of -P, and any one of the information recording medium and the incident light The information recording medium moved in the z-axis direction so that w is minimized by repeating the movement in one z-axis direction and the second and third processes, or the incident light The fourth process for adjusting the movement in the z-axis direction and the information recording medium that has been adjusted for movement in the z-axis direction, or the incident light each time Δy moves in the y-axis direction from the measurement start position y0 The intensity distribution J (x) in the x-axis direction in the imaging plane of the diffracted light from the guided light intensity distribution observation hologram is obtained, and then the intensity distribution J (x) for each measurement position in the x-axis direction And apply this to the error function The information recording medium in which the fifth processing for obtaining the peak values xp, 0, xp, 1,..., Xp, M of the intensity distribution J (x) and the movement adjustment in the z-axis direction are performed, or X-axis from which the peak value of the intensity distribution J (x) in the x-axis direction of the diffracted light obtained from the error function obtained in the fifth process is obtained each time the incident light is moved by Δy in the y-axis direction. Sixth processing for obtaining a characteristic curve indicating the relationship between the upper positions xp, 0, xp, 1,..., Xpx, M and the corresponding measurement positions y0, y0 + Δy,..., Y0 + MΔy in the y-axis direction, A rotation angle φ centered on the z-axis, which is the inclination between the information recording medium and the incident light, is obtained from the slope of the characteristic curve obtained by the processing of step 1, and the information recording is performed so that the rotation angle φ is zero. And a seventh process for adjusting the angle of the incident light.  It has a planar waveguide as its internal structure, an information recording hologram is prepared in advance in the planar waveguide, and the intensity distribution of the guided light propagating in the waveguide is observed in at least one of the planar waveguides. The light emitted from the light source is incident on a hologram information recording medium in which a hologram for observing the distribution of the guided light intensity distribution is recorded in advance, and the guided light propagating to the planar waveguide is used for the information recording in the planar waveguide. Hologram information recording medium at the time of reproduction of hologram information recording medium configured to be able to read information contained in the information recording hologram by observing the light diffracted by the hologram and hologram information recording medium from the light source A computer-readable recording of a hologram information recording medium alignment program for positioning with incident light on In a recordable recording medium, the program uses the traveling direction of the guided light as the z-axis in the xyz orthogonal coordinate system, the normal direction of the planar waveguide as the y-axis, and is perpendicular to both the z-axis and the y-axis. The x-axis is the measurement start position y0 of the guided light intensity in the y-axis direction and the movement step Δy in one y-axis direction of the information recording medium and the incident light. The initial setting value is read from the memory, and one of the information recording medium and the incident light is moved to the measurement start position y0, and from the measurement start position y0 Obtained by the second process for calculating the power P of the diffracted light on the imaging plane obtained from the guided light intensity distribution observation hologram every time it moves by the movement step Δy in the y-axis direction, and the second process. Each measurement position in the y-axis direction and the front A third process for determining the peak center position yp, peak width 2w and height A in the diffracted light power change curve from the relationship with the power P of the diffracted light; the information recording medium and the incident light; The information recording medium moved in the z-axis direction so that w is minimized by repeatedly performing the movement in either the z-axis direction and the second and third processes, or A fourth process for adjusting the movement of the incident light in the z-axis direction, and the information recording medium that has been adjusted for movement in the z-axis direction, or Δy in the y-axis direction from the measurement start position y0 for the incident light. The intensity J (x) in the x-axis direction in the imaging plane of the diffracted light from the guided-wave intensity distribution observation hologram is obtained every time it moves only, and then the intensity J (x) for each measurement position in the x-axis direction ) And calculate this as an error function. The information recording medium in which the fifth processing for obtaining the peak values xp, 0, xp, 1,..., Xp, M of the intensity distribution J (x) and the movement adjustment in the z-axis direction are performed, or X-axis from which the peak value of the intensity distribution J (x) in the x-axis direction of the diffracted light obtained from the error function obtained in the fifth process is obtained each time the incident light is moved by Δy in the y-axis direction. Sixth processing for obtaining a characteristic curve indicating the relationship between the upper positions xp, 0, xp, 1,..., Xpx, M and the corresponding measurement positions y0, y0 + Δy,..., Y0 + MΔy in the y-axis direction, A rotation angle φ centered on the z-axis, which is the inclination between the information recording medium and the incident light, is obtained from the slope of the characteristic curve obtained by the processing of step 1, and the information recording is performed so that the rotation angle φ is zero. Hologram information recording medium for causing a computer to execute the medium or the seventh processing for adjusting the angle of the incident light A recording medium recording a positioning program. In holographic data recording medium stacked planar waveguide is a multi-layer, at least one of said planar waveguide, have a hologram for measuring the intensity distribution of the guided light propagating through the plane waveguide,
The traveling direction of the guided light propagating through the planar waveguide is the z-axis of the xyz orthogonal coordinate system, the normal direction of the planar waveguide is the y-axis, and the direction perpendicular to both the z-axis and the y-axis is the x-axis. In the hologram information recording , the intensity distribution in the x-axis direction of the diffracted light of the hologram is constant when the intensity distribution of the guided light in the x-axis direction is constant. Medium. The hologram according to claim, characterized in that to produce a linear reconstructed image is parallel to the x-axis direction on the imaging surface when the emitted light is incident from the light source into the planar waveguide to which the hologram belongs 6 The hologram information recording medium described in 1.  A planar waveguide is used as an internal structure, and light emitted from a light source is incident on a hologram information recording medium in which a hologram is previously produced in the planar waveguide. Hologram information recording medium and hologram information recording from light source during reproduction of hologram information recording medium configured to be able to read information contained in hologram by observing diffracted light diffracted by hologram in waveguide A hologram information recording medium alignment program executed by a computer for positioning with incident light on the medium, wherein the program uses the traveling direction of the guided light as the z-axis of an xyz orthogonal coordinate system, When the normal direction of the planar waveguide is the y-axis and the direction perpendicular to both the z-axis and the y-axis is the x-axis, One of the information recording medium and the incident light is moved in the y-axis direction, and the amount of movement of the information recording medium or the incident light in the y-axis direction at this time, the peak in the intensity distribution of the waveguide light or diffracted light Based on the moving direction and moving amount of the position on the x-axis, a rotation angle φ centered on the z-axis, which is an inclination between the information recording medium and the incident light, is obtained, so that the rotation angle φ becomes zero. A program causing a computer to execute a function of adjusting an angle of the information recording medium or the incident light.  A planar waveguide is used as an internal structure, and light emitted from a light source is incident on a hologram information recording medium in which a hologram is previously produced in the planar waveguide. Hologram information recording medium and hologram source recording light source at the time of reproduction of hologram information recording medium configured to be able to read out information contained in hologram by observing diffracted light diffracted by hologram in waveguide In a computer-readable recording medium recording a hologram information recording medium alignment program for positioning with incident light on the medium, the program uses the traveling direction of the guided light as the z-axis of the xyz orthogonal coordinate system. The normal direction of the planar waveguide is the y-axis, and the direction perpendicular to both the z-axis and the y-axis is the x-axis. One of the information recording medium and the incident light is moved in the y-axis direction, the amount of movement of the information recording medium or the incident light in the y-axis direction, the guided light or the diffracted light A rotation angle φ centered on the z-axis, which is the inclination between the information recording medium and the incident light, is obtained based on the movement direction and movement amount of the peak position in the intensity distribution on the x-axis, and the rotation angle φ is A recording medium on which the information recording medium or a registration program for causing a computer to execute a function of adjusting the angle of the incident light is recorded so as to be zero.

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