JP4109088B2 - Measuring method and measuring device - Google Patents

Description

試料の誘電率ε_Ｓ が分かれば、所定の較正曲線等に基づいて試料中の特定物質の濃度が分かるので、結局、上記反射光強度が低下する入射角θ_ＳＰを知ることにより、試料の誘電率つまりは屈折率に関連する特性を求めることができる。
【００１０】
また、全反射減衰（ＡＴＲ）を利用する類似のセンサーとして、例えば非特許文献１に記載がある漏洩モードセンサーも知られている。この漏洩モードセンサーは基本的に、例えばプリズム状に形成された誘電体ブロックと、この誘電体ブロックの一面に形成されたクラッド層と、このクラッド層の上に形成されて、試料に接触させられる光導波層と、光ビームを発生させる光源と、上記光ビームを上記誘電体ブロックに対して、該誘電体ブロックとクラッド層との界面で全反射条件が得られ、かつ光導波層での導波モードの励起による全反射減衰が生じ得るように種々の角度で入射させる入射光学系と、上記界面で全反射した光ビームの強度を測定して導波モードの励起状態、つまり全反射減衰状態を検出する光検出手段とを備えてなるものである。
【００１１】
上記構成の漏洩モードセンサーにおいて、光ビームを誘電体ブロックを通してクラッド層に対して全反射角以上の入射角で入射させると、このクラッド層を透過した後に光導波層においては、ある特定の波数を有する特定入射角の光のみが導波モードで伝搬するようになる。こうして導波モードが励起されると、入射光のほとんどが光導波層に取り込まれるので、上記界面で全反射する光の強度が鋭く低下する全反射減衰が生じる。そして導波光の波数は光導波層の上の試料の屈折率に依存するので、全反射減衰が生じる上記特定入射角を知ることによって、試料の屈折率や、それに関連する試料の特性を分析することができる。
【００１２】
【特許文献１】
特開平０６−１６７４４３号
【００１３】
【非特許文献１】
「分光研究」第４７巻 第１号（１９９８）
第２１〜２３頁および第２６〜２７頁
【００１４】
【発明が解決しようとする課題】
ところで、以上説明したタイプの従来の表面プラズモンセンサーや漏洩モードセンサー等の測定装置においては、装置内の誘電体ブロック周囲の温度によって、試料の屈折率が変化してしまうため、測定を行う際には一定の温度環境下で行う必要がある。
【００１５】
しかしながら、測定時に、誘電体ブロックに光ビームを照射し続けることにより、誘電体ブロック周囲の温度上昇が生じ、それにより試料の屈折率が変化するため、検出信号のドリフトの原因となっていた。
【００１６】
本発明は、上記事情に鑑みてなされたものであり、検出信号に対してドリフト現象を生じさせない測定方法および測定装置を提供することを目的とするものである。
【００１７】
【課題を解決するための手段】
本発明の第１の測定方法は、試料に接触させられる薄膜層が一面に形成された誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られるように光ビームを種々の角度で入射させ、前記界面で全反射した光ビームの強度を測定して、全反射減衰の状態を検知する測定方法において、誘電体ブロックの温度変動を抑制するために、光ビームを誘電体ブロックに間歇的に照射して測定を行うことを特徴とするものである。
【００１８】
また、本発明の第２の測定方法は、誘電体ブロックと、この誘電体ブロックの一面に形成されて、試料に接触させられる薄膜層と、光ビームを発生させる光源と、光ビームを誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られる入射角で入射させる入射光学系と、複数の受光素子からなり、前記界面で全反射した光ビームの強度を測定する光検出手段とを備えてなる測定装置により試料の分析を行う測定方法において、光ビームを誘電体ブロックに間歇的に照射し、複数の受光素子をいくつかの受光素子群に分割し、隣接する２つの受光素子群毎にそれぞれの出力の合計を受光素子の並設方向に関して微分し、この微分値に基づいて前記界面での反射光強度が極小値を取る反射角を求める処理を、入射光学系と誘電体ブロックとを、前記界面における光ビームの入射位置が変化するように相対移動させて、光ビームの入射位置が相異なる状態のときにそれぞれ行い、得られた複数通りのデータを統計処理して、反射角に対応する１つの代表データを取得し、一連の時系列で得られた複数の代表データをスムージングし、このスムージングした複数の測定データに基づいて試料の分析を行うことを特徴とするものである。
【００１９】
また、本発明の第３の測定方法は、誘電体ブロックと、この誘電体ブロックの一面に形成されて、試料に接触させられる薄膜層と、光ビームを発生させる光源と、光ビームを誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られる入射角で入射させる入射光学系と、複数の受光素子からなり、前記界面で全反射した光ビームの強度を測定する光検出手段とを備えてなる測定装置により試料の分析を行う測定方法において、光ビームを誘電体ブロックに間歇的に照射し、隣接する２つ以上の所定数の受光素子それぞれの出力の平均値を、受光素子の並設方向に順次算出し、平均値を受光素子の並設方向に関して微分し、この微分値に基づいて前記界面での反射光強度が極小値を取る反射角を求める処理を、入射光学系と誘電体ブロックとを、前記界面における光ビームの入射位置が変化するように相対移動させて、光ビームの入射位置が相異なる状態のときにそれぞれ行い、得られた複数通りのデータを統計処理して、反射角に対応する１つの代表データを取得し、一連の時系列で得られた複数の代表データをスムージングし、このスムージングした複数の測定データに基づいて試料の分析を行うことを特徴とするものである。
【００２０】
また、本発明の第４の測定方法は、誘電体ブロックと、この誘電体ブロックの一面に形成されて、試料に接触させられる薄膜層と、光ビームを発生させる光源と、光ビームを誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られる入射角で入射させる入射光学系と、複数の受光素子からなり、前記界面で全反射した光ビームの強度を測定する光検出手段とを備えてなる測定装置により試料の分析を行う測定方法において、光ビームを前記界面上の相異なる複数の入射位置に間歇的に照射し、複数の受光素子をいくつかの受光素子群に分割し、隣接する２つの受光素子群毎にそれぞれの出力の合計を受光素子の並設方向に関して微分し、この微分値に基づいて前記界面での反射光強度が極小値を取る反射角を求める処理を、光ビームの入射位置が相異なる状態のときにそれぞれ行い、得られた複数通りのデータを統計処理して、反射角に対応する１つの代表データを取得し、一連の時系列で得られた複数の代表データをスムージングし、このスムージングした複数の測定データに基づいて試料の分析を行うことを特徴とするものである。
【００２１】
さらに、本発明の第５の測定方法は、誘電体ブロックと、この誘電体ブロックの一面に形成されて、試料に接触させられる薄膜層と、光ビームを発生させる光源と、光ビームを誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られる入射角で入射させる入射光学系と、複数の受光素子からなり、前記界面で全反射した光ビームの強度を測定する光検出手段とを備えてなる測定装置により試料の分析を行う測定方法において、光ビームを前記界面上の相異なる複数の入射位置に間歇的に照射し、隣接する２つ以上の所定数の受光素子それぞれの出力の平均値を、受光素子の並設方向に順次算出し、平均値を受光素子の並設方向に関して微分し、この微分値に基づいて前記界面での反射光強度が極小値を取る反射角を求める処理を、光ビームの入射位置が相異なる状態のときにそれぞれ行い、得られた複数通りのデータを統計処理して、反射角に対応する１つの代表データを取得し、一連の時系列で得られた複数の代表データをスムージングし、このスムージングした複数の測定データに基づいて試料の分析を行うことを特徴とするものである。
【００２２】
上記第１から第５の測定方法においては、前記界面での光ビームの反射光強度の測定による光ビームの照射開始からの過渡応答時間が経過した後、測定を開始することが望ましい。ここで、「過渡応答時間」とは、光ビームの照射を開始してから、前記界面で全反射した光ビームの検出信号の出力が略一定になるまでの時間を意味する。
【００２３】
本発明の第１から第５の測定装置は、上記第１から第５の測定方法に用いられるものであって、本発明の第１の測定装置は、誘電体ブロックと、この誘電体ブロックの一面に形成されて、試料に接触させられる薄膜層と、光ビームを発生させる光源と、光ビームを誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られるように種々の角度で入射させる入射光学系と、前記界面で全反射した光ビームの強度を測定して、全反射減衰の状態を検知する光検出手段とを備えてなる測定装置において、光ビームを誘電体ブロックに間歇的に照射させるための間歇照射手段を備えたことを特徴とするものである。
【００２４】
また、本発明の第２の測定装置は、誘電体ブロックと、この誘電体ブロックの一面に形成されて、試料に接触させられる薄膜層と、光ビームを発生させる光源と、光ビームを誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られるように種々の角度で入射させる入射光学系と、複数の受光素子からなり、前記界面で全反射した光ビームの強度を測定して、全反射減衰の状態を検知する光検出手段とを備えてなる測定装置において、光ビームを誘電体ブロックに間歇的に照射させるための間歇照射手段と、入射光学系と誘電体ブロックとを、前記界面における光ビームの入射位置が変化するように相対移動させる手段と、複数の受光素子をいくつかの受光素子群に分割し、隣接する２つの受光素子群毎にそれぞれの出力の合計を受光素子の並設方向に関して微分し、この微分値に基づいて前記界面での反射光強度が極小値を取る反射角を求める処理を、光ビームの入射位置が相異なる状態のときにそれぞれ行い、得られた複数通りのデータを統計処理して、反射角に対応する１つの代表データを得る演算手段と、演算手段により一連の時系列で検出された複数の代表データをスムージング処理するスムージング処理手段とを備えてなることを特徴とするものである。
【００２５】
また、本発明の第３の測定装置は、誘電体ブロックと、この誘電体ブロックの一面に形成されて、試料に接触させられる薄膜層と、光ビームを発生させる光源と、光ビームを誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られるように種々の角度で入射させる入射光学系と、複数の受光素子からなり、前記界面で全反射した光ビームの強度を測定して、全反射減衰の状態を検知する光検出手段とを備えてなる測定装置において、光ビームを誘電体ブロックに間歇的に照射させるための間歇照射手段と、入射光学系と誘電体ブロックとを、前記界面における光ビームの入射位置が変化するように相対移動させる手段と、隣接する２つ以上の所定数の受光素子それぞれの出力の平均値を、受光素子の並設方向に順次算出し、平均値を受光素子の並設方向に関して微分し、この微分値に基づいて前記界面での反射光強度が極小値を取る反射角を求める処理を、光ビームの入射位置が相異なる状態のときにそれぞれ行い、得られた複数通りのデータを統計処理して、反射角に対応する１つの代表データを得る演算手段と、演算手段により一連の時系列で検出された複数の測定データをスムージング処理するスムージング処理手段とを備えてなることを特徴とするものである。
【００２６】
また、本発明の第４の測定装置は、誘電体ブロックと、この誘電体ブロックの一面に形成されて、試料に接触させられる薄膜層と、光ビームを発生させる光源と、光ビームを誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られるように種々の角度で入射させる入射光学系と、複数の受光素子からなり、前記界面で全反射した光ビームの強度を測定して、全反射減衰の状態を検知する光検出手段とを備えてなる測定装置において、光ビームを誘電体ブロックに間歇的に照射させるための間歇照射手段と、入射光学系が、光ビームを前記界面上の相異なる複数の入射位置に入射可能に形成されるとともに、複数の受光素子をいくつかの受光素子群に分割し、隣接する２つの受光素子群毎にそれぞれの出力の合計を受光素子の並設方向に関して微分し、この微分値に基づいて前記界面での反射光強度が極小値を取る反射角を求める処理を、光ビームの入射位置が相異なる状態のときにそれぞれ行い、得られた複数通りのデータを統計処理して、反射角に対応する１つの代表データを得る演算手段と、演算手段により一連の時系列で検出された複数の測定データをスムージング処理するスムージング処理手段とを備えてなることを特徴とするものである。
【００２７】
さらに、本発明の第５の測定装置は、誘電体ブロックと、この誘電体ブロックの一面に形成されて、試料に接触させられる薄膜層と、光ビームを発生させる光源と、光ビームを誘電体ブロックに対して、誘電体ブロックと薄膜層との界面で全反射条件が得られるように種々の角度で入射させる入射光学系と、複数の受光素子からなり、前記界面で全反射した光ビームの強度を測定して、全反射減衰の状態を検知する光検出手段とを備えてなる測定装置において、光ビームを誘電体ブロックに間歇的に照射させるための間歇照射手段と、入射光学系が、光ビームを前記界面上の相異なる複数の入射位置に入射可能に形成されるとともに、隣接する２つ以上の所定数の受光素子それぞれの出力の平均値を、受光素子の並設方向に順次算出し、平均値を受光素子の並設方向に関して微分し、この微分値に基づいて前記界面での反射光強度が極小値を取る反射角を求める処理を、光ビームの入射位置が相異なる状態のときにそれぞれ行い、得られた複数通りのデータを統計処理して、反射角に対応する１つの代表データを得る演算手段と、演算手段により一連の時系列で検出された複数の測定データをスムージング処理するスムージング処理手段とを備えてなることを特徴とするものである。
【００２８】
上記のような測定装置としては、金属膜を上記薄膜層として用いる前述の表面プラズモン測定装置や、誘電体ブロックの一面に形成されたクラッド層と、このクラッド層の上に形成された光導波層とからなる層を上記薄膜層として用いる前述の漏洩モード測定装置等がある。
【００２９】
本発明の第１から第５の測定装置において、光検出手段により前記界面で全反射した光ビームの強度を測定して試料の分析を行うには種々の方法があり、例えば、光ビームを前記界面で全反射条件が得られる種々の入射角で入射させ、各入射角に対応した位置毎に前記界面で全反射した光ビームの強度を測定して、全反射減衰により発生した暗線の位置（角度）を検出することにより試料分析を行ってもよいし、D.V.Noort,K.johansen,C.-F.Mandenius, Porous Gold in Surface Plasmon Resonance Measurement, EUROSENSORS XIII, 1999, pp.585-588 に記載されているように、複数の波長の光ビームを前記界面で全反射条件が得られる入射角で入射させ、各波長毎に前記界面で全反射した光ビームの強度を測定して、各波長毎の全反射減衰の程度を検出することにより試料分析を行ってもよい。
【００３０】
また、本発明の第１の測定装置においては、P.I.Nikitin,A.N.Grigorenko,A.A.Beloglazov,M.V.Valeiko,A.I.Savchuk,O.A.Savchuk, Surface Plasmon Resonance Interferometry for Micro-Array Biosensing, EUROSENSORS XIII, 1999, pp.235-238 に記載されているように、光ビームを前記界面で全反射条件が得られる入射角で入射させるとともに、この光ビームの一部を、この光ビームが前記界面に入射する前に分割し、この分割した光ビームを、前記界面で全反射した光ビームと干渉させて、その干渉後の光ビームの強度を測定することにより試料分析を行ってもよい。
【００３１】
本発明において、「複数の受光素子をいくつかの受光素子群に分割し、隣接する２つの受光素子群毎にそれぞれの出力の合計を受光素子の並設方向に関して微分する」とは、各受光素子群の出力を合計した後に、隣接する２つの受光素子群毎にそれぞれの出力の合計を受光素子の並設方向に関して微分する場合に限らず、隣接する２つの受光素子群の受光素子をそれぞれ１つずつ受光素子の並設方向に関して微分した後に、この微分値を合計する等、結果的に同じ微分値が得られるのであれば計算の過程はどのようなものであってもよい。
【００３２】
例えば１番の受光素子から６番の受光素子まで順に並んだ６個の受光素子を、１番から３番の受光素子からなる第１の受光素子群と、４番から６番の受光素子からなる第２の受光素子群に分割し、この受光素子群の出力の合計を受光素子の並設方向に関して微分する場合、第１の受光素子群の１番から３番の受光素子のそれぞれの受光素子の出力を合計し、第２の受光素子群の４番から６番の受光素子のそれぞれの受光素子の出力を合計し、第１の受光素子群の出力の合計と第２の受光素子群の出力の合計とを受光素子の並設方向に関して微分してもよいし、１番と４番の受光素子、２番と５番の受光素子、３番と６番の受光素子の出力をそれぞれ受光素子の並設方向に関して微分し、この３つの微分値を合計してもよい。あるいは、１番と６番の受光素子の出力の差分、２番と５番の受光素子の出力の差分、３番と４番の受光素子の出力の差分を合計し、受光素子群間の距離、この場合には受光素子３つ分に相当する距離で除算してもよい。
【００３３】
また、「隣接する２つ以上の所定数の受光素子それぞれの出力の平均値を、受光素子の並設方向に順次算出し、平均値を受光素子の並設方向に関して微分する」とは、各所定数の受光素子の出力の平均値を算出した後に、該平均値を前記受光素子の並設方向に関して微分する場合に限らず、例えば、まず隣接する２つの受光素子間の微分値を求め、次に連続した所定数の微分値の平均値を、前記受光素子の並設方向に順次算出する等、結果的に同じ微分値が得られるのであれば計算の過程はどのようなものであってもよい。
【００３４】
例えば１番の受光素子から４番の受光素子まで順に並んだ４個の受光素子から、隣接する３つの受光素子それぞれの出力の平均値を、前記受光素子の並設方向に順次算出し、該平均値を前記受光素子の並設方向に関して微分する場合、１番から３番までの受光素子の出力の平均値と、２番から４番までの受光素子の出力の平均値とを求め、この平均値を受光素子の並設方向に関して微分してもよいし、１番と２番の受光素子、２番と３番の受光素子、３番と４番の受光素子の出力をそれぞれ受光素子の並設方向に関して微分し、これらの微分値の平均値を求めてもよい。なお、「隣接する２つ以上の所定数の受光素子それぞれの出力の平均値」とは、平均値そのものに限定されるものではなく、平均値を反映する値であればよく、例えば所定数の受光素子それぞれの出力の合計値や、この合計値を所望の値で除算した値、あるいは合計値に所望の値を乗算した値等であってもよい。
【００３５】
また、「微分値に基づいて前記界面での反射光強度が極小値を取る反射角を求める」とは、極小値を取る反射角そのものを求めることに限定されるものではなく、極小値を取る反射角を反映する値、例えば極小値を取る反射角近傍の微分値などを求める場合も含むものである。なお、「極小値」とは、全反射減衰の状態を反映して生じる極小値を意味し、ノイズ等の影響により生じるものは含まない。
【００３６】
また、「スムージング（処理）」とは、各受光素子の感度特性に起因する測定誤差を低減させるための処理であって、例えば、最小二乗法により一連の時系列で検出された複数の測定データの値と真値の推定値との誤差を低減させてもよいし、連続的に検出した光検出手段の出力信号からロー・パス・フィルタ（ＬＰＦ）、ハイ・パス・フィルタ（ＨＰＦ）またはバンド・パス・フィルタ（ＢＰＦ）等の周波数フィルタを用いて余分な周波数成分をカットしてもよい。
【００３７】
上記の測定装置において、間歇照射手段は、光源と誘電体ブロックとの間に設けられ、光源から誘電体ブロックに至る光路を間歇的に開閉するシャッターとしてもよいし、光源を間歇的に駆動する光源駆動手段としてもよい。ここで、間歇照射手段を光源駆動手段とした場合には、光源に、発生させる光ビームの波長を安定化させる発振波長安定化手段を備えたものとすることが好ましい。
【００３８】
ところで、測定に用いる代表的な溶媒の温度変化に対する屈折率変化の比（ｄｎ／ｄｔ）は４．５×１０^−４であり、屈折率変化を１０^−４に抑えるためには、温度変化を最低でも１℃以下に抑える必要がある。
【００３９】
そのため、間歇照射手段は、光ビームによる試料の温度変化を０．５℃以下とするように駆動することが好ましく、また、温度変化を０．１℃以下とするとより好ましい。
【００４０】
また、光検出手段は、前記界面での光ビームの反射光強度の測定による光ビームの照射開始からの過渡応答時間が経過した後、測定を開始することが望ましい。
【００４１】
【発明の効果】
本発明の第１の測定方法および測定装置は、誘電体ブロックに間歇的に光ビームを照射するようにして誘電体ブロックに光ビームが照射される時間を短縮させたため、光ビームの照射による試料および試料に影響する誘電体ブロックの温度変化を抑えることができるため、検出信号に対してドリフト現象を生じさせないようにすることができる。
【００４２】
また、本発明の第２および第４の測定方法および測定装置は、上記第１の測定方法および測定装置の効果に加えて、複数の受光素子をいくつかの受光素子群に分割し、隣接する２つの受光素子群毎にそれぞれの出力の合計を受光素子の並設方向に関して微分し、この微分値に基づいて、前記界面での反射光強度が極小値を取る反射角を求めるようにしたので、サイズが小さい受光素子を用いる場合であっても、全反射減衰角θ_ＳＰを算出する際には、複数の受光素子をいくつかの受光素子群に分割し、この受光素子群毎に出力を合計するため、微分する際の信号の出力を大きくすることができる。そのため、配列ピッチが細かい受光素子アレイを用いることができるようになるので、これにより高い解像度でビームプロファイルを検出できるとともに、全反射減衰角θ_ＳＰを正確に算出することができる。
【００４３】
また、誘電体ブロックと薄膜層との界面における光ビームの反射角の測定の際に、光ビームの入射位置が相異なる複数の状態のデータを統計処理して、反射角に対応する１つの代表データを得るように構成されているので、この代表データは、薄膜層の膜厚やセンシング物質の反応特性が特異的に異なることや、さらにはゴミ等の外乱に起因する変動を排除したものとなり得る。したがって、薄膜層の膜厚やセンシング物質の反応特性が不均一であったり、薄膜層上にゴミが存在する等していても、それらによる測定結果のバラツキを防止することができる。
【００４４】
さらに、一連の時系列で得られた複数の代表データをスムージングすることにより、光検出手段の各受光素子の感度特性に起因する測定誤差を低減することができるため、測定精度を向上させることができる。
【００４５】
また、本発明の第３および第５の測定方法および測定装置は、上記第１の測定方法および測定装置の効果に加えて、隣接する２つ以上の所定数の受光素子それぞれの出力の平均値を、受光素子の並設方向に順次算出し、平均値を受光素子の並設方向に関して微分し、この微分値に基づいて、前記界面での反射光強度が極小値を取る反射角を求めるようにしたので、サイズが小さい受光素子を用いる場合あるいは受光素子が受光する光量が少ない場合であっても、ノイズの影響を受けにくく、精度よく反射光強度が極小値を取る反射角、すなわち全反射減衰角θ_ＳＰを求めることができる。また、受光素子数と同数の平均値を算出することができ、高い解像度で全反射減衰角θ_ＳＰを求めることができる。またこの平均値を用いて、高い解像度のビームプロファイルを得ることができる。
【００４６】
また、誘電体ブロックと薄膜層との界面における光ビームの反射角の測定の際に、光ビームの入射位置が相異なる複数の状態のデータを統計処理して、反射角に対応する１つの代表データを得るように構成されているので、この代表データは、薄膜層の膜厚やセンシング物質の反応特性が特異的に異なることや、さらにはゴミ等の外乱に起因する変動を排除したものとなり得る。したがって、薄膜層の膜厚やセンシング物質の反応特性が不均一であったり、薄膜層上にゴミが存在する等していても、それらによる測定結果のバラツキを防止することができる。
【００４７】
さらに、一連の時系列で得られた複数の代表データをスムージングすることにより、光検出手段の各受光素子の感度特性に起因する測定誤差を低減することができるため、測定精度を向上させることができる。
【００４８】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態を詳細に説明する。本発明の第１の実施形態の測定装置は、表面プラズモン共鳴を利用した表面プラズモンセンサーであり、図１は表面プラズモンセンサーの側面形状を示すものである。
【００４９】
この表面プラズモンセンサーは、例えば概略四角錐の一部が切り取られた形状とされた誘電体ブロック10と、この誘電体ブロック10の一面（図中の上面）に形成された、例えば金、銀、銅、アルミニウム等からなる金属膜12とを有している。
【００５０】
誘電体ブロック10は例えば透明樹脂等からなり、金属膜12が形成された部分の周囲が嵩上げされた形とされ、この嵩上げされた部分10ａは液体の試料11を貯える試料保持部として機能する。なお本例では、金属膜12の上にセンシング媒体30が固定されるが、このセンシング媒体30については後述する。
【００５１】
誘電体ブロック10は金属膜12とともに、使い捨ての測定チップを構成しており、例えばターンテーブル31に複数設けられたチップ保持孔31ａに１個ずつ嵌合固定される。誘電体ブロック10がこのようにターンテーブル31に固定された後、ターンテーブル31が一定角度ずつ間欠的に回動され、所定位置に停止した誘電体ブロック10に対して液体試料11が滴下され、該液体試料11が試料保持部10ａ内に保持される。その後さらにターンテーブル31が一定角度回動されると、誘電体ブロック10がこの図１に示した測定位置に送られ、そこで停止する。
【００５２】
本実施形態の表面プラズモンセンサーは、上記誘電体ブロック10に加えてさらに、１本の光ビーム13を発生させる半導体レーザ等からなる光源14（以下、レーザ光源14という）と、上記光ビーム13を誘電体ブロック10に通し、該誘電体ブロック10と金属膜12との界面10ｂに対して、種々の入射角が得られるように入射させる入射光学系15と、上記界面10ｂで全反射した光ビーム13を平行光化するコリメーターレンズ16と、この平行光化された光ビーム13を検出する光検出手段17と、光検出手段17に接続された差動アンプアレイ18と、ドライバ19と、コンピュータシステム等からなる信号処理部（ＣＰＵ）20と、レーザ光源14から誘電体ブロック10に至る光路を間歇的に開閉するシャッター50とを備えている。
【００５３】
入射光学系15は、レーザ光源14から発散光状態で出射した光ビーム13を平行光化するコリメーターレンズ15ａと、該平行光化された光ビーム13を上記界面10ｂ上で収束させる集光レンズ15ｂとから構成されている。
【００５４】
光ビーム13は、集光レンズ15ｂにより上述のように集光されるので、界面10ｂに対して種々の入射角θで入射する成分を含むことになる。なおこの入射角θは、全反射角以上の角度とされる。そこで、光ビーム13は界面10ｂで全反射し、この反射した光ビーム13には、種々の反射角で反射する成分が含まれることになる。なお、上記入射光学系15は、光ビーム13を界面10ｂにデフォーカス状態で入射させるように構成されてもよい。そのようにすれば、表面プラズモン共鳴の状態検出の誤差が平均化されて、測定精度が高められる。
【００５５】
なお光ビーム13は、界面10ｂに対してｐ偏光で入射させる。そのようにするためには、予めレーザ光源14をその偏光方向が所定方向となるように配設すればよい。その他、波長板で光ビーム13の偏光の向きを制御してもよい。
【００５６】
シャッター50は、信号処理部（ＣＰＵ）20からの指示に基づいてシャッター50の開閉動作を制御する図示しないドライバを備える。なお、シャッター50が請求項で記載した間歇照射手段として機能するものである。図２（Ａ）は、シャッター50によりレーザ光源14から誘電体ブロック10に至る光路を間歇的に開閉した場合の光ビーム13の界面10ｂにおける照射強度を示す図である。シャッター50により光路を間歇的に開閉した場合、シャッター50の開閉時には光ビーム13の界面10ｂにおける照射強度が一定とならないため、シャッター50の開閉の影響を受けない期間、すなわちシャッター50が開き切ってから閉まり始めるまでの期間に測定を行うことが望ましい。また、光検出手段17で検出される信号特性は、図２（Ｂ）に示すような過渡応答特性を示す。そのため、過渡応答時間が経過してからシャッター50が閉まり始めるまでの期間に測定を行うことがより望ましい。ここで、光ビーム13による液体試料11および試料に影響する誘電体ブロック10の温度変化を０．５℃以下とするようにシャッター50を駆動させることが好ましい。さらに、温度変化を０．１℃以下とするとより精確な測定を行うことが可能となる。
【００５７】
以下、上記構成の表面プラズモンセンサーによる試料分析について説明する。
【００５８】
測定時には、信号処理部20からの信号によりシャッター50が開かれ、光ビーム13が入射光学系１５に入射される。図１に示す通り、レーザ光源14から発散光状態で出射した光ビーム13は、入射光学系15の作用により、誘電体ブロック10と金属膜12との界面10ｂ上で収束する。したがって光ビーム13は、界面10ｂに対して種々の入射角θで入射する成分を含むことになる。なおこの入射角θは、全反射角以上の角度とされる。そこで、光ビーム13は界面10ｂで全反射し、この反射した光ビーム13には、種々の反射角で反射する成分が含まれることになる。
【００５９】
界面10ｂで全反射した後、コリメーターレンズ16によって平行光化された光ビーム13は、光検出手段17により検出される。なお、本実施の形態において測定は、図２に示すように、光ビーム13の光検出手段17の検出面における信号強度が最大になるタイミングで行われる。本例における光検出手段17は、複数のフォトダイオード17ａ、17ｂ、17ｃ……が１列に並設されてなるフォトダイオードアレイであり、図１の図示面内において、平行光化された光ビーム13の進行方向に対してフォトダイオード並設方向がほぼ直角となる向きに配設されている。したがって、上記界面10ｂにおいて種々の反射角で全反射した光ビーム13の各成分を、それぞれ異なるフォトダイオード17ａ、17ｂ、17ｃ……が受光することになる。
【００６０】
図３は、この表面プラズモンセンサーの電気的構成を示すブロック図である。図示の通り上記ドライバ19は、差動アンプアレイ18の各差動アンプ18ａ、18ｂ、18ｃ……の出力をサンプルホールドするサンプルホールド回路22ａ、22ｂ、22ｃ……、これらのサンプルホールド回路22ａ、22ｂ、22ｃ……の各出力が入力されるマルチプレクサ23、このマルチプレクサ23の出力をデジタル化して信号処理部20に入力するＡ／Ｄ変換器24、マルチプレクサ23とサンプルホールド回路22ａ、22ｂ、22ｃ……とを駆動する駆動回路25、および信号処理部20からの指示に基づいて駆動回路25の動作を制御するコントローラ26から構成されている。なお、信号処理部20からコントローラ26への指示は、信号処理部20からシャッター50への指示と連動して行われる。上記フォトダイオード17ａ、17ｂ、17ｃ……の各出力は、差動アンプアレイ18の各差動アンプ18ａ、18ｂ、18ｃ……に入力される。この際、互いに隣接する２つのフォトダイオードの出力が、共通の差動アンプに入力される。したがって各差動アンプ18ａ、18ｂ、18ｃ……の出力は、複数のフォトダイオード17ａ、17ｂ、17ｃ……が出力する光検出信号を、それらの並設方向に関して微分したものと考えることができる。
【００６１】
各差動アンプ18ａ、18ｂ、18ｃ……の出力は、それぞれサンプルホールド回路22ａ、22ｂ、22ｃ……により所定のタイミングでサンプルホールドされ、マルチプレクサ23に入力される。マルチプレクサ23は、サンプルホールドされた各差動アンプ18ａ、18ｂ、18ｃ……の出力を、所定の順序に従ってＡ／Ｄ変換器24に入力する。Ａ／Ｄ変換器24はこれらの出力をデジタル化して信号処理部20に入力する。
【００６２】
図４は、界面10ｂで全反射した光ビーム13の入射角θ毎の光強度と、差動アンプ18ａ、18ｂ、18ｃ……の出力との関係を説明するものである。ここで、光ビーム13の界面10ｂへの入射角θと上記光強度Ｉとの関係は、同図（１）のグラフに示すようなものであるとする。
【００６３】
界面10ｂにある特定の入射角θ_ＳＰで入射した光は、金属膜12と液体試料11との界面に表面プラズモンを励起させるので、この光については反射光強度Ｉが鋭く低下する。つまりθ_ＳＰが全反射解消角であり、この角度θ_ＳＰにおいて反射光強度Ｉは最小値を取る。この反射光強度Ｉの低下は、図１にＤで示すように、反射光中の暗線として観察される。
【００６４】
また図４の（２）は、フォトダイオード17ａ、17ｂ、17ｃ……の並設方向を示しており、先に説明した通り、これらのフォトダイオード17ａ、17ｂ、17ｃ……の並設方向位置は上記入射角θと一義的に対応している。
【００６５】
そしてフォトダイオード17ａ、17ｂ、17ｃ……の並設方向位置、つまりは入射角θと、差動アンプ18ａ、18ｂ、18ｃ……の出力Ｉ’（反射光強度Ｉの微分値）との関係は、同図（３）に示すようなものとなる。
【００６６】
信号処理部20は、Ａ／Ｄ変換器24から入力された微分値Ｉ’の値に基づいて、差動アンプ18ａ、18ｂ、18ｃ……の中から、全反射解消角θ_ＳＰに対応する微分値Ｉ’＝０に最も近い出力が得られているもの（図４の例では差動アンプ18ｄとなる）を選択し、それが出力する微分値Ｉ’に所定の補正処理を施してから、その値を表示手段21に表示させる。なお、場合によっては微分値Ｉ’＝０を出力している差動アンプが存在することもあり、そのときは当然その差動アンプが選択される。
【００６７】
以後、所定時間が経過する毎に上記選択された差動アンプ18ｄが出力する微分値Ｉ’が、所定の補正処理を受けてから表示手段21に表示される。この微分値Ｉ’は、測定チップの金属膜12に接している物質の誘電率つまりは屈折率が変化して、図４（１）に示す曲線が左右方向に移動する形で変化すると、それに応じて上下する。したがって、この微分値Ｉ’を時間の経過とともに測定し続けることにより、金属膜12に接している物質の屈折率変化、つまりは特性の変化を調べることができる。
【００６８】
特に本実施形態では金属膜12に、液体試料11の中の特定物質と結合するセンシング媒体30を固定しており、それらの結合状態に応じてセンシング媒体30の屈折率が変化するので、上記微分値Ｉ’を測定し続けることにより、この結合状態の変化の様子を調べることができる。つまりこの場合は、液体試料11およびセンシング媒体30の双方が、分析対象の試料となる。そのような特定物質とセンシング媒体30との組合せとしては、例えば抗原と抗体等が挙げられる。
【００６９】
以上の説明から明かなように本実施形態では、光検出手段17として複数のフォトダイオード17ａ、17ｂ、17ｃ……が１列に並設されてなるフォトダイオードアレイを用いているので、液体試料11に応じて図４（１）に示す曲線が左右方向に移動する形である程度大きく変化しても、暗線検出が可能である。つまり、このようなアレイ状の光検出手段17を用いることにより、測定のダイナミックレンジを大きく確保することができる。
【００７０】
なお、複数の差動アンプ18ａ、18ｂ、18ｃ……からなる差動アンプアレイ18を用いる代わりに１つの差動アンプを設け、フォトダイオード17ａ、17ｂ、17ｃ……の各出力をマルチプレクサで切り替えて、それらのうちの隣接する２つの出力をこの１つの差動アンプに順次入力するようにしても構わない。
【００７１】
なお、液体試料11の中の特定物質とセンシング媒体30との結合状態の変化の様子を時間経過とともに調べるためには、所定時間が経過する毎の微分値Ｉ’を求めて表示するほか、最初に計測した微分値Ｉ’(0)と所定時間経過時に計測した微分値Ｉ’(t)との差ΔＩ’を求めて表示してもよい。
【００７２】
所定の測定時間経過後、信号処理部20からの信号によりシャッター50が閉じられ、レーザ光源14から誘電体ブロック10に至る光路が遮断される。
【００７３】
本実施の形態による全反射減衰を利用したセンサーによれば、レーザ光源14と入射光学系15との間にシャッター50を設けて、誘電体ブロック10に間歇的に光ビーム13を照射するようにして誘電体ブロック10に光ビーム13が照射される時間を短縮させたため、光ビーム13の照射による液体試料11および試料に影響する誘電体ブロック10の温度変化を抑えることができるため、検出信号に対してドリフト現象を生じさせないようにすることができる。
【００７４】
次に、図５を参照して本発明の第２の実施の形態について説明する。なおこの図５において、図１中の要素と同等の要素には同番号を付してあり、それらについての説明は特に必要の無い限り省略する。この第２の実施の形態の測定装置は、第１の実施の形態から、間歇照射手段を変更したものである。
【００７５】
本実施の形態の表面プラズモンセンサーは、誘電体ブロック10と、１本の光ビーム13を発生させる半導体レーザ等からなる光源14（以下、レーザ光源14という）と、上記光ビーム13を誘電体ブロック10に通し、該誘電体ブロック10と金属膜12との界面10ｂに対して、種々の入射角が得られるように入射させる入射光学系15と、上記界面10ｂで全反射した光ビーム13を平行光化するコリメーターレンズ16と、この平行光化された光ビーム13を検出する光検出手段17と、光検出手段17に接続された差動アンプアレイ18と、ドライバ19と、コンピュータシステム等からなる信号処理部（ＣＰＵ）20と、レーザ光源14を間歇的に駆動するドライバ51とを備えている。
【００７６】
なお、ドライバ51が請求項で記載した光源駆動手段、すなわち間歇照射手段として機能するものである。このドライバ51は、信号処理部（ＣＰＵ）20からの指示に基づいてレーザ光源14を駆動するものである。本実施の形態においてレーザ光源14は、ドライバ51によって間歇的に駆動されるため、発振波長を安定化させるために図示しない発振波長安定化手段を備えるものとしてもよい。この発振波長安定化手段については、特開２０００−１５５０９３号公報に記載されているようなものを用いることができる。
【００７７】
なお、本実施の形態においても、レーザ光源14のＯＮ、ＯＦＦ時における光ビーム13の界面10ｂにおける照射強度は、概ね図２（Ａ）のようになるため、レーザ光源14のＯＮ、ＯＦＦ時の影響を受けない期間、すなわちレーザ光源14が完全にＯＮ状態となってからＯＦＦするまでの期間に測定を行うことが望ましい。また、光検出手段17で検出される信号特性は、図２（Ｂ）に示すような過渡応答特性を示すため、過渡応答時間が経過してからレーザ光源14をＯＦＦするまでの期間に測定を行うことがより望ましい。ここで、光ビーム13による液体試料11および試料に影響する誘電体ブロック10の温度変化を０．５℃以下とするようにレーザ光源14を駆動させることが好ましい。さらに、温度変化を０．１℃以下とするとより精確な測定を行うことが可能となる。
【００７８】
以下、上記構成の表面プラズモンセンサーによる試料分析について説明する。
【００７９】
測定時には、ドライバ51は、信号処理部20からの信号によりレーザ光源14を駆動させる。レーザ光源14が駆動された後、上記第１の実施の形態と同様に測定が行われる。所定の測定時間経過後、ドライバ51は、信号処理部20からの信号によりレーザ光源14を停止させる。
【００８０】
上記第２の実施の形態においても第１の実施の形態と同様の効果を得ることができる。
【００８１】
次に、図６を参照して本発明の第３の実施の形態について説明する。なおこの図６において、図１中の要素と同等の要素には同番号を付してあり、それらについての説明は特に必要の無い限り省略する。
【００８２】
この第３の実施の形態の測定装置は、第１の実施の形態で説明した表面プラズモンセンサーを漏洩モードセンサーに変更したものであり、本例でも測定チップ化された誘電体ブロック10を用いるように構成されている。この誘電体ブロック10の一面（図中の上面）にはクラッド層40が形成され、さらにその上には光導波層41が形成されている。
【００８３】
誘電体ブロック10は、例えば合成樹脂やＢＫ７等の光学ガラスを用いて形成されている。一方クラッド層40は、誘電体ブロック10よりも低屈折率の誘電体や、金等の金属を用いて薄膜状に形成されている。また光導波層41は、クラッド層40よりも高屈折率の誘電体、例えばＰＭＭＡを用いてこれも薄膜状に形成されている。クラッド層40の膜厚は、例えば金薄膜から形成する場合で36.5ｎｍ、光導波層41の膜厚は、例えばＰＭＭＡから形成する場合で700ｎｍ程度とされる。
【００８４】
上記構成の漏洩モードセンサーにおいて、レーザ光源14から出射した光ビーム13を誘電体ブロック10を通してクラッド層40に対して全反射角以上の入射角で入射させると、該光ビーム13が誘電体ブロック10とクラッド層40との界面10ｂで全反射するが、クラッド層40を透過して光導波層41に特定入射角で入射した特定波数の光は、該光導波層41を導波モードで伝搬するようになる。こうして導波モードが励起されると、入射光のほとんどが光導波層41に取り込まれるので、上記界面10ｂで全反射する光の強度が鋭く低下する全反射減衰が生じる。
【００８５】
光導波層41における導波光の波数は、該光導波層41の上の液体試料11の屈折率に依存するので、全反射減衰が生じる上記特定入射角を知ることによって、液体試料11の屈折率や、それに関連する液体試料11の特性を分析することができる。そして、上記特定入射角の近傍における反射光強度Ｉや、差動アンプアレイ18の各差動アンプが出力する微分値Ｉ’に基づいて液体試料11の特性を分析することもできる。
【００８６】
上記第３の実施の形態においても第１の実施の形態と同様の効果を得ることができる。
【００８７】
次に、図７を参照して本発明の第４の実施の形態について説明する。なおこの図７において、図１中の要素と同等の要素には同番号を付してあり、それらについての説明は特に必要の無い限り省略する。
【００８８】
この第４の実施の形態の測定装置は、第２の実施の形態で説明した表面プラズモンセンサーを漏洩モードセンサーに変更したものであり、本例でも測定チップ化された誘電体ブロック10を用いるように構成されている。この誘電体ブロック10の一面（図中の上面）にはクラッド層40が形成され、さらにその上には光導波層41が形成されている。
【００８９】
上記第４の実施の形態においても第２の実施の形態と同様の効果を得ることができる。
【００９０】
次に、図８を参照して本発明の第５の実施の形態について説明する。なお、すでに説明している要素と同等の要素についての説明は特に必要の無い限り省略する。
【００９１】
本実施の形態の表面プラズモンセンサーは、誘電体ブロック110と、光ビーム113を発生する光源であるレーザ光源114と、上記光ビーム113を誘電体ブロック110に対して入射させる入射光学系115と、誘電体ブロック110で反射された光ビーム113を平行光化して光検出器117に向けて射出するコリメーターレンズ116と、コリメーターレンズ116より出射された光ビーム113を受光して光強度を検出するフォトダイオードアレイ（光検出器）117と、フォトダイオードアレイ117に接続された差動アンプアレイ118と、差動アンプアレイ118に接続されたドライバ119と、ドライバ119に接続されたコンピュータシステム等からなる信号処理部120と、フォトダイオードアレイ117から出力された信号をデジタル信号へ変換し、信号処理部120へ出力するＡ／Ｄ変換器127と、レーザ光源114から誘電体ブロック110に至る光路を間歇的に開閉するシャッター160とからなる。なお、請求項に記載の演算手段は、差動アンプアレイ118、ドライバ119および信号処理部120により構成される。
【００９２】
誘電体ブロック110は金属膜112とともに、使い捨ての測定チップ（測定ユニット）を構成しており、例えばターンテーブル131に複数取り付けられた移動台132のチップ保持孔に１個ずつ嵌合固定される。なお移動台132は、ターンテーブル131に対して図８の紙面に直角な方向、つまり図９中の上下方向に移動自在に取り付けられており、アクチュエータ133の駆動によってこの方向に移動する。
【００９３】
誘電体ブロック110が上述のようにターンテーブル131に固定された後、ターンテーブル131が一定角度ずつ間欠的に回動され、所定位置に停止した誘電体ブロック110に対して液体試料111が滴下され、該液体試料111が試料保持部110ａ内に保持される。その後さらにターンテーブル131が一定角度回動されると、誘電体ブロック110が図８に示した測定位置に送られ、そこで停止する。
【００９４】
以下、上記構成の表面プラズモンセンサーにおける、光ビーム113の強度分布を示す信号の処理について詳細に説明する。図１０は、この表面プラズモン測定装置の電気的構成を示すブロック図である。
【００９５】
図示の通り差動アンプアレイ118は、フォトダイオード117ａ、117ｂ、117ｃ…毎に設けられたスイッチ151ａ、151ｂ、151ｃ…、これらスイッチ151ａ、151ｂ、151ｃ…の３つの出力毎に設けられた加算機150ａ、150ｂ、150ｃ…、互いに隣接する２つの加算機毎に設けられた差動アンプ118ａ、118ｂ、118ｃ…から構成されている。すなわち、本実施の形態ではそれぞれ３つのフォトダイオードによってフォトダイオード群（受光素子群）が形成されている。なお、スイッチ151ａ、151ｂ、151ｃ…は、信号処理部120からの指示に基づいて開閉されるものである。
【００９６】
また、ドライバ119は、差動アンプアレイ118の各差動アンプ118ａ、118ｂ、118ｃ…の出力をサンプルホールドするサンプルホールド回路122ａ、122ｂ、122ｃ…、これらのサンプルホールド回路122ａ、122ｂ、122ｃ…の各出力が入力されるマルチプレクサ123、このマルチプレクサ123の出力をデジタル化して信号処理部120に入力するＡ／Ｄ変換器124、マルチプレクサ123とサンプルホールド回路122ａ、122ｂ、122ｃ…とを駆動する駆動回路125、および信号処理部120からの指示に基づいて駆動回路125の動作を制御するコントローラ126から構成されている。
【００９７】
上記フォトダイオード117ａ、117ｂ、117ｃ…の各出力は加算機150ａ、150ｂ、150ｃ…により３つの出力毎に加算され、加算機150ａ、150ｂ、150ｃ…の各出力は差動アンプアレイ118の各差動アンプ118ａ、118ｂ、118ｃ…に入力される。この際、互いに隣接する２つの加算機の出力が、共通の差動アンプに入力される。したがって各差動アンプ118ａ、118ｂ、118ｃ…の出力は、複数のフォトダイオード117ａ、117ｂ、117ｃ…が出力する光検出信号を、３つのフォトダイオードの出力毎にそれらの出力の合計をフォトダイオードアレイ117並設方向に関して微分したものと考えることができる。
【００９８】
各差動アンプ118ａ、118ｂ、118ｃ…の出力は、それぞれサンプルホールド回路122ａ、122ｂ、122ｃ…により所定のタイミングでサンプルホールドされ、マルチプレクサ123に入力される。マルチプレクサ123は、サンプルホールドされた各差動アンプ118ａ、118ｂ、118ｃ…の出力を、所定の順序に従ってＡ／Ｄ変換器124に入力する。Ａ／Ｄ変換器124はこれらの出力をデジタル化して信号処理部120に入力する。
【００９９】
図１１は、界面110ｂで全反射された光ビーム113の界面110ｂへの入射角θ毎の光強度と、差動アンプ118ａ、118ｂ、118ｃ…の出力との関係を説明するものである。ここで、光ビーム113の界面110ｂへの入射角θと上記反射された光ビーム113の光強度Ｉとの関係は、同図（１）に示すようなものであるとする。
【０１００】
また図１１（２）は、フォトダイオード117ａ、117ｂ、117ｃ…の並設方向を示しており、先に説明した通り、これらのフォトダイオード117ａ、117ｂ、117ｃ…の並設方向位置は上記入射角θと一義的に対応している。
【０１０１】
またフォトダイオード117ａ、117ｂ、117ｃ…の並設方向位置、つまりは入射角θと、差動アンプ118ａ、118ｂ、118ｃ…の出力Ｉ’（反射光強度Ｉの微分値）との関係は、同図（３）に示すようなものとなる。
【０１０２】
また図１１（４）は、フォトダイオード117ａ、117ｂ、117ｃ…により検出され、Ａ／Ｄ変換器127によりＡ／Ｄ変換されて信号処理部120に入力された信号により表されるビームプロファイルを示している。
【０１０３】
信号処理部120は、Ａ／Ｄ変換器124から入力された微分値Ｉ’の値に基づいて、差動アンプ118ａ、118ｂ、118ｃ…の中から、微分値として正の値を有し、かつ全反射減衰角θ_ＳＰに対応する微分値Ｉ’＝０に最も近い出力が得られているもの（図１１（３）の例では差動アンプ118ｋとなる）と、微分値として負の値を有し、かつ全反射減衰角θ_ＳＰに対応する微分値Ｉ’＝０に最も近い出力が得られているもの（図１１（３）の例では差動アンプ118ｊとなる）を選択し、それらの差動アンプが出力する微分値に基づいて、全反射減衰角θ_ＳＰを算出する。なお、場合によっては微分値Ｉ’＝０を出力している差動アンプが存在することもあり、そのときはその差動アンプに基づいて全反射減衰角θ_ＳＰを算出する。
【０１０４】
また、信号処理部120は、上記全反射減衰角θ_ＳＰの算出結果とともに、フォトダイオード117ａ、117ｂ、117ｃ…からＡ／Ｄ変換器127を介して信号処理部120に入力された信号により図１１（４）に示すようなビームプロファイルを表示手段121に表示させることができる。この際は、フォトダイオード117ａ、117ｂ、117ｃ…の各出力をＡ／Ｄ変換器127によりＡ／Ｄ変換し、その信号に基づいてビームプロファイルを生成するので、上記全反射減衰角θ_ＳＰを算出する際の解像度よりも高い解像度でビームプロファイルを生成することができる。
【０１０５】
ここでは、各フォトダイオード群の出力を全て加算して全反射減衰角θ_ＳＰの算出を行ったが、必ずしもそのような態様に限定されるものではなく、各フォトダイオードに接続されたスイッチを適宜開閉させてフォトダイオード群のそれぞれ１つもしくは２つのフォトダイオードの出力を加算して全反射減衰角θ_ＳＰの算出を行ってもよい。また、フォトダイオード群は、３つのフォトダイオードからなるものに限らず、２つもしくは４つ以上の複数のフォトダイオードにより構成してもよい。
【０１０６】
また、差動アンプアレイ118の構成は図１０に示す構成に限定されるものではない。
【０１０７】
基本的には、上述の操作を行なうことにより、液体試料111の中の特定物質とセンシング物質130との結合状態を調べることができるが、前述したようにこのセンシング物質130の反応特性や金属膜112の膜厚が該金属膜112の面内で不均一になっていたり、金属膜112やセンシング物質130の上にゴミが付着している等すると、その状態に応じて上記結合状態の測定結果にバラツキが生じることになる。以下、このような問題の発生を防止する点に関して説明する。
【０１０８】
本実施の形態においては、１回の測定に際して、移動台132がアクチュエータ133の駆動によって図９中の上下方向に間欠的に移動され、最初と最後の停止を含めてＮ回（Ｎは複数）移動台132が停止される。そしてこの各停止状態下で、上記と同様に光ビーム113が界面110ｂに照射され、該界面110ｂで全反射した光ビーム113の強度が、フォトダイオード117ａ、117ｂ、117ｃ……によって検出される。つまりこの場合は、界面110ｂの相異なるＮ個の光ビーム入射位置において、全反射した光ビーム113の強度が検出される。
【０１０９】
そこで信号処理部120にはＡ／Ｄ変換器124から、差動アンプ118ａ、118ｂ、118ｃ…の各出力毎にＮ個の微分値Ｉ’が入力されることになる。そして信号処理部120は、各位置に関するＮ個の微分値Ｉ’のメディアン値を求めて、それを当該位置を代表する微分値Ｉ’とする。このようにして、Ｎ個の微分値Ｉ’から代表データとして求められた１つの微分値Ｉ’は、前述の場合と同様に用いられ、液体試料111の中の特定物質とセンシング物質130との結合状態が調べられる。
【０１１０】
なおアクチュエータ133の駆動は不図示の全体制御部によって制御され、移動台132がＮ回停止する毎に全体制御部から信号処理部120に所定のタイミング信号が入力される。そして信号処理部120は、このタイミング信号が入力される毎にＡ／Ｄ変換器124からの微分値Ｉ’を取り込んで、差動アンプ118ａ、118ｂ、118ｃ…の各出力毎にＮ個の微分値Ｉ’を得る。
【０１１１】
以上のようにして、界面110ｂの相異なる光ビーム入射位置に関するＮ個の微分値Ｉ’から代表データとして求められた１つの微分値Ｉ’は、金属膜112の膜厚やセンシング物質130の反応特性が特異的に異なることや、さらにはセンシング物質130上のゴミ等の外乱に起因する変動を排除したものとなり得る。したがって、この測定装置によれば、金属膜112の膜厚やセンシング物質130の反応特性が不均一であったり、センシング物質130上にゴミが存在する等していても、それらによる測定結果のバラツキを防止可能となる。
【０１１２】
ここでは、演算手段としての信号処理部120が、Ｎ個の微分値Ｉ’のメディアン値を求めて、それを代表データとするように構成されているが、その代わりに、Ｎ個の微分値Ｉ’のメディアン値から上下所定幅内に含まれるデータの平均値を求めて、それを代表データとするようにしてもよい。さらには、Ｎ個の微分値Ｉ’のうち、それらの最大値および／または最小値を除いた微分値Ｉ’の平均値を求めて、それを代表データとするようにしてもよい。
【０１１３】
また、代表データを取得するための複数回の測定は、光ビームを複数に分岐させ、分岐させた複数の光ビームを界面110ｂの互いに異なる位置に同時に入射させ、複数のフォトダイオードアレイにより同時に測定を行うようにしてもよい。
【０１１４】
さらに、上記の測定を時系列に沿って複数回行う場合について説明する。最初に上記フォトダイオード117ａ、117ｂ、117ｃ…の感度特性と、信号処理部120による全反射減衰角θ_ＳＰの算出特性との関係について説明する。
【０１１５】
図１２（１）、（２）、（３）は、左側は暗線の位置と各受光素子に接続された差動アンプの出力特性との関係を示すグラフ、右側は実際の暗線の位置と算出される暗線の位置（全反射減衰角θ_ＳＰ）との関係を示すグラフである。
【０１１６】
図１２（１）は、各受光素子の感度特性が線形であり、また各受光素子の感度が一様である場合について示したものであり、この場合は右側のグラフに示すように実際の暗線の位置と算出される暗線の位置との関係は理想的な線形を示す。しかしながら、図１２（２）に示すように各受光素子の感度特性が非線形であると算出特性にうねりを生じ、また図１２（３）に示すように各受光素子の感度が一様でないと算出特性が非線形となってしまう。
【０１１７】
そのため、本実施の形態の表面プラズモンセンサーにおいては、図１３に示すように、一連の時系列で検出された複数の測定データを信号処理部120内の図示しない記憶部に記憶しておき、これら複数の測定データを最小二乗法によりスムージングすることにより、各受光素子の感度特性に起因する測定誤差を低減することができるため、測定精度を向上させることができる。なお、スムージングの方法は最小二乗法に限るものではない。また、第５の実施の形態の表面プラズモン測定装置も、第１の実施の形態と同様に、一部の構成を変更することにより漏洩モードセンサーとすることができる。
【０１１８】
次に、図１４を参照して本発明の第６の実施の形態について説明する。なお、すでに説明している要素と同等の要素についての説明は特に必要の無い限り省略する。
【０１１９】
本実施の形態の表面プラズモンセンサーは、誘電体ブロック110と、光ビーム113を発生する光源であるレーザ光源114と、上記光ビーム113を誘電体ブロック110に対して入射させる入射光学系115と、誘電体ブロック110で反射された光ビーム113を平行光化して光検出器117に向けて射出するコリメーターレンズ116と、コリメーターレンズ116より出射された光ビーム113を受光して光強度を検出するフォトダイオードアレイ（光検出器）117と、Ａ／Ｄ変換器170と、演算処理部171と、コンピュータシステム等からなる信号処理部172と、レーザ光源114から誘電体ブロック110に至る光路を間歇的に開閉するシャッター170とからなる。なお、請求項に記載の演算手段は、演算処理部171および信号処理部172により構成される。演算処理部171および信号処理部172の動作は後述する。
【０１２０】
以下、上記構成の表面プラズモンセンサーによる試料分析について説明する。図１４に示す通り、レーザ光源114から射出された光ビーム113は、入射光学系115を通して、誘電体ブロック110と金属膜112との界面110ｂ上に収束され、この界面110ｂで全反射された光ビーム113は、コリメーターレンズ116を通して光検出器117によって検出される。光検出器117は、上記界面110ｂにおいて種々の反射角で全反射された光ビーム113の各成分を、それぞれ異なるフォトダイオード117ａ、117ｂ、117ｃ…で受光する。そして、光検出器117は、各フォトダイオード117ａ、117ｂ、117ｃ…によって検出された上記光ビーム113の強度分布を示す信号をＡ／Ｄ変換器170に出力する。Ａ／Ｄ変換器170でＡ／Ｄ変換された信号は演算処理部171に入力される。なお、本実施の形態においては、解像度を向上させるために、第５の実施の形態に比べて、光検出器117が界面110ｂから離れた位置に配置されている。
【０１２１】
演算処理部171では、まず上記フォトダイオード117ａ、117ｂ、117ｃ…の各出力から、隣接する３つのフォトダイオードの出力の平均値を、順次フォトダイオードを１つずつずらしながら算出し、その後、前後する平均値の差を求め、信号処理部172へ出力する。すなわち、まず、フォトダイオード117ａ、117ｂ、117ｃの平均値、フォトダイオード117ｂ、117ｃ、117ｄの平均値、フォトダイオード117ｃ、117ｄ、117ｅの平均値…を順次算出し、その後、フォトダイオード117ｂ、117ｃ、117ｄの平均値−フォトダイオード117ａ、117ｂ、117ｃの平均値、フォトダイオード117ｃ、117ｄ、117ｅの平均値−フォトダイオード117ｂ、117ｃ、117ｄの平均値…を順次求め、信号処理部172へ出力する。これらの、平均値の差は、複数のフォトダイオード117ａ、117ｂ、117ｃ…が出力する光検出信号を、隣接する３つのフォトダイオードの出力毎にそれらの出力の平均値をフォトダイオードアレイ１７の並設方向に関して微分した微分値Ｉ’と考えることができる。
【０１２２】
図１５は、上記の演算処理部171において演算処理を行う際の信号値を説明するものである。例えば、光ビーム113の界面110ｂへの入射角θと上記反射された光ビーム113の光強度Ｉとの関係は、同図（１）に示すようなものであるとする。図１５（２）に、示すような配置で、フォトダイオード117ａ、117ｂ、117ｃ…が設けられている場合には、同図（３）に示すような出力値が各フォトダイオード117ａ、117ｂ、117ｃ…から出力される。すなわち、同図（３）は、演算処理部171に入力される信号である。なお、同図（３）は、フォトダイオード117ａ、117ｂ、117ｃ…の配列ピッチが、ビームプロファイルに対して狭いため、各フォトダイオード117ａ、117ｂ、117ｃ…から出力される信号値が小さく、ノイズの影響を受けやすい場合の出力値の一例であり、凹凸の大きいグラフとなっている。同図（４）は、隣接する３つのフォトダイオードの出力の平均値を、順次フォトダイオードを１つずつずらしながら算出した値である。ノイズが相殺されるため、同図（３）に示すグラフに比べ、滑らかなグラフとなり、かつ同図（１）に示す、実際の入射角θと反射された光ビーム113の光強度Ｉとの関係を示すグラフに近い形状のグラフが得られている。同図（５）は、各平均値の差、すなわち演算処理部171から出力される微分値Ｉ’を示すものである。
【０１２３】
信号処理部172は、演算処理部172から入力された微分値Ｉ’の値に基づいて、全反射減衰角θ_ＳＰに対応する微分値Ｉ’＝０に最も近い出力が得られているフォトダイオードの組（図１０（２）の例ではフォトダイオード117ｈ、117ｉおよび117ｊとなる）から全反射減衰角θ_ＳＰを算出する。以後、所定時間が経過する毎に上記と同様な動作を繰り返し、全反射減衰角θ_ＳＰを算出し、測定開始時からの角度変化量を求め表示手段121に表示する。試料液111の中の特定物質とセンシング物質130との結合状態に応じてセンシング物質130の屈折率が変化するので、上記全反射減衰角θ_ＳＰの角度変化量を測定することにより、この結合状態の変化の様子を調べることができる。
【０１２４】
なお、本実施の形態においては、３つのフォトダイオードの平均値から微分値Ｉ’を求め、この微分値Ｉ’に基づいて、全反射減衰角θ_ＳＰの算出を行ったが、必ずしもそのような態様に限定されるものではなく、隣接した２つのフォトダイオードの平均値あるいは隣接した４つ以上のフォトダイオードの平均値を順次求めて、微分値Ｉ’を求めてもよい。
【０１２５】
本実施の形態においては、光検出器117の隣接する３つのフォトダイオードの出力の平均値を、順次フォトダイオードを１つずつずらしながら算出し、その後、前後する平均値の差、すなわち微分値Ｉ’を求め、該微分値Ｉ’に基づいて、全反射減衰角θ_ＳＰの角度を測定するようにしたので、サイズが小さい受光素子を用いる場合あるいは受光素子が受光する光量が少ない場合であっても、ノイズの影響を受けにくく、高い解像度で、かつ正確に全反射減衰角θ_ＳＰの角度を測定することができる。なお、各フォトダイオードの平均値の代わりに合計値を使用してもよく、微分する際の信号値を大きくすることができる。また、平均値の代わりに、合計値を所望の値で除算した値、あるいは合計値に所望の値を乗算した値等を用いてもよい。
【０１２６】
なお、演算処理部171から、微分値に加え各３つのフォトダイオードの平均値を出力し、信号処理部172において、この平均値に基づいてビームプロファイルを生成すれば、高い解像度で、かつノイズの影響の少ないビームプロファイルを生成することができる。また、第６の実施の形態の表面プラズモンセンサーも、第１の実施形態と同様に、一部の構成を変更することにより漏洩モードセンサーとすることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態による表面プラズモンセンサーの側面図
【図２】光ビームの検出面における強度特性を示すグラフ
【図３】上記表面プラズモンセンサーの電気的構成を示すブロック図
【図４】上記表面プラズモンセンサーにおける光ビーム入射角と検出光強度との関係、並びに光ビーム入射角と光強度検出信号の微分値との関係を示す概略図
【図５】本発明の第２の実施の形態による表面プラズモンセンサーの側面図
【図６】本発明の第３の実施の形態による漏洩モードセンサーの側面図
【図７】本発明の第４の実施の形態による漏洩モードセンサーの側面図
【図８】本発明の第５の実施の形態による表面プラズモンセンサーの側面図
【図９】上記表面プラズモンセンサーの光学系部分を示す平面図
【図１０】上記表面プラズモンセンサーの電気的構成を示すブロック図
【図１１】光ビームの界面への入射角と差動アンプの出力との関係を示す図
【図１２】各受光素子の感度特性と信号処理部の出力特性との関係を示すグラフ
【図１３】信号処理部の出力特性をスムージングした場合の説明図
【図１４】本発明の第６の実施の形態による表面プラズモンセンサーの側面図
【図１５】光ビームの界面への入射角と演算処理部の出力との関係を示す図
【符号の説明】
10、110 誘電体ブロック
10ａ、110ａ 誘電体ブロックの試料保持部
10ｂ、110ｂ 誘電体ブロックと金属膜との界面
11、111 試料
12、112 金属膜
13、113 光ビーム
14、114 半導体レーザ等
15、115 入射光学系
16、116 コリメーターレンズ
17、117 光検出手段（フォトダイオードアレイ）
17ａ、17ｂ、17ｃ…… フォトダイオード
117ａ、117ｂ、117ｃ…… フォトダイオード
18、118 差動アンプアレイ
18ａ、18ｂ、18ｃ…… 差動アンプ
118ａ、118ｂ、118ｃ…… 差動アンプ
19、119 ドライバ
20、120 信号処理部
21、121 表示手段
22ａ、22ｂ、22ｃ…… サンプルホールド回路
122ａ、122ｂ、122ｃ…… サンプルホールド回路
23、123 マルチプレクサ
24、124 Ａ／Ｄ変換器
25、125 駆動回路
26、126 コントローラ
30、130 センシング媒体
31、131 ターンテーブル
40 クラッド層
41 光導波層
50、160 シャッター
51 ドライバ
127 Ａ／Ｄ変換器
132 移動台
133 アクチュエータ
150ａ、150ｂ、150ｃ…… 加算機
151ａ、151ｂ、151ｃ…… スイッチ
170 Ａ／Ｄ変換器
171 演算処理部
172 信号処理部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a measurement method and a measurement apparatus, such as a surface plasmon sensor that quantitatively analyzes a substance in a sample using generation of surface plasmons, and more particularly, to detect a dark line generated in measurement light by total reflection attenuation. The present invention relates to a measuring method and a measuring apparatus that detect using means.
[0002]
[Prior art]
In the metal, free electrons collectively vibrate to generate a dense wave called a plasma wave. A quantized version of this dense wave generated on the metal surface is called surface plasmon.
[0003]
Conventionally, various surface plasmon sensors that quantitatively analyze a substance in a sample using a phenomenon in which the surface plasmon is excited by a light wave have been proposed. Among them, one that uses a system called Kretschmann configuration is well known (for example, see Patent Document 1).
[0004]
A surface plasmon sensor using the above system basically includes, for example, a dielectric block formed in a prism shape, a metal film formed on one surface of the dielectric block and brought into contact with a sample, and a light source that generates a light beam. The light beam is incident on the dielectric block at various angles so that a total reflection condition is obtained at the interface between the dielectric block and the metal film, and total reflection attenuation due to surface plasmon resonance can occur. The optical system includes an incident optical system and light detection means for detecting the surface plasmon resonance state, that is, the state of total reflection attenuation by measuring the intensity of the light beam totally reflected at the interface.
[0005]
In order to obtain various incident angles as described above, a relatively thin light beam may be incident on the interface by changing the incident angle, or a component incident on the light beam at various angles is included. As described above, a relatively thick light beam may be incident on the interface in a convergent light state or a divergent light state. In the former case, a light beam whose reflection angle changes according to the change in the incident angle of the incident light beam is detected by a small photodetector that moves in synchronization with the change in the reflection angle, or the direction in which the reflection angle changes Can be detected by an area sensor extending along the line. On the other hand, in the latter case, it can be detected by an area sensor extending in a direction in which each light beam reflected at various reflection angles can be received.
[0006]
In the surface plasmon sensor having the above-described configuration, the specific incident angle θ is greater than the total reflection angle with respect to the metal film. _SP The evanescent wave having an electric field distribution is generated in the sample in contact with the metal film, and surface plasmons are excited at the interface between the metal film and the sample by the evanescent wave. When the wave number vector of the evanescent light is equal to the wave number of the surface plasmon and the wave number matching is established, both are in a resonance state and the energy of the light is transferred to the surface plasmon, so that the entire energy is transferred to the interface between the dielectric block and the metal film. The intensity of the reflected light decreases sharply. This decrease in light intensity is generally detected as a dark line by the light detection means.
[0007]
The resonance described above occurs only when the incident beam is p-polarized light. Therefore, it is necessary to set in advance so that the light beam is incident as p-polarized light.
[0008]
Incident angle θ at which this total reflection attenuation (ATR) occurs _SP From the surface plasmon wave number, the dielectric constant of the sample can be determined. In other words, the wave number of surface plasmon is K _SP , Ω is the angular frequency of the surface plasmon, c is the speed of light in vacuum, ε _m And ε _S Are the metal and the dielectric constant of the sample, respectively.
[0009]
[Expression 1]

Dielectric constant of sample ε _S Is known, the concentration of the specific substance in the sample can be known based on a predetermined calibration curve or the like, and eventually, the incident angle θ at which the reflected light intensity decreases. _SP By knowing, it is possible to obtain the characteristics related to the dielectric constant, that is, the refractive index of the sample.
[0010]
As a similar sensor using total reflection attenuation (ATR), for example, a leak mode sensor described in Non-Patent Document 1 is also known. This leakage mode sensor is basically a dielectric block formed in a prism shape, for example, a clad layer formed on one surface of the dielectric block, and formed on the clad layer to be brought into contact with a sample. An optical waveguide layer, a light source that generates a light beam, and a total reflection condition at the interface between the dielectric block and the cladding layer with respect to the dielectric block. Waveguide mode excitation state, that is, total reflection attenuation state by measuring the intensity of the light beam totally reflected at the above interface and incident optical system that makes incident at various angles so that total reflection attenuation by wave mode excitation can occur And a light detecting means for detecting.
[0011]
In the leaky mode sensor having the above configuration, when a light beam is incident on the cladding layer through the dielectric block at an incident angle greater than the total reflection angle, the light waveguide layer transmits a specific wave number after passing through the cladding layer. Only light having a specific incident angle is propagated in the guided mode. When the waveguide mode is excited in this way, most of the incident light is taken into the optical waveguide layer, resulting in total reflection attenuation in which the intensity of light totally reflected at the interface is sharply reduced. Since the wave number of guided light depends on the refractive index of the sample on the optical waveguide layer, the refractive index of the sample and its related sample characteristics are analyzed by knowing the specific incident angle at which total reflection attenuation occurs. be able to.
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 06-167443
[0013]
[Non-Patent Document 1]
“Spectroscopy” Vol. 47, No. 1 (1998)
Pages 21-23 and pages 26-27
[0014]
[Problems to be solved by the invention]
By the way, in the measurement apparatus such as the conventional surface plasmon sensor or leakage mode sensor of the type described above, the refractive index of the sample changes depending on the temperature around the dielectric block in the apparatus. It is necessary to carry out in a constant temperature environment.
[0015]
However, by continuing to irradiate the dielectric block with the light beam at the time of measurement, a temperature rise around the dielectric block is caused, thereby changing the refractive index of the sample, which causes a drift of the detection signal.
[0016]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a measurement method and a measurement apparatus that do not cause a drift phenomenon with respect to a detection signal.
[0017]
[Means for Solving the Problems]
In the first measurement method of the present invention, a light beam is used so that a total reflection condition can be obtained at the interface between the dielectric block and the thin film layer with respect to the dielectric block having the thin film layer that is brought into contact with the sample on the entire surface. In a measurement method for detecting the state of total reflection attenuation by measuring the intensity of the light beam totally reflected at the interface and detecting the state of total reflection attenuation, the light beam is The measurement is performed by intermittently irradiating the dielectric block.
[0018]
Further, the second measuring method of the present invention includes a dielectric block, a thin film layer formed on one surface of the dielectric block and brought into contact with a sample, a light source for generating a light beam, and a light beam as a dielectric. Measures the intensity of a light beam that consists of an incident optical system that makes incident light at an angle of incidence that provides a total reflection condition at the interface between the dielectric block and the thin film layer, and a plurality of light receiving elements. In a measurement method in which a sample is analyzed by a measurement device comprising a light detection means that performs a light beam intermittently irradiates a dielectric block, a plurality of light receiving elements are divided into several light receiving element groups, and adjacent to each other A process for differentiating the sum of the outputs of each of the two light receiving element groups with respect to the direction in which the light receiving elements are arranged, and obtaining a reflection angle at which the reflected light intensity at the interface takes a minimum value based on this differential value. With optics The electrical block is moved relative to each other so that the incident position of the light beam at the interface changes, and each is performed when the incident position of the light beam is different, and the obtained data is statistically processed. And obtaining one representative data corresponding to the reflection angle, smoothing a plurality of representative data obtained in a series of time series, and analyzing the sample based on the plurality of smoothed measurement data. To do.
[0019]
The third measuring method of the present invention includes a dielectric block, a thin film layer formed on one surface of the dielectric block and brought into contact with a sample, a light source for generating a light beam, and a light beam as a dielectric. Measures the intensity of a light beam that consists of an incident optical system that makes incident light at an angle of incidence that provides a total reflection condition at the interface between the dielectric block and the thin film layer, and a plurality of light receiving elements. In a measuring method for analyzing a sample by a measuring device comprising a photodetecting means that performs the above, an average of outputs of each of a predetermined number of two or more adjacent light receiving elements is irradiated intermittently with a light beam on a dielectric block The value is sequentially calculated in the direction in which the light receiving elements are arranged, the average value is differentiated with respect to the direction in which the light receiving elements are arranged, and the reflection angle at which the reflected light intensity at the interface takes a minimum value based on this differential value The incident optics And the dielectric block are moved relative to each other so that the incident position of the light beam at the interface changes, and when the incident position of the light beam is different, statistical processing is performed on the obtained data. Then, one representative data corresponding to the reflection angle is obtained, a plurality of representative data obtained in a series of time series is smoothed, and the sample is analyzed based on the plurality of smoothed measurement data. It is what.
[0020]
According to a fourth measuring method of the present invention, there is provided a dielectric block, a thin film layer formed on one surface of the dielectric block and brought into contact with a sample, a light source for generating a light beam, and the light beam as a dielectric. Measures the intensity of a light beam that consists of an incident optical system that makes incident light at an angle of incidence that provides a total reflection condition at the interface between the dielectric block and the thin film layer, and a plurality of light receiving elements. In a measuring method for analyzing a sample by a measuring device comprising a photodetecting means, a light beam is intermittently applied to a plurality of different incident positions on the interface, and a plurality of light receiving elements receive a plurality of light receiving elements. Dividing into element groups, the sum of the outputs of each of the two adjacent light receiving element groups is differentiated with respect to the direction in which the light receiving elements are arranged in parallel, and the reflected light intensity at the interface takes a minimum value based on this differential value Find the corner Each time the incident position of the light beam is different, statistical processing is performed on the obtained data, and one representative data corresponding to the reflection angle is obtained and obtained in a series of time series. The plurality of representative data is smoothed, and the sample is analyzed based on the plurality of smoothed measurement data.
[0021]
Furthermore, the fifth measurement method of the present invention includes a dielectric block, a thin film layer formed on one surface of the dielectric block and brought into contact with the sample, a light source for generating a light beam, and a light beam as a dielectric. Measures the intensity of a light beam that consists of an incident optical system that makes incident light at an angle of incidence that provides a total reflection condition at the interface between the dielectric block and the thin film layer, and a plurality of light receiving elements. In a measuring method for analyzing a sample by a measuring device comprising a photodetecting means, a plurality of different incident positions on the interface are intermittently irradiated with two or more predetermined numbers of adjacent ones. The average value of the outputs of the light receiving elements is sequentially calculated in the direction in which the light receiving elements are juxtaposed, the average value is differentiated with respect to the direction in which the light receiving elements are juxtaposed, and the reflected light intensity at the interface is minimal based on this differential value. Take the reflection angle Processing is performed when the incident positions of the light beams are different from each other, and a plurality of obtained data are statistically processed to obtain one representative data corresponding to the reflection angle, and a series of time series The plurality of representative data obtained in step (1) is smoothed, and the sample is analyzed based on the plurality of smoothed measurement data.
[0022]
In the first to fifth measurement methods, it is desirable to start measurement after a transient response time from the start of irradiation of the light beam by measuring the reflected light intensity of the light beam at the interface. Here, the “transient response time” means the time from the start of light beam irradiation until the output of the detection signal of the light beam totally reflected at the interface becomes substantially constant.
[0023]
The first to fifth measuring devices of the present invention are used in the first to fifth measuring methods, and the first measuring device of the present invention includes a dielectric block, and the dielectric block. A thin film layer formed on one surface and brought into contact with the sample, a light source for generating a light beam, and the light beam to the dielectric block so that a total reflection condition can be obtained at the interface between the dielectric block and the thin film layer. In a measuring apparatus, comprising: an incident optical system that is incident at various angles; and a light detector that measures the intensity of the light beam totally reflected at the interface and detects the state of total reflection attenuation. It is characterized by comprising intermittent irradiation means for intermittently irradiating the dielectric block.
[0024]
The second measuring apparatus of the present invention includes a dielectric block, a thin film layer formed on one surface of the dielectric block and brought into contact with a sample, a light source for generating a light beam, and a light beam as a dielectric. An incident optical system that is incident on the block at various angles so that a total reflection condition is obtained at the interface between the dielectric block and the thin film layer, and a plurality of light receiving elements, and a light beam totally reflected at the interface. In a measuring apparatus comprising a light detecting means for measuring the intensity and detecting the state of total reflection attenuation, an intermittent irradiating means for intermittently irradiating the dielectric block with a light beam, an incident optical system and a dielectric Means for relatively moving the body block so that the incident position of the light beam at the interface changes, and dividing the plurality of light receiving elements into several light receiving element groups, and for each of two adjacent light receiving element groups Differentiating the total force with respect to the direction in which the light receiving elements are juxtaposed, and determining the reflection angle at which the reflected light intensity at the interface takes a minimum value based on this differential value, when the incident position of the light beam is different Each of the obtained data is statistically processed to obtain one representative data corresponding to the reflection angle, and a plurality of representative data detected in a series of time series by the computing means is smoothed. And a smoothing processing means.
[0025]
The third measuring apparatus of the present invention includes a dielectric block, a thin film layer formed on one surface of the dielectric block and brought into contact with a sample, a light source for generating a light beam, and a light beam as a dielectric. An incident optical system that is incident on the block at various angles so that a total reflection condition is obtained at the interface between the dielectric block and the thin film layer, and a plurality of light receiving elements, and a light beam totally reflected at the interface. In a measuring apparatus comprising a light detecting means for measuring the intensity and detecting the state of total reflection attenuation, an intermittent irradiating means for intermittently irradiating the dielectric block with a light beam, an incident optical system and a dielectric Means for moving the body block relative to each other so that the incident position of the light beam at the interface changes, and the average value of the outputs of two or more adjacent light receiving elements in the direction in which the light receiving elements are arranged side by side. Sequentially The average value is differentiated with respect to the direction in which the light receiving elements are arranged side by side, and a process for obtaining a reflection angle at which the reflected light intensity at the interface takes a minimum value based on this differential value is obtained in a state where the incident positions of the light beams are different. Sometimes, each of the obtained data is statistically processed to obtain one representative data corresponding to the reflection angle, and a plurality of measurement data detected in a series of time series by the computing means is smoothed. And a smoothing processing means for processing.
[0026]
The fourth measuring apparatus of the present invention includes a dielectric block, a thin film layer formed on one surface of the dielectric block and brought into contact with a sample, a light source for generating a light beam, and a light beam as a dielectric. An incident optical system that is incident on the block at various angles so that a total reflection condition is obtained at the interface between the dielectric block and the thin film layer, and a plurality of light receiving elements, and a light beam totally reflected at the interface. In a measuring apparatus comprising a light detecting means for measuring the intensity and detecting the state of total reflection attenuation, an intermittent irradiating means for intermittently irradiating the dielectric block with a light beam, and an incident optical system, The light beam is formed so as to be incident on a plurality of different incident positions on the interface, and the plurality of light receiving elements are divided into several light receiving element groups. Receive the total Differentiating with respect to the direction in which the elements are juxtaposed, and processing for obtaining a reflection angle at which the reflected light intensity at the interface takes a minimum value based on this differential value is performed when the incident positions of the light beams are different from each other. Statistical processing of a plurality of received data and obtaining one representative data corresponding to the reflection angle; smoothing processing means for smoothing a plurality of measurement data detected in a series of time series by the computing means; It is characterized by comprising.
[0027]
Furthermore, a fifth measuring apparatus of the present invention includes a dielectric block, a thin film layer formed on one surface of the dielectric block and brought into contact with a sample, a light source for generating a light beam, and a light beam as a dielectric. An incident optical system that is incident on the block at various angles so that a total reflection condition is obtained at the interface between the dielectric block and the thin film layer, and a plurality of light receiving elements, and a light beam totally reflected at the interface. In a measuring apparatus comprising a light detecting means for measuring the intensity and detecting the state of total reflection attenuation, an intermittent irradiating means for intermittently irradiating the dielectric block with a light beam, and an incident optical system, A light beam is formed so as to be incident on a plurality of different incident positions on the interface, and an average value of outputs of two or more adjacent light receiving elements adjacent to each other is sequentially calculated in the direction in which the light receiving elements are arranged side by side. And average Are differentiated with respect to the direction in which the light receiving elements are juxtaposed, and a process for obtaining a reflection angle at which the reflected light intensity at the interface takes a minimum value based on the differential value is performed when the incident positions of the light beams are different from each other. A plurality of obtained data are statistically processed to obtain one representative data corresponding to the reflection angle, and a smoothing process for smoothing a plurality of measurement data detected in a series of time series by the computing means Means.
[0028]
As the above-described measuring apparatus, the above-described surface plasmon measuring apparatus using a metal film as the thin film layer, a clad layer formed on one surface of a dielectric block, and an optical waveguide layer formed on the clad layer And the above-described leaky mode measuring device using the above-mentioned layer as the thin film layer.
[0029]
In the first to fifth measuring apparatuses of the present invention, there are various methods for analyzing the sample by measuring the intensity of the light beam totally reflected at the interface by the light detection means. The incident light is incident at various incident angles at which the total reflection condition is obtained at the interface, and the intensity of the light beam totally reflected at the interface is measured for each position corresponding to each incident angle, and the position of the dark line generated by the total reflection attenuation ( Samples may be analyzed by detecting angle) or described in DV Noort, K. Johansen, C.-F. Mandenius, Porous Gold in Surface Plasmon Resonance Measurement, EUROSENSORS XIII, 1999, pp. 585-588. As shown in the figure, a light beam having a plurality of wavelengths is incident at an incident angle at which the total reflection condition is obtained at the interface, and the intensity of the light beam totally reflected at the interface is measured for each wavelength. Even if sample analysis is performed by detecting the degree of total reflection attenuation Good.
[0030]
Moreover, in the 1st measuring apparatus of this invention, it describes in PINikitin, ANGrigorenko, AABeloglazov, MVValeiko, AISavchuk, OASavchuk, Surface Plasmon Resonance Interferometry for Micro-Array Biosensing, EUROSENSORS XIII, 1999, pp.235-238. As described above, the light beam is incident at an angle of incidence at which the total reflection condition is obtained at the interface, and a part of the light beam is divided before the light beam is incident on the interface. The sample analysis may be performed by interfering with the light beam totally reflected at the interface and measuring the intensity of the light beam after the interference.
[0031]
In the present invention, “dividing a plurality of light receiving elements into several light receiving element groups and differentiating the sum of outputs for each of the two adjacent light receiving element groups with respect to the direction in which the light receiving elements are arranged in parallel” means After summing up the outputs of the element groups, not only when the sum of the outputs of each of the two adjacent light receiving element groups is differentiated with respect to the parallel arrangement direction of the light receiving elements, but the light receiving elements of the two adjacent light receiving element groups are respectively Any one of the calculation processes may be used as long as the same differential value is obtained as a result, for example, by summing the differential values after differentiating one by one with respect to the direction in which the light receiving elements are arranged side by side.
[0032]
For example, six light receiving elements arranged in order from the first light receiving element to the sixth light receiving element are divided into a first light receiving element group consisting of the first to third light receiving elements and a fourth light receiving element to the sixth light receiving element. Are divided into second light receiving element groups, and the total of the outputs of the light receiving element groups is differentiated with respect to the parallel arrangement direction of the light receiving elements, the respective light receiving elements of the first to third light receiving elements of the first light receiving element group The outputs of the elements are summed, the outputs of the respective light receiving elements of Nos. 4 to 6 in the second light receiving element group are summed, and the sum of the outputs of the first light receiving element group and the second light receiving element group May be differentiated with respect to the direction in which the light receiving elements are arranged, and the outputs of the first and fourth light receiving elements, the second and fifth light receiving elements, and the third and sixth light receiving elements, respectively. Differentiation may be performed with respect to the direction in which the light receiving elements are arranged, and the three differential values may be summed. Alternatively, the difference between the outputs of the first and sixth light receiving elements, the difference between the outputs of the second and fifth light receiving elements, the difference between the outputs of the third and fourth light receiving elements, and the distance between the light receiving element groups In this case, it may be divided by a distance corresponding to three light receiving elements.
[0033]
In addition, “the average value of outputs of two or more adjacent adjacent light receiving elements is sequentially calculated in the direction in which the light receiving elements are juxtaposed, and the average value is differentiated with respect to the direction in which the light receiving elements are juxtaposed”. After calculating the average value of the outputs of the constant light receiving elements, the average value is not limited to differentiation with respect to the direction in which the light receiving elements are arranged side by side. For example, first, a differential value between two adjacent light receiving elements is obtained. For example, the average value of a predetermined number of consecutive differential values is sequentially calculated in the direction in which the light receiving elements are arranged, so that the same differential value can be obtained as a result. Good.
[0034]
For example, from four light receiving elements arranged in order from the first light receiving element to the fourth light receiving element, the average value of the output of each of the three adjacent light receiving elements is sequentially calculated in the parallel arrangement direction of the light receiving elements, When differentiating the average value with respect to the direction in which the light receiving elements are arranged side by side, the average value of the outputs of the first to third light receiving elements and the average value of the outputs of the second to fourth light receiving elements are obtained, The average value may be differentiated with respect to the direction in which the light receiving elements are arranged, and the outputs of the first and second light receiving elements, the second and third light receiving elements, and the third and fourth light receiving elements are respectively Differentiation may be performed with respect to the juxtaposed direction, and an average value of these differential values may be obtained. The “average value of the outputs of each of a predetermined number of adjacent two or more light receiving elements” is not limited to the average value itself, and may be any value that reflects the average value. It may be a total value of outputs of the respective light receiving elements, a value obtained by dividing the total value by a desired value, a value obtained by multiplying the total value by a desired value, or the like.
[0035]
Further, “determining the reflection angle at which the reflected light intensity at the interface takes the minimum value based on the differential value” is not limited to obtaining the reflection angle itself taking the minimum value, but takes the minimum value. This includes the case where a value reflecting the reflection angle, for example, a differential value in the vicinity of the reflection angle that takes a minimum value, is obtained. The “minimum value” means a minimum value that reflects the state of total reflection attenuation, and does not include those that are caused by the influence of noise or the like.
[0036]
Further, “smoothing (processing)” is a process for reducing measurement errors caused by sensitivity characteristics of each light receiving element. For example, a plurality of measurement data detected in a series of time series by the least square method. May be reduced, or a low-pass filter (LPF), a high-pass filter (HPF), or a band is detected from the output signal of the photodetection means detected continuously. -An extra frequency component may be cut using a frequency filter such as a pass filter (BPF).
[0037]
In the above measurement apparatus, the intermittent irradiation means may be provided between the light source and the dielectric block, and may be a shutter that intermittently opens and closes an optical path from the light source to the dielectric block, or drives the light source intermittently. Light source driving means may be used. Here, when the intermittent irradiation means is a light source driving means, it is preferable that the light source is provided with an oscillation wavelength stabilizing means for stabilizing the wavelength of the generated light beam.
[0038]
By the way, the ratio (dn / dt) of the refractive index change to the temperature change of a typical solvent used for measurement is 4.5 × 10. ^-4 And the refractive index change is 10 ^-4 Therefore, it is necessary to suppress the temperature change to 1 ° C. or less at a minimum.
[0039]
Therefore, the intermittent irradiation means is preferably driven so that the temperature change of the sample by the light beam is 0.5 ° C. or less, and more preferably, the temperature change is 0.1 ° C. or less.
[0040]
Further, it is desirable that the light detection means starts measurement after a transient response time has elapsed from the start of irradiation of the light beam by measuring the reflected light intensity of the light beam at the interface.
[0041]
【The invention's effect】
In the first measuring method and measuring apparatus according to the present invention, the time for irradiating the dielectric block with the light beam is shortened by intermittently irradiating the dielectric block with the light beam. In addition, since the temperature change of the dielectric block that affects the sample can be suppressed, it is possible to prevent a drift phenomenon from occurring in the detection signal.
[0042]
In addition to the effects of the first measurement method and measurement apparatus, the second and fourth measurement methods and measurement apparatuses of the present invention divide a plurality of light receiving elements into several light receiving element groups and are adjacent to each other. Since the sum of the outputs of each of the two light receiving element groups is differentiated with respect to the direction in which the light receiving elements are arranged side by side, the reflection angle at which the reflected light intensity at the interface takes a minimum value is obtained based on this differential value. Even when a light receiving element with a small size is used, the total reflection attenuation angle θ _SP Is calculated, the plurality of light receiving elements are divided into several light receiving element groups, and the outputs are summed for each light receiving element group, so that the output of the signal when differentiating can be increased. As a result, a light receiving element array having a fine arrangement pitch can be used, so that a beam profile can be detected with high resolution and a total reflection attenuation angle θ. _SP Can be calculated accurately.
[0043]
In addition, when measuring the reflection angle of the light beam at the interface between the dielectric block and the thin film layer, the data of a plurality of states having different incident positions of the light beam are statistically processed to provide one representative corresponding to the reflection angle. Since the data is configured to be obtained, this representative data excludes fluctuations caused by disturbances such as dust and the like, in which the film thickness of the thin film layer and the response characteristics of the sensing substance are specifically different. obtain. Therefore, even if the film thickness of the thin film layer and the reaction characteristics of the sensing substance are non-uniform or dust is present on the thin film layer, variations in measurement results due to them can be prevented.
[0044]
Furthermore, by smoothing a plurality of representative data obtained in a series of time series, it is possible to reduce measurement errors due to sensitivity characteristics of each light receiving element of the light detection means, thereby improving measurement accuracy. it can.
[0045]
In addition to the effects of the first measurement method and measurement apparatus, the third and fifth measurement methods and measurement apparatuses of the present invention provide an average value of outputs of each of a predetermined number of adjacent two or more light receiving elements. Are sequentially calculated in the direction in which the light receiving elements are juxtaposed, the average value is differentiated with respect to the direction in which the light receiving elements are juxtaposed, and the reflection angle at which the reflected light intensity at the interface takes a minimum value is obtained based on this differential value. Therefore, even when using a light receiving element with a small size or when the amount of light received by the light receiving element is small, it is not easily affected by noise, and the reflection angle at which the reflected light intensity takes a minimum value accurately, that is, total reflection. Attenuation angle θ _SP Can be requested. In addition, an average value equal to the number of light receiving elements can be calculated, and the total reflection attenuation angle θ can be obtained with high resolution. _SP Can be requested. Further, a high resolution beam profile can be obtained by using this average value.
[0046]
In addition, when measuring the reflection angle of the light beam at the interface between the dielectric block and the thin film layer, the data of a plurality of states having different incident positions of the light beam are statistically processed to provide one representative corresponding to the reflection angle. Since the data is configured to be obtained, this representative data excludes fluctuations caused by disturbances such as dust and the like, in which the film thickness of the thin film layer and the response characteristics of the sensing substance are specifically different. obtain. Therefore, even if the film thickness of the thin film layer and the reaction characteristics of the sensing substance are non-uniform or dust is present on the thin film layer, variations in measurement results due to them can be prevented.
[0047]
Furthermore, by smoothing a plurality of representative data obtained in a series of time series, it is possible to reduce measurement errors due to sensitivity characteristics of each light receiving element of the light detection means, thereby improving measurement accuracy. it can.
[0048]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The measuring apparatus according to the first embodiment of the present invention is a surface plasmon sensor using surface plasmon resonance, and FIG. 1 shows a side shape of the surface plasmon sensor.
[0049]
The surface plasmon sensor includes, for example, a dielectric block 10 having a shape in which a part of a substantially quadrangular pyramid is cut off, and formed on one surface (the upper surface in the drawing) of the dielectric block 10, for example, gold, silver, And a metal film 12 made of copper, aluminum, or the like.
[0050]
The dielectric block 10 is made of, for example, a transparent resin and has a raised shape around the portion where the metal film 12 is formed. The raised portion 10a functions as a sample holding unit for storing the liquid sample 11. In this example, the sensing medium 30 is fixed on the metal film 12, and the sensing medium 30 will be described later.
[0051]
The dielectric block 10 constitutes a disposable measuring chip together with the metal film 12, and is fitted and fixed, for example, one by one into a plurality of chip holding holes 31a provided in the turntable 31. After the dielectric block 10 is fixed to the turntable 31 in this way, the turntable 31 is intermittently rotated by a fixed angle, and the liquid sample 11 is dropped on the dielectric block 10 stopped at a predetermined position, The liquid sample 11 is held in the sample holder 10a. Thereafter, when the turntable 31 is further rotated by a certain angle, the dielectric block 10 is sent to the measurement position shown in FIG. 1 and stops there.
[0052]
In addition to the dielectric block 10, the surface plasmon sensor of the present embodiment further includes a light source 14 (hereinafter referred to as a laser light source 14) composed of a semiconductor laser or the like that generates one light beam 13, and the light beam 13 An incident optical system 15 that passes through the dielectric block 10 and enters the interface 10b between the dielectric block 10 and the metal film 12 so as to obtain various incident angles, and a light beam totally reflected by the interface 10b. A collimator lens 16 for collimating 13; a light detecting means 17 for detecting the collimated light beam 13; a differential amplifier array 18 connected to the light detecting means 17; a driver 19; and a computer. A signal processing unit (CPU) 20 including a system and the like, and a shutter 50 that intermittently opens and closes an optical path from the laser light source 14 to the dielectric block 10 are provided.
[0053]
The incident optical system 15 includes a collimator lens 15a that collimates the light beam 13 emitted from the laser light source 14 in a divergent light state, and a condensing lens that converges the collimated light beam 13 on the interface 10b. 15b.
[0054]
Since the light beam 13 is condensed by the condenser lens 15b as described above, it includes components that are incident on the interface 10b at various incident angles θ. In addition, this incident angle (theta) shall be an angle more than a total reflection angle. Therefore, the light beam 13 is totally reflected at the interface 10b, and the reflected light beam 13 includes components reflected at various reflection angles. The incident optical system 15 may be configured to cause the light beam 13 to enter the interface 10b in a defocused state. By doing so, errors in surface plasmon resonance state detection are averaged, and measurement accuracy is improved.
[0055]
The light beam 13 is incident on the interface 10b as p-polarized light. In order to do so, the laser light source 14 may be disposed in advance so that the polarization direction thereof is a predetermined direction. In addition, the direction of polarization of the light beam 13 may be controlled with a wave plate.
[0056]
The shutter 50 includes a driver (not shown) that controls the opening / closing operation of the shutter 50 based on an instruction from the signal processing unit (CPU) 20. The shutter 50 functions as the intermittent irradiation means described in the claims. FIG. 2A is a diagram showing the irradiation intensity at the interface 10 b of the light beam 13 when the optical path from the laser light source 14 to the dielectric block 10 is intermittently opened and closed by the shutter 50. When the light path is intermittently opened and closed by the shutter 50, the irradiation intensity at the interface 10b of the light beam 13 is not constant when the shutter 50 is opened and closed. It is desirable to perform the measurement during the period from when it starts to close. Further, the signal characteristic detected by the light detection means 17 shows a transient response characteristic as shown in FIG. Therefore, it is more desirable to perform the measurement in the period from when the transient response time has elapsed until the shutter 50 starts to close. Here, it is preferable to drive the shutter 50 so that the temperature change of the liquid sample 11 and the dielectric block 10 affecting the sample by the light beam 13 is 0.5 ° C. or less. Furthermore, if the temperature change is 0.1 ° C. or less, more accurate measurement can be performed.
[0057]
Hereinafter, sample analysis by the surface plasmon sensor having the above-described configuration will be described.
[0058]
At the time of measurement, the shutter 50 is opened by a signal from the signal processing unit 20, and the light beam 13 is incident on the incident optical system 15. As shown in FIG. 1, the light beam 13 emitted from the laser light source 14 in a divergent light state is converged on the interface 10 b between the dielectric block 10 and the metal film 12 by the action of the incident optical system 15. Therefore, the light beam 13 includes components incident on the interface 10b at various incident angles θ. In addition, this incident angle (theta) shall be an angle more than a total reflection angle. Therefore, the light beam 13 is totally reflected at the interface 10b, and the reflected light beam 13 includes components reflected at various reflection angles.
[0059]
After the total reflection at the interface 10b, the light beam 13 converted into parallel light by the collimator lens 16 is detected by the light detection means 17. In the present embodiment, the measurement is performed at the timing when the signal intensity on the detection surface of the light detection means 17 of the light beam 13 becomes maximum, as shown in FIG. The light detection means 17 in this example is a photodiode array in which a plurality of photodiodes 17a, 17b, 17c,... Are arranged in a line, and a light beam that has been collimated in the plane shown in FIG. The photodiodes are arranged so that the direction in which the photodiodes are juxtaposed is substantially perpendicular to the 13 traveling directions. Therefore, different photodiodes 17a, 17b, 17c,... Receive each component of the light beam 13 totally reflected at various reflection angles at the interface 10b.
[0060]
FIG. 3 is a block diagram showing an electrical configuration of the surface plasmon sensor. As shown in the figure, the driver 19 samples and holds the outputs of the differential amplifiers 18a, 18b, 18c,... Of the differential amplifier array 18, and these sample-hold circuits 22a, 22b. , 22c... Are input to the multiplexer 23, the A / D converter 24 which digitizes the output of the multiplexer 23 and inputs it to the signal processing unit 20, the multiplexer 23 and the sample hold circuits 22a, 22b, 22c. And a controller 26 that controls the operation of the drive circuit 25 based on an instruction from the signal processing unit 20. The instruction from the signal processing unit 20 to the controller 26 is performed in conjunction with the instruction from the signal processing unit 20 to the shutter 50. The outputs of the photodiodes 17a, 17b, 17c,... Are input to the differential amplifiers 18a, 18b, 18c,. At this time, the outputs of two photodiodes adjacent to each other are input to a common differential amplifier. Therefore, it can be considered that the outputs of the differential amplifiers 18a, 18b, 18c,... Are obtained by differentiating the photodetection signals output from the plurality of photodiodes 17a, 17b, 17c,.
[0061]
The outputs of the differential amplifiers 18a, 18b, 18c... Are sampled and held at predetermined timings by the sample hold circuits 22a, 22b, 22c. The multiplexer 23 inputs the sampled and held outputs of the differential amplifiers 18a, 18b, 18c,... Into the A / D converter 24 in a predetermined order. The A / D converter 24 digitizes these outputs and inputs them to the signal processing unit 20.
[0062]
FIG. 4 explains the relationship between the light intensity for each incident angle θ of the light beam 13 totally reflected at the interface 10b and the outputs of the differential amplifiers 18a, 18b, 18c. Here, it is assumed that the relationship between the incident angle θ of the light beam 13 on the interface 10b and the light intensity I is as shown in the graph of FIG.
[0063]
Specific incident angle θ at the interface 10b _SP Since the light incident on the surface excites surface plasmons at the interface between the metal film 12 and the liquid sample 11, the reflected light intensity I sharply decreases for this light. That is, θ _SP Is the total reflection elimination angle, and this angle θ _SP The reflected light intensity I takes a minimum value. This decrease in the reflected light intensity I is observed as a dark line in the reflected light, as indicated by D in FIG.
[0064]
(2) in FIG. 4 shows the direction in which the photodiodes 17a, 17b, 17c... Are arranged, and as described above, the positions of the photodiodes 17a, 17b, 17c. It uniquely corresponds to the incident angle θ.
[0065]
The relationship between the positions of the photodiodes 17a, 17b, 17c..., That is, the incident angle θ, and the output I ′ (differential value of the reflected light intensity I) of the differential amplifiers 18a, 18b, 18c. As shown in FIG.
[0066]
Based on the value of the differential value I ′ input from the A / D converter 24, the signal processing unit 20 selects the total reflection elimination angle θ from among the differential amplifiers 18a, 18b, 18c. _SP Is selected (the differential amplifier 18d is the differential amplifier 18d in the example of FIG. 4), and a predetermined correction process is applied to the differential value I 'output from the differential value I' = 0. Then, the value is displayed on the display means 21. In some cases, there may be a differential amplifier that outputs a differential value I ′ = 0. In this case, the differential amplifier is naturally selected.
[0067]
Thereafter, every time a predetermined time elapses, the differential value I ′ output from the selected differential amplifier 18d is displayed on the display means 21 after receiving a predetermined correction process. This differential value I ′ changes when the dielectric constant of the substance in contact with the metal film 12 of the measuring chip, that is, the refractive index changes, and the curve shown in FIG. Move up and down accordingly. Therefore, by continuously measuring this differential value I ′ with the passage of time, it is possible to investigate a change in the refractive index of the substance in contact with the metal film 12, that is, a change in characteristics.
[0068]
In particular, in the present embodiment, the sensing medium 30 that binds to a specific substance in the liquid sample 11 is fixed to the metal film 12, and the refractive index of the sensing medium 30 changes according to the binding state, so that the above differentiation By continuing to measure the value I ′, it is possible to examine the state of change in the coupling state. That is, in this case, both the liquid sample 11 and the sensing medium 30 are samples to be analyzed. Examples of the combination of the specific substance and the sensing medium 30 include an antigen and an antibody.
[0069]
As is apparent from the above description, in this embodiment, a photodiode array in which a plurality of photodiodes 17a, 17b, 17c,... Accordingly, even if the curve shown in FIG. 4 (1) is changed to a certain extent by moving in the left-right direction, the dark line can be detected. That is, by using such an array-like light detection means 17, a large measurement dynamic range can be secured.
[0070]
Instead of using the differential amplifier array 18 composed of a plurality of differential amplifiers 18a, 18b, 18c..., One differential amplifier is provided, and the outputs of the photodiodes 17a, 17b, 17c. Of these, two adjacent outputs may be sequentially input to this one differential amplifier.
[0071]
In addition, in order to examine the change in the binding state between the specific substance in the liquid sample 11 and the sensing medium 30 over time, the differential value I ′ is obtained and displayed every time a predetermined time elapses. Alternatively, the difference ΔI ′ between the measured differential value I ′ (0) and the differential value I ′ (t) measured when a predetermined time has elapsed may be obtained and displayed.
[0072]
After a predetermined measurement time has elapsed, the shutter 50 is closed by a signal from the signal processing unit 20, and the optical path from the laser light source 14 to the dielectric block 10 is blocked.
[0073]
According to the sensor using the total reflection attenuation according to the present embodiment, a shutter 50 is provided between the laser light source 14 and the incident optical system 15 so as to irradiate the dielectric block 10 with the light beam 13 intermittently. Since the time during which the dielectric block 10 is irradiated with the light beam 13 is shortened, the temperature change of the liquid sample 11 and the dielectric block 10 that affects the sample due to the irradiation of the light beam 13 can be suppressed. On the other hand, the drift phenomenon can be prevented from occurring.
[0074]
Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 5, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted unless particularly necessary. The measuring apparatus according to the second embodiment is obtained by changing the intermittent irradiation means from the first embodiment.
[0075]
The surface plasmon sensor according to the present embodiment includes a dielectric block 10, a light source 14 (hereinafter referred to as a laser light source 14) composed of a semiconductor laser or the like that generates one light beam 13, and the light beam 13 that is a dielectric block. 10, an incident optical system 15 that makes the incident light incident on the interface 10b between the dielectric block 10 and the metal film 12 so that various incident angles can be obtained, and a light beam 13 totally reflected by the interface 10b. From the collimator lens 16 to be converted into light, the light detection means 17 for detecting the collimated light beam 13, the differential amplifier array 18 connected to the light detection means 17, the driver 19, and the computer system A signal processing unit (CPU) 20 and a driver 51 for driving the laser light source 14 intermittently.
[0076]
The driver 51 functions as the light source driving means described in the claims, that is, the intermittent irradiation means. The driver 51 drives the laser light source 14 based on an instruction from the signal processing unit (CPU) 20. In the present embodiment, the laser light source 14 is intermittently driven by the driver 51, and therefore may include an oscillation wavelength stabilizing unit (not shown) in order to stabilize the oscillation wavelength. As this oscillation wavelength stabilizing means, the one described in JP 2000-155093 A can be used.
[0077]
Also in the present embodiment, the irradiation intensity at the interface 10b of the light beam 13 when the laser light source 14 is turned on and off is substantially as shown in FIG. 2A, so that the laser light source 14 is turned on and off. It is desirable to perform the measurement in a period that is not affected, that is, a period from when the laser light source 14 is completely turned on to when it is turned off. Further, since the signal characteristic detected by the light detection means 17 shows a transient response characteristic as shown in FIG. 2B, the measurement is performed during the period from when the transient response time elapses until the laser light source 14 is turned off. More desirable to do. Here, it is preferable to drive the laser light source 14 so that the temperature change of the liquid sample 11 and the dielectric block 10 affecting the sample by the light beam 13 is 0.5 ° C. or less. Furthermore, if the temperature change is 0.1 ° C. or less, more accurate measurement can be performed.
[0078]
Hereinafter, sample analysis by the surface plasmon sensor having the above-described configuration will be described.
[0079]
At the time of measurement, the driver 51 drives the laser light source 14 with a signal from the signal processing unit 20. After the laser light source 14 is driven, measurement is performed as in the first embodiment. After a predetermined measurement time has elapsed, the driver 51 stops the laser light source 14 by a signal from the signal processing unit 20.
[0080]
Also in the second embodiment, the same effect as in the first embodiment can be obtained.
[0081]
Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 6, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted unless particularly required.
[0082]
The measurement apparatus according to the third embodiment is obtained by changing the surface plasmon sensor described in the first embodiment to a leakage mode sensor, and in this example, the dielectric block 10 formed as a measurement chip is used. It is configured. A clad layer 40 is formed on one surface (upper surface in the figure) of the dielectric block 10, and an optical waveguide layer 41 is further formed thereon.
[0083]
The dielectric block 10 is formed using, for example, synthetic resin or optical glass such as BK7. On the other hand, the cladding layer 40 is formed in a thin film shape using a dielectric having a lower refractive index than the dielectric block 10 or a metal such as gold. The optical waveguide layer 41 is also formed into a thin film using a dielectric having a higher refractive index than that of the cladding layer 40, such as PMMA. The thickness of the cladding layer 40 is, for example, 36.5 nm when formed from a gold thin film, and the thickness of the optical waveguide layer 41 is, for example, about 700 nm when formed from PMMA.
[0084]
In the leakage mode sensor configured as described above, when the light beam 13 emitted from the laser light source 14 is incident on the cladding layer 40 through the dielectric block 10 at an incident angle equal to or greater than the total reflection angle, the light beam 13 is incident on the dielectric block 10. The light having a specific wave number that is totally reflected at the interface 10b between the first and second cladding layers 40 and is incident on the optical waveguide layer 41 at a specific incident angle after passing through the cladding layer 40 propagates through the optical waveguide layer 41 in a waveguide mode. It becomes like this. When the waveguide mode is excited in this way, most of the incident light is taken into the optical waveguide layer 41, and total reflection attenuation occurs in which the intensity of light totally reflected at the interface 10b sharply decreases.
[0085]
Since the wave number of guided light in the optical waveguide layer 41 depends on the refractive index of the liquid sample 11 on the optical waveguide layer 41, the refractive index of the liquid sample 11 can be obtained by knowing the specific incident angle at which total reflection attenuation occurs. In addition, the characteristics of the liquid sample 11 related thereto can be analyzed. The characteristics of the liquid sample 11 can also be analyzed based on the reflected light intensity I in the vicinity of the specific incident angle and the differential value I ′ output from each differential amplifier of the differential amplifier array 18.
[0086]
In the third embodiment, the same effect as that of the first embodiment can be obtained.
[0087]
Next, a fourth embodiment of the present invention will be described with reference to FIG. In FIG. 7, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted unless particularly required.
[0088]
The measurement apparatus according to the fourth embodiment is obtained by replacing the surface plasmon sensor described in the second embodiment with a leakage mode sensor, and in this example, the dielectric block 10 formed as a measurement chip is used. It is configured. A clad layer 40 is formed on one surface (upper surface in the figure) of the dielectric block 10, and an optical waveguide layer 41 is further formed thereon.
[0089]
In the fourth embodiment, the same effect as in the second embodiment can be obtained.
[0090]
Next, a fifth embodiment of the present invention will be described with reference to FIG. In addition, the description about the element equivalent to the element already demonstrated is abbreviate | omitted unless there is particular need.
[0091]
The surface plasmon sensor of the present embodiment includes a dielectric block 110, a laser light source 114 that is a light source that generates a light beam 113, an incident optical system 115 that makes the light beam 113 incident on the dielectric block 110, and A collimator lens 116 that collimates the light beam 113 reflected by the dielectric block 110 and emits it toward the photodetector 117, and receives the light beam 113 emitted from the collimator lens 116 to detect the light intensity. A photodiode array (photodetector) 117, a differential amplifier array 118 connected to the photodiode array 117, a driver 119 connected to the differential amplifier array 118, a computer system connected to the driver 119, etc. A signal processing unit 120, an A / D converter 127 that converts a signal output from the photodiode array 117 into a digital signal and outputs the digital signal, and a laser From the source 114 consisting of a shutter 160. for intermittently opening and closing the optical path to the dielectric block 110. Note that the calculation means described in the claims includes a differential amplifier array 118, a driver 119, and a signal processing unit 120.
[0092]
The dielectric block 110, together with the metal film 112, constitutes a disposable measurement chip (measurement unit). For example, the dielectric block 110 is fitted and fixed one by one in the chip holding holes of the moving table 132 attached to the turntable 131. The moving table 132 is attached to the turntable 131 so as to be movable in a direction perpendicular to the paper surface of FIG. 8, that is, in the vertical direction in FIG. 9, and moves in this direction by driving the actuator 133.
[0093]
After the dielectric block 110 is fixed to the turntable 131 as described above, the turntable 131 is intermittently rotated by a certain angle, and the liquid sample 111 is dropped on the dielectric block 110 stopped at a predetermined position. The liquid sample 111 is held in the sample holder 110a. Thereafter, when the turntable 131 is further rotated by a certain angle, the dielectric block 110 is sent to the measurement position shown in FIG. 8 and stops there.
[0094]
Hereinafter, processing of a signal indicating the intensity distribution of the light beam 113 in the surface plasmon sensor having the above configuration will be described in detail. FIG. 10 is a block diagram showing an electrical configuration of the surface plasmon measuring apparatus.
[0095]
As shown in the figure, the differential amplifier array 118 includes switches 151a, 151b, 151c... Provided for each of the photodiodes 117a, 117b, 117c. 150a, 150b, 150c,..., And differential amplifiers 118a, 118b, 118c,... Provided for every two adders adjacent to each other. That is, in this embodiment, a photodiode group (light receiving element group) is formed by three photodiodes. The switches 151a, 151b, 151c... Are opened and closed based on instructions from the signal processing unit 120.
[0096]
Further, the driver 119 samples and holds the outputs of the differential amplifiers 118a, 118b, 118c... Of the differential amplifier array 118, and the sample hold circuits 122a, 122b, 122c. A multiplexer 123 to which each output is input, an A / D converter 124 that digitizes the output of the multiplexer 123 and inputs it to the signal processing unit 120, a drive circuit that drives the multiplexer 123 and the sample hold circuits 122a, 122b, 122c. 125, and a controller 126 that controls the operation of the drive circuit 125 based on an instruction from the signal processing unit 120.
[0097]
The outputs of the photodiodes 117a, 117b, 117c,... Are added every three outputs by the adders 150a, 150b, 150c, and the outputs of the adders 150a, 150b, 150c,. Input to the dynamic amplifiers 118a, 118b, 118c. At this time, the outputs of two adders adjacent to each other are input to a common differential amplifier. Therefore, the output of each differential amplifier 118a, 118b, 118c... Is the photodetection signal output from the plurality of photodiodes 117a, 117b, 117c. 117 It can be considered that it is differentiated with respect to the juxtaposed direction.
[0098]
The outputs of the differential amplifiers 118a, 118b, 118c... Are sampled and held at predetermined timings by the sample hold circuits 122a, 122b, 122c. The multiplexer 123 inputs the sampled and held outputs of the differential amplifiers 118a, 118b, 118c... To the A / D converter 124 in a predetermined order. The A / D converter 124 digitizes these outputs and inputs them to the signal processing unit 120.
[0099]
FIG. 11 illustrates the relationship between the light intensity at each incident angle θ of the light beam 113 totally reflected by the interface 110b and the output of the differential amplifiers 118a, 118b, 118c. Here, it is assumed that the relationship between the incident angle θ of the light beam 113 with respect to the interface 110b and the light intensity I of the reflected light beam 113 is as shown in FIG.
[0100]
11 (2) shows the direction in which the photodiodes 117a, 117b, 117c,... Are arranged side by side. As described above, the position in the direction in which the photodiodes 117a, 117b, 117c,. Corresponds uniquely to θ.
[0101]
Further, the relationship between the positions of the photodiodes 117a, 117b, 117c..., That is, the incident angle θ, and the output I ′ (differential value of the reflected light intensity I) of the differential amplifiers 118a, 118b, 118c. The result is as shown in FIG.
[0102]
FIG. 11 (4) shows a beam profile represented by a signal detected by the photodiodes 117a, 117b, 117c,... A / D converted by the A / D converter 127 and input to the signal processing unit 120. ing.
[0103]
Based on the value of the differential value I ′ input from the A / D converter 124, the signal processing unit 120 has a positive value as a differential value from among the differential amplifiers 118a, 118b, 118c. Total reflection attenuation angle θ _SP The output closest to the differential value I ′ = 0 corresponding to is obtained (in the example of FIG. 11 (3), the differential amplifier 118k), and the differential value has a negative value and is totally reflected. Attenuation angle θ _SP Are selected (the differential amplifier 118j in the example of FIG. 11 (3)), and the differential values output by those differential amplifiers are selected. Based on the total reflection attenuation angle θ _SP Is calculated. In some cases, there may be a differential amplifier that outputs a differential value I ′ = 0. In that case, the total reflection attenuation angle θ is based on the differential amplifier. _SP Is calculated.
[0104]
In addition, the signal processing unit 120 has the total reflection attenuation angle θ _SP The beam profile as shown in FIG. 11 (4) is displayed on the display means 121 by the signal input from the photodiodes 117a, 117b, 117c... To the signal processing unit 120 via the A / D converter 127. Can be made. In this case, each output of the photodiodes 117a, 117b, 117c,... Is A / D converted by the A / D converter 127, and a beam profile is generated based on the signal. _SP It is possible to generate a beam profile at a higher resolution than the resolution used when calculating.
[0105]
Here, the total reflection attenuation angle θ is obtained by adding all the outputs of each photodiode group. _SP However, the present invention is not necessarily limited to such a mode. The switches connected to the photodiodes are appropriately opened and closed, and the outputs of one or two photodiodes in each photodiode group are added. Total reflection attenuation angle θ _SP May be calculated. Further, the photodiode group is not limited to the one composed of three photodiodes, and may be composed of a plurality of two or four or more photodiodes.
[0106]
Further, the configuration of the differential amplifier array 118 is not limited to the configuration shown in FIG.
[0107]
Basically, by performing the above-described operation, the binding state between the specific substance in the liquid sample 111 and the sensing substance 130 can be examined. As described above, the reaction characteristics of the sensing substance 130 and the metal film If the film thickness of 112 is non-uniform in the plane of the metal film 112, or if dust adheres on the metal film 112 or the sensing substance 130, the measurement result of the above-mentioned bonding state according to the state Will result in variations. Hereinafter, the point of preventing the occurrence of such a problem will be described.
[0108]
In the present embodiment, at the time of one measurement, the moving table 132 is intermittently moved in the vertical direction in FIG. 9 by driving the actuator 133, and N times (N is plural) including the first and last stops. The moving table 132 is stopped. Under each stop state, the light beam 113 is irradiated onto the interface 110b as described above, and the intensity of the light beam 113 totally reflected at the interface 110b is detected by the photodiodes 117a, 117b, 117c,. That is, in this case, the intensity of the totally reflected light beam 113 is detected at N different light beam incident positions on the interface 110b.
[0109]
Therefore, N differential values I ′ are input to the signal processing unit 120 from the A / D converter 124 for each output of the differential amplifiers 118a, 118b, 118c. Then, the signal processing unit 120 obtains the median value of N differential values I ′ for each position, and sets it as the differential value I ′ representing the position. In this way, one differential value I ′ obtained as representative data from N differential values I ′ is used in the same manner as described above, and the specific substance in the liquid sample 111 and the sensing substance 130 are used. The binding state is examined.
[0110]
The driving of the actuator 133 is controlled by a general control unit (not shown), and a predetermined timing signal is input from the general control unit to the signal processing unit 120 every time the moving table 132 stops N times. The signal processing unit 120 takes in the differential value I ′ from the A / D converter 124 every time this timing signal is input, and N differentials for each output of the differential amplifiers 118a, 118b, 118c. The value I ′ is obtained.
[0111]
As described above, one differential value I ′ obtained as representative data from N differential values I ′ relating to different light beam incident positions on the interface 110b is the thickness of the metal film 112 or the reaction of the sensing material 130. The characteristic can be specifically different, and further, fluctuations caused by disturbance such as dust on the sensing material 130 can be eliminated. Therefore, according to this measuring apparatus, even if the film thickness of the metal film 112 and the reaction characteristics of the sensing substance 130 are non-uniform or dust is present on the sensing substance 130, the measurement results vary due to them. Can be prevented.
[0112]
Here, the signal processing unit 120 as a calculation means is configured to obtain median values of N differential values I ′ and use them as representative data, but instead, N differential values. An average value of data included in the upper and lower predetermined widths may be obtained from the median value of I ′ and used as representative data. Furthermore, among N differential values I ′, an average value of the differential values I ′ excluding their maximum value and / or minimum value may be obtained and used as representative data.
[0113]
In addition, multiple measurements to obtain representative data are performed by splitting the light beam into a plurality of light beams, allowing the branched light beams to simultaneously enter different positions on the interface 110b, and simultaneously measuring with a plurality of photodiode arrays. May be performed.
[0114]
Furthermore, a case where the above measurement is performed a plurality of times along a time series will be described. First, the sensitivity characteristics of the photodiodes 117a, 117b, 117c, and the total reflection attenuation angle θ by the signal processing unit 120 are described. _SP The relationship with the calculation characteristic will be described.
[0115]
12 (1), (2), and (3) are graphs showing the relationship between the dark line position and the output characteristics of the differential amplifier connected to each light receiving element on the left side, and the actual dark line position and calculation on the right side. Dark line position (total reflection attenuation angle θ _SP ).
[0116]
FIG. 12 (1) shows a case where the sensitivity characteristic of each light receiving element is linear and the sensitivity of each light receiving element is uniform. In this case, as shown in the graph on the right side, an actual dark line is shown. And the calculated dark line position are ideally linear. However, if the sensitivity characteristic of each light receiving element is non-linear as shown in FIG. 12 (2), the calculation characteristic swells, and if the sensitivity of each light receiving element is not uniform as shown in FIG. 12 (3). The characteristic becomes non-linear.
[0117]
Therefore, in the surface plasmon sensor of the present embodiment, as shown in FIG. 13, a plurality of measurement data detected in a series of time series is stored in a storage unit (not shown) in the signal processing unit 120. By smoothing a plurality of measurement data by the least square method, a measurement error due to the sensitivity characteristic of each light receiving element can be reduced, so that measurement accuracy can be improved. The smoothing method is not limited to the least square method. Further, the surface plasmon measuring apparatus according to the fifth embodiment can also be a leakage mode sensor by changing a part of the configuration as in the first embodiment.
[0118]
Next, a sixth embodiment of the present invention will be described with reference to FIG. In addition, the description about the element equivalent to the element already demonstrated is abbreviate | omitted unless there is particular need.
[0119]
The surface plasmon sensor of the present embodiment includes a dielectric block 110, a laser light source 114 that is a light source that generates a light beam 113, an incident optical system 115 that makes the light beam 113 incident on the dielectric block 110, and The collimator lens 116 that collimates the light beam 113 reflected by the dielectric block 110 and emits it toward the photodetector 117, and receives the light beam 113 emitted from the collimator lens 116 to detect the light intensity. A photodiode array (photodetector) 117, an A / D converter 170, an arithmetic processing unit 171, a signal processing unit 172 including a computer system, and an optical path from the laser light source 114 to the dielectric block 110. And a shutter 170 that opens and closes automatically. Note that the calculation means described in the claims includes an arithmetic processing unit 171 and a signal processing unit 172. The operations of the arithmetic processing unit 171 and the signal processing unit 172 will be described later.
[0120]
Hereinafter, sample analysis by the surface plasmon sensor having the above-described configuration will be described. As shown in FIG. 14, the light beam 113 emitted from the laser light source 114 is converged on the interface 110b between the dielectric block 110 and the metal film 112 through the incident optical system 115, and is totally reflected by the interface 110b. Beam 113 is detected by photodetector 117 through collimator lens 116. The photodetector 117 receives each component of the light beam 113 totally reflected at various reflection angles at the interface 110b by different photodiodes 117a, 117b, 117c. Then, the photodetector 117 outputs a signal indicating the intensity distribution of the light beam 113 detected by each photodiode 117a, 117b, 117c... To the A / D converter 170. The signal A / D converted by the A / D converter 170 is input to the arithmetic processing unit 171. In the present embodiment, in order to improve the resolution, the photodetector 117 is arranged at a position farther from the interface 110b than in the fifth embodiment.
[0121]
The arithmetic processing unit 171 first calculates the average value of the outputs of the three adjacent photodiodes from the outputs of the photodiodes 117a, 117b, 117c,... By sequentially shifting the photodiodes one by one. The difference between the average values is obtained and output to the signal processing unit 172. That is, first, an average value of the photodiodes 117a, 117b, and 117c, an average value of the photodiodes 117b, 117c, and 117d, an average value of the photodiodes 117c, 117d, and 117e, and the like are sequentially calculated. The average value of 117d—the average value of photodiodes 117a, 117b, and 117c, the average value of photodiodes 117c, 117d, and 117e—the average value of photodiodes 117b, 117c, and 117d, and the like are sequentially obtained and output to signal processing unit 172. The difference between the average values is obtained by calculating the photodetection signal output from the plurality of photodiodes 117a, 117b, 117c,... And the average value of the outputs for each of the three adjacent photodiodes. It can be considered as a differential value I ′ differentiated with respect to the installation direction.
[0122]
FIG. 15 is a diagram for explaining signal values when the arithmetic processing unit 171 performs arithmetic processing. For example, it is assumed that the relationship between the incident angle θ of the light beam 113 to the interface 110b and the light intensity I of the reflected light beam 113 is as shown in FIG. When photodiodes 117a, 117b, 117c,... Are provided in the arrangement as shown in FIG. 15 (2), the output values as shown in FIG. 15 (3) are the photodiodes 117a, 117b, 117c. Is output from…. That is, (3) in the figure is a signal input to the arithmetic processing unit 171. In FIG. 3 (3), since the arrangement pitch of the photodiodes 117a, 117b, 117c,... Is narrow with respect to the beam profile, the signal value output from each photodiode 117a, 117b, 117c,. It is an example of an output value when it is easily affected, and is a graph with large unevenness. FIG. 4 (4) is a value obtained by calculating the average value of the outputs of three adjacent photodiodes while sequentially shifting the photodiodes one by one. Since the noise is canceled out, the graph becomes smoother than the graph shown in FIG. 3 (3), and the actual incident angle θ and the light intensity I of the reflected light beam 113 shown in FIG. A graph having a shape close to the graph indicating the relationship is obtained. FIG. 5 (5) shows the difference between the average values, that is, the differential value I ′ output from the arithmetic processing unit 171.
[0123]
Based on the value of the differential value I ′ input from the arithmetic processing unit 172, the signal processing unit 172 calculates the total reflection attenuation angle θ. _SP The total reflection attenuation angle θ from the set of photodiodes (which are the photodiodes 117h, 117i, and 117j in the example of FIG. 10B) from which the output closest to the differential value I ′ = 0 corresponding to is obtained. _SP Is calculated. Thereafter, the same operation as described above is repeated every time a predetermined time elapses, and the total reflection attenuation angle θ _SP And the angle change amount from the start of measurement is obtained and displayed on the display means 121. Since the refractive index of the sensing substance 130 changes according to the binding state between the specific substance in the sample liquid 111 and the sensing substance 130, the total reflection attenuation angle θ _SP By measuring the amount of change in the angle, it is possible to investigate the state of change in the coupling state.
[0124]
In the present embodiment, the differential value I ′ is obtained from the average value of the three photodiodes, and the total reflection attenuation angle θ is calculated based on the differential value I ′. _SP However, the present invention is not necessarily limited to such an embodiment. The average value of two adjacent photodiodes or the average value of four or more adjacent photodiodes is sequentially obtained to obtain a differential value I ′. You may ask for.
[0125]
In the present embodiment, the average value of the outputs of the three adjacent photodiodes of the photodetector 117 is calculated while sequentially shifting the photodiodes one by one, and then the difference between the average values before and after, that is, the differential value I 'Is obtained, and based on the differential value I', the total reflection attenuation angle θ _SP The angle is measured so that even if a light receiving element with a small size is used or the amount of light received by the light receiving element is small, it is not easily affected by noise, and is attenuated in total reflection with high resolution and accuracy. Angle θ _SP Can be measured. The total value may be used instead of the average value of each photodiode, and the signal value for differentiation can be increased. Instead of the average value, a value obtained by dividing the total value by a desired value, a value obtained by multiplying the total value by a desired value, or the like may be used.
[0126]
If the arithmetic processing unit 171 outputs an average value of each of the three photodiodes in addition to the differential value, and the signal processing unit 172 generates a beam profile based on this average value, it is possible to obtain a high resolution and noise level. A beam profile with less influence can be generated. Also, the surface plasmon sensor of the sixth embodiment can be a leakage mode sensor by changing a part of the configuration, as in the first embodiment.
[Brief description of the drawings]
FIG. 1 is a side view of a surface plasmon sensor according to a first embodiment of the present invention.
FIG. 2 is a graph showing intensity characteristics on the detection surface of a light beam.
FIG. 3 is a block diagram showing an electrical configuration of the surface plasmon sensor.
FIG. 4 is a schematic diagram showing the relationship between the light beam incident angle and the detected light intensity and the relationship between the light beam incident angle and the differential value of the light intensity detection signal in the surface plasmon sensor.
FIG. 5 is a side view of a surface plasmon sensor according to a second embodiment of the present invention.
FIG. 6 is a side view of a leakage mode sensor according to a third embodiment of the present invention.
FIG. 7 is a side view of a leakage mode sensor according to a fourth embodiment of the present invention.
FIG. 8 is a side view of a surface plasmon sensor according to a fifth embodiment of the present invention.
FIG. 9 is a plan view showing an optical system portion of the surface plasmon sensor.
FIG. 10 is a block diagram showing an electrical configuration of the surface plasmon sensor.
FIG. 11 is a diagram showing the relationship between the incident angle of the light beam on the interface and the output of the differential amplifier.
FIG. 12 is a graph showing the relationship between the sensitivity characteristic of each light receiving element and the output characteristic of the signal processing unit.
FIG. 13 is an explanatory diagram when smoothing the output characteristics of a signal processing unit.
FIG. 14 is a side view of a surface plasmon sensor according to a sixth embodiment of the present invention.
FIG. 15 is a diagram showing the relationship between the incident angle of the light beam on the interface and the output of the arithmetic processing unit.
[Explanation of symbols]
10, 110 Dielectric block
10a, 110a Dielectric block sample holder
10b, 110b Interface between dielectric block and metal film
11, 111 samples
12, 112 Metal film
13, 113 Light beam
14, 114 Semiconductor laser, etc.
15, 115 Incident optics
16, 116 Collimator lens
17, 117 Photodetection means (photodiode array)
17a, 17b, 17c …… Photodiode
117a, 117b, 117c …… Photodiode
18, 118 Differential amplifier array
18a, 18b, 18c ... Differential amplifier
118a, 118b, 118c ... Differential amplifier
19,119 drivers
20, 120 Signal processor
21, 121 Display means
22a, 22b, 22c ... Sample hold circuit
122a, 122b, 122c ... Sample hold circuit
23, 123 multiplexer
24, 124 A / D converter
25, 125 Drive circuit
26, 126 controller
30, 130 Sensing media
31, 131 turntable
40 Clad layer
41 Optical waveguide layer
50, 160 shutter
51 drivers
127 A / D converter
132 Moving platform
133 Actuator
150a, 150b, 150c ... Adder
151a, 151b, 151c …… Switch
170 A / D converter
171 Arithmetic processing section
172 Signal processor

Claims (15)

A dielectric block;
A thin film layer formed on one surface of the dielectric block and brought into contact with the sample;
A light source that generates a light beam;
An incident optical system that causes the light beam to be incident on the dielectric block at an incident angle at which a total reflection condition is obtained at an interface between the dielectric block and the thin film layer;
In a measurement method for analyzing the sample by a measurement device comprising a plurality of light receiving elements and comprising a light detection means for measuring the intensity of a light beam totally reflected at the interface,
Intermittently irradiating the dielectric block with the light beam;
The plurality of light receiving elements are divided into several light receiving element groups, and a total of outputs for each of two adjacent light receiving element groups is differentiated with respect to the parallel arrangement direction of the light receiving elements, and the interface is based on the differential value. In the processing for obtaining the reflection angle at which the reflected light intensity at the minimum takes a minimum value, the incident optical system and the dielectric block are relatively moved so that the incident position of the light beam at the interface changes, and the light beam Each time the incident position of is different, perform statistical processing of the obtained data,
Obtain one representative data corresponding to the reflection angle,
Smooth multiple representative data obtained in a series of time series,
A measurement method comprising analyzing the sample based on the plurality of smoothed measurement data. A dielectric block;
A thin film layer formed on one surface of the dielectric block and brought into contact with the sample;
A light source that generates a light beam;
An incident optical system that causes the light beam to be incident on the dielectric block at an incident angle at which a total reflection condition is obtained at an interface between the dielectric block and the thin film layer;
In a measurement method for analyzing the sample by a measurement device comprising a plurality of light receiving elements and comprising a light detection means for measuring the intensity of a light beam totally reflected at the interface,
Intermittently irradiating the dielectric block with the light beam;
An average value of outputs of two or more adjacent light receiving elements adjacent to each other is sequentially calculated in the direction in which the light receiving elements are arranged in parallel, and the average value is differentiated with respect to the direction in which the light receiving elements are arranged in parallel. Based on the processing for obtaining the reflection angle at which the reflected light intensity at the interface takes a minimum value, the incident optical system and the dielectric block are relatively moved so that the incident position of the light beam at the interface changes. , Each when the incident position of the light beam is in a different state, statistically processing a plurality of obtained data, to obtain one representative data corresponding to the reflection angle,
Smooth multiple representative data obtained in a series of time series,
A measurement method comprising analyzing the sample based on the plurality of smoothed measurement data. A dielectric block;
A thin film layer formed on one surface of the dielectric block and brought into contact with the sample;
A light source that generates a light beam;
An incident optical system that causes the light beam to be incident on the dielectric block at an incident angle at which a total reflection condition is obtained at an interface between the dielectric block and the thin film layer;
In a measurement method for analyzing the sample by a measurement device comprising a plurality of light receiving elements and comprising a light detection means for measuring the intensity of a light beam totally reflected at the interface,
Intermittently irradiating a plurality of different incident positions on the interface with the light beam;
The plurality of light receiving elements are divided into several light receiving element groups, and a total of outputs for each of two adjacent light receiving element groups is differentiated with respect to the parallel arrangement direction of the light receiving elements, and the interface is based on the differential value. The processing for obtaining the reflection angle at which the reflected light intensity at the local area takes a minimum value is performed when the incident positions of the light beams are different from each other, and statistical processing is performed on a plurality of obtained data to obtain the reflection angle. One corresponding representative data is acquired,
Smooth multiple representative data obtained in a series of time series,
A measurement method comprising analyzing the sample based on the plurality of smoothed measurement data. A dielectric block;
A thin film layer formed on one surface of the dielectric block and brought into contact with the sample;
A light source that generates a light beam;
An incident optical system that causes the light beam to be incident on the dielectric block at an incident angle at which a total reflection condition is obtained at an interface between the dielectric block and the thin film layer;
In a measurement method for analyzing the sample by a measurement device comprising a plurality of light receiving elements and comprising a light detection means for measuring the intensity of a light beam totally reflected at the interface,
Intermittently irradiating a plurality of different incident positions on the interface with the light beam;
An average value of outputs of two or more adjacent light receiving elements adjacent to each other is sequentially calculated in the direction in which the light receiving elements are arranged in parallel, and the average value is differentiated with respect to the direction in which the light receiving elements are arranged in parallel. The processing for obtaining the reflection angle at which the reflected light intensity at the interface takes a minimum value based on each is performed when the incident position of the light beam is different from each other, and statistical processing is performed on a plurality of obtained data, Obtain one representative data corresponding to the reflection angle,
Smooth multiple representative data obtained in a series of time series,
A measurement method comprising analyzing the sample based on the plurality of smoothed measurement data. After the transient response time from the irradiation start of the light beam by measuring the reflected light intensity of the light beam at the interface has passed any one of claims 1, characterized in that to start the measurement 4 Measuring method. A dielectric block;
A thin film layer formed on one surface of the dielectric block and brought into contact with the sample;
A light source that generates a light beam;
An incident optical system that makes the light beam incident on the dielectric block at various angles so that a total reflection condition is obtained at an interface between the dielectric block and the thin film layer;
In a measuring device comprising a plurality of light receiving elements, and comprising a light detecting means for measuring the intensity of the light beam totally reflected at the interface and detecting the state of total reflection attenuation,
Intermittent irradiation means for intermittently irradiating the dielectric block with the light beam;
Means for relatively moving the incident optical system and the dielectric block so that the incident position of the light beam at the interface changes;
The plurality of light receiving elements are divided into several light receiving element groups, and a total of outputs for each of two adjacent light receiving element groups is differentiated with respect to the parallel arrangement direction of the light receiving elements, and the interface is based on the differential value. The reflection angle at which the intensity of reflected light takes a minimum value is calculated when the incident positions of the light beams are different from each other, and a plurality of obtained data are statistically processed to obtain the reflection angle. A computing means for obtaining one corresponding representative data;
A measuring apparatus comprising: smoothing processing means for smoothing a plurality of representative data detected in a series of time series by the arithmetic means. A dielectric block;
A thin film layer formed on one surface of the dielectric block and brought into contact with the sample;
A light source that generates a light beam;
An incident optical system that makes the light beam incident on the dielectric block at various angles so that a total reflection condition is obtained at an interface between the dielectric block and the thin film layer;
In a measuring device comprising a plurality of light receiving elements, and comprising a light detecting means for measuring the intensity of the light beam totally reflected at the interface and detecting the state of total reflection attenuation,
Intermittent irradiation means for intermittently irradiating the dielectric block with the light beam;
Means for relatively moving the incident optical system and the dielectric block so that the incident position of the light beam at the interface changes;
An average value of outputs of two or more adjacent light receiving elements adjacent to each other is sequentially calculated in the direction in which the light receiving elements are arranged in parallel, and the average value is differentiated with respect to the direction in which the light receiving elements are arranged in parallel. The processing for obtaining the reflection angle at which the reflected light intensity at the interface takes a minimum value based on each is performed when the incident position of the light beam is different from each other, and statistical processing is performed on a plurality of obtained data, Computing means for obtaining one representative data corresponding to the reflection angle;
A measuring apparatus comprising: smoothing processing means for smoothing a plurality of measurement data detected in a series of time series by the arithmetic means. A dielectric block;
A thin film layer formed on one surface of the dielectric block and brought into contact with the sample;
A light source that generates a light beam;
An incident optical system that makes the light beam incident on the dielectric block at various angles so that a total reflection condition is obtained at an interface between the dielectric block and the thin film layer;
In a measuring device comprising a plurality of light receiving elements, and comprising a light detecting means for measuring the intensity of the light beam totally reflected at the interface and detecting the state of total reflection attenuation,
Intermittent irradiation means for intermittently irradiating the dielectric block with the light beam;
The incident optical system is formed such that the light beam can be incident on a plurality of different incident positions on the interface,
The plurality of light receiving elements are divided into several light receiving element groups, and a total of outputs for each of two adjacent light receiving element groups is differentiated with respect to the parallel arrangement direction of the light receiving elements, and the interface is based on the differential value. The reflection angle at which the intensity of reflected light takes a minimum value is calculated when the incident positions of the light beams are different from each other, and a plurality of obtained data are statistically processed to obtain the reflection angle. A computing means for obtaining one corresponding representative data;
A measuring apparatus comprising: smoothing processing means for smoothing a plurality of measurement data detected in a series of time series by the arithmetic means. A dielectric block;
A thin film layer formed on one surface of the dielectric block and brought into contact with the sample;
A light source that generates a light beam;
An incident optical system that makes the light beam incident on the dielectric block at various angles so that a total reflection condition is obtained at an interface between the dielectric block and the thin film layer;
In a measuring device comprising a plurality of light receiving elements, and comprising a light detecting means for measuring the intensity of the light beam totally reflected at the interface and detecting the state of total reflection attenuation,
Intermittent irradiation means for intermittently irradiating the dielectric block with the light beam;
The incident optical system is formed such that the light beam can be incident on a plurality of different incident positions on the interface,
An average value of outputs of two or more adjacent light receiving elements adjacent to each other is sequentially calculated in the direction in which the light receiving elements are arranged in parallel, and the average value is differentiated with respect to the direction in which the light receiving elements are arranged in parallel. The processing for obtaining the reflection angle at which the reflected light intensity at the interface takes a minimum value based on each is performed when the incident position of the light beam is different from each other, and statistical processing is performed on a plurality of obtained data, Computing means for obtaining one representative data corresponding to the reflection angle;
A measuring apparatus comprising: smoothing processing means for smoothing a plurality of measurement data detected in a series of time series by the arithmetic means. 10. The shutter according to claim 6 , wherein the intermittent irradiation means is a shutter that is provided between the light source and the dielectric block and intermittently opens and closes an optical path from the light source to the dielectric block. The measuring apparatus of any one of Claims. The measuring apparatus according to claim 6 , wherein the intermittent irradiation unit is a light source driving unit that intermittently drives the light source. The measuring apparatus according to claim 11 , wherein the light source includes an oscillation wavelength stabilizing unit that stabilizes a wavelength of a light beam to be generated. The measuring apparatus according to any one of claims 6 to 12 , wherein the intermittent irradiation means is driven so that a temperature change of the sample by the light beam is 0.5 ° C or less. The measuring apparatus according to claim 6 , wherein the intermittent irradiation unit is driven so that a temperature change of the sample by the light beam is 0.1 ° C. or less. It said light detection means, after the transient response time from the irradiation start of the light beam by measuring the reflected light intensity of the light beam at the interface has elapsed, claim 6, characterized in that the measurement is started 14 The measuring device according to any one of the above.

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