JP2004113405A - Measuring instrument for characteristics of eye - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring instrument capable of precisely measuring optical characteristics of an eye to be examined having a large quantity of aberration. <P>SOLUTION: This measuring instrument has a first illumination optical system 10 for illuminating the retina of the eye to be examined from a light source part 11, a first photodetection optical system 20A having a first conversion member 22A of a long focus or high sensitivity for converting the reflected light fluxes from the retina of the eye to be examined to a plurality of beams, a second photodetection optical system having a second conversion member of a short focus or low sensitivity for converting the reflected light flux from the retina of the eye to be oxamined, a first detection part 21A and a second photodetection part for detecting the detected luminous fluxes of the first and second photodetection optical systems and a compensation optical part 60 arranged in the first light detection optical system 20A and/or the second detection optical system to compensate the aberration of passed or reflected light flux. The aberration of the eye to be examined, calculated on the basis of the output of the first light detection part 21A and/or the second light detection part, or the output from an anterior eye observation part 40, is compensated by the compensation optical part 60 and the compensated minute aberration is measured precisely. <P>COPYRIGHT: (C)2004,JPO

Description

（ｆ：第１測定部２５Ａのハルトマン板とＣＣＤとの距離）
【００３９】
ここで、波面Ｗをゼルニケ多項式Ｚ_ｉ ^２ｊ−ｉを使った展開であらわすと、
【００４０】
【数２】

【００４１】
上の２つの式と、測定で求められた△ｘ、△ｙ（よって、Ｘ、Ｙも含む）に関する測定値を使って、ゼルニケ係数ｃ_ｉ ^２ｊ−ｉの各値を求めることができる。また、角膜収差を求める場合、前眼部観察部４０の第３受光部４１からの信号に基づき、角膜の傾き及び角膜の高さを計算し、角膜を光学レンズと同様に扱うことにより光学特性が計算される。なお、図１３、図１４に、ゼルニケ多項式についての説明図（１）（２）を示す。
【００４２】
次に、演算部６００は、測定結果が得られたか判断する（Ｓ１０３）。演算部６００は、例えば、収差測定１において取得したハルトマン像の各点像の重心位置が所定の数以上（例えば３分の１以上）取れない、又は各点像のぼけが大きいとき（例えば、無収差時の２０倍以上など）、又は隣接するスポット像と分離できずに検出できない点が所定の数以上ある等の予め定められたひとつ又は複数の適宜の条件に従い判断することができる。ここで、演算部６００は、測定結果が得られた場合（Ｓ１０３）、ステップＳ１０５の処理へ移り、一方、測定結果が得られなかった場合（Ｓ１０３）、図７に示すステップＳ１５１の処理へ進む。
【００４３】
ステップＳ１０５では、演算部６００は、求められた収差を打ち消すような補償光学部６０における補償量Ｍを求め、制御部６１０及び第５駆動部９１４を介して、補償量Ｍに応じた信号（１５）を出力し、可変鏡等の補償光学部６０をゆがませる（Ｓ１０５）。また、補償光学部６０は、信号（１５）に従い適宜の変形手段により変形する。なお、補償光学部６０は、可変鏡以外に、液晶空間光変調器を用いても良い。以下、収差を打ち消すために必要な補償光学部６０における補償量Ｍの算出について説明する。
図８は、可変鏡上の座標（Ｘ_ｍ、Ｙ_ｍ）と光学系の座標（Ｘ、Ｙ）の関係の説明図である。補償する収差をＷｃとし、解析された収差の式が、
【００４４】
【数３】

【００４５】
であるとき、可変鏡上の座標（Ｘ_ｍ、Ｙ_ｍ）と光学系の座標（Ｘ、Ｙ）の関係は、可変鏡への入射角θを考慮して、
【００４６】
【数４】

【００４７】
となる。可変鏡の補償量Ｍは、反射であることから２倍効くことと、目の瞳孔と可変鏡での倍率を考慮する。可変鏡の瞳孔に対する倍率をｋとすると、補償量Ｍは、
【００４８】
【数５】

【００４９】
となる。ここで求められた補償量Ｍは、収差の高次成分を含むことができる。補償光学部６０は、演算部６００から出力された補償量Ｍに基づいて変形する。なお、倍率ｋ及び無補償状態での入射角θは予め設定された値であり、予めメモリ８００に記憶されている。
【００５０】
なお、低次成分の球面度数成分は、移動部１５によって第１受光部２５Ａ及び／又は第２受光部２５Ｂを移動させることにより補償することもできる。また、ゆがませた可変鏡をさらにゆがませる場合、補償後に測定された収差に対して上記の解析と同様に補償量Ｍを求め、補償後の可変鏡にさらにその分を付加すればよい。また、補償光学部６０により完全に収差をなくすのではなく、若干ハルトマン板への入射光を発散方向にする又は傾けるようにしてもよい。これにより長焦点又は高感度の第１測定部２５Ａにおいて感度の高い測定を行うことができる。
演算部６００は、収差測定１の測定結果が得られなかった場合（Ｓ１０３）、図７の収差補償の処理へ移る。
【００５１】
図７は、ハルトマン像から被検眼１００の光学特性が求められない場合の収差測定のフローチャートである。以下、図７に示す処理について説明する。
【００５２】
まず、演算部６００は、おおよその収差量が分かる、もしくは適当に収差補正をしてみるか判断する（Ｓ１５１）。例えば、角膜収差，過去の収差データ等を参考に測定を続けるかどうか判断する。判断方法としては、演算部６００は、自動的に表示したダイアログボックス、もしくはメニューから立ち上げた入力部６５０等から測定を続ける又は終了する信号を入力しても良い。また、演算部６００は、メモリ８００に角膜収差データ又は過去の収差データがあるかを検索し、データの有無によって測定を続けるか終了するかを判断しても良い。
【００５３】
演算部６００は、測定を続けない場合、表示部７００に解析不可能通知表示を行い（Ｓ１５３）、測定を終了する。一方、演算部６００は、測定を続ける場合、角膜収差データ、過去の収差データ等のゼルニケ係数、収差データ等を、装置内のメモリ８００、もしくは入力部６５０から入力し、可変鏡等の補償光学部６０の補償量Ｍを求め、制御部６１０及び第５駆動部９１４を介して可変鏡をゆがませる（Ｓ１５５）。また、演算部６００は、前眼部観察部４０の第３受光部４１からの信号を入力して角膜収差を求め、求めた収差に基づいて補償量Ｍを算出してもよい。補償量Ｍの算出についてはステップＳ１０５と同様である。演算部６００は、制御部６１０及び第５駆動部９１４を介して、補償量Ｍに応じた信号（１５）を出力し、補償光学部６５をゆがませる。
【００５４】
次に、演算部６００は、補償後に光学特性の測定が可能か判断する（Ｓ１５７）。演算部６００は、例えば、第１受光部２１Ａからハルトマン像を入力し、入力したハルトマン像の重心位置が所定の数以上（例えば３分の１）取れない、もしくは各点像のぼけが大きい（例えば、無収差時の２０倍以上など）、もしくは隣接するスポット像と分離できずに検出できない点が所定の数以上ある等の予め定められたひとつ又は複数の適宜の条件に従い判断することができる。演算部６００は、測定不可能な場合、さらに補償するか判断する（Ｓ１５９）。例えば、演算部６００は、自動的に表示したダイアログボックス、もしくはメニューから立ち上げた入力部等から測定を続ける又は終了する信号を入力しても良い。また、演算部６００は、メモリ８００に別の収差データがあるかを検索しても良い。演算部６００は、補償する場合はステップＳ１５５へ戻り、一方、補償しない場合は、表示部７００に解析不可能通知を表示し（Ｓ１６１）、測定を終了する。
【００５５】
一方、演算部６００は、測定可能な場合（Ｓ１５７）、図６のステップＳ１０７へ進み被検眼１００の収差測定を行う。
【００５６】
図６に戻り、演算部６００は、収差測定２として、第１受光部２１Ａから第１信号を取得し、収差を求める（Ｓ１０７）。ここで求められる収差は、補償された収差であり、長焦点又は高感度の第１測定部２５Ａによって、微小な収差を高精度に測定可能である。また、角膜収差を補償光学部６５により補償した場合、ここで求められる収差は眼内収差となる。
【００５７】
次に、演算部６００は、ステップＳ１０７で得られた収差が、予め定められた許容値以下であるか判断する（Ｓ１０９）。例えば、演算部６００は、高次収差ＲＭＳ値が０．１以下であるかを判断しても良い。収差のＲＭＳ値（平均２乗誤差）は、ゼルニケ係数ｃ_ｉ ^２ｊ−ｉを用いて次式で算出される。
【００５８】
【数６】

【００５９】
演算部６００は、これら収差のＲＭＳ値の予め定められた一つ又は複数が許容値以下であるか判断する。
【００６０】
演算部６００は、収差が許容値より大きい場合（Ｓ１０９）、ステップＳ１０５へ戻り、さらに補償光学部６５をゆがませる。一方、演算部６００は、許容値より小さい場合（Ｓ１０９）、ステップＳ１０７で測定された収差Ｗ２に、補償光学部６０で打ち消した収差Ｗ１を加えて、実際の被検眼１００の収差Ｗ（ゼルニケ係数ｃ_ｉ ^２ｊ−ｉを含む）を求める（Ｓ１１１）。また、演算部６００は、求められたゼルニケ係数ｃ_ｉ ^２ｊ−ｉと光学系の配置（例、移動位置が初期条件でどこに来ているかなどの情報）により、既知の方法をつかって、球面度数Ｓ、乱視度数Ｃ、乱視軸Ａ、高次球面収差を得ることができる。演算部６００は、次式のようにゼルニケ係数の２次項から球面度数Ｓ、乱視度数Ｃ、乱視軸Ａを求めることができる。
【００６１】
【数７】

（ここに、ＳＥ：等価球面度数、Ｓ_ｍｏｖｅ：固視移動分の球面度数、ｒ：瞳径）
【００６２】
演算部６００は、求められた収差マップ、収差係数、ハルトマン像等の測定結果を表示部７００に表示し、メモリ８００に記憶する（Ｓ１１３）。また、演算部６００は、メモリ８００から角膜形状データ等を読み出し、表示部７００にさらに表示しても良い。
【００６３】
さらに、演算部６００は、測定を終了するか判断し（Ｓ１１５）、測定を続ける場合はステップＳ１０１に戻り、終了の場合は測定を終了する。測定終了の判断は、例えば、演算部６００は、自動的に表示したダイアログボックス、もしくはメニューから立ち上げた入力部６５０等から測定を続ける又は終了する信号を入力しても良い。
【００６４】
図９は、収差測定のフローチャートの変形例である。本変形例は、図１又は図４に示す第１の実施の形態における光学系を用いて、補償後の収差測定毎に、被検眼１００の収差演算及び演算結果の出力を行う例である。
【００６５】
まず、演算部６００は、ステップＳ１０１〜Ｓ１０７及びステップＳ１１１の処理を実行する。処理の詳細については上述と同様であるので省略する。
【００６６】
演算部６００は、求められた収差マップ、収差係数、ハルトマン像等の測定結果を表示部７００に表示し、メモリ８００に記憶する（Ｓ２０１）。なお、表示部７００への表示は必ずしも毎回行う必要はない。例えば、表示部７００への表示処理に時間がかかる等、測定に影響を及ぼす場合、一定の測定回数毎に結果を表示するようにしても良い。
【００６７】
演算部６００は、ステップＳ１１１で得られた収差が、予め定められた許容値以下であるか判断する（Ｓ１０９）。判断基準は、上述と同様とすることができる。演算部６００は、収差が許容値より大きい場合、ステップＳ１０５へ戻り、許容値より小さい場合、求められた収差マップ、収差係数等の測定結果を表示部７００に表示し、メモリ８００に記憶する（Ｓ２０３）。なお、ステップＳ２０１において、既に当該測定結果の表示、記憶を行っている場合は、ステップＳ２０３の処理を省略しても良い。また、演算部６００は、収差が許容値以下であるかを判断する代わりに、さらに補償光学部６０をゆがませるかの入力を指示する表示を表示部７００に出力し、入力部６５０から信号を入力するようにしてもよい。次に、演算部６００は、ステップＳ１１５の処理を実行する。処理の詳細は上述と同様である。
【００６８】
図１０は、第２の実施の形態における収差測定のフローチャートである。図１０は、例えば、図２又は図３に示すような長焦点又は高感度の第１測定部２５Ａと、短焦点または低感度の第２測定部２５Ｂを備える光学系を用いて、短焦点または低感度の第２受光光学系２０Ｂからの信号に基づいて補償量を決定する収差測定のフローチャートである。演算部６００は、第２測定部２５Ｂの信号に基づいて、補償光学部６０の補償量Ｍを高速に求め、補償光学部６０によって収差が補償されている光束を長焦点又は高感度の第１測定部２５Ａで精密に測定することにより、高感度、かつ高速な測定を可能とする。
【００６９】
まず、演算部６００は、短焦点又は低感度の第２測定部２５Ｂでの信号に基づいて収差測定１を行う（Ｓ２５１）。演算部６００は、第２測定部２５Ｂの第２受光部２１Ｂからハルトマン像を取得し、取得した画像に基づき、スポット像の重心点を検出する。無収差での重心点を中心とする矩形エリア内でそのスポットと対応する重心位置を探すことで高速可能となるように対応付けする。演算部６００は、得られたスポット像の重心点に基づいて、被検眼１００の粗い収差を求める。
【００７０】
次に、演算部６００は、ステップＳ１０３、Ｓ１０５の処理を実行する。処理の詳細は上述と同様であるので省略する。
【００７１】
演算部６００は、長焦点又は高感度の第１測定部２５Ａからの信号に基づいて収差測定２を行う（Ｓ２５７）。演算部６００は、第１測定部２５Ａの第１受光部２１Ａから、ハルトマン像の第１信号を入力する。次に、演算部６００は、入力した第１信号から、ハルトマン像の点像移動量を求め、点像移動量に基づき被検眼１００の光学特性を求める。従来の長焦点又は高感度の測定部を用いる収差測定では、スポット像のずれが大きくなることがあり、スポット像の対応付けに時間がかかる、又は、対応が取れず測定ができない場合がある。本実施の形態では、入力したハルトマン像の第１信号は、被検眼１００の収差がある程度打ち消されているハルトマン像であるため、長焦点又は高感度であってもスポットの位置ずれは小さくなっており、精密かつ高速な収差演算が可能である。
【００７２】
次に、演算部６００は、ステップＳ１０９〜Ｓ１１５の処理を実行する。処理の詳細は上述と同様であるので省略する。
【００７３】
また、演算部６００は、短焦点または低感度の第２受光光学系２０Ｂからの信号に基づいて補償量を決定した後に、補償後の収差及び点像の移動量をリアルタイムでシミュレーション可能である。演算部６００は、第１測定部２５Ａから得られる点像は、先の第２測定部２５Ｂで得られた測定の結果から予測することができる。点像の移動量とゼルニケ係数は、次式のように同様な関係が成り立つ。
【００７４】
【数８】

（Ｆ：第１測定部２５Ａのハルトマン板とＣＣＤの距離）
【００７５】
補償後に第１測定部２５Ａによって測定される収差は、測定精度による違いはあるものの、第２測定部２５Ｂで測定された収差と補償された収差の差として予測できる。補償後の収差が予測できれば、上記の式を逆に使うことにより、第１受光部２０Ａで受光する点像の移動量を予測できる。実際には、補償後の収差予測をＷ_ｅとすると、次式により点像の移動量を算出することができる。
【００７６】
【数９】

【００７７】
第２測定部２５Ｂで測定された収差を、完全に打ち消すように補償光学部６０を変形させた場合、補償後の収差予測は無くなる（０になる）が、収差を完全に打ち消さずにハルトマンプレートへの入射光を発散方向にする又は傾けるようにした場合、数式９を参考に点像の対応付けを行うことにより、より高速な測定、より長焦点又は高感度な第１受光光学系２０Ａを用いた測定が可能となる。
【００７８】
図１１は、第２の実施の形態における収差測定のフローチャートの第１の変形例である。本変形例は、補償後の収差測定毎に、被検眼１００の収差演算及び演算結果の出力を行う例である。各ステップの処理は、図９及び図１０に示す処理と同様であるので、同じ符号を付し、その詳細な説明は省略する。
【００７９】
図１２は、第２の実施の形態における収差測定のフローチャートの第２の変形例である。本変形例は、図３に示す光学系を用いて収差が補償された光束を第２受光部２１Ｂで受光し、第２受光部２１Ｂからの信号に基づき求められる収差が、予め定められた許容値以下になるように補償を行う例である。
【００８０】
まず、演算部６００は、ステップＳ２５１、Ｓ１０３、Ｓ１０５の各処理を実行する。処理の詳細については上述と同様であるので省略する。次に、演算部６００は、第２測定部２５Ｂでの信号に基づいて、補償された収差の測定を行う（Ｓ２５３）。処理の詳細は、上述のステップＳ２５１と同様であるので省略する。演算部６００は、ステップＳ２５３で求められた収差が、予め定められた第１許容値以下であるか判断する（Ｓ２５５）。例えば、演算部６００は、高次収差のＲＭＳ値が０．１以下であるかを判断しても良い。演算部６００は、収差が第１許容値より大きい場合、ステップＳ１０５へ戻り、さらに補償光学部６５をゆがませる。一方、演算部６００は、収差が第１許容値より小さい場合、ステップＳ２５７の処理へ移る。
【００８１】
また、演算部６００は、収差が第１許容値以下であるかを判断する代わりに、第１受光部２１Ａから第１信号を入力し、第１信号に基づく測定が可能かを判断しても良い。演算部６００は、例えば、入力した第１信号に基づく各点像の重心位置が所定の数以上（例えば３分の１以上）取れない、又は各点像のぼけが大きい（例えば、無収差時の２０倍以上など）、又は隣接するスポット像と分離できずに検出できない点が所定の数以上ある等の予め定められたひとつ又は複数の条件により、第１信号に基づく測定が不可能と判断することができる。また、判断条件は、適宜の条件を用いてよい。ここで、演算部６００は、測定不可能と判断した場合、ステップＳ１０５の処理へ移り、一方、測定可能と判断した場合ステップＳ２５７の処理へ移る。
【００８２】
演算部６００は、ステップＳ２５７の処理を実行する。処理の詳細については上述と同様であるので省略する。次に、演算部６００は、ステップＳ２５７で求められた収差２が、予め定められた第２許容値以下であるか判断する（Ｓ２５９）。例えば、演算部６００は、高次収差のＲＭＳ値が０．１以下であるかを判断しても良い。また、第１許容値と第２許容値は、異なる値を取ることができる。例えば、測定の感度を考慮して、第１許容値≧第２許容値としてもよい。演算部６００は、収差２が第２許容値より大きい場合（Ｓ２５９）、収差２に従い、補償光学部６０をさらにゆがませ（Ｓ２６１）、ステップＳ２５７へ戻る。補償光学部６０をゆがませる処理の詳細は、ステップＳ１０５と同様である。一方、演算部６００は、収差２が第２許容値より小さい場合、ステップＳ１１１の処理へ移る。
【００８３】
次に、演算部６００は、ステップＳ１１１〜Ｓ１１５の処理を実行する。処理の詳細は上述と同様であるので省略する。
【００８４】
【発明の効果】
本発明によると、補償光学部により収差の一部を打ち消し、残りの収差を高精度に測定することで被検眼１００の光学特性を精密に測定できる。また、本発明によると、低感度と高感度の光学系を用いてより精密に、且つ、より高速に光学特性の測定ができる。さらに、本発明によると、収差が大きく、高感度の測定が不可能な被検眼１００に対しても、低感度による測定又は角膜付近での光学特性等に基づき、ある程度の収差を補償することで高感度な測定を可能とすることができる。また、本発明によると、測定レンジの広い眼特性測定装置が提供できる。
【図面の簡単な説明】
【図１】眼特性測定装置の光学系の構成図。
【図２】眼特性測定装置の光学系の第２の構成図。
【図３】眼特性測定装置の光学系の第３の構成図。
【図４】ダブルパス測定の光学系の構成図。
【図５】眼特性測定装置の電気系の構成図。
【図６】収差測定のフローチャート。
【図７】ハルトマン像から被検眼の光学特性が求められない場合の収差補償のフローチャート。
【図８】可変鏡上の座標と光学系の座標の関係の説明図。
【図９】収差測定のフローチャートの変形例。
【図１０】第２の実施の形態における収差測定のフローチャート。
【図１１】第２の実施の形態における収差測定のフローチャートの第１の変形例。
【図１２】第２の実施の形態における収差測定のフローチャートの第２の変形例。
【図１３】ゼルニケ多項式（１）。
【図１４】ゼルニケ多項式（２）。
【符号の説明】
１０　第１照明光学系
１１　第１光源部
２０Ａ　第１受光光学系
２１Ａ　第１受光部
２５Ａ　第１測定部
２０Ｂ　第２受光光学系
２１Ｂ　第２受光部
２５Ｂ　第２測定部
３０　前眼部観察部
４０　前眼部照明部
５０　第１調整光学部
６０　補償光学部
７０　第２調整光学部
９０　視標光学部
６００　演算部
６１０　制御部
６５０　入力部
７００　表示部
８００　メモリ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an eye characteristic measuring device, and more particularly to an eye characteristic measuring device that precisely measures optical characteristics of an eye to be inspected using a wavefront sensor.
[0002]
[Prior art]
2. Description of the Related Art In recent years, optical devices used for medical use have become widespread, particularly in ophthalmology, as optical characteristics measuring devices for examining eye functions such as refraction and accommodation of eyes and the inside of an eyeball. For example, there is a device called a photo-refractometer that determines the refractive power and the corneal shape of the eye to be examined.
[0003]
In addition, a retinal image resolution improving device that corrects a wave aberration by deforming a correction optical member such as a deformable mirror and has a half width but the same shape as the wave aberration is disclosed. (For example, see Patent Document 1). In this device, the laser light reflected from the retina of the eye forms a wavefront on a Hartmann-Shack wavefront sensor via a deformable mirror. The formed wavefront is digitized by a digital processor via a camera, and the wave aberration is measured. The digital data processor emits a correction signal that feeds back to the deformable mirror based on the measured wave aberration. The deformable mirror is deformed to correct the wave aberration of the eye, and has the same shape, although the width of the wave aberration is half.
[Patent Document 1]
JP 2001-507258 A
[0004]
[Problems to be solved by the invention]
However, in an apparatus for measuring the optical characteristics of an eye to be examined having an aberration, accurate measurement may be difficult when the amount of aberration is large. In particular, when performing precise measurement, if the amount of aberration is large, it takes time to associate each spot of the point image in the Hartmann image with the Hartmann lattice point, or the measurement cannot be performed because the association cannot be performed. There was something.
[0005]
The present invention has been made in view of the above points, and when measuring the optical characteristics of an eye to be inspected, corrects such that the aberration of the measurement light is canceled out, further measures the amount of uncorrected aberration, and performs accurate measurement. It is an object to provide a characteristic measuring device. In addition, the present invention provides an eye characteristic measuring apparatus that performs correction to cancel out aberrations of measurement light, and more precisely, and uses a low-sensitivity and high-sensitivity optical system to measure optical characteristics more quickly. The purpose is to provide. Another object of the present invention is to provide an eye characteristic measuring apparatus having a wide measurement range capable of performing measurement even when the amount of aberration is large, by performing correction so as to cancel out the aberration of the measurement light.
[0006]
[Means for Solving the Problems]
According to a first solution of the present invention,
A first light source unit that emits a light beam of a first wavelength;
A first illumination optical system for illuminating a minute area on the retina of the eye with the light beam from the first light source unit;
A second part for receiving a part of the reflected light beam reflected from the retina to be examined through a first conversion member having a long focal point or a highly sensitive lens part that converts at least substantially 17 beams. One light receiving optical system,
A second part for receiving light via a second conversion member having a short focus or low sensitivity lens unit that converts a part of the reflected light flux reflected from the retina of the subject's eye and returned to at least substantially 17 beams. Two light receiving optical systems,
A first light receiving unit that receives a light beam received by the first light receiving optical system;
A second light receiving unit that receives a light beam received by the second light receiving optical system;
A compensation amount calculation unit that calculates and outputs a compensation amount for canceling aberration based on an output of the first light receiving unit and / or the second light receiving unit;
A compensating optical unit disposed in the first and / or second light receiving optical system and compensating aberration of a light beam passing or reflected according to the compensation amount output from the compensation amount calculating unit;
The optical characteristics of the eye to be inspected are determined in consideration of the optical characteristics based on the output of the first light receiving unit and / or the second light receiving unit after the compensation by the compensation optical unit and the optical characteristics compensated by the compensation optical unit. An eye characteristic measurement device including a measurement calculation unit is provided.
[0007]
According to a second solution of the present invention,
A first light source unit that emits a light beam of a first wavelength;
A first illumination optical system for illuminating a minute area on the retina of the eye with the light beam from the first light source unit;
A first light receiving optical system for receiving a part of the reflected light flux reflected from the retina of the subject's eye and returning through at least substantially a first conversion member that converts the light into 17 beams;
A first light receiving unit that receives a light beam received by the first light receiving optical system;
A second light source unit that emits a light beam of a second wavelength;
A second illumination optical system that illuminates the vicinity of the cornea of the eye to be examined in a predetermined pattern with a light beam from the second light source unit;
A third light receiving unit that receives a reflected light beam that is reflected from the vicinity of the cornea of the subject's eye and returns,
A third light receiving optical system that guides the reflected light flux from near the cornea to the third light receiving unit;
A compensation amount calculating unit that determines an optical characteristic of the subject's eye from the output of the third light receiving unit, determines a compensation amount for canceling aberration based on the optical characteristic, and outputs the compensation amount;
A compensating optical unit disposed in the first light receiving optical system and compensating for aberration of a light beam passing or reflected according to the compensation amount output from the compensation amount calculating unit;
Taking into account the optical characteristics based on the output of the first light receiving unit after compensation by the compensation optical unit and the optical characteristics compensated by the compensation optical unit, a measurement calculation unit for determining the optical characteristics of the eye to be inspected;
An eye characteristic measuring device comprising:
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
1. Optical system configuration
(Optical system in first embodiment)
FIG. 1 shows a first configuration diagram of an optical system of the eye characteristic measuring device.
The eye characteristic measuring device includes a first illumination optical system 10, a first light source unit 11, a first measurement unit 25A, an anterior eye illumination unit 30, an anterior eye observation unit 40, and a first adjustment optical unit 50. A compensating optical unit 60, a second adjusting optical unit 70, and a target optical unit 90. The first measuring unit 25A includes a first light receiving optical system 20A and a first light receiving unit 21A. In addition, as for the subject's eye 100, the retina (the fundus) and the cornea (the anterior segment) are shown.
[0009]
Hereinafter, each part will be described in detail.
The first illumination optical system 10 illuminates a minute area on the fundus of the subject's eye 100 with a light beam from the first light source unit 11. The first illumination optical system 10 includes, for example, a condenser lens, a cylinder lens, and a relay lens.
[0010]
The first light source unit 11 emits a light beam of a first wavelength. It is desirable that the first light source unit 11 has high spatial coherence and not high temporal coherence. Here, as an example, an SLD (super luminescence diode) is adopted as the first light source unit 11, and a point light source with high luminance can be obtained. Note that the first light source unit 11 is not limited to the SLD. Even if the first light source unit 11 has a high coherence in space and time like a laser, the first light source unit 11 can be used by appropriately lowering the time coherence by inserting a rotating diffuser or the like. it can. Then, even if the coherence is not high in space and time, such as an LED, as long as the light quantity is sufficient, it can be used by inserting a pinhole or the like at the position of the light source in the optical path. Further, as the wavelength of the first light source unit 11 for illumination, for example, a wavelength in an infrared region (for example, 780 nm) can be used.
[0011]
The first light receiving optical system 20A is for receiving, for example, a light beam reflected from the retina of the eye 100 and returning to the first light receiving unit 21A. The first light receiving optical system 20A includes, for example, a first conversion member 22A (for example, a Hartmann plate), an afocal lens, a cylinder lens, and a relay lens. The first conversion member 22A is a wavefront conversion member having a long focal point or a highly sensitive lens unit for converting the reflected light beam into at least 17 plural beams. A plurality of micro Fresnel lenses arranged in a plane orthogonal to the optical axis can be used for the first conversion member 22A. The light reflected from the fundus is focused on the first light receiving unit 21A via the first conversion member 22A. The first light receiving unit 21A receives the light from the first light receiving optical system 20A that has passed through the first conversion member 22A, and generates a first signal. The front focal point of the afocal lens 42 substantially coincides with the pupil of the eye 100 to be inspected.
[0012]
The moving unit 15 integrally moves a portion surrounded by a dotted line in FIG. 1 including the first illumination optical system 10 and the first light receiving optical system 20A. For example, assuming that the light beam from the first light source unit 11 is reflected at a converging point, the relationship in which the signal peak at the first light receiving unit 21A due to the reflected light is maintained at a maximum is maintained at the first light receiving unit 21A. Move in the direction in which the signal peak becomes stronger, and can stop at the position where the intensity becomes maximum. In addition, the first illumination optical system 10 and the first light receiving optical system 20A are moved separately, for example, assuming that the light beam from the first light source unit 11 is reflected at a converging point, and the first light receiving unit due to the reflected light. It is also possible to maintain the relationship where the signal peak at 21A is maximum, move in the direction in which the signal peak at the first light receiving unit 21A is strong, and stop at the position where the strength is maximum.
[0013]
The incident light from the first light source unit 11 to the subject's eye 100 changes the incident position of the light beam in a direction perpendicular to the optical axis by decentering the stop 12 and suppresses noise by preventing the vertex reflection of the lens and the cornea. The diameter of the aperture 12 is smaller than the effective range of the Hartmann plate 22A, and so-called single-pass aberration measurement, in which eye aberration affects only the light receiving side, can be established.
[0014]
After the incident light beam emitted from the first light source unit 11 has a common optical path with the measurement light beam diffusely reflected from the fundus, it is paraxially transmitted in the same way as the measurement light beam diffusely reflected from the fundus. I do. However, in the case of single-pass measurement, the diameter of each light beam is different, and the beam diameter of the incident light beam is set to be considerably smaller than the measurement light beam. Specifically, the beam diameter of the incident light beam may be, for example, about 1 mm at the pupil position of the subject's eye 100, and the beam diameter of the measurement light beam may be about 7 mm. It should be noted that double-path measurement can be performed by appropriately arranging the optical system.
[0015]
The anterior segment illuminating unit 30 includes a second light source unit 31 that emits a light beam of a second wavelength. The luminous flux from the second light source unit 31 uses, for example, a placido ring or a kerat ring to pattern the anterior segment to a predetermined pattern. Irradiate with In the case of kerattling, a pattern only near the center of curvature of the cornea can be obtained from the keratogram. The second wavelength of the light beam emitted from the second light source unit 31 is different from, for example, the first wavelength (here, 780 nm), and a longer wavelength can be selected (for example, 940 nm).
[0016]
The anterior eye observation unit 40 includes, for example, a third light receiving unit 41 including a relay lens, a telecentric aperture, and a CCD. For example, the pattern of the anterior eye illumination unit 30 such as a placido ring or a kerat ring is measured. The luminous flux reflected from the anterior segment of the eye 100 and returned is observed. Note that the telecentric aperture is an aperture for preventing an anterior ocular segment image from being blurred.
[0017]
The first adjustment optical unit 50 mainly performs, for example, working distance adjustment, and includes a light source unit, a condenser lens, and a light receiving unit. Here, the working distance adjustment is performed, for example, by irradiating a parallel light flux near the optical axis emitted from the light source unit toward the eye 100 to be measured, and condensing the light reflected from the eye 100 to be measured. This is performed by receiving light at a light receiving unit via a lens. When the eye to be measured 100 is at an appropriate working distance, a spot image from the light source unit is formed on the optical axis of the light receiving unit. On the other hand, when the eye to be measured 100 deviates from the proper working distance back and forth, the spot image from the light source unit is formed above or below the optical axis of the light receiving unit. The light receiving unit only needs to be able to detect a change in the light flux position in a plane including the light source unit, the optical axis, and the light receiving unit. For example, a one-dimensional CCD, a position sensing device (PSD), or the like disposed in this plane Can be applied.
[0018]
The compensating optical unit 60 is an adaptive optical system (adaptive optics) that deforms to compensate for aberrations of the measurement light, and is disposed in the first light receiving optical system 20A and / or the second light receiving optical system 20B. As the adaptive optics unit 60, for example, a variable mirror or a liquid crystal spatial light modulator can be used. In addition, an appropriate optical system that can compensate for the aberration of the measurement light may be used. The deformable mirror changes the reflection direction of the light beam by deforming the mirror by an actuator provided inside the mirror. In addition, there are a method of deforming by capacitance, a method of deforming by piezo, and the like, but any other appropriate method can be used. The liquid crystal spatial light modulator modulates the phase using the light distribution of the liquid crystal, and is used by reflecting it in the same manner as a mirror. Although a polarizer is required in the optical path, the beam splitter 63 plays a role in this embodiment. The beam splitter 63 is configured by a mirror (for example, a polarization beam splitter) that reflects a light beam from the first light source unit 11 and transmits a light beam reflected by the retina of the subject's eye 100 and returned. As the adaptive optics system 60, a transmission type optical system may be used other than the one used by reflecting. It should be noted that, although not limited to this, it is preferable that a parallel light beam be incident on these adaptive optics units 60.
[0019]
The beam splitter 61 is composed of, for example, a dichroic mirror that reflects a light beam of the first wavelength and transmits a light beam of the second wavelength. Further, a rotary prism 62 for uniformizing light due to uneven reflection from the fundus is arranged.
The second adjustment optical unit 70 performs alignment adjustment in the XY directions, for example, and includes an alignment light source unit, a lens, and a beam splitter.
[0020]
The optotype optical unit 90 includes, for example, a landscape chart of the eye 100 to be inspected, an optical path for projecting an optotype for fixation and fogging, and includes a light source unit (for example, a lamp), a fixation target 92, Equipped with a relay lens. The fixation target 92 can be illuminated to the fundus with a light beam from the light source, and the subject's eye 100 observes the image.
[0021]
Although the above-described optical system has been mainly described as a single pass in which the incident light beam is thin, the present invention can also be applied to an eye-specific measurement apparatus in which the incident light beam is a double pass. At this time, the optical system is arranged in a double-pass configuration, but the measurement and calculation processing by the arithmetic unit is the same.
[0022]
FIG. 4 is a configuration diagram of an optical system for double-pass measurement. For example, the aperture 13 for double-path measurement of the first illumination optical system 10 can make the incident light beam from the first illumination optical system 10 into a wide beam. Other configurations are the same as those in FIG.
[0023]
(Optical System in Second Embodiment)
FIG. 2 is a second configuration diagram of the optical system of the eye characteristic measuring device. FIG. 2 shows only a portion corresponding to the dotted frame in FIG. 1, but the other portions are the same as those in FIG. The eye characteristic measuring device in FIG. 2 further includes a short focus or low sensitivity second measuring unit 25 </ b> B and a half mirror 23.
[0024]
The second measuring unit 25B includes a second light receiving optical system 20B and a second light receiving unit 21B. The second light receiving optical system 20B, like the first light receiving optical system 20A, is for receiving the light flux reflected from the retina of the eye 100 and returning to the second light receiving unit 21B. The second light receiving optical system 20B includes, for example, a second conversion member 22B (for example, a Hartmann plate), and an afocal lens, a cylinder lens, and a relay lens shared with the first light receiving optical system 20A. The second conversion member 22B is a wavefront conversion member having a short focus or low sensitivity lens unit for converting the reflected light beam into at least 17 plural beams. A plurality of micro Fresnel lenses arranged in a plane orthogonal to the optical axis can be used for the second conversion member 22B. The light reflected from the fundus is collected on the second light receiving unit 21B via the second conversion member 22B. The second light receiving unit 21B receives the light from the second light receiving optical system 20B that has passed through the second conversion member 22B, and generates a second signal. The light fluxes of the first measuring unit 25A and the second measuring unit 25B are split by the half mirror 23. Alternatively, it is also possible to use a mirror unit instead of the half mirror 23 and switch to the first or second measuring unit 25A or 25B by moving the mirror unit and inserting it into the optical path.
[0025]
The short focus and the low sensitivity in the present embodiment mean that the change of the beam converted by the second conversion member 22B over the measurable range is set smaller than the conversion pitch of the second conversion member 22B. As a result, it is easy to associate each spot obtained by the second light receiving unit 21B with a grid point, and signal processing can be easily performed at high speed. On the other hand, in the measurement using a long focus or high sensitivity, the spot position is largely displaced, and a spot may exist outside the range of the Hartmann grating. Therefore, if the spot positions are shifted too much due to a large amount of aberration or the like, it may be difficult to associate each spot with a grid point, and it may take time for signal processing. Therefore, as one of the present embodiments, the compensation amount of the compensation optical unit 60 is determined based on the signal of the short focus or low sensitivity second measurement unit 25B, and the compensated light flux is measured with the long focus or high sensitivity. By doing so, high-speed and accurate measurement is enabled. In the present embodiment, for example, when no aberration is obtained from the Hartmann image from the first light receiving unit 21A or the second light receiving unit 21B, compensation is performed based on the optical characteristics near the cornea based on the third light receiving unit 41. Is performed so that aberration measurement can be performed.
[0026]
FIG. 3 is a third configuration diagram of the optical system of the eye characteristic measuring device. FIG. 3 shows only the portion corresponding to the dotted frame in FIG. 1, but the other portions are the same as those in FIG. In the optical system of FIG. 3, the adaptive optics unit 60 is inserted in common in the first and second measuring units 25A and 25B. The light flux reflected from the retina of the subject's eye 100 and returned is guided to the first and second measurement units 25A and 25B via the adaptive optics unit 60. By guiding the light beam passing through the adaptive optics unit 60 to the second measurement unit 25B, the aberration after compensation can be measured by the second measurement unit 25B. Further, it is also possible to deform the adaptive optics unit 60 until the aberration measured by the output from the second measurement unit 25B becomes equal to or less than a predetermined allowable value. Although the optical systems in FIGS. 2 and 3 are mainly described as a single-pass type in which the incident light beam is thin, the optical system can be appropriately changed for double-pass measurement.
[0027]
(Conjugate relationship)
The fundus of the eye 100 to be measured, the fixation target 92 of the target optical unit 90, the first light source unit 11, the first light receiving unit 21A, and the second light receiving unit 21B are conjugate. Further, the pupil (iris) of the eye of the eye to be measured 100, the rotary prism 62, the conversion members (Hartmann plates) 22A and 22B of the first and second light receiving optical systems, and the stop on the measurement light incident side of the first illumination optical system 10. 12. The adaptive optics section 60 such as a variable mirror is conjugate.
[0028]
2. Electrical system configuration
FIG. 5 is a configuration diagram of an electric system of the eye characteristic measuring device.
The configuration of the electrical system of the eye characteristic measuring device includes an arithmetic unit 600, a control unit 610, an input unit 650, a display unit 700, a memory 800, a first driving unit 910, a second driving unit 911, A third drive unit 912, a fourth drive unit 913, and a fifth drive unit 914 are provided. The calculation unit 600 includes, for example, a compensation amount calculation unit 601 and a measurement calculation unit 602 that performs various eye characteristic measurements. Further, the input unit 650 includes a pointing device for designating appropriate buttons, icons, positions, areas, and the like displayed on the display unit 700, a keyboard for inputting various data, and the like.
[0029]
In addition, the arithmetic unit 600 includes a first signal (4) from the first light receiving unit 21A, a second signal (14) from the second light receiving unit 21B, and a signal (7) from the anterior eye observation unit 40. And the signal (10) from the first adjustment optical unit 50 are input.
[0030]
The measurement calculation unit 602 receives the first signal (4) and the second signal (14) from the first and second light receiving units 21A and 21B, and the signal (7) from the anterior eye observation unit 40, for example, The optical characteristics of the subject's eye 100 are determined based on the tilt angle of the light beam. Further, the compensation amount calculation unit 601 is based on, for example, the optical characteristics obtained from the signal {circle around (7)} from the anterior eye observation unit 40 and the optical characteristics obtained from the output of the short focus or low sensitivity second measurement unit 25B. , The amount of compensation in the compensation optical unit 60 is determined. The arithmetic unit 600 appropriately outputs signals or other signals / data corresponding to these arithmetic results to the control unit 610 for controlling the electric drive system, the display unit 700, and the memory 800, respectively.
[0031]
The control unit 610 controls the turning on and off of the first light source unit 11 and the second light source unit 31 and controls the first driving unit 910 to the fifth driving unit 914 based on the control signal from the arithmetic unit 600. It is for. The control unit 610 outputs a signal {circle around (1)} to the first light source unit 11 and outputs a signal {circle around (5)} to the second adjustment optical unit 70 based on a signal corresponding to the calculation result in the calculation unit 600, for example. And outputs a signal {circle around (6)} to the anterior ocular segment illumination unit 30, outputs signals {circle around (8)} and {9} to the first adjusting optical unit 50, and outputs a signal to the optotype optical unit 90. And outputs a signal to the first drive unit 910 to the fifth drive unit 914.
[0032]
The first drive unit 910 outputs a signal (2) based on the signal (4) or (14) from the first or second light receiving unit 21A or 21B input to the arithmetic unit 600, and outputs the first illumination. The cylinder lens of the optical system 10 and the cylinder lens of the first light receiving optical system 20A (or the second light receiving optical system 20B) are rotated by driving appropriate lens moving means.
[0033]
The second driving unit 911 is configured to perform, for example, the first illumination based on the light receiving signal (4) and / or (14) from the first and / or second light receiving units 21A and / or 21B input to the arithmetic unit 600. The optical system 10 and the first and second light receiving optical systems 20A and 20B are moved in the optical axis direction. The signal (3) is output to the moving unit 15 and the lens moving means of the moving unit 15 is driven. I do. By moving the first and second light receiving optical systems 20A and 20B in the optical axis direction, low order aberration can be compensated.
[0034]
The third driving unit 912 moves the optotype optical unit 90, for example, and outputs a signal (12) to an appropriate moving unit (not shown) and drives the moving unit. The fourth drive unit 913 rotates the rotary prism 62, outputs a signal (13) to an appropriate lens moving unit (not shown), and drives the lens moving unit. The fifth driving unit 914 drives the adaptive optics unit 60, and outputs a signal (15) to a deformation unit of the adaptive optics unit 60 based on the compensation amount obtained by the compensation amount calculation unit 602. This deformation means is driven.
[0035]
3. flowchart
6 and 7 are flowcharts of the aberration measurement. 6 is a flowchart for the first embodiment using the optical system shown in FIG. 1 or FIG. The calculation unit 600 determines the amount of compensation based on the output from the first measurement unit 25A in the aberration measurement 1 to distort the compensation optical unit 60, and further converts the first signal received by the first light receiving unit 21A. Based on the corrected aberration, the optical characteristic of the eye 100 is determined from the corrected aberration and the amount of compensation by the compensation optical unit 60.
[0036]
First, the calculation unit 600 obtains the aberration of the subject's eye 100 based on the first signal from the first light receiving unit 21A as the aberration measurement 1 (S101). The calculation unit 600 receives the first signal of the Hartmann image from the first light receiving unit 21A of the first measurement unit 25A. Next, the calculation unit 600 calculates the point image movement amounts △ x and △ y of the Hartmann image from the input first signal, calculates the Zernike coefficients based on the point image movement amounts, and calculates the aberration of the eye 100 to be examined. . Further, the arithmetic unit 600 may obtain a corneal shape, a corneal aberration, and the like based on a signal from the third light receiving unit 41 of the anterior ocular segment observation unit 40. The arithmetic unit 600 stores these calculation results in the memory 800.
[0037]
Hereinafter, the aberration calculation will be described. The calculation unit 600 calculates the movement amounts Δx and Δy of each point image from the image of the first measurement unit 25A. The movement amount and the aberration W are related by the following partial differential equation.
[0038]
(Equation 1)

(F: distance between the Hartmann plate of the first measurement unit 25A and the CCD)
[0039]
Here, the wavefront W is represented by the Zernike polynomial Z_i ^2j-iWhen expressed by using,
[0040]
(Equation 2)

[0041]
Using the above two equations and the measured values of △ x and △ y (and thus also including X and Y) obtained by the measurement, the Zernike coefficient c_i ^2j-iCan be obtained. Further, when the corneal aberration is obtained, the inclination of the cornea and the height of the cornea are calculated based on the signal from the third light receiving unit 41 of the anterior ocular segment observation unit 40, and the cornea is treated in the same manner as the optical lens. Is calculated. FIGS. 13 and 14 are explanatory diagrams (1) and (2) of Zernike polynomials.
[0042]
Next, the arithmetic part 600 determines whether a measurement result has been obtained (S103). For example, when the barycentric position of each point image of the Hartmann image acquired in the aberration measurement 1 cannot be more than a predetermined number (for example, one third or more), or when the point image has a large blur (for example, It can be determined according to one or more predetermined conditions such as a predetermined number or more, such as 20 times or more of the aberration-free state, or a predetermined number of points that cannot be detected because they cannot be separated from an adjacent spot image. Here, when the measurement result is obtained (S103), the processing proceeds to step S105, whereas when the measurement result is not obtained (S103), the processing proceeds to step S151 shown in FIG. .
[0043]
In step S105, the calculation unit 600 obtains a compensation amount M in the compensation optical unit 60 that cancels the obtained aberration, and outputs a signal (15) corresponding to the compensation amount M via the control unit 610 and the fifth driving unit 914. ) Is output to distort the adaptive optics section 60 such as a variable mirror (S105). Further, the adaptive optics section 60 is deformed by appropriate deformation means in accordance with the signal (15). The adaptive optics unit 60 may use a liquid crystal spatial light modulator other than the variable mirror. Hereinafter, calculation of the compensation amount M in the compensation optical unit 60 required to cancel the aberration will be described.
FIG. 8 shows the coordinates (X_m, Y_mFIG. 4 is an explanatory diagram of the relationship between the coordinates (X, Y) of the optical system. The aberration to be compensated is represented by Wc, and the equation of the analyzed aberration is
[0044]
(Equation 3)

[0045]
, The coordinates (X_m, Y_m) And the coordinates (X, Y) of the optical system are determined by considering the incident angle θ to the variable mirror.
[0046]
(Equation 4)

[0047]
Becomes The compensation amount M of the variable mirror takes into account the effect of doubling because of reflection and the magnification of the pupil of the eye and the variable mirror. Assuming that the magnification of the deformable mirror with respect to the pupil is k, the compensation amount M is
[0048]
(Equation 5)

[0049]
Becomes The compensation amount M obtained here can include a high-order component of aberration. The adaptive optics unit 60 is deformed based on the compensation amount M output from the arithmetic unit 600. Note that the magnification k and the angle of incidence θ in the uncompensated state are preset values and are stored in the memory 800 in advance.
[0050]
The low-order component spherical power component can be compensated by moving the first light receiving unit 25A and / or the second light receiving unit 25B by the moving unit 15. When the distorted variable mirror is further distorted, the compensation amount M is obtained for the aberration measured after compensation in the same manner as in the above analysis, and the compensation amount M is added to the compensated variable mirror. . Further, instead of completely eliminating the aberration by the adaptive optics unit 60, the light incident on the Hartmann plate may be slightly diverged or inclined. Thereby, high-sensitivity measurement can be performed in the long focus or high-sensitivity first measurement unit 25A.
When the measurement result of the aberration measurement 1 is not obtained (S103), the calculation unit 600 proceeds to the aberration compensation processing of FIG.
[0051]
FIG. 7 is a flowchart of aberration measurement when the optical characteristics of the subject's eye 100 cannot be obtained from the Hartmann image. Hereinafter, the processing illustrated in FIG. 7 will be described.
[0052]
First, the calculation unit 600 determines whether the approximate amount of aberration is known or whether aberration correction is appropriately performed (S151). For example, it is determined whether to continue the measurement with reference to corneal aberration, past aberration data, and the like. As a determination method, the arithmetic unit 600 may input a signal to continue or end the measurement from an automatically displayed dialog box, an input unit 650 started from a menu, or the like. The arithmetic unit 600 may search the memory 800 for corneal aberration data or past aberration data, and determine whether to continue or terminate the measurement based on the presence or absence of the data.
[0053]
When the measurement is not to be continued, the arithmetic unit 600 displays an analysis impossible notification on the display unit 700 (S153), and ends the measurement. On the other hand, when the measurement is continued, the arithmetic unit 600 inputs the corneal aberration data, the Zernike coefficients such as the past aberration data, the aberration data, and the like from the memory 800 in the apparatus or the input unit 650, and performs adaptive optics such as a variable mirror. The compensation amount M of the unit 60 is obtained, and the variable mirror is distorted via the control unit 610 and the fifth driving unit 914 (S155). In addition, the calculation unit 600 may obtain a corneal aberration by inputting a signal from the third light receiving unit 41 of the anterior ocular segment observation unit 40, and calculate the compensation amount M based on the obtained aberration. The calculation of the compensation amount M is the same as in step S105. The arithmetic unit 600 outputs a signal (15) according to the compensation amount M via the control unit 610 and the fifth driving unit 914, and distorts the adaptive optics unit 65.
[0054]
Next, the arithmetic unit 600 determines whether the optical characteristics can be measured after the compensation (S157). The calculation unit 600 receives, for example, a Hartmann image from the first light receiving unit 21A, and the center of gravity of the input Hartmann image cannot be more than a predetermined number (for example, one third), or each point image has a large blur ( For example, the determination can be made in accordance with one or more predetermined conditions such as a predetermined number or more of points that cannot be detected because they cannot be separated from an adjacent spot image because they are not separated from an adjacent spot image. . If the measurement is not possible, the arithmetic unit 600 determines whether to perform further compensation (S159). For example, the arithmetic unit 600 may input a signal for continuing or ending the measurement from an automatically displayed dialog box or an input unit started from a menu. The calculation unit 600 may search the memory 800 to determine whether there is another aberration data. The arithmetic unit 600 returns to step S155 when compensating, or displays an analysis impossible notification on the display unit 700 when not compensating (S161), and ends the measurement.
[0055]
On the other hand, when the measurement can be performed (S157), the processing proceeds to step S107 in FIG.
[0056]
Returning to FIG. 6, the arithmetic unit 600 obtains the first signal from the first light receiving unit 21A as the aberration measurement 2, and obtains the aberration (S107). The aberration obtained here is a compensated aberration, and a minute aberration can be measured with high accuracy by the long focus or the high sensitivity first measurement unit 25A. Further, when the corneal aberration is compensated for by the compensation optical unit 65, the aberration obtained here becomes an intraocular aberration.
[0057]
Next, the calculation unit 600 determines whether the aberration obtained in step S107 is equal to or less than a predetermined allowable value (S109). For example, the calculation unit 600 may determine whether the high-order aberration RMS value is 0.1 or less. The RMS value (mean square error) of the aberration is the Zernike coefficient c_i ^2j-iIs calculated using the following equation.
[0058]
(Equation 6)

[0059]
The calculation unit 600 determines whether one or more of the predetermined RMS values of the aberrations is equal to or less than an allowable value.
[0060]
When the aberration is larger than the allowable value (S109), the calculation unit 600 returns to step S105, and further distorts the adaptive optics unit 65. On the other hand, when the calculated value is smaller than the permissible value (S109), the arithmetic unit 600 adds the aberration W1 canceled by the adaptive optics unit 60 to the aberration W2 measured in step S107 to obtain the actual aberration W (Zernike coefficient) of the eye 100 to be examined. c_i ^2j-i(S111). The arithmetic unit 600 calculates the Zernike coefficient c_i ^2j-iAnd obtaining the spherical power S, astigmatic power C, astigmatic axis A, and higher-order spherical aberration by using a known method according to the arrangement of the optical system (eg, information on where the moving position comes under the initial conditions). Can be. The arithmetic unit 600 can calculate the spherical power S, the astigmatic power C, and the astigmatic axis A from the second-order terms of the Zernike coefficients as in the following equation.
[0061]
(Equation 7)

(Where, SE: equivalent spherical power, S_move: Spherical power for fixation movement, r: pupil diameter)
[0062]
The calculation unit 600 displays the obtained measurement results such as the aberration map, the aberration coefficient, and the Hartmann image on the display unit 700, and stores the measurement results in the memory 800 (S113). The arithmetic unit 600 may read corneal shape data and the like from the memory 800 and further display the data on the display unit 700.
[0063]
Further, the arithmetic unit 600 determines whether to end the measurement (S115), and returns to step S101 if the measurement is to be continued, and ends the measurement if it is to be ended. For the determination of the end of the measurement, for example, the arithmetic unit 600 may input a signal for continuing or ending the measurement from an automatically displayed dialog box or an input unit 650 started from a menu.
[0064]
FIG. 9 is a modified example of the flowchart of the aberration measurement. This modification is an example in which the optical system according to the first embodiment shown in FIG. 1 or FIG. 4 is used to calculate the aberration of the subject's eye 100 and output the calculation result every time the aberration is measured after the compensation.
[0065]
First, the calculation unit 600 performs the processing of steps S101 to S107 and step S111. Details of the processing are the same as those described above, and a description thereof will be omitted.
[0066]
The calculation unit 600 displays the obtained measurement results such as the aberration map, the aberration coefficient, and the Hartmann image on the display unit 700, and stores the measurement results in the memory 800 (S201). The display on the display unit 700 does not always need to be performed every time. For example, in a case where it takes a long time for the display processing on the display unit 700 to affect the measurement, the result may be displayed every certain number of measurements.
[0067]
The calculation unit 600 determines whether the aberration obtained in step S111 is equal to or smaller than a predetermined allowable value (S109). The criteria can be the same as described above. If the aberration is larger than the allowable value, the operation unit 600 returns to step S105. If the aberration is smaller than the allowable value, the calculation unit 600 displays the obtained measurement results such as the aberration map and the aberration coefficient on the display unit 700 and stores the measurement result in the memory 800 ( S203). If the measurement result is already displayed and stored in step S201, the process of step S203 may be omitted. Further, instead of judging whether the aberration is equal to or less than the allowable value, arithmetic unit 600 outputs a display for instructing input of whether to further distort adaptive optics unit 60 to display unit 700, and outputs a signal from input unit 650. May be input. Next, arithmetic unit 600 performs the process of step S115. The details of the processing are the same as described above.
[0068]
FIG. 10 is a flowchart of the aberration measurement in the second embodiment. FIG. 10 shows an example in which an optical system including a long focus or high sensitivity first measurement unit 25A and a short focus or low sensitivity second measurement unit 25B as shown in FIG. 2 or FIG. 13 is a flowchart of aberration measurement for determining a compensation amount based on a signal from a low-sensitivity second light receiving optical system 20B. The calculation unit 600 quickly obtains the compensation amount M of the compensation optical unit 60 based on the signal of the second measurement unit 25B, and converts the light beam whose aberration has been compensated by the compensation optical unit 60 into a long focus or high sensitivity first light. Highly sensitive and high-speed measurement is enabled by performing precise measurement with the measuring unit 25A.
[0069]
First, the calculation unit 600 performs the aberration measurement 1 based on the signal from the short focus or low sensitivity second measurement unit 25B (S251). The calculation unit 600 acquires the Hartmann image from the second light receiving unit 21B of the second measurement unit 25B, and detects the center of gravity of the spot image based on the acquired image. By searching for a barycentric position corresponding to the spot in a rectangular area centered on the barycentric point with no aberration, the correspondence is made so that high speed is possible. The calculation unit 600 obtains a coarse aberration of the subject's eye 100 based on the obtained center of gravity of the spot image.
[0070]
Next, the arithmetic part 600 performs the processing of steps S103 and S105. Details of the processing are the same as those described above, and will not be described.
[0071]
The calculation unit 600 performs the second aberration measurement based on the signal from the first measurement unit 25A having a long focus or high sensitivity (S257). The calculation unit 600 receives the first signal of the Hartmann image from the first light receiving unit 21A of the first measurement unit 25A. Next, the calculation unit 600 obtains a point image movement amount of the Hartmann image from the input first signal, and obtains an optical characteristic of the eye 100 based on the point image movement amount. In the aberration measurement using the conventional long focal point or high sensitivity measurement unit, the displacement of the spot image may be large, and it may take time to associate the spot image, or the measurement may not be performed due to lack of correspondence. In the present embodiment, since the input first signal of the Hartmann image is a Hartmann image in which the aberration of the subject's eye 100 is canceled out to some extent, even if it has a long focus or high sensitivity, the spot displacement is small. As a result, accurate and high-speed aberration calculation is possible.
[0072]
Next, arithmetic unit 600 performs the processing of steps S109 to S115. Details of the processing are the same as those described above, and will not be described.
[0073]
After determining the amount of compensation based on the signal from the short-focus or low-sensitivity second light receiving optical system 20B, the computing unit 600 can simulate the aberration and the amount of movement of the point image after compensation in real time. The calculation unit 600 can predict the point image obtained from the first measurement unit 25A from the measurement result obtained in the second measurement unit 25B. The same relationship holds between the movement amount of the point image and the Zernike coefficient as in the following equation.
[0074]
(Equation 8)

(F: Distance between the Hartmann plate of the first measurement unit 25A and the CCD)
[0075]
The aberration measured by the first measurement unit 25A after the compensation can be predicted as a difference between the aberration measured by the second measurement unit 25B and the compensated aberration, although there is a difference due to the measurement accuracy. If the aberration after the compensation can be predicted, the movement amount of the point image received by the first light receiving unit 20A can be predicted by using the above equation in reverse. In practice, the compensated aberration prediction is W_eThen, the moving amount of the point image can be calculated by the following equation.
[0076]
(Equation 9)

[0077]
When the compensation optical unit 60 is deformed so as to completely cancel the aberration measured by the second measurement unit 25B, the aberration prediction after compensation disappears (becomes 0), but the Hartmann plate does not completely cancel the aberration. When the incident light to the divergent direction is set to be divergent or inclined, the first light receiving optical system 20A having higher measurement speed, longer focus, or higher sensitivity can be obtained by associating a point image with reference to Expression 9. The used measurement becomes possible.
[0078]
FIG. 11 is a first modified example of the flowchart of the aberration measurement in the second embodiment. This modified example is an example in which the aberration calculation of the eye 100 to be inspected and the output of the calculation result are performed every aberration measurement after compensation. Since the processing of each step is the same as the processing shown in FIGS. 9 and 10, the same reference numerals are given and the detailed description thereof will be omitted.
[0079]
FIG. 12 is a second modification of the flowchart of the aberration measurement according to the second embodiment. In the present modified example, the light beam whose aberration has been compensated for using the optical system shown in FIG. 3 is received by the second light receiving unit 21B, and the aberration obtained based on the signal from the second light receiving unit 21B has a predetermined tolerance. This is an example in which compensation is performed so as to be equal to or less than the value.
[0080]
First, the calculation unit 600 executes each processing of steps S251, S103, and S105. Details of the processing are the same as those described above, and a description thereof will be omitted. Next, the calculation section 600 measures the compensated aberration based on the signal from the second measurement section 25B (S253). The details of the processing are the same as in step S251 described above, and a description thereof will not be repeated. The calculation unit 600 determines whether the aberration obtained in step S253 is equal to or less than a predetermined first allowable value (S255). For example, the calculation unit 600 may determine whether the RMS value of the higher-order aberration is 0.1 or less. When the aberration is larger than the first allowable value, the calculation unit 600 returns to step S105, and further distorts the adaptive optics unit 65. On the other hand, when the aberration is smaller than the first allowable value, the calculation unit 600 proceeds to the process of step S257.
[0081]
In addition, instead of determining whether the aberration is equal to or less than the first allowable value, the arithmetic unit 600 receives the first signal from the first light receiving unit 21A and determines whether measurement based on the first signal is possible. good. For example, the arithmetic unit 600 cannot obtain the center of gravity position of each point image based on the input first signal by a predetermined number or more (for example, one third or more), or each point image has a large blur (for example, when there is no aberration). Is determined to be impossible to measure based on the first signal due to one or more predetermined conditions such as a predetermined number or more points that cannot be detected because they cannot be separated from an adjacent spot image. can do. In addition, an appropriate condition may be used as the determination condition. Here, when the arithmetic unit 600 determines that measurement is not possible, the process proceeds to step S105, and when it determines that measurement is possible, the process proceeds to step S257.
[0082]
The calculation unit 600 performs the process of step S257. Details of the processing are the same as those described above, and a description thereof will be omitted. Next, the calculation unit 600 determines whether the aberration 2 obtained in step S257 is equal to or smaller than a predetermined second allowable value (S259). For example, the calculation unit 600 may determine whether the RMS value of the higher-order aberration is 0.1 or less. Further, the first allowable value and the second allowable value can take different values. For example, considering the sensitivity of the measurement, the first allowable value may be equal to or larger than the second allowable value. When the aberration 2 is larger than the second allowable value (S259), the calculation unit 600 further deflects the adaptive optics unit 60 according to the aberration 2 (S261), and returns to step S257. The details of the process of distorting the adaptive optics unit 60 are the same as in step S105. On the other hand, when the aberration 2 is smaller than the second allowable value, the calculation unit 600 proceeds to the process of step S111.
[0083]
Next, the arithmetic unit 600 performs the processing of steps S111 to S115. Details of the processing are the same as those described above, and will not be described.
[0084]
【The invention's effect】
According to the present invention, the optical characteristics of the eye 100 can be precisely measured by canceling a part of the aberration by the adaptive optics unit and measuring the remaining aberration with high accuracy. Further, according to the present invention, optical characteristics can be measured more precisely and at higher speed by using low-sensitivity and high-sensitivity optical systems. Furthermore, according to the present invention, even for the subject's eye 100 having large aberration and incapable of high-sensitivity measurement, a certain degree of aberration can be compensated based on measurement with low sensitivity or optical characteristics near the cornea. Highly sensitive measurement can be performed. Further, according to the present invention, an eye characteristic measuring device having a wide measuring range can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an optical system of an eye characteristic measuring apparatus.
FIG. 2 is a second configuration diagram of an optical system of the eye characteristic measuring device.
FIG. 3 is a third configuration diagram of an optical system of the eye characteristic measuring device.
FIG. 4 is a configuration diagram of an optical system for double-pass measurement.
FIG. 5 is a configuration diagram of an electric system of the eye characteristic measuring device.
FIG. 6 is a flowchart of aberration measurement.
FIG. 7 is a flowchart of aberration compensation when optical characteristics of an eye to be inspected cannot be obtained from a Hartmann image.
FIG. 8 is an explanatory diagram of a relationship between coordinates on a deformable mirror and coordinates of an optical system.
FIG. 9 is a modified example of the flowchart of the aberration measurement.
FIG. 10 is a flowchart of aberration measurement according to the second embodiment.
FIG. 11 is a first modified example of the flowchart of the aberration measurement in the second embodiment.
FIG. 12 is a second modified example of the flowchart of the aberration measurement in the second embodiment.
FIG. 13 shows a Zernike polynomial (1).
FIG. 14 is a Zernike polynomial (2).
[Explanation of symbols]
10 ° first illumination optical system
11 First light source unit
20A @ 1st light receiving optical system
21A @ 1st light receiving section
25A First measurement unit
20B @ 2nd light receiving optical system
21B second light receiving unit
25B @ 2nd measuring part
30 ° anterior eye observation unit
40 anterior eye lighting section
50 ° first adjustment optical unit
60 ° adaptive optics
70 ° second adjustment optical unit
90 ° optotype optical unit
600 calculation unit
610 control unit
650 input section
700 mm display
800 memory

Claims (12)

A first light source unit that emits a light beam of a first wavelength;
A first illumination optical system for illuminating a minute area on the retina of the eye with the light beam from the first light source unit;
A second part for receiving a part of the reflected light beam reflected from the retina to be examined through a first conversion member having a long focal point or a highly sensitive lens part that converts at least substantially 17 beams. One light receiving optical system,
A second part for receiving light via a second conversion member having a short focus or low sensitivity lens unit that converts a part of the reflected light flux reflected from the retina of the subject's eye and returned to at least substantially 17 beams. Two light receiving optical systems,
A first light receiving unit that receives a light beam received by the first light receiving optical system;
A second light receiving unit that receives a light beam received by the second light receiving optical system;
A compensation amount calculation unit that calculates and outputs a compensation amount for canceling aberration based on an output of the first light receiving unit and / or the second light receiving unit;
A compensating optical unit disposed in the first and / or second light receiving optical system and compensating aberration of a light beam passing or reflected according to the compensation amount output from the compensation amount calculating unit;
The optical characteristics of the eye to be inspected are determined in consideration of the optical characteristics based on the output of the first light receiving unit and / or the second light receiving unit after the compensation by the compensation optical unit and the optical characteristics compensated by the compensation optical unit. An eye characteristic measurement device comprising a measurement calculation unit. In the second light receiving optical system, the change in the beam converted by the second conversion member over the measurable range is set smaller than the conversion pitch of the second conversion member. As a result, signal processing is easy and The eye characteristic measuring device according to claim 1, wherein the eye characteristic measuring device is configured to be able to achieve high speed. The compensation amount calculation unit obtains and outputs an aberration compensation amount based on the output of the second light receiving unit,
The measurement calculation unit is configured to obtain the optical characteristics of the eye to be examined with high sensitivity in consideration of the optical characteristics based on the output of the first light receiving unit and the optical characteristics compensated by the compensation optical unit. Item 3. The eye characteristic measuring device according to item 1 or 2. 4. The compensation amount calculation unit according to claim 1, wherein the compensation amount calculation unit calculates the compensation amount so as not to completely cancel the aberration obtained from the output of the first light receiving unit and / or the second light receiving unit. An eye characteristic measuring device according to any one of the above. The eye characteristic measuring apparatus according to any one of claims 1 to 4, wherein the compensation optical unit is configured to perform compensation including at least a higher-order component of the optical characteristics of the eye to be inspected. The compensation amount calculation unit can compensate the spherical power component, which is a low-order aberration, by moving the first and second light receiving optical systems based on the output of the first and / or second light receiving unit. The eye characteristic measuring device according to claim 1, wherein the eye characteristic measuring device is configured as described above. A first light source unit that emits a light beam of a first wavelength;
A first illumination optical system for illuminating a minute area on the retina of the eye with the light beam from the first light source unit;
A first light receiving optical system for receiving a part of the reflected light flux reflected from the retina of the subject's eye and returning through at least substantially a first conversion member that converts the light into 17 beams;
A first light receiving unit that receives a light beam received by the first light receiving optical system;
A second light source unit that emits a light beam of a second wavelength;
A second illumination optical system that illuminates the vicinity of the cornea of the eye to be examined in a predetermined pattern with a light beam from the second light source unit;
A third light receiving unit that receives a reflected light beam that is reflected from the vicinity of the cornea of the subject's eye and returns,
A third light receiving optical system that guides the reflected light flux from near the cornea to the third light receiving unit;
A compensation amount calculating unit that determines an optical characteristic of the subject's eye from the output of the third light receiving unit, determines a compensation amount for canceling aberration based on the optical characteristic, and outputs the compensation amount;
A compensating optical unit disposed in the first light receiving optical system and compensating for aberration of a light beam passing or reflected according to the compensation amount output from the compensation amount calculating unit;
An eye characteristic including a measurement calculation unit for determining an optical characteristic of the eye to be examined in consideration of an optical characteristic based on an output of the first light receiving unit after compensation by the compensation optical unit and an optical characteristic compensated by the compensation optical unit; measuring device. The eye characteristic measuring device according to claim 7, wherein the measurement calculation unit is further configured to obtain a corneal shape of the subject's eye based on an output from the third light receiving unit. 9. The eye characteristic measuring device according to claim 1, wherein the adaptive optics unit is configured by at least one of a liquid crystal spatial light modulator and a variable mirror. The said 1st illumination optical system has the light beam incident position change part which can change the position where the thin beam for illumination injects into an anterior eye part of a to-be-tested eye in the direction orthogonal to an optical axis. An eye characteristic measuring device according to any one of the above. The first illumination optical system is configured to illuminate a minute area on the retina of the eye with a light beam from the first light source unit with a wide beam when passing through the cornea of the eye. The eye characteristic measuring device according to any one of claims 1 to 10, wherein The optical characteristic of the eye to be inspected is displayed on a display unit after the compensation by the compensation optical unit, and the aberration is further compensated by the compensation amount calculation unit and the compensation optical unit according to an instruction from an input unit. An eye characteristic measuring device according to any one of 1 to 11.

Images