JP3667716B2

JP3667716B2 - Optical coherence tomography device

Info

Publication number: JP3667716B2
Application number: JP2002137376A
Authority: JP
Inventors: 直弘丹野
Original assignee: 直弘丹野
Priority date: 2002-05-13
Filing date: 2002-05-13
Publication date: 2005-07-06
Anticipated expiration: 2022-05-13
Also published as: JP2003329577A

Description

【０００１】
【発明の属する技術分野】
本発明は、光コヒーレンストモグラフィー装置に関するものである。
【０００２】
【従来の技術】
従来の光コヒーレンストモグラフィーにおける高速光遅延発生方法として、参照光路の経路をハーフミラー→高速回転する第１のミラー→同第２のミラー→固定ミラー→第２のミラー→第１のミラー→ハーフミラーとし、光経路を回帰遅延反射する方法が知られている。
【０００３】
図７は、従来の光コヒーレンストモグラフィー装置の概略構成図である。
【０００４】
この図において、１０１は低コヒーレンス光源〔例えばＳＬＤ（スーパールミネッセンスダイオード）光源〕、１０２はハーフミラー（２分割用ハーフミラー）、１０３は回転体、１０４は、第１のミラー１０４Ａ及び第２のミラー１０４Ｂから構成される光遅延用反射体、１０５は固定ミラー、１０６，１０７はミラー、１０９は被検査物、１１０は光検出器である。
【０００５】
【発明が解決しようとする課題】
しかしながら、上記した従来の光コヒーレンストモグラフィーにおける高速光遅延方法では、奥行き方向（Ｚ方向）の走査距離を長くとれる代わりに、回転体円周上へのミラーの配置数を多くとれないため、１回転あたりのトモグラフィー画像を数多く効率よく取得できないなどの欠点があった。
【０００６】
従来の方法では、図７に示すように、回転体の接線に垂直な中心線ＡＢにミラーの対角線を合わせて配置し、入射光が第１のミラー１０４Ａ→第２のミラー１０４Ｂ→固定ミラー１０５と回帰遅延する場合のみ考えられ、ミラーが回転によって逆に第２のミラー→第１のミラーと入射する場合の反射遅延は利用されていなかった。
【０００７】
また、生体などの動いている被検査物では、Ｚ方向の走査をできるだけ高速にする必要があるが、機械的回転数は限られているので、ミラーを複数配置し１秒当たりの取得断層画像を多くすることは、上記した従来の方法では対応ができなかった。
【０００８】
さらに、１回転で、異なる部位あるいは連続した部位を多重に連続してトモグラフィーを構成する方法などは、上記の従来の方法のみならず他の手段においても、全く開示されていなかった。
【０００９】
本発明は、上記状況に鑑みて、奥行き方向（Ｚ方向）の走査速度が速く、同時に多重に連続して断層画像を映像化できる、光コヒーレンストモグラフィー装置を提供することを目的とする。
【００１０】
【課題を解決するための手段】
本発明は、上記目的を達成するために、
〔１〕光コヒーレンストモグラフィー装置において、低コヒーレンス光源と、この低コヒーレンス光源からの光を被検査物への物体光と参照光に２分割する２分割用ハーフミラーと、前記参照光を回転角により２方向へ反射が連続して生じるように反射体を配置した回転反射体により遅延させる光遅延機構と、この光遅延機構からの複数方向への反射をそれぞれ任意の光学距離で反射回帰する複数の固定ミラーと、前記被検査物から回帰する物体光と前記光遅延機構から回帰する参照光とを合波する前記２分割用ハーフミラーとこの２分割用ハーフミラーで合成されたヘテロダイン干渉ビート信号を含む干渉光を検出する光検出器とを具備することを特徴とする。
【００１１】
〔２〕光コヒーレンストモグラフィー装置において、低コヒーレンス光源と、この低コヒーレンス光源からの光を被検査物への物体光と参照光に２分割する２分割用ハーフミラーと、前記参照光を回転角により２方向へ反射が連続して生じるように反射体を配置した回転反射体により遅延させる光遅延機構と、この光遅延機構からの複数方向への反射をそれぞれ任意の光学距離で反射回帰するハーフミラーを含む複数の固定ミラーと、前記物体光で被検査物の面内を走査する面走査機構と、対物レンズと、前記被検査物から回帰する物体光と前記光遅延機構から回帰する参照光とを合波する前記２分割用ハーフミラーと、この２分割用ハーフミラーで合成されたヘテロダイン干渉ビート信号を含む干渉光を検出する光検出器とを具備することを特徴とする。
【００１２】
〔３〕上記〔１〕又は〔２〕記載の光コヒーレンストモグラフィー装置において、前記光遅延機構は、高速回転する回転体上に放射状に反射体を配置し、かつその反射体は前記回転体の円周の法線に対し適度な入射角で入射する光を回帰反射するように、所定の回転角度範囲では第１のミラーに入射し第２のミラーで反射して所定の光路長に設定した第１の固定ミラーで回帰反射し、次なる回転角度範囲では逆に第２のミラーに入射し第１のミラーで反射して別途所定の光路長に設定した第２の固定ミラーで回帰反射するように、各第１のミラーと第２のミラーの対を前記回転体の表面に複数対配置し、ハーフミラーを含む複数の固定ミラーを所定の位置に配置することを特徴とする。
【００１３】
〔４〕上記〔３〕記載の光コヒーレンストモグラフィー装置において、前記２分割ミラーを経た参照光を別途ハーフミラーで２分割し、この２分割した光を各々参照光とするように、前記光遅延機構は、高速回転する回転体上に放射状に反射体を配置し、かつその反射体は前記回転体の円周の法線に対し適度な入射角で入射するその各参照光を独自に回帰反射するように、所定の角度範囲では第１のミラーに入射し第２のミラーで反射して所定の光路長に設定した第１の固定ミラーで回帰反射し、次なる回転角度範囲では逆に第２のミラーに入射し第１のミラーで反射して別途所定の光路長に設定した第２の固定ミラーで回帰反射するように、各第１のミラーと第２のミラーの対を前記回転体の表面に複数対配置し、複数の固定ミラーを所定の位置に配置することを特徴とする。
【００１４】
〔５〕上記〔１〕から〔４〕の何れか１項記載の光コヒーレンストモグラフィー装置において、前記ハーフミラーを含む複数の固定ミラーは各々スキャン開始位置調整ミラーであり、前記物体光における光軸の奥行き方向であるＺ方向に一致させ、深さ方向の異なる所望の地点から走査開始をするよう各々独立に光路長を設定でき調整可能としたことを特徴とする。
【００１５】
〔６〕上記〔３〕記載の光コヒーレンストモグラフィー装置において、前記光遅延機構のうち、第１のミラーと第２のミラーからなる１対の反射体を前記参照光の入射光軸と直交する法線の立つ円周の一点に配置し、大深度Ｚ方向走査を可能とする少なくとも１対の反射体を具備し、他の前記複数の反射体の走査位置を特定する役割を有することを特徴とする。
【００１６】
〔７〕上記〔１〕から〔６〕の何れか１項記載の光コヒーレンストモグラフィー装置において、前記参照光と物体光に２分割する２分割用ハーフミラーを介してファイバー結合するレンズ系と、このレンズ系からの光を伝送する物体光用の光ファイバーと参照光用の光ファイバーと、これらの光ファイバーからのそれぞれの出射光をおよそ平行光束にするレンズ系とを具備したことを特徴とする。
【００１７】
〔８〕上記〔２〕記載の光コヒーレンストモグラフィー装置において、前記面走査機構はＸ軸走査ミラー及びＹ軸走査ミラーを備え、前記複数の遅延参照光に対応した所定の位置において、前記被検査物に対する物体光でその被検査物の面（Ｘ−Ｙ）を高速に走査することを特徴とする。
【００１８】
【発明の実施の形態】
以下、本発明の実施の形態について詳細に説明する。
【００１９】
図１は本発明の実施例を示す多重連映像化光コヒーレンストモグラフィー装置の構成図である。
【００２０】
この図において、１は低コヒーレンス光源〔例えば、ＳＬＤ（スーパールミネッセンスダイオード）光源〕、２はファイバー結合用レンズ、３はハーフミラー（２分割用ハーフミラー）、４は参照光用光ファイバー、５および１１は出射光平行光束用レンズ、６ｐは光遅延機構への入射光及び回帰反射光、７１は第１のミラー７ａ及び第２のミラー７ｂからなる光遅延機構反射体、７ａ′は所定の回転角θｐ回転後の第１のミラー位置、７ｂ′も同様に回転後の第２のミラー位置、８は回転体、９１，９２は第１、第２の固定ミラー、９１ａ，９２ａは第１、第２の固定ミラー９１，９２の光軸方向へのスキャン開始位置調整機構であり、６Ａ，６Ｂはそれぞれ回帰反射遅延光、１０は物体光用光ファイバー、１２はＸ軸方向への面走査用ミラー、１３はＹ軸方向への面走査用ミラー、１４は対物レンズである。また、１５はファイバー結合用レンズ、１６は光検出器、１７はＰＣ（パーソナルコンピュータ）システム、１８は表示装置、１０９は被検査物である。
【００２１】
このように、光遅延機構は反射体７１と回転体８から構成され、反射体７１は高速回転する回転体８上に放射状に、かつ回転体８の円周の法線に対し適度の角度で入射する参照光を平行に反射するように、第１のミラー７ａ、第２のミラー７ｂで１対となる反射体７１を複数配置しておく。
【００２２】
例えばＳＬＤなどの低コヒーレンス光源１からの光波をファイバー結合用レンズ２を介して、ハーフミラー３で参照光と物体光に２分割する。参照光は光ファイバー４と平行光束用レンズ５を伝搬して光遅延機構の反射体７１に至る。反射体７１が実線で示す角度の位置にあるときには、参照光は第１のミラー７ａ、第２のミラー７ｂと反射して第１の方向に向かい、第１の固定ミラー９１より同一光路を反射回帰し、反射体７１の回転とともに所定の光遅延長を得てハーフミラー３に戻る。この回転により参照光の入射位置が、第１のミラー７ａと第２のミラー７ｂの合わせ境界を越えたとき、参照光は点線で示す第２のミラー７ｂ′、第１のミラー７ａ′、第２の固定ミラー（スキャン開始位置調整機構付きミラー）９２と第２の方向へ反射する。すなわち、回転角に応じ、入射参照光６ｐは２方向へ反射される。
【００２３】
このような光遅延機構としたので、反射光を２方向へ形成することができて、第１の回転反射遅延光６Ａが所定の光遅延長に亘りＺ走査をするとき、第２の回帰反射遅延光６Ｂは、第２の固定ミラー９２の位置に応じて、第１の固定ミラー９１と全く同域の被検査物１０９の深層のＺ走査も、あるいは異なる分域でのＺ走査も可能となる。前記両ミラー７ａ，７ｂの合わせ境界点が、回転角度が例えばθｐの範囲で参照光が反射されつづければ、その前半と後半で異なる分域でのＺ走査、すなわち被検査物１０９の深層方向のＺ軸に対し、異なる範囲で深層の構造を反映する反射光分布図を測定できるものとなり従来にない特徴がある。
【００２４】
前記回転体８は高速回転しているので、反射体７１が角度θｐの範囲で参照光を反射しつづけ、かつ光遅延を発生する変移が生じる結果、回転方向により紫方または赤方に光ドップラー周波数シフトが生じる。このドップラー周波数シフトは前記２方向への回帰反射に際してもシフト周波数こそ異なるものの回転に応じて、前記ヘテロダイン干渉ビート信号が得られる。このシフト周波数が回転の前半と後半で異なることを利用して、ビート周波数の弁別によりＺ走査位置を識別して被検査物の深層からの反射光分布を画像化できる特徴もある。
【００２５】
前記２分割した他方の物体光は、物体光用光ファイバー１０と平行光束用レンズ１１を伝搬して、面走査機構（Ｘ軸走査ミラー１２、Ｙ軸走査ミラー１３）、対物レンズ１４を経て被検査物１０９に入射し、その反射光は同一光路を回帰反射し、ハーフミラー３を経て前記回帰反射してきた参照光と合波し、ファイバー結合用レンズ１５により集光され、光検出器１６でヘテロダイン干渉信号を発生し、電気信号となる。
【００２６】
この面走査機構は、例えばガルバノメーターにより同期駆動して、該ミラーの反射により物体光をＸ−Ｙ平面上に走査する。
【００２７】
低コヒーレンス光源を用いているので、固定ミラー９１，９２までの参照光路長と被検査物１０９までの光路長が一致するときに干渉ビート信号が発生し、光検出器１６より、ＰＣ（パーソナルコンピュータ）システム１７に送られる。ＰＣシステム１７では、ヘテロダイン干渉信号の周波数弁別、信号増幅、３次元画像化処理などを行い、表示装置１８に被検査物１０９の断層画像を表示する。
【００２８】
反射体７１は、第１のミラー７ａと第２のミラー７ｂとで表面反射ミラーを直角に配置するものでも、直角プリズムや３面反射のコーナーキューブリフレクター、リトロリフレクター、キャッツアイ等でも構わない。しかし、回転体８の回転には機械的な面ぶれが必ず生じるので、物体回帰光との安定な干渉信号を得るためには、面ぶれに影響されず安定に回帰反射する３面反射のコーナーキューブリフレクターやリトロリフレクターが実用的である。
【００２９】
また、物体光の光路途中にハーフミラーを設置し、被検査物１０９からの表面実態をＣＣＤ素子などの撮像装置にて映像化することにより、被検査物に対する検査光軸の位置合わせを容易に行うことができることは明らかである。
【００３０】
さらに、従来は固定ミラーは１個であり、走査開始位置の調整で１つの観測域のみに限られていたが、本発明では、複数の固定ミラーとそれらの調整機構９１ａ，９２ａを設置することにより、任意に二つ以上の観測域を同時的に走査観測の対象域とすることが可能となる。
【００３１】
本発明の原理を、図２及び図３を用いて説明する。
【００３２】
図２は本発明の多重連光遅延発生機構の幾何学的説明図であり、図３は本発明の上記機構の回転角度対光遅延距離のグラフである。
【００３３】
図２において、６ｐは参照光の入射光および回帰反射光、Ｏは回転中心、ＰＶは円周の参照光の入射点Ｐにおける法線、ＯＨは入射光に平行な線分、ｄは反射体７１の反射ミラーの合わせ頂点の回転半径、ｒはその回転軌跡をそれぞれ表す。
【００３４】
まず、反射体７１の該頂点が回転開始角度θ１の位置にあるとき、反射光６Ａが発生し始めるとする。回転体８の回転に伴い漸次遅延反射光が発生し、入射光６ｐが該頂点の位置を越え第２のミラー７ｂ′で反射すると、反射光は図の点線で示す遅延反射光６Ｂを発生し、回転とともに漸次遅延反射光を発生し、回転終端角度θ２で終わるとする。この間、遅延距離は、
Ｚ（θ）＝２ｄ（ｃｏｓθ１−ｃｏｓθ２） …（１）
と計算される。因子２は固定ミラーで回帰反射して２度遅延を経験するためである。例えば、ｄ＝３０ｍｍの場合の遅延距離を図３に示す。図３で中心角度θ_Oは、該頂点が図２のＰ点に来たときを示す。例えば、回転角度θ１（＝３７．５度）−θ_O（＝４５度）で約５ｍｍ、次の角度θ_O（＝４５度）−θ２（＝５１．５度）でさらに約５ｍｍの遅延が得られることが分かる。
【００３５】
反射光６Ａ，６Ｂの先に図１で示した回帰反射ミラー９１，９２を、被検査物１０９の深層の観測したい分域の走査開始位置に合致するように配置することで、空気中で約５ｍｍの深部の断層をそれぞれ独立に多重連に観測できる。被検査物１０９の深層方向Ｚ軸の異なる観測域を観測する代わりに、同一観測域をＸ軸走査で観測すれば、従来の観測速度の２倍の速さで走査して断層画像が取得できる。
【００３６】
例えば、その頂角の回転半径をｄ＝３０ｍｍとした上記の例で、コーナーキューブリトロリフレクタープリズムの大きさが入射面直径１０ｍｍ、該頂点までの高さ８．６ｍｍの既製品を用いると、回転体８の円周に２０度毎に１８個を配置できる。回転体の回転数を約３３００ｒｐｍとすると、Ｚ走査は毎秒２０００本、すなわち２ＫＨｚの走査速度を実現できる。例えば、断層画像の画素数を（Ｘ軸１００）×（Ｚ軸１００）とすると、毎秒当たり２０枚の断層画像が取得でき、３次元断層画像を容易に高速に実時間で観測できるものである。従来の方法では、該プリズム数は上記の半径では４個程度に限られ、走査速度は毎秒２２０本程度に限られたが、本実施例では９倍速が実現される。
【００３７】
また、本実施例では、上記約５ｍｍの光遅延距離は、回転角に対しほぼ線型に発生し、その線型率は９５％以上が得られる。さらに、回転当たりの反射光の有効率は約７０％と高効率である。
【００３８】
このような光遅延動作において生じるドップラーシフト周波数は、簡単な計算から、
ｆ_D（θ）＝２（ｄ／λ₀）（１−ｃｏｓθ）（３６０／θ）ｆｖ …（２）
で与えられる。ここで、λ₀は低コヒーレンス光源の中心波長、ｆｖは回転体の回転周波数である。上記の実施例では、ｆ_D（θ）＝１６．４〜２１．８ＭＨｚと変化するので、中心周波数１９ＭＨｚ、バンド幅約５ＭＨｚのビート信号増幅器を用いればよい。
【００３９】
本発明の原理は、従来入射方向に平行な円周の接線成分のみの遅延光発生に注目して反射体７１を配置したのに対し、より一般的に円周の法線に対する光の入射角を任意に設定して参照光６ｐに対し、反射体７１の描く円弧（θｐの範囲）の参照光軸への射影成分が光遅延を発生することによるもので、所望の光遅延距離をより高速で、さらに回転当たりの反射光を高効率で利用できるようにして、かつ次の実施例で示すように複数の遅延光の発生をも可能としたものである。
【００４０】
図４は本発明の３重連光遅延機構を組み込んだ多重連映像化光コヒーレンストモグラフィー装置の実施例を示す図である。
この図において、９５は回帰反射用のハーフミラー、９５ａはその位置調整機構であり、他の構成素子は図１と同じであるのでその説明は省略する。
【００４１】
上記回帰反射用ハーフミラー９５は、反射体７１と固定ミラー９１の間の適宜な位置に配備することによって、固定ミラー９１による回帰反射光より先に、すなわち短い光路長でのあらたな遅延光６Ｅの発生ができ、固定ミラー９１および９２による参照遅延光の発生に加え、３重連の遅延光を発生し３重連映像化光コヒーレンストモグラフィーを実現できる特徴がある。
【００４２】
図５は本発明の４重連光遅延機構を組み込んだ多重連映像化光コヒーレンストモグラフィー装置の実施例を示す図である。
【００４３】
この図において、７２は反射体７１とは異なる角度範囲で遅延光を発生する反射体、９３，９４は調整機構付きの回帰反射ミラー、１９は参照光分岐ハーフミラー、２０はミラー、６Ｃ，６Ｄはそれぞれ回帰反射光であり、他の構成素子は図１と同じであるのでその説明は省略する。
【００４４】
本実施例では、参照光を分岐ハーフミラー１９で２分割し、一方は、例えば図３に示すのと同じ角度範囲θｐで遅延光を発生させる。他方の参照光は、異なる角度範囲θｓあるいは同一角度範囲θｐで遅延光を発生させることができる。すなわち、Ｚ方向の４つの分域をそれぞれ独立、かつ同時にＺ走査を可能ならしめる。さらに、回帰反射ミラー９３，９４の位置を調整して、回帰反射光６Ａ，６Ｂ，６Ｃ，６Ｄを全て同じＺ方向の分域を走査する場合には、従来の約１８倍速でのＺ走査を実現できる。上記の実施例の数値では、実に４ＫＨｚでのＺ走査を可能とする多重連映像化光コヒーレンストモグラフィーを実現するものである。参照光をさらに分岐すれば、５４倍速、１２ＫＨｚでの映像化を実現できる。
【００４５】
図６は大深度用回転反射体を組み込んだ多重連映像化光コヒーレンストモグラフィー装置の実施例を示す図である。
【００４６】
この図において、７Ｘは大深度用反射体、角ＰＯＱは大深度反射体の回転角度Ｄ、２１は回帰反射ミラー、２１ａは回帰反射体位置調整機構、７１′，７２′，７３′…は小深度用反射体列であり、他の構成素子は図１と同じであるのでその説明は省略する。
【００４７】
参照光の入射方向に平行にかつ円周の接線成分を利用して遅延光を発生する方法は、従来技術として開示されているが、他の反射体と光軸が抵触しないように広角度を必要とする。本実施例では、そのような大深度用反射体７Ｘを該参照光の入射光軸と直交する法線の立つ円周の一点Ｈに配置し、光遅延可能な角度を広角度Ｄにする。他方、回転体８の他の円周部に図３の実施例で説明したような反射体７１を、例えば上記のように２０度ごとに複数配列する。大深度用反射体７Ｘによる取得断層画像は、回転当たりの個数を１個あるいは２個とすると必然的に画素数が限られ粗い画像となる。
【００４８】
しかし、反面大深度の光遅延反射体７Ｘでは大きい領域が観測できる。この大画面の断層像をあらかじめ参照して、小深度用反射体７１′，７２′，７３′…で観測できる領域を特定して固定ミラーを調整し、所望の領域を正確に位置決めして解像度の高い断層画像を観測できるものとなる。
【００４９】
上記のように、本発明による多重連映像化光コヒーレンストモグラフィー装置によれば、ハーフミラー３からの参照光は、回転角度の異なる領域で２方向に遅延反射を連続して発生でき、異なる観測領域の同時観測や同一領域の８倍速走査などが実現され、さらには複数に参照光を分岐して、それに対応してハーフミラーを含む複数の固定ミラー９１，９２，…を配置することで多重連映像化を可能とする。これらはいずれも従来の光コヒーレンストモグラフィーにおける高速光遅延発生法では実現できなかったもので、Ｚ方向の走査を数十倍速にまで増速可能とし、かつ同時に異なる領域を特定して多重に連続して断層像を観測できる装置を実現したものである。
【００５０】
また、本発明によれば、参照光の有効効率を従来比で４倍以上も高めることができ、高ＳＮ比でのヘテロダインビート信号の取得が可能となり、高精度な断層情報を超高速に、且つ任意の複数領域を広範囲に選択して取込み表示することが可能となるので、例えば、眼科疾患診断装置に応用すれば、従来、眼科医の勘と経験に頼っていた、眼底の診断や硝子体の診断を、高速、広範囲に独立な分域で、且つ同時に容易に行うことができ、早期治療による治療が期待でき、患者の負担を大幅に軽減できるようになる。
【００５１】
さらには、本発明の多重連高速遅延法を胃カメラでの断層観測に適用すれば、生体などの動的被検査物を揺動などの影響を排除して瞬時に観測可能とする特徴を有するものとなる。
【００５２】
本発明の多重連映像化光コヒーレンストモグラフィー装置は、高精度な断層情報を高速、広範囲で独立な分域で、さらには被検査物の揺動の影響などを排除して、多重に且つ連続して取り込み表示することができ、特に眼科疾患診断装置をはじめとする各種の医療用診断装置に好適である。
【００５３】
なお、本発明は上記実施例に限定されるものではなく、本発明の趣旨に基づいて種々の変形が可能であり、これらを本発明の範囲から排除するものではない。
【００５４】
【発明の効果】
以上、詳細に説明したように、本発明によれば、以下のような効果を奏することができる。
【００５５】
（Ａ）奥行き方向（Ｚ方向）の走査速度が速く、同時に多重に連続して断層画像を映像化できる。
【００５６】
（Ｂ）より具体的には、ハーフミラーからの参照光は、回転角度の異なる領域で２方向に遅延反射を連続して発生でき、異なる観測領域の同時観測や同一領域の８倍速走査などが実現され、さらには複数に参照光を分岐し、それに対応してハーフミラーを含む複数の固定ミラーを配置することで多重連映像化を可能とする。これらはいずれも従来の光コヒーレンストモグラフィーにおける高速光遅延発生法では実現できなかったもので、Ｚ方向の走査を数十倍速にまで増速可能とし、かつ同時に異なる領域を特定して多重に連続して断層像を観測できる装置を実現することができる。
【００５７】
（Ｃ）また、参照光の有効効率を従来比で４倍以上も高めることができ、高ＳＮ比でのヘテロダインビート信号の取得が可能となり、高精度な断層情報を超高速且つ任意の複数領域を広範囲に選択して取込み表示することが可能となるので、例えば、眼科疾患診断装置に応用すれば、従来、眼科医の勘と経験に頼っていた、眼底の診断や硝子体の診断を、高速、広範囲に独立な分域で、且つ同時に容易に行うことができ、早期治療による治療が期待でき、患者の負担を大幅に軽減できるようになる。
【００５８】
（Ｄ）さらに、多重連高速遅延法を胃カメラでの断層観測に適用すれば、生体などの動的被検査物を揺動などの影響を排除して瞬時に観測可能とする特徴を有するものとなる。
【図面の簡単な説明】
【図１】本発明の実施例を示す多重連映像化光コヒーレンストモグラフィー装置の構成図である。
【図２】本発明の多重連光遅延発生機構の幾何学的説明図である。
【図３】図２の多重連光遅延発生機構の回転角度対光遅延距離のグラフである。
【図４】本発明の３重連光遅延機構を組み込んだ多重連映像化光コヒーレンストモグラフィー装置の実施例を示す図である。
【図５】本発明の４重連光遅延機構を組み込んだ多重連映像化光コヒーレンストモグラフィー装置の実施例を示す図である。
【図６】大深度用回転反射体を組み込んだ多重連映像化光コヒーレンストモグラフィー装置の実施例を示す図である。
【図７】従来の光コヒーレンストモグラフィー装置の構成図である。
【符号の説明】
１低コヒーレンス光源（例えばＳＬＤ光源）
２，１５ファイバー結合用レンズ
３ハーフミラー（２分割用ハーフミラー）
４参照光用光ファイバー
５，１１出射光平行光束用レンズ
６Ａ，６Ｂ，６Ｃ，６Ｄ，６Ｅ回帰反射遅延光
６ｐ光遅延機構への入射光及び回帰反射光
７ａ第１のミラー
７ａ′ 所定の回転角θｐ回転後の第１のミラー位置
７ｂ第２のミラー
７ｂ′ 所定の回転角θｐ回転後の第２のミラー位置
７Ｘ大深度用反射体
８回転体
１０物体光用光ファイバー
１２Ｘ軸方向への面走査用ミラー
１３Ｙ軸方向への面走査用ミラー
１４対物レンズ
１６光検出器
１７ＰＣ（パーソナルコンピュータ）システム
１８表示装置
１９参照光分岐ハーフミラー
２０ミラー
２１回帰反射ミラー
２１ａ回帰反射体位置調整機構
７１光遅延機構反射体
７１′，７２′，７３′… 小深度用反射体列
７２異なる角度範囲で遅延光を発生する反射体
９１第１の固定ミラー
９２第２の固定ミラー
９１ａ，９２ａ第１、第２の固定ミラーの光軸方向へのスキャン開始位置調整機構
９３，９４調整機構付きの回帰反射ミラー
９５回帰反射用のハーフミラー
９５ａ回帰反射用のハーフミラーの位置調整機構
１０９被検査物
Ｏ回転中心
ＰＶ円周の参照光の入射点Ｐにおける法線
ＯＨ入射光に平行な線分
ｄ反射体の反射ミラーの合わせ頂点の回転半径
ｒ回転軌跡
θ１回転開始角度
θ２回転終端角度
θｐ所定の回転角
θｓ異なる角度範囲[0001]
BACKGROUND OF THE INVENTION
The present invention ,light The present invention relates to a coherence tomography apparatus.
[0002]
[Prior art]
As a method of generating high-speed optical delay in conventional optical coherence tomography, the path of the reference optical path is a half mirror → the first mirror that rotates at high speed → the second mirror → the fixed mirror → the second mirror → the first mirror → the half mirror. And a method of delay-reflecting the optical path is known.
[0003]
FIG. 7 is a schematic configuration diagram of a conventional optical coherence tomography apparatus.
[0004]
In this figure, 101 is a low coherence light source (for example, SLD (super luminescence diode) light source), 102 is a half mirror (half mirror for splitting), 103 is a rotating body, 104 is a first mirror 104A and a second mirror. 104B is an optical delay reflector, 105 is a fixed mirror, 106 and 107 are mirrors, 109 is an inspection object, and 110 is a photodetector.
[0005]
[Problems to be solved by the invention]
However, the high speed in the conventional optical coherence tomography described above light In the delay method, instead of increasing the scanning distance in the depth direction (Z direction), it is not possible to increase the number of mirrors arranged on the circumference of the rotating body, and therefore it is not possible to efficiently acquire many tomographic images per rotation. There were drawbacks.
[0006]
In the conventional method, as shown in FIG. 7, the mirror diagonal line is aligned with the center line AB perpendicular to the tangent line of the rotating body, and the incident light is changed from the first mirror 104A → the second mirror 104B → the fixed mirror 105. The reflection delay when the mirror is incident on the second mirror → the first mirror due to the rotation is not used.
[0007]
Moreover, in a moving object such as a living body, it is necessary to perform scanning in the Z direction as fast as possible. However, since the number of mechanical rotations is limited, a plurality of mirrors are arranged and acquired tomographic images per second. Increasing the number cannot be handled by the conventional method described above.
[0008]
Furthermore, a method of constructing tomography by continuously multiplexing different parts or consecutive parts in one rotation has not been disclosed at all in other means as well as the above conventional method.
[0009]
In view of the above situation, the present invention has a high scanning speed in the depth direction (Z direction), and can simultaneously tomographically image tomographic images. ,light An object is to provide a coherence tomography apparatus.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides
[ 1 In an optical coherence tomography apparatus, a low coherence light source, a half mirror for splitting the light from the low coherence light source into an object light and a reference light to be inspected into two parts, and the reference light in two directions depending on the rotation angle An optical delay mechanism that delays by a rotating reflector in which reflectors are arranged so that reflection is continuously generated, and a plurality of fixed mirrors that reflect and return reflections in multiple directions from the optical delay mechanism at arbitrary optical distances, respectively. And an interference including a heterodyne interference beat signal synthesized by the half mirror for bisection that combines the object light returning from the inspection object and the reference light returning from the optical delay mechanism, and the half mirror for bisection And a photodetector for detecting light.
[0011]
[ 2 In an optical coherence tomography apparatus, a low coherence light source, a half mirror for splitting the light from the low coherence light source into an object light and a reference light to be inspected into two parts, and the reference light in two directions depending on the rotation angle Includes a light delay mechanism that delays by a rotating reflector in which reflectors are arranged so that reflection is continuously generated, and a half mirror that reflects and returns reflections in multiple directions from the light delay mechanism at arbitrary optical distances. A plurality of fixed mirrors, a surface scanning mechanism that scans the surface of the inspection object with the object light, an objective lens, the object light that returns from the inspection object, and the reference light that returns from the optical delay mechanism are combined. And a photodetector for detecting interference light including a heterodyne interference beat signal synthesized by the half mirror for splitting. To.
[0012]
[ 3 〕the above〔 1 ] Or [ 2 In the optical coherence tomography apparatus described above, the optical delay mechanism has a reflector disposed radially on a rotating body that rotates at a high speed, and the reflecting body has an appropriate incident angle with respect to a normal line of the circumference of the rotating body. So that the incident light is recursively reflected in the predetermined rotation angle range, the light is incident on the first mirror, reflected by the second mirror, and recursively reflected by the first fixed mirror set to a predetermined optical path length. In the rotation angle range, the first mirror and the second mirror are incident on the second mirror, reflected by the first mirror, and recursively reflected by the second fixed mirror separately set to a predetermined optical path length. A plurality of pairs of mirrors are arranged on the surface of the rotating body, and a plurality of fixed mirrors including half mirrors are arranged at predetermined positions.
[0013]
[ 4 〕the above〔 3 In the optical coherence tomography apparatus described above, the optical delay mechanism is rotated at a high speed so that the reference light that has passed through the two-part mirror is divided into two by a half mirror and each of the two parts is used as reference light. A reflector is arranged radially on the body, and the reflector has a predetermined angle so that each reference light incident at an appropriate incident angle with respect to the normal line of the circumference of the rotating body is independently reflected and reflected. In the range, it is incident on the first mirror, is reflected by the second mirror, is reflected by the first fixed mirror set to a predetermined optical path length, and is incident on the second mirror in the next rotation angle range. A plurality of pairs of each of the first mirror and the second mirror are arranged on the surface of the rotating body so as to be reflected by a second fixed mirror that is reflected by one mirror and separately set to a predetermined optical path length. Multiple fixed mirrors in place It is characterized in.
[0014]
[ 5 〕the above〔 1 ] To [ 4 In the optical coherence tomography device according to any one of the above, the plurality of fixed mirrors including the half mirror are each a scan start position adjustment mirror, and are made to coincide with the Z direction that is the depth direction of the optical axis in the object light, The optical path length can be independently set and adjusted so that scanning can be started from desired points in different depth directions.
[0015]
[ 6 〕the above〔 3 In the optical coherence tomography apparatus described above, a pair of reflectors composed of a first mirror and a second mirror of the optical delay mechanism has a circumference with a normal line perpendicular to the incident optical axis of the reference light. At least one pair of reflectors arranged at one point and capable of scanning in the deep Z direction are provided, and has a role of specifying scanning positions of the other reflectors.
[0016]
[ 7 〕the above〔 1 ] To [ 6 In the optical coherence tomography device according to any one of claims 1 to 3, a lens system that is fiber-coupled through a half-dividing half mirror that divides the reference light and object light into two, and object light that transmits light from the lens system And an optical fiber for reference light, and a lens system for making each outgoing light from these optical fibers approximately parallel light beams.
[0017]
[ 8 〕the above〔 2 In the optical coherence tomography apparatus described above, the surface scanning mechanism includes an X-axis scanning mirror and a Y-axis scanning mirror, and the object is irradiated with object light on the inspection object at a predetermined position corresponding to the plurality of delayed reference lights. It is characterized in that the surface (XY) of the inspection object is scanned at high speed.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0019]
FIG. 1 is a configuration diagram of a multiplex continuous imaging optical coherence tomography apparatus showing an embodiment of the present invention.
[0020]
In this figure, 1 is a low coherence light source (for example, an SLD (super luminescence diode) light source), 2 is a fiber coupling lens, 3 is a half mirror (half mirror for splitting), 4 is an optical fiber for reference light, 5 and 11 Is a lens for a parallel beam of outgoing light, 6p is incident light and return reflected light to the optical delay mechanism, 71 is an optical delay mechanism reflector made up of the first mirror 7a and the second mirror 7b, and 7a 'is a predetermined rotation angle. Similarly, the first mirror position after rotation by θp, 7b ′ is also the second mirror position after rotation, 8 is a rotating body, 91 and 92 are first and second fixed mirrors, 91a and 92a are first and second mirrors, respectively. 2 is a mechanism for adjusting the scanning start position in the optical axis direction of the fixed mirrors 91 and 92, 6A and 6B are respectively return reflection delayed light, 10 is an optical fiber for object light, and 12 is a mirror for surface scanning in the X-axis direction. Chromatography, 13 mirror surface scanning in the Y-axis direction, 14 is an objective lens. 15 is For fiber coupling A lens, 16 is a photodetector, 17 is a PC (personal computer) system, 18 is a display device, and 109 is an inspection object.
[0021]
As described above, the optical delay mechanism is composed of the reflector 71 and the rotator 8, and the reflector 71 radiates on the rotator 8 rotating at high speed and at an appropriate angle with respect to the normal line of the circumference of the rotator 8. A plurality of pairs of reflectors 71 are arranged by the first mirror 7a and the second mirror 7b so as to reflect the incident reference light in parallel.
[0022]
For example, a light wave from a low coherence light source 1 such as an SLD is divided into a reference beam and an object beam by a half mirror 3 through a fiber coupling lens 2. The reference light propagates through the optical fiber 4 and the parallel light beam lens 5 and reaches the reflector 71 of the optical delay mechanism. When the reflector 71 is at the angle indicated by the solid line, the reference light is reflected by the first mirror 7a and the second mirror 7b and travels in the first direction, and is reflected from the first fixed mirror 91 on the same optical path. It returns, and with the rotation of the reflector 71, it obtains a predetermined optical delay length and returns to the half mirror 3. When the incident position of the reference light exceeds the alignment boundary between the first mirror 7a and the second mirror 7b by this rotation, the reference light is reflected by the second mirror 7b ', the first mirror 7a', Two fixed mirrors (mirrors with a scan start position adjusting mechanism) 92 are reflected in the second direction. That is, the incident reference light 6p is reflected in two directions according to the rotation angle.
[0023]
With such an optical delay mechanism, reflected light can be formed in two directions, and the first rotational reflection delay Light 6A is predetermined light delay The second recursive reflection when Z scanning over a long delay The light 6B is inspected in the same region as the first fixed mirror 91 according to the position of the second fixed mirror 92. 109 It is possible to perform Z scanning in the deep layer or Z scanning in different domains. Both mirrors 7a, 7b If the reference light continues to be reflected within the range of the rotation angle, for example, θp, Z scanning in different domains in the first half and the second half, that is, the inspection object 109 With respect to the Z axis in the deep layer direction, a reflected light distribution diagram reflecting the structure of the deep layer can be measured in a different range, and there is an unprecedented feature.
[0024]
Since the rotator 8 rotates at a high speed, the reflector 71 continues to reflect the reference light in the range of the angle θp, and as a result of a transition that generates an optical delay, the optical Doppler is violet or red depending on the rotation direction. A frequency shift occurs. The Doppler frequency shift can be obtained in the heterodyne interference beat signal in response to the rotation of the two different directions, even though the shift frequency is different. By utilizing the fact that the shift frequency is different between the first half and the second half of the rotation, there is also a feature that the reflected light distribution from the deep layer of the inspection object can be imaged by discriminating the Z scanning position by discriminating the beat frequency.
[0025]
The other object light divided into two propagates through the optical fiber 10 for object light and the lens 11 for parallel light flux, and is inspected through the surface scanning mechanism (X-axis scanning mirror 12 and Y-axis scanning mirror 13) and the objective lens 14. The incident light is incident on the object 109, the reflected light is recursively reflected along the same optical path, and is combined with the reference light that has been recursively reflected through the half mirror 3, For fiber coupling The light is condensed by the lens 15 and a heterodyne interference signal is generated by the photodetector 16 to be an electric signal.
[0026]
This surface scanning mechanism is synchronously driven by, for example, a galvanometer, and scans object light on the XY plane by reflection of the mirror.
[0027]
Since a low coherence light source is used, an interference beat signal is generated when the reference optical path length to the fixed mirrors 91 and 92 and the optical path length to the inspection object 109 coincide with each other. ) Sent to system 17. The PC system 17 performs heterodyne interference signal frequency discrimination, signal amplification, three-dimensional imaging processing, and the like, and displays a tomographic image of the inspection object 109 on the display device 18.
[0028]
The reflector 71 may be a first mirror 7a and a second mirror 7b in which surface reflection mirrors are arranged at right angles, or a right-angle prism, a three-surface reflection corner cube reflector, a retro reflector, a cat's eye, or the like. However, since the mechanical surface shake always occurs in the rotation of the rotating body 8, in order to obtain a stable interference signal with the object return light, the corner of the three-surface reflection that stably returns and is not affected by the surface shake. Cubri reflectors and retro reflectors are practical.
[0029]
In addition, a half mirror is installed in the middle of the optical path of the object light, and the surface actual condition from the inspection object 109 is visualized by an imaging device such as a CCD element, so that the inspection optical axis can be easily aligned with the inspection object. Obviously it can be done.
[0030]
Further, conventionally, there is only one fixed mirror, and the adjustment of the scan start position is limited to only one observation area. However, in the present invention, a plurality of fixed mirrors and their adjustment mechanisms 91a and 92a are installed. Thus, it is possible to arbitrarily set two or more observation areas as scanning observation areas simultaneously.
[0031]
The principle of the present invention will be described with reference to FIGS.
[0032]
FIG. 2 is a geometrical explanatory diagram of the multiple light delay generation mechanism of the present invention, and FIG. 3 is a graph of the rotation angle versus the light delay distance of the mechanism of the present invention.
[0033]
In FIG. 2, 6p is the incident light of the reference light and the retroreflected light, O is the rotation center, PV is the normal line at the incident point P of the circumferential reference light, OH is a line segment parallel to the incident light, and d is the reflector. The rotation radius of the apex of the reflection mirrors 71 and r represents the rotation trajectory.
[0034]
First, it is assumed that the reflected light 6A starts to be generated when the vertex of the reflector 71 is at the rotation start angle θ1. As the rotating body 8 rotates, delayed reflected light is gradually generated, and when the incident light 6p is reflected by the second mirror 7b 'beyond the position of the apex, the reflected light generates delayed reflected light 6B indicated by a dotted line in the figure. Suppose that the delayed reflected light is gradually generated with the rotation and ends at the rotation end angle θ2. During this time, the delay distance is
Z (θ) = 2d (cos θ1−cos θ2) (1)
Is calculated. Factor 2 is to experience a delay of 2 degrees by retroreflection with a fixed mirror. For example, the delay distance in the case of d = 30 mm is shown in FIG. In FIG. 3, the center angle θ _O Indicates when the vertex has reached point P in FIG. For example, the rotation angle θ1 (= 37.5 degrees) −θ _O (= 45 degrees) about 5mm, next angle θ _O It can be seen that a delay of about 5 mm can be obtained at (= 45 degrees) −θ2 (= 51.5 degrees).
[0035]
By arranging the retroreflective mirrors 91 and 92 shown in FIG. 1 ahead of the reflected light 6A and 6B so as to coincide with the scanning start position of the region to be observed in the deep layer of the inspection object 109, the reflection reflection mirrors 91 and 92 are reduced in the air. 5 mm deep faults can be observed independently in multiple series. If the same observation area is observed by X-axis scanning instead of observing observation areas with different Z-axis in the depth direction of the inspection object 109, a tomographic image can be acquired by scanning at twice the conventional observation speed. .
[0036]
For example, in the above example in which the apex angle has a radius of rotation of d = 30 mm, the corner cube retro-reflector prism has an incident surface diameter of 10 mm and a height of 8.6 mm to the apex. 18 pieces can be arranged on the circumference of the body 8 every 20 degrees. If the rotational speed of the rotating body is about 3300 rpm, Z scanning can be performed at 2000 lines per second, that is, a scanning speed of 2 KHz. For example, if the number of pixels of a tomographic image is (X axis 100) × (Z axis 100), 20 tomographic images can be acquired per second, and a three-dimensional tomographic image can be easily observed at high speed in real time. . In the conventional method, the number of prisms is limited to about 4 at the above radius, and the scanning speed is limited to about 220 per second. In this embodiment, 9 times speed is realized.
[0037]
In the present embodiment, the optical delay distance of about 5 mm occurs almost linearly with respect to the rotation angle, and the linearity ratio is 95% or more. Furthermore, the effective rate of reflected light per rotation is as high as about 70%.
[0038]
The Doppler shift frequency generated in such an optical delay operation can be calculated from a simple calculation,
f _D (Θ) = 2 (d / λ ₀ ) (1-cos θ) (360 / θ) fv (2)
Given in. Where λ ₀ Is the center wavelength of the low coherence light source, and fv is the rotational frequency of the rotating body. In the above example, f _D Since (θ) = 16.4 to 21.8 MHz, a beat signal amplifier having a center frequency of 19 MHz and a bandwidth of about 5 MHz may be used.
[0039]
The principle of the present invention is that the reflector 71 is arranged focusing attention on the generation of delayed light of only the circumferential tangential component parallel to the incident direction, but more generally the incident angle of light with respect to the circumferential normal. Is arbitrarily set, and the projection component of the arc (the range of θp) drawn by the reflector 71 onto the reference optical axis generates an optical delay with respect to the reference light 6p. Thus, the reflected light per rotation can be used with high efficiency, and a plurality of delayed lights can be generated as shown in the next embodiment.
[0040]
FIG. 4 is a diagram showing an embodiment of a multiple continuous imaging optical coherence tomography apparatus incorporating the triple continuous optical delay mechanism of the present invention.
In this figure, 95 is a half mirror for retroreflection, 95a is its position adjusting mechanism, and the other components are the same as in FIG.
[0041]
The regressive reflection half mirror 95 is disposed at an appropriate position between the reflector 71 and the fixed mirror 91, Fixed Prior to the return reflected light by the mirror 91, that is, a new delayed light 6E can be generated with a short optical path length, in addition to the generation of the reference delayed light by the fixed mirrors 91 and 92, triple delayed light is generated 3 It has the feature that can realize double image visualization optical coherence tomography.
[0042]
FIG. 5 is a diagram showing an embodiment of a multiple continuous imaging optical coherence tomography apparatus incorporating the quadruple optical delay mechanism of the present invention.
[0043]
In this figure, 72 is a reflector that generates delayed light in an angular range different from that of the reflector 71, 93 and 94 are retroreflective mirrors with an adjusting mechanism, 19 is a reference beam branching half mirror, 20 is a mirror, and 6C and 6D. Are regressed reflected light, and the other components are the same as in FIG.
[0044]
In this embodiment, the reference light is divided into two by the branch half mirror 19, and one of them generates delayed light in the same angular range θp as shown in FIG. 3, for example. The other reference light can generate delayed light in different angle ranges θs or the same angle range θp. In other words, the four domains in the Z direction are made independent and simultaneously capable of Z scanning. Further, when the positions of the return reflection mirrors 93 and 94 are adjusted and the return reflection lights 6A, 6B, 6C, and 6D are all scanned in the same domain in the Z direction, the Z scan at about 18 times the conventional speed is performed. realizable. With the numerical values of the above-described embodiments, multiple continuous imaging optical coherence tomography that enables Z scanning at 4 KHz is realized. If the reference light is further branched, 54 × speed imaging at 12 KHz can be realized.
[0045]
FIG. 6 is a diagram showing an embodiment of a multiple continuous imaging optical coherence tomography apparatus incorporating a deep-depth rotating reflector.
[0046]
In this figure, 7X is a reflector for large depth, angle POQ is a rotation angle D of the deep reflector, 21 is a retroreflective mirror, 21a is a retroreflector position adjusting mechanism, 71 ', 72', 73 '... are small This is a depth reflector row, and the other components are the same as in FIG.
[0047]
Although a method of generating delayed light using a tangential component of the circumference parallel to the incident direction of the reference light has been disclosed as a prior art, a wide angle should be set so that the optical axis does not conflict with other reflectors. I need. In the present embodiment, such a large-depth reflector 7X is arranged at one point H on the circumference where the normal line is perpendicular to the incident optical axis of the reference light, and the angle capable of optical delay is set to the wide angle D. On the other hand, a plurality of reflectors 71 as described in the embodiment of FIG. 3 are arranged on the other circumferential portion of the rotating body 8 every 20 degrees as described above, for example. An acquired tomographic image by the reflector 7X for large depths is necessarily a coarse image with a limited number of pixels if the number per rotation is one or two.
[0048]
However, a large area can be observed on the optical delay reflector 7X having a large depth. With reference to this large-screen tomographic image in advance, the area that can be observed by the small-depth reflectors 71 ', 72', 73 ', ... is specified, the fixed mirror is adjusted, the desired area is accurately positioned, and the resolution is High tomographic images can be observed.
[0049]
As described above, multiple continuous imaging optical coherence tomography according to the present invention ー dress According to the arrangement, the reference light from the half mirror 3 can continuously generate delayed reflections in two directions in regions with different rotation angles, and simultaneous observation of different observation regions, 8 × speed scanning of the same region, and the like are realized. Further, a plurality of fixed mirrors 91, 92,... Including a half mirror are arranged correspondingly to a plurality of reference beams, thereby enabling multiple continuous imaging. None of these can be realized by the high-speed optical delay generation method in the conventional optical coherence tomography, and the scanning in the Z direction can be increased up to several tens of times. Sometimes A device capable of observing tomographic images continuously in multiples by specifying different regions is realized.
[0050]
In addition, according to the present invention, the effective efficiency of the reference light can be increased by a factor of 4 or more compared to the conventional one, and it is possible to obtain a heterodyne beat signal with a high SN ratio, High spirit It is possible to select and display various tomographic information at a very high speed and a wide range of arbitrary areas. Reliable diagnosis of the fundus and vitreous body, high speed A wide range of independent domains and Sometimes It can be easily performed, and treatment by early treatment can be expected, and the burden on the patient can be greatly reduced.
[0051]
Furthermore, when the multiple continuous high-speed delay method of the present invention is applied to tomographic observation with a gastric camera, it has the feature that it can observe a dynamic inspected object such as a living body instantaneously without the influence of rocking or the like. It will be a thing.
[0052]
Multiple consecutive imaging optical coherence tomography of the present invention ー dress The position is High spirit High-speed tomographic information can be captured and displayed in multiple, continuous, high-speed, wide-range and independent domains, and also eliminates the influence of the shaking of the test object. It is suitable for various medical diagnostic apparatuses including the first one.
[0053]
In addition, this invention is not limited to the said Example, A various deformation | transformation is possible based on the meaning of this invention, and these are not excluded from the scope of the present invention.
[0054]
【The invention's effect】
As described above in detail, according to the present invention, the following effects can be obtained.
[0055]
(A) The scanning speed in the depth direction (Z direction) is fast, and tomographic images can be visualized simultaneously in a multiplexed manner.
[0056]
(B) More specifically, the reference light from the half mirror can continuously generate delayed reflection in two directions in regions with different rotation angles, and simultaneous observation of different observation regions, 8 × speed scanning of the same region, etc. In addition, a plurality of fixed mirrors including half mirrors are arranged correspondingly to a plurality of reference beams, and multiple continuous images can be formed. None of these can be realized by the high-speed optical delay generation method in the conventional optical coherence tomography, and the scanning in the Z direction can be increased up to several tens of times. Sometimes It is possible to realize an apparatus capable of observing tomographic images continuously in multiples by specifying different regions.
[0057]
(C) In addition, the effective efficiency of the reference light can be increased by more than 4 times compared to the conventional one, and it becomes possible to obtain a heterodyne beat signal with a high SN ratio, High spirit It is possible to select and display a wide range of arbitrary tomographic information at a very high speed, and for example, if it is applied to an ophthalmic disease diagnosis device, it has traditionally relied on the intuition and experience of an ophthalmologist. The diagnosis of the fundus and the vitreous body high speed A wide range of independent domains and Sometimes It can be easily performed, and treatment by early treatment can be expected, and the burden on the patient can be greatly reduced.
[0058]
(D) Further, if the multiple continuous high-speed delay method is applied to tomographic observation with a gastric camera, the dynamic inspected object such as a living body can be observed instantaneously while eliminating the influence of shaking or the like. It becomes.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a multiplex continuous imaging optical coherence tomography apparatus showing an embodiment of the present invention.
FIG. 2 is a geometric explanatory diagram of a multiple light delay generating mechanism of the present invention.
3 is a graph of the rotation angle versus the optical delay distance of the multiple light delay generation mechanism of FIG. 2. FIG.
FIG. 4 is a diagram showing an embodiment of a multiple continuous imaging optical coherence tomography apparatus incorporating the triple continuous optical delay mechanism of the present invention.
FIG. 5 is a diagram showing an embodiment of a multiplex continuous imaging optical coherence tomography apparatus incorporating the quadruple optical delay mechanism of the present invention.
FIG. 6 is a diagram showing an embodiment of a multi-continuous imaging optical coherence tomography apparatus incorporating a deep-depth rotating reflector.
FIG. 7 is a configuration diagram of a conventional optical coherence tomography apparatus.
[Explanation of symbols]
1 Low coherence light source (eg SLD) light source )
2,15 Fiber coupling lens
3 Half mirror (half mirror for 2 split)
4 Optical fiber for reference light
5,11 Lens for outgoing light parallel luminous flux
6A, 6B, 6C, 6D, 6E Regression reflection delay light
6p Incident light and retroreflected light to optical delay mechanism
7a First mirror
7a ′ First mirror position after rotation by a predetermined rotation angle θp
7b Second mirror
7b ′ Second mirror position after rotation by a predetermined rotation angle θp
7X Deep reflector
8 Rotating body
10 Optical fiber for object light
12 Mirror for surface scanning in the X-axis direction
13 Mirror for surface scanning in the Y-axis direction
14 Objective lens
16 photodetectors
17 PC (personal computer) system
18 Display device
19 Reference beam splitting half mirror
20 mirror
21 Retro-reflective mirror
21a Retroreflector position adjustment mechanism
71 Reflector for optical delay mechanism
71 ', 72', 73 '... Reflector row for small depth
72 Reflectors that generate delayed light in different angular ranges
91 First fixed mirror
92 Second fixed mirror
91a, 92a Scan start position adjusting mechanism in the optical axis direction of the first and second fixed mirrors
93,94 Retroreflective mirror with adjustment mechanism
95 Half mirror for retroreflection
95a Half mirror position adjustment mechanism for retroreflection
109 Inspection object
O Center of rotation
Normal at the incident point P of the reference beam of the PV circumference
OH Line segment parallel to incident light
d Rotation radius of reflection vertex of reflector
r Rotation locus
θ1 rotation start angle
θ2 End angle of rotation
θp Predetermined rotation angle
θs Different angle ranges

Claims

(A) a low coherence light source;
(B) a half mirror for splitting that splits light from the low-coherence light source into object light and reference light for the object to be inspected;
(C) an optical delay mechanism that delays the reference light by a rotating reflector in which a reflector is arranged so that reflection continuously occurs in two directions depending on a rotation angle;
(D) a plurality of fixed mirrors that respectively reflect and return reflections from the optical delay mechanism in a plurality of directions at arbitrary optical distances;
(E) the half mirror for two divisions for combining the object light returning from the inspection object and the reference light returning from the optical delay mechanism;
(F) An optical coherence tomography apparatus comprising: a photodetector for detecting interference light including a heterodyne interference beat signal synthesized by the half mirror for splitting into two.

(A) a low coherence light source;
(B) a half mirror for splitting that splits light from the low-coherence light source into object light and reference light for the object to be inspected;
(C) an optical delay mechanism that delays the reference light by a rotating reflector in which a reflector is arranged so that reflection continuously occurs in two directions depending on a rotation angle;
(D) a plurality of fixed mirrors including a half mirror that reflects and returns reflections from the optical delay mechanism in a plurality of directions at arbitrary optical distances;
(E) a surface scanning mechanism that scans the surface of the inspection object with the object light;
(F) an objective lens;
(G) the half mirror for bisection for combining the object light returning from the inspection object and the reference light returning from the optical delay mechanism;
(H) An optical coherence tomography apparatus comprising: a photodetector for detecting interference light including a heterodyne interference beat signal synthesized by the half mirror for splitting into two.

3. The optical coherence tomography apparatus according to claim 1 , wherein the optical delay mechanism includes a reflector disposed radially on a rotating body that rotates at a high speed, and the reflecting body is perpendicular to a circumferential normal of the rotating body. In order to recursively reflect the light incident at an appropriate incident angle, the light is incident on the first mirror in the predetermined rotation angle range, reflected by the second mirror, and returned by the first fixed mirror set to a predetermined optical path length. In the next rotation angle range, each of the first mirrors is reflected so as to be incident on the second mirror, reflected by the first mirror, and recursively reflected by the second fixed mirror set to a predetermined optical path length. An optical coherence tomography apparatus, wherein a plurality of pairs of mirrors and second mirrors are arranged on the surface of the rotating body, and a plurality of fixed mirrors including half mirrors are arranged at predetermined positions.

4. The optical coherence tomography apparatus according to claim 3 , wherein the optical delay mechanism is rotated at high speed so that the reference light that has passed through the two-part mirror is divided into two by a half mirror, and each of the two parts is used as reference light. A reflector is arranged radially on the rotating body, and the reflector is predetermined to reflect the reference light incident at an appropriate incident angle with respect to the normal line of the circumference of the rotating body independently. Is incident on the first mirror, is reflected by the second mirror, is reflected by the first fixed mirror set to a predetermined optical path length, and is incident on the second mirror in the next rotation angle range. A plurality of pairs of the first mirror and the second mirror are arranged on the surface of the rotating body so as to be reflected by the second fixed mirror that is reflected by the first mirror and separately set to a predetermined optical path length. Place multiple fixed mirrors in place Optical coherence tomography apparatus characterized by.

In the optical coherence tomography apparatus according to any one of claims 1 to 4, wherein the plurality of fixed mirrors, including a half mirror are each scan start position adjusting mirrors, Z direction is the depth direction of the optical axis in the object light beam The optical coherence tomography apparatus is characterized in that the optical path length can be independently set and adjusted so as to start scanning from a desired point having a different depth direction.

4. The optical coherence tomography apparatus according to claim 3 , wherein, in the optical delay mechanism, a pair of reflectors each including a first mirror and a second mirror is a circle having a normal line perpendicular to the incident optical axis of the reference light. An optical coherence tomography comprising: at least one pair of reflectors arranged at one point in the circumference and capable of scanning in the deep Z direction, and having a role of specifying scanning positions of the other reflectors apparatus.

The optical coherence tomography apparatus according to any one of claims 1 to 6 , wherein a lens system that is fiber-coupled via a half-dividing half mirror that divides the reference light and the object light into two parts, and light from the lens system An optical coherence tomography apparatus comprising: an optical fiber for object light to be transmitted; an optical fiber for reference light; and a lens system that makes each outgoing light from these optical fibers approximately parallel light beams.

3. The optical coherence tomography apparatus according to claim 2 , wherein the surface scanning mechanism includes an X-axis scanning mirror and a Y-axis scanning mirror, and an object beam with respect to the object to be inspected at a predetermined position corresponding to the plurality of delayed reference beams. An optical coherence tomography apparatus that scans the surface (XY) of the inspection object at high speed.