JP3588880B2

JP3588880B2 - Biological light measurement device

Info

Publication number: JP3588880B2
Application number: JP29954295A
Authority: JP
Inventors: 敦牧; 優一山下; 英明小泉
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1995-11-17
Filing date: 1995-11-17
Publication date: 2004-11-17
Anticipated expiration: 2015-11-17
Also published as: JPH09135825A

Description

【０００１】
【発明の属する技術分野】
本発明は、生体光計測装置に関し、特に生体内部の光吸収物質の濃度変化を光を用いて無侵襲で計測するものであって、さらには生体深部での濃度変化を高い検出感度で計測可能な生体光計測装置に関する。
【０００２】
【従来の技術】
生体内部を簡便かつ無侵襲に測定する装置が臨床医療で望まれており、この要望に対し、生体光計測は非常に有効である。その第一の理由は、生体内部の酸素代謝機能は生体中の特定色素（ヘモグロビン、チトクロ−ムａａ３、ミオグロビン等）すなわち光吸収物質の濃度に対応し、この色素濃度は光（可視から近赤外領域の波長）吸収量から求められるからである。また、光計測が有効である第二、第三の理由としては、光は光ファイバによって扱いが簡便であり、さらに安全基準の範囲内での使用により生体に害を与えないことが挙げられる。
【０００３】
上記光計測の利点を利用して、可視から近赤外の波長の光を生体に照射し、照射位置から１０〜５０ｍｍ程度離れた位置での反射光から生体内部を測定する生体光計測装置が、例えば、特開昭６３−２７７０３８号公報および特開平５−３００８８７号公報に記載されている。
【０００４】
【発明が解決しようとする課題】
光を用いた生体計測では、生体の強い光散乱特性（散乱係数＝約１．０［１／ｍｍ］程度）により、照射された光は生体内で大きく拡がるため、計測量には生体内部の広範囲な吸収物質濃度が含まれてしまう。特に、検出感度の空間特性は、光照射及び検出位置に近い生体の浅部の感度が生体の深部の感度に比して大きい点に問題がある。そのため、生体深部の吸収物質濃度変化を精度良く計測することは困難である。例えば、生体脳の血行動態変化を頭皮上から計測する場合には、上記理由により、皮膚や頭骨部の血行動態変化が計測値に大きく反映する点に問題がある。
【０００５】
以下、上記従来技術を用いて生体深部での吸収物質の濃度変化の相対感度分布を求めた例を示す。生体表面を平面と仮定し、生体表面と平行な平面をＸ−Ｙ平面と定義し、生体表面上ｘ＝３２．５ｍｍかつｙ＝１７．５ｍｍの位置から光を照射し、光照射位置より３０ｍｍ離れた位置ｘ＝３２．５ｍｍかつｙ＝４７．５ｍｍの位置で集光した場合における、深さ２．５ｍｍの位置での相対感度分布を図１１に、深さ７．５ｍｍの位置での相対感度分布を図１２に、深さ１２．５ｍｍの位置での相対感度分布を図１３に示す。これらの図では、生体表面の影響が非常に大きく、生体深部の吸収物質の濃度変化を高い精度で計測することは困難である。
【０００６】
本発明の目的は、生体深部で吸収物質の濃度変化を高い精度で計測する生体光計測装置を提供することにある。
【０００７】
【課題を解決するための手段】
本発明の代表的な構成は次の通りである。
（１）請求項１記載の、被検体の頭部表面であって、その表面を平面と見なせる程度の小さな領域にある第１の照射位置から前記領域の深さ方向にある前記頭部内部へ第１の照射光を照射させる第１の光照射手段と、前記領域にある第２の照射位置から前記頭部内部へ第２の照射光を照射させる第２の光照射手段と、前記領域にある第１の検出位置において前記頭部内部を透過した前記第１の照射光を検出する第１の検出手段と、前記領域にある第２の検出位置において前記頭部内部を透過した前記第２の照射光を検出する第２の検出手段と、
前記第１の検出手段で検出した前記第１の光照射手段からの照射光の第１の透過光信号に基づく第１の信号と、前記第２の検出手段で検出した前記第２の光照射手段からの照射光の第２の透過光信号に基づく第２の信号とを演算装置内で乗算又は加算する手段を有し、
前記第１の照射位置から前記第１の検出位置に至る第１の透過光の光路と、前記第２の照射位置から前記第２の検出位置に至る第２の透過光の光路とが前記頭部内部の特定領域で重なり合うように前記第１および第２の照射位置と前記第１および第２の検出位置とが位置決めされており、
前記第１の照射位置と前記第１の検出位置とを結ぶ第１の直線と、前記第２の照射位置と前記第２の検出位置とを結ぶ第２の直線とは非平行であることを特徴とする生体光計測装置。
（２）請求項 2 記載の、被検体の頭部表面であって、その表面を平面とみなし、その表面領域上において所定の大きさの直径を有する円の中心が点対称中心となるような点対称位置に第１の光照射手段と第１の光検出手段とが配置され、前記点対称位置であって前記第１の光照射手段および第１の光検出手段が配置された位置とは異なる位置に第２の光照射手段と第２の光検出手段が配置され、前記第１の光照射手段と前記第１の光検出手段と結ぶ第１の直線と、前記第２の光照射手段と前記第２の光検出手段と結ぶ第２の直線とは非平行であり、
前記第１の検出手段で検出した前記第１の光照射手段からの照射光の第１の透過光信号に基づく第１の信号と、前記第２の検出手段で検出した前記第２の光照射手段からの照射光の第２の透過光信号に基づく第２の信号とを演算装置内で乗算又は加算する手段を有することを特徴とする生体光計測装置。
（３）請求項 4 記載の、被検体の頭部表面であって、その表面を平面とみなし、その平面領域上において所定の大きさの直径を有する円上に等間隔に第１および第２の光照射手段と第１および第２の光検出手段が配置され、前記第１の光照射手段と前記第１の光検出手段と結ぶ第１の直線は前記円の中心を通り、前記第２の光照射手段と前記第２の光検出手段と結ぶ第２の直線は前記円の中心を通り、前記第１の直線と前記第２の直線とは非平行であり、
前記第１の検出手段で検出した前記第１の光照射手段からの照射光の第１の透過光信号に基づく第１の信号と、前記第２の検出手段で検出した前記第２の光照射手段からの照射光の第２の透過光信号に基づく第２の信号とを演算装置内で乗算又は加算する手段とを有し、
前記第１の照射位置から前記第１の検出位置に至る第１の透過光の光路と、前記第２の照射位置から前記第２の検出位置に至る第２の透過光の光路とが前記頭部内部の特定領域で重なり合うことを特徴とする生体光計測装置。
（４）請求項 6 記載の、被検体の頭部表面であって、その表面を平面とみなし、その平面領域上に所定の大きさの直径を有する第１の円上に等間隔に第１および第２の光照射手段と第１および第２の光検出手段が配置され、前記第１の光照射手段と前記第２の光検出手段と結ぶ第１の直線は前記第１の円の中心を通り、前記第２の光照射手段と前記第１の光検出手段と結ぶ第２の直線は前記第１の円の中心を通り、前記第１の直線と前記第２の直線とは非平行であり、
前記第１の円と同じ大きさの直径を有し、かつ、前記平面領域上にある第２の円上に等間隔に第３および第４の光照射手段と前記第１および前記第２の光検出手段が配置され、前記第３の光照射手段と前記第２の光検出手段と結ぶ第３の直線は前記第２の円の中心を通り、前記第４の光照射手段と前記第１の光検出手段と結ぶ第４の直線は前記第２の円の中心を通り、前記第３の直線と前記第４の直線とは非平行であり、
前記第１の光検出手段で検出した前記第２の光照射手段からの照射光の第１の透過光信号に基づく第１の信号と前記第２の光検出手段で検出した前記第１の光照射手段からの照射光の第２の透過光信号に基づく第２の信号とを演算装置内で乗算又は加算し、前記第２の光検出手段で検出した前記第３の光照射手段からの照射光の第３の透過光信号に基づく第３の信号と前記第１の光検出手段で検出した前記第４の光照射手段からの照射光の第４の透過光信号に基づく第４の信号とを前記演算装置内で乗算又は加算するように構成されたことを特徴とする生体光計測装置。
（５）請求項 8 記載の、被検体の頭部表面であって、その表面の特定の小さな領域を平面とみたとき、その平面領域上に所定の大きさの直径を有する第１の円上に等間隔に第１、第２および第３の光照射手段と第１、第２および第３の光検出手段が配置され、前記第１の光照射手段と前記第１の光検出手段とを結ぶ第１の直線、前記第２の光照射手段と前記第２の光検出手段とを結ぶ第２の直線および前記第３の光照射手段と前記第３の光検出手段とを結ぶ第３の直線はそれぞれ前記第１の円の中心を通り、それら第１乃至第３の直線は互いに非平行であり、
前記第１の円と同じ大きさの直径を有し、かつ、前記平面領域上にある第２の円上に等間隔に第４、第６および前記第２の光照射手段と第５、第６および前記第１の光検出手段が配置され、前記第２の光照射手段と前記第５の光検出手段とを結ぶ第４の直線、前記第４の光照射手段と前記第１の光検出手段とを結ぶ第５の直線および前記第６の光照射手段と前記第６の光検出手段とを結ぶ第６の直線はそれぞれ前記第２の円の中心を通り、それら第４乃至第６の直線は互いに非平行であり、
前記第１の光検出手段で検出した前記第１の光照射手段からの照射光の第１の透過光信号に基づく第１の信号と、前記第２の光検出手段で検出した前記第２の光照射手段からの照射光の第２の透過光信号に基づく第２の信号と、前記第３の光検出手段で検出した前記第３の光照射手段からの照射光の第３の透過光信号に基づく第３の信号とを演算装置内で乗算又は加算し、かつ、前記第１光検出手段で検出した前記第４の光照射手段からの照射光の第４の透過光信号に基づく第４の信号と、前記第５の光検出手段で検出した前記第２の光照射手段からの照射光の第５の透過光信号に基づく第５の信号と、前記第６の光検出手段で検出した前記第６の光照射手段からの照射光の第６の透過光信号に基づく第６の信号とを前記演算装置内で乗算又は加算するように構成されたことを特徴とする生体光計測装置。
（６）請求項１３記載の、被検体表面の第１の照射位置から被検体内部へ可視から赤外領域の波長λ 1 の光を周波数 f1 で強度変調したものおよび前記λ 1 と異なる波長λ 2 の光を前記 f1 とは異なる周波数 f2 で強度変調したものを有する第１の照射光を照射するための第１の光照射手段と、
前記被検体表面の前記第１の照射位置とは異なる第２の照射位置から前記被検体内部へ前記波長λ 1 の光を前記 f1 および f2 とは異なる周波数 f3 で強度変調したものおよび前記波長λ 2 の光を前記 f1 〜 f3 とは異なる周波数 f4 で強度変調したものを有する第２の照射光を照射するための第２の光照射手段とを有し、
前記第１の照射位置に対応する前記被検体表面上の第１の検出位置において前記第１の照射光の前記被検体内を透過する透過光のうち、前記周波数 f1 で強度変調されたもの及び前記周波数 f2 で強度変調されたものを個別に選択検出する第１の光検出手段とを有し、
前記第２の照射位置に対応する前記被検体表面上の前記第１の検出位置とは異なる第２の検出位置において前記第２の照射光の前記被検体内を透過する透過光のうち、前記周波数 f3 で強度変調されたもの及び前記周波数 f4 で強度変調されたものを個別に選択検出する第２の光検出手段と、
前記第１の光検出手段で検出した前記周波数 f1 の信号の第１の透過光強度に基づく第１の信号と前記第２の光検出手段で検出した前記周波数 f3 の信号の第２の透過光強度に基づく第２の信号とを演算装置内で乗算又は加算すると共に、前記第１の光検出手段で検出した前記周波数 f2 の信号の第３の透過光強度に基づく第３の信号と前記第２の光検出手段で検出した前記周波数 f4 の信号の第４の透過光強度に基づく第４の信号とを前記演算装置内で乗算又は加算するように構成され、
前記第１の照射位置から前記第１の検出位置に至る前記被検体内の第１の透過光の光路と、前記第２の照射位置から前記第２の検出位置に至る前記被検体内の第２の透過光の光路とが、前記被検体内の所定の計測領域において互いに重なり合うように前記第１および第２の照射位置と前記第１および第２の検出位置とが位置決めされており、
前記第１の照射位置と前記第１の検出位置とを結ぶ第１の直線と、前記第２の照射位置と前記第２の検出位置とを結ぶ第２の直線とは非平行であることを特徴とする生体光計測装置。
次の本発明に関連する構成を記載する。
複数の照射部から照射された照射光を被検体を透過した透過光として被検体の複数の検出位置で集光し、それぞれの照射部から発せられた照射光のそれぞれの光路が重なるように透過光を集光し、被検体の第１の所定領域の光学パラメータを検出する感度を向上させて、透過光の強度を演算処理する生体光計測装置。
【０００８】
引き続き本発明に関連する事項を記載する。
複数の波長の照射光を被検体の複数の照射位置に照射する複数の照射部を有する光照射手段と、被検体を透過した透過光を被検体の複数の検出位置で集光する複数の集光部であり、それぞれの照射部から発せられた照射光のそれぞれの光路が重なるように透過光を集光する複数の集光部を有する集光手段と、透過光から複数の光照射位置ごとに波長ごとに透過光の光強度を検出する検出手段と、被検体の第１の所定領域の光学パラメータを検出する感度を向上させて、透過光の強度を演算処理する演算処理手段と、を有する生体光計測装置。
照射光に波長ごとに異なる周波数の強度変調を与え、透過光の中から所定の強度変調周波数の光を検出してもよく、または透過光の中から所定の強度変調周波数の光の強度を演算してもよい。さらに、透過光を波長ごとに分光し、分光された透過光の中から所定の強度変調周波数の光を検出してもよく、または分光された透過光の中から所定の強度変調周波数の光の強度を演算してもよい。前記光学パラメータは吸収係数である。
【０００９】
引き続き本発明に関連する事項を記載する。
強度変調周波数を有する透過光または所定の強度変調周波数を有する所定の波長の透過光を光電変換により前記所定の強度変調周波数を有する透過光強度信号に変換する光電変換部と透過光強度信号が入力される位相検波部とを有し、位相検波部に光照射位置の所定の波長の光に与えた強度変調周波数に対応する信号を入力し、位相検波部からの出力信号を、所定の強度変調周波数をもつ透過光の強度として検出する構成。あるいは、透過光強度信号が入力されるアナログ−デジタル変換部を有し、透過光強度信号をアナログ−デジタル変換部に入力してフーリエ変換して周波数空間の生体透過光強度信号を求め、光照射位置の所定の波長毎または所定の光照射位置ごとに与えられた強度変調周波数に対応する信号をアナログ−デジタル変換部に入力してフーリエ変換することにより所定の参照周波数を求め、所定の参照周波数と等しい周波数における前記周波数空間の生体透過光強度信号を、所定の強度変調周波数をもつ透過光の強度として演算する構成。
【００１０】
引き続き本発明に関連する事項を記載する。
照射部と集光部とは、前記第１の所定領域のほぼ中心を通る直線と被検体の表面とが交わる点を中心とする少なくとも一つの円上であり、所定の直径を有する円上に等間隔に配置され、円の中心が点対称中心となるような点対称位置に照射部と集光部とが配置され、光照射位置のそれぞれからの複数の波長毎の透過光強度を複数の集光位置ごとに検出し、光照射位置のそれぞれからの複数の波長毎の透過光強度から集光位置と点対称位置にある照射位置からの波長毎の透過光強度を選択し、選択した透過光強度の中から同一円上で検出された透過光強度を選択し、同一円上で検出された所定波長を有する透過光の透過光強度を乗算または積算して演算処理することを特徴とする。さらに、直径が小さい前記円上に設置された集光部で集光された透過光を被検体の浅部の情報とし、直径が大きい円上に設置された集光部で集光された透過光を被検体の深部の情報として、透過光を演算処理する。
【００１１】
照射部と集光部は、正方格子状に配置され、照射部と集光部はそれぞれ、正方格子の所定の複数のそれぞれの行の格子点上に、照射部が配置された正方格子の行と集光部が配置された正方格子の行とが交互になるように配置されることを特徴とする。あるいは、照射部と集光部は、正六角形格子状に配置され、正六角形格子の各格子点に交互に配置される。
【００１２】
照射光は、８０５ｎｍ近傍の波長の光であり、透過光の強度から、酸化ヘモグロビン濃度変化、還元ヘモグロビン濃度変化および酸化ヘモグロビン濃度変化と還元ヘモグロビン濃度変化との和から演算される総ヘモグロビン濃度変化を求め、総ヘモグロビン濃度変化の時間変化を表示することを特徴とする。あるいは、透過光の強度から、総ヘモグロビン濃度変化を求めてもよく、照射光は、７００ｎｍから１１００ｎｍの範囲から少なくとも２波長の照射光であってもよい。
【００１３】
酸化ヘモグロビン濃度変化と還元ヘモグロビン濃度変化との和から演算される総ヘモグロビン濃度変化、酸化ヘモグロビン濃度変化または還元ヘモグロビン濃度変化の時間変化を、酸化ヘモグロビン濃度変化と還元ヘモグロビン濃度変化との和から演算される総ヘモグロビン濃度変化、酸化ヘモグロビン濃度変化または還元ヘモグロビン濃度変化ごとに色、線の種類または線の太さを変えて表示することを特徴とする。酸化ヘモグロビン濃度変化を赤色または橙色、還元ヘモグロビン濃度変化を青色、藍色または緑色、総ヘモグロビン濃度変化を黒色または茶色で表示してもよい。また、酸化ヘモグロビン濃度変化と還元ヘモグロビン濃度変化との和から演算される総ヘモグロビン濃度変化、酸化ヘモグロビン濃度変化または還元ヘモグロビン濃度変化の画像を、濃度変化に対応した色あるいは輝度で表示してもよく、濃度変化が正の場合、濃度変化の値の絶対値が大になるほど濃い赤色または高い輝度で表示し、濃度変化が負の場合、濃度変化の値の絶対値が小になるほど濃い青色または低い輝度で表示してもよい。
【００１４】
同一円上で検出された所定波長を有する透過光の透過光強度を、円の中心を通り被検体の表面に垂直な垂線上の被検体の所定の深さの所定範囲領域あるいは前記垂線を回転中心とする所定の回転体の所定範囲領域における、酸化ヘモグロビン濃度変化と還元ヘモグロビン濃度変化との和から演算される総ヘモグロビン濃度変化、酸化ヘモグロビン濃度変化または還元ヘモグロビン濃度変化を反映していると見做して演算することを特徴とし、円の直径が２５ｍｍから３５ｍｍとし、深さを１２ｍｍから２５ｍｍとすることを特徴とする。照射部または集光部と被検体との接触面に、柔軟かつ照射光の透過性の高い部材を用い被覆することにより、照射部または集光部が被検体に与える刺激をやわらげることができる。
【００１５】
引き続き本発明に関連する事項を記載する。
照射部から発せられた照射光のそれぞれの光路が重なる様に、照射部と集光部を所定の直径の円上に複数配置し、集光部と対向位置にある照射部からの生体透過光のみを選択的に検出し、検出された透過光の透過光強度を乗算することにより、前記円の中心の位置からの所定の深さでの感度を向上させることが可能となる。
【００１６】
【発明の実施の形態】
本発明に基づく実施の形態を示す。本実施の形態では、生体中の酸化および還元ヘモグロビン濃度変化計測を目的として照射波長として２波長用い、光照射位置および光検出位置を２カ所設定した場合について説明するが、それぞれ波長数、光照射位置および光検出位置を増やすことは容易である。また、波長数を増加させることにより、酸化および還元ヘモグロビン濃度の変化に加えて、チトクロームやミオグロビン等他の光吸収物質濃度の変化を計測することができる。
【００１７】
図１に、本発明による装置構成を示す。
特定波長の光が、光源１−１、１−２、１−３、１−４より発せられ、それぞれ光ファイバー２−１、２−２、２−３、２−４に入射される。ここで、光源１−１、１−３からの波長はλ１であり、光源１−２、１−４からの波長はλ２で、４００ｎｍから２４００ｎｍの範囲から選択する。特に、生体中の血行動態を計測する場合に、７００ｎｍから１１００ｎｍの範囲から、波長差が５０ｎｍ以内となるように選択することが望ましい。また、光源１−１、１−２、１−３、１−４はそれぞれ光源駆動回路４−１、４−２、４−３、４−４により１００Ｈｚから１０ＭＨｚの間の異なる周波数ｆ１、ｆ２、ｆ３、ｆ４で強度変調されている。各光源駆動回路４−１、４−２、４−３、４−４からの周波数信号は参照周波数信号として、それぞれ、位相検波器１０−１、１０−２、１０−３、１０−４に入力されている。
【００１８】
光ファイバー２−１、２−２は光方向性結合器３−１と接続し、光ファイバー２−３、２−４は光方向性結合器３−２と接続しており、光源１−１、１−２からの光は混合され照射用光ファイバー５−１に入射され、光源１−３、１−４からの光は混合され照射用光ファイバー５−２に入射される。照射用光ファイバー５−１、５−２、および集光用光ファイバー８−１、８−２は光ファイバーホルダー６で固定されている。
【００１９】
照射用光ファイバー５−１、５−２から被検者７に光を照射し、集光用光ファイバー８−１、８−２で生体透過光を集光する。ここで、照射用光ファイバー５−１、５−２と集光用光ファイバー８−１、８−２は、光ファイバーホルダー６の円上に等間隔に配置され、照射用光ファイバー５−１、５−２に対向した位置に集光用光ファイバー８−１、８−２が配置される。光ファイバーホルダー６は、遮光性を高めるため黒色の材料もしくは黒色の材料で被覆し、中空構造とすることが望ましい。また、照射用光ファイバー５−１、５−２および集光用光ファイバー８−１、８−２も黒色材料で被検者接触面以外を被覆することが望ましい。さらに、照射用光ファイバー５−１、５−２および集光用光ファイバー８−１、８−２の被検者接触面には、接触による痛みを軽減する目的で、例えばビニール樹脂などのような照射波長に対して透過性の良い材料で被覆する。
【００２０】
集光用光ファイバー８−１、８−２で集光された生体透過光は、それぞれ光検出器９−１、９−２に入射され、各集光位置における生体透過光が光電変換および増幅される。光検出器９−１、９−２には、光電子増倍管やアバランシェフォトダイオードを用いる。光検出器９−１からの出力信号は２つに分配された後、位相検波器１０−１、１０−２に入力し、光検出器９−２からの出力信号は２つに分配された後、位相検波器１０−３、１０−４に入力する。
【００２１】
各位相検波器に入力した信号には照射した全波長の生体透過光が混合しているが、位相検波器１０−１、１０−２、１０−３、１０−４には、それぞれ光源駆動回路４−１、４−２、４−３、４−４から参照周波数が入力されているので、位相検波器１０−１では光源１−１からの生体透過光強度を、位相検波器１０−２では光源１−２からの生体透過光強度を、位相検波器１０−３では光源１−３からの生体透過光強度を、位相検波器１０−４では光源１−４からの生体透過光強度を分離検出する。
【００２２】
位相検波器１０−１、１０−３で検出した各生体透過光強度信号（対向位置から照射された同一波長λ１の生体透過光強度）を乗算器１１−１に入力して乗算し、位相検波器１０−２、１０−４で検出した各生体透過光強度（対向位置から照射された波長λ２の生体透過光強度）を乗算器１１−２に入力して乗算し、乗算器１１−１、１１−２からの出力信号をログアンプ１２−１、１２−２にそれぞれ入力する。さらに、各ログアンプからの出力信号をアナログ−デジタル変換器（以降Ａ／Ｄ変換器と略す）１３−１、１３−２に入力し、デジタル信号に変換した後、演算装置１４に取り込む。
【００２３】
演算装置１４では、取り込まれた２波長の透過光強度の時系列信号より、酸化ヘモグロビン濃度の変化および還元ヘモグロビン濃度変化および血液量を表す酸化ヘモグロビン濃度の変化と還元ヘモグロビン濃度の変化の和を演算し時系列グラフとして表示装置１５に表示する。また、同様の装置で多点計測を行った場合には、画像として表示装置１５に表示する。各ヘモグロビン濃度の変化を時系列グラフとして表示する際に、表示装置が色付き表示可能な場合には各ヘモグロビン濃度の変化ごとに色を変えて表示し、表示装置が色付き表示不可能な場合には各ヘモグロビン濃度の変化ごとに線種または線の太さを変えて表示する。例えば、酸化ヘモグロビン濃度の変化は赤色または橙色、還元ヘモグロビン濃度の変化は青色、藍色または緑色、総ヘモグロビン濃度の変化は黒色、灰色または茶色で表示する。また、画像を表示する場合には、等高線画像で表示してもよく、濃度変化値の変化に対応して色あるいは輝度を変えて表示してもよい。例えば、正の濃度変化値の絶対値が大きいほど濃い赤色または濃い灰色とし、負の濃度変化値の絶対値が大きくなるほど濃い青色または淡い白色とする。
【００２４】
本発明の装置構成としては、図１に示した光検出器９から演算装置１４までのデータ収集部について様々な組み合わせが考えられる。図２から図６に、光検出器９から演算装置１４までのデータ収集部に関する装置構成例を示す。
【００２５】
図２にデータ収集部に関する装置構成の第１例を示す。図中、丸印付き記号Ａ、Ｂ、ＣおよびＤは、図１に示した装置構成例と同様に参照周波数信号を表している。また、簡単のため図１の光源１から集光用光ファイバー８までは同じ構成としている。本データ収集部に関する装置構成例は、光検出器９−１、９−２と、位相検波器１０−１、１０−２、１０−３、１０−４と、Ａ／Ｄ変換器１３−１、１３−２、１３−３、１３−４と、演算装置１４とからなる。
【００２６】
各位相検波器１０−１、１０−２、１０−３、１０−４までは図１に示した構成と同じであるが、各位相検波器１０−１、１０−２、１０−３、１０−４からの出力信号を各々Ａ／Ｄ変換器１３−１、１３−２、１３−３、１３−４でデジタル信号に変換した後、演算装置１４に入力する。演算装置１４では、入力された全同一波長の生体透過光信号を乗算後、乗算結果を自然対数演算で行うか、または、各同一波長の生体透過光信号の自然対数演算後、自然対数演算の演算結果を加算する。ここで、同一波長の生体透過光信号の組み合わせは、Ａ／Ｄ変換器１３−１およびＡ／Ｄ変換器１３−３からの出力信号の組と、Ａ／Ｄ変換器１３−２およびＡ／Ｄ変換器１３−４からの出力信号の組の２組ある。
【００２７】
図３にデータ収集部に関する装置構成の第２例を示す。図中、丸印付き記号Ａ、Ｂ、ＣおよびＤは、図１に示した装置構成例と同様に参照周波数信号を表している。また、簡単のため図１の光源１から集光用光ファイバー８までは同じ構成としている。本データ収集部に関する装置構成例は、光検出器９−１、９−２と、位相検波器１０−１、１０−２、１０−３、１０−４と、乗算器１１−１、１１−２と、Ａ／Ｄ変換器１３−１、１３−２と演算装置１４からなる。乗算器１１−１、１１−２、１１−３、１１−４までは図１に示した構成と同じであるが、各乗算器１１−１および乗算器１１−２からの出力信号を各Ａ／Ｄ変換器１３−１およびＡ／Ｄ変換器１３−２でデジタル信号に変換した後、演算装置１４に入力する。演算装置１４では、各Ａ／Ｄ変換器１３−１、１３−２からの信号に対してそれぞれ自然対数演算を行う。
【００２８】
図４にデータ収集部に関する装置構成の第３例を示す。図中、丸印付き記号Ａ、Ｂ、ＣおよびＤは図１に示した装置構成例と同様に参照周波数信号を表している。また、簡単のため図１の光源１から集光用光ファイバー８までは同じ構成としている。本データ収集部に関する装置構成例は、光検出器９−１、９−２と、位相検波器１０−１、１０−２、１０−３、１０−４と、ログアンプ１２−１、１２−２、１２−３、１２−４と、加算器１６−１、１６−２と、Ａ／Ｄ変換器１３−１、１３−２と演算装置１４からなる。位相検波器１０−１、１０−２、１０−３、１０−４までは図１に示した構成と同様であるが、各位相検波器１０−１、１０−２、１０−３、１０−４からの出力信号をそれぞれログアンプ１２−１、１２−２、１２−３、１２−４に入力する。ログアンプ１２−１およびログアンプ１２−３からの各生体透過光強度信号（対向位置から照射された同一波長λ１の生体透過光強度）を加算器１６−１に入力して加算し、ログアンプ１２−２およびログアンプ１２−４からの各生体透過光強度信号（対向位置から照射された同一波長λ２の生体透過光強度）を加算器１６−２に入力して加算し、各加算器１６−１、１６−２からの出力信号を各々Ａ／Ｄ変換器１３−１、１３−２に入力する。各Ａ／Ｄ変換器１３−１、１３−２でデジタル信号に変換した後に演算装置１４に入力する。
【００２９】
図５にデータ収集部に関する装置構成の第４例を示す。図中、丸印付き記号Ａ、Ｂ、ＣおよびＤは図１に示した装置構成例と同様に参照周波数信号を表している。また、簡単のため図１の光源１から集光用光ファイバー８までは同じ構成としている。本データ収集部に関する装置構成例は、光検出器９−１、９−２と、位相検波器１０−１、１０−２、１０−３、１０−４と、ログアンプ１２−１、１２−２、１２−３、１２−４と、Ａ／Ｄ変換器１３−１、１３−２、１３−３、１３−４と、演算装置１４からなる。位相検波器１０−１、１０−２、１０−３、１０−４までは図１に示した構成と同じであるが、各位相検波器１０−１、１０−２、１０−３、１０−４からの出力信号をそれぞれログアンプ１２−１、１２−２、１２−３、１２−４に入力する。ログアンプ１２−１、１２−２、１２−３、１２−４からの出力信号を各々Ａ／Ｄ変換器１３−１、１３−２、１３−３、１３−４でデジタル信号に変換した後演算装置１４に入力する。演算装置１４では、入力された全同一波長の生体透過光信号を加算する。ここで、同一波長の生体透過光信号の組み合わせは、Ａ／Ｄ変換器１３−１およびＡ／Ｄ変換器１３−３からの出力信号の組と、Ａ／Ｄ変換器１３−２およびＡ／Ｄ変換器１３−４からの出力信号の組の２組ある。
【００３０】
図６にデータ収集部に関する装置構成の第５例を示す。図中丸印付き記号Ａ、Ｂ、ＣおよびＤは図１に示した装置構成例と同様に参照周波数信号を表している。また、簡単のため図１の光源１から集光用光ファイバー８までは同じ構成としている。本データ収集部に関する装置構成例は、光検出器９−１、９−２と、Ａ／Ｄ変換器１３−１、１３−２、１３−３、１３−４、１３−５、１３−６と、演算装置１４からなる。光検出器９−１、９−２までは図１に示した構成と同じであるが、各光検出器９−１および光検出器９−２からの出力信号を各々Ａ／Ｄ変換器１３−１およびＡ／Ｄ変換器１３−２に入力する。各Ａ／Ｄ変換器１３−１および１３−２からの出力信号を演算装置１４に入力する。また、照射光に与えた参照周波数信号Ａ、Ｂ、ＣおよびＤを各Ａ／Ｄ変換器１３−３、１３−４、１３−５、１３−６に入力し、デジタル信号に変換した後演算装置１４に入力する。演算装置では、各Ａ／Ｄ変換器１３−１、１３−２、１３−３、１３−４、１３−５、１３−６からの信号をフーリエ変換する。Ａ／Ｄ変換器１３−３、１３−４、１３−５、１３−６からの信号をフーリエ変換し、得られた最高強度の周波数を各々ｆ１、ｆ２、ｆ３およびｆ４とする。Ａ／Ｄ変換器１３−１からの信号をフーリエ変換した結果の中から、周波数ｆ１およびｆ２に相当する信号強度をＩ（ｆ１）およびＩ（ｆ２）とし、Ａ／Ｄ変換器１３−２からの信号をフーリエ変換した結果の中から、周波数ｆ３およびｆ４に相当する信号強度をＩ（ｆ３）およびＩ（ｆ４）とする。ここで、Ｉ（ｆ１）およびＩ（ｆ３）は対向位置から照射された同一波長（図１の光源１−１および１−３からの光）の生体透過光信号であるので、それぞれ相互に乗算して自然対数演算を行い、Ｉ（ｆ２）およびＩ（ｆ４）も対向位置から照射された同一波長（図１の光源１−２および１−４からの光）の生体透過光信号であるので、それぞれ相互に乗算して自然対数演算を行う。
【００３１】
以上、１つの円上に照射用光ファイバー２本と集光用光ファイバー２本を配置した場合について説明を行った。以下、照射用光ファイバー数および集光用光ファイバー数を多数配置する場合の実施の形態を示す。
【００３２】
図７に照射用光ファイバーおよび集光用光ファイバー配置の第１例を示す。本配置例では２重の同心円上に、照射用光ファイバーおよび集光用光ファイバーを各３本ずつ前記各同心円上に配置する例を示すが、照射用光ファイバーおよび集光用光ファイバーを同心円上に多重化して設けることにより、種々の所定の深さの位置で測定の感度を高めることができる。
【００３３】
照射用光ファイバー５−１、５−２、５−３は同心円１７−１の上に１２０度ごとに配置し、各照射用光ファイバーに対向する位置に、集光用光ファイバー８−１、８−２、８−３を配置する。照射用光ファイバー５−４、５−５、５−６は上記同心円１７−１の内部に設けた同心円１７−２の上に１２０度ごとに配置し、各照射用光ファイバーの対向（１８０度）位置に、集光用光ファイバー８−４、８−５、８−６を配置する。このような配置位置の固定手段は前記光ファイバーホルダー６を用いて行う。同心円１７−１の上で検出される乗算した生体透過光強度を深部の情報として割り当てて生体内部のヘモグロビン濃度変化を演算し、同心円１７−２の上で検出される乗算した生体透過光強度を浅部の情報として割り当てて生体内部のヘモグロビン濃度の変化を演算することができる。また、同心円１７−２の上で検出される乗算した生体透過光強度から計算されるヘモグロビン濃度変化に感度分布から推定される所定の重み係数を乗じ、同心円１７−１の上で検出される乗算した生体透過光強度から計算されるヘモグロビン濃度の変化から減算することで、所定の深さの深部の相対感度をさらに向上することも可能である。
【００３４】
図８に照射用光ファイバーおよび集光用光ファイバー配置の第２例を示す。本配置例では、本発明に基づき生体の様々な位置での計測を行う場合の効率的な配置例を示している。本例では１つの円上に２組の照射用光ファイバーと集光用光ファイバーの配置例を示す。
【００３５】
１つの円上に２組の照射用光ファイバーと集光用光ファイバーを配置し、計測領域の拡張を行う場合には、図８に示すように正方格子頂点上に照射用光ファイバーおよび集光用光ファイバーを配置し、各格子の対角線方向には相互に照射用光ファイバーと集光用光ファイバーが位置するように配置する。ここでは、計測位置を９か所、即ち円１８−１から円１８−９までの９個設定した場合、図８のように、照射用光ファイバー５−１から照射用光ファイバー５−１２までと、集光用光ファイバー８−１から集光用光ファイバー８−１２までを正方格子頂点上に配置する。この配置により、異なる円の交差点に配置した照射用光ファイバーと集光用光ファイバーは、円交差数と同数の計測位置に関して機能するため、より少ない本数の光ファイバーでの計測が可能となる。さらに広い領域の計測を行うため、計測位置を増加させることは容易である。このような計測領域の広域化によって得られた結果より生体深部の血行動態の画像を得ることができる。
【００３６】
図９に照射用光ファイバーおよび集光用光ファイバー配置の第２例を示す。本配置例では、本発明に基づき生体の様々な位置での計測を行う場合の効率的な配置例を示している。本例では１つの円上に３組の照射用光ファイバーと集光用光ファイバーの配置例を示す。
【００３７】
１つの円上に３組の照射用光ファイバーと集光用光ファイバーを配置し、計測領域の拡張を行う場合には、図９に示すように正６角形格子頂点上に照射用光ファイバーおよび集光用光ファイバーを配置し、各格子頂点の対向位置の頂点には相互に照射用光ファイバーと集光用光ファイバーが位置するように配置する。ここでは、計測位置を４か所、即ち円１８−１から円１８−４までの４個設定した場合、図８のように、照射用光ファイバー５−１から照射用光ファイバー５−８までと、集光用光ファイバー８−１から集光用光ファイバー８−８までを正６角形格子頂点上に配置する。この配置により、異なる円の交差点に配置した照射用光ファイバーと集光用光ファイバーは、円交差数と同数の計測位置に関して機能するため、少ない本数の光ファイバーでの計測が可能となる。さらに広い領域の計測を行うため、計測位置を増加させることは容易である。このような計測領域の広域化によって得られた結果より生体血行動態の画像を得ることができる。
【００３８】
（参考例）
図１０に、本発明の参考例に係る装置構成を示す。
連続的な波長スペクトルを有する光が、白色光源１９−１、１９−２より発せられ、硝子フィルタ２０−１、２０−２を通過して計測に必要な波長域が選択され、レンズ２１−１、２１−２によって、照射用光ファイバー５−１、５−２に入射される。ここで、光源１９−１および光源１９−２からの波長は４００nmから２４００nmの範囲である。特に、生体中の血行動態を計測する場合に、７００nmから１１００nmの範囲となるように硝子フィルター２０−１および硝子フィルター２０−２で選択することが望ましい。また、光源１９−１および光源１９−２はそれぞれ光源駆動回路４−１および光源駆動回路４−２により１００Ｈｚから１０ＭＨｚの間の異なる周波数ｆ１および周波数ｆ２で強度変調されている。各光源駆動回路４−１、４−２からの周波数信号は参照周波数信号として、それぞれ、位相検波器１０−１、１０−２、１０−３、１０−４に入力されている。照射用光ファイバー５−１および照射用光ファイバー５−２は、集光用光ファイバー８−１および集光用光ファイバー８−２と供に光ファイバーホルダー６で固定されている。
【００３９】
照射用光ファイバー５−１、５−２から被検者７に光を照射し、集光用光ファイバー８−１、８−２で生体透過光を集光する。ここで、照射用光ファイバー５−１、５−２と集光用光ファイバー８−１、８−２は、光ファイバーホルダー６に円上で等間隔に配置され、照射用光ファイバー５−１、５−２から対向した位置に集光用光ファイバー８−１、８−２が配置される。
【００４０】
集光用光ファイバー８−１、８−２で集光された生体透過光は、それぞれ分光器２２−１、２２−２に入射され、所定の波長ごとに分光される。ここでは、分光された複数波長の中から波長λ１および波長λ２を選択する。分光器２２−１からの波長λ１の生体透過光が光検出器９−１に、分光器２２−１からの波長λ２の生体透過光が光検出器９−２に、分光器２２−２からの波長λ１の生体透過光が光検出器９−３に、分光器２２−２からの波長λ２の生体透過光が光検出器９−４に入力され、各光検出器で光電変換および増幅される。光検出器９−１、９−２、９−３、９−４として、光電子増倍管あるいはアバランシェフォトダイオードが用いられる。光検出器９−１からの出力信号は位相検波器１０−１に入力され、光検出器９−２からの出力信号は位相検波器１０−２に入力され、光検出器９−３からの出力信号は位相検波器１０−３に入力され、光検出器９−４からの出力信号は位相検波器１０−４に入力される。
【００４１】
各位相検波器に入力した信号には同波長の異なる強度変調周波数を持つ生体透過光が混合しているが、各位相検波器１０−１、１０−２、１０−３、１０−４には、それぞれ光源駆動回路４−１、４−２から参照周波数が入力されているので、位相検波器１０−１では光源１９−１からの波長λ１の生体透過光強度を、位相検波器１０−２では光源１９−１からの波長λ２の生体透過光強度を、位相検波器１０−３では光源１９−２からの波長λ１の生体透過光強度を、位相検波器１０−４では光源１９−２からの波長λ２の生体透過光強度を分離検出することができる。
【００４２】
位相検波器１０−１および位相検波器１０−３で検出した各生体透過光強度信号（対向位置から照射された波長λ１の生体透過光強度）を乗算器１１−１に入力して乗算し、位相検波器１０−２および位相検波器１０−４で検出した各生体透過光強度（対向位置から照射された波長λ２の生体透過光強度）を乗算器１１−２に入力して乗算し、各乗算器からの出力信号をログアンプ１２−１およびログアンプ１２−１１２−２にそれぞれ入力する。さらに、各ログアンプからの出力信号をアナログ−デジタル変換器１３−１、１３−２に入力し、デジタル信号に変換した後、演算装置１４に取り込む。
【００４３】
演算装置１４では、取り込まれた２波長の透過光強度の時系列信号より、酸化ヘモグロビン濃度の変化、還元ヘモグロビン濃度の変化および血液量を表す酸化ヘモグロビン濃度の変化と還元ヘモグロビン濃度の変化の和を演算し時系列グラフとして表示装置１５に表示する。
【００４４】
図１で示した装置構成では、光ファイバーホルダー６に照射用光ファイバーと集光用光ファイバーとの組をさらに増やして設置してもよい。例えば、照射用光ファイバーと集光用光ファイバーとの組を４組設けて、測定した測定結果を図１４、図１５および図１６に示す。生体表面を平面と仮定し、前記生体表面と平行な平面をＸ−Ｙ平面と定義し、生体表面上に、中心がｘ＝３２．５ｍｍかつｙ＝３２．５の直径３０ｍｍの円上に、円の中心を点対称中心とするように照射用光ファイバーと集光用光ファイバーとを４組配置した。測定結果を、深さ２．５ｍｍの位置での相対感度分布（図１４）、深さ７．５ｍｍの位置での相対感度分布（図１５）、深さ１２．５ｍｍの位置での相対感度分布（図１６）として示す。従来例による測定結果（図１１、図１２および図１３）と本発明の測定結果（図１４、図１５および図１６）とを比較すると、所定の生体深部において測定感度を向上させることができた。
【００４５】
本実施の形態では、所定の円上の対向位置からの生体透過光強度を同一波長ごとに全て乗算する様な構成で説明したが、同様に、同一波長ごとに全て加算する様な装置構成でも物理的な意味は低下するが、深部の相対感度を向上することは可能である。また、複数の位置で計測した生体透過光強度を四則演算する装置構成を用いて、目的とする計測領域の感度を向上してもよい。また、本発明により、深部に感度分布が必要な計測として、脳機能活動に伴う血行動態の変化を頭皮上から計測を行うことができる。
【００４６】
【発明の効果】
本発明によって、生体の所定の深さの吸収物質濃度を精度良く計測することができる。
【図面の簡単な説明】
【図１】本発明に係る光計測装置の構成を示す図。
【図２】本発明に係る光計測装置におけるデータ収集部の他の構成図。
【図３】本発明に係る光計測装置におけるデータ収集部の他の構成図。
【図４】本発明に係る光計測装置におけるデータ収集部の他の構成図。
【図５】本発明に係る光計測装置におけるデータ収集部の他の構成図。
【図６】本発明に係る光計測装置におけるデータ収集部の他の構成図。
【図７】本発明に係る光計測装置における照射用光ファイバーおよび集光用光ファイバーの配置を示す図。
【図８】本発明に係る光計測装置における照射用光ファイバーおよび集光用光ファイバーの他の配置を示す図。
【図９】本発明に係る光計測装置における照射用光ファイバーおよび集光用光ファイバーの他の配置を示す図。
【図１０】本発明の参考例に係る光計測装置の他の構成を示す図。
【図１１】従来技術による生体深さ２．５ｍｍでの感度分布を示す図。
【図１２】従来技術による生体深さ７．５ｍｍでの感度分布を示す図。
【図１３】従来技術による生体深さ１２．５ｍｍでの感度分布を示す図。
【図１４】本発明の装置により求めた生体深さ２．５ｍｍにおける感度分布を示す図。
【図１５】本発明の装置により求めた生体深さ７．５ｍｍにおける感度分布を示す図。
【図１６】本発明の装置により求めた生体深さ１２．５ｍｍにおける感度分布を示す図。
【符号の説明】
１−１，１−２，１−３，１−４…光源、２−１，２−２，２−３，２−４…光ファイバー、３−１，３−２…光方向性結合器、４−１，４−２，４−３，４−４…光源駆動装置、５−１，５−２，５−３，５−４，５−５，５−６，５−７，５−８…照射用光ファイバー、６…光ファイバーホルダー、７…被検者、８−１，８−２…集光用光ファイバー、９−１，９−２…光検出器、１０−１，１０−２，１０−３，１０−４…位相検波器、１１−１，１１−２…乗算器、１２−１，１２−２…ログアンプ、１３−１，１３−２，１３−３，１３−４…アナログ−デジタル変換器、１４…演算装置、１５…表示装置、１６−１，１６−２…加算器、１７−１，１７−２…同心円、１８−１，１８−２，１８−３，１８−４，１８−５，１８−６，１８−７，１８−８，１８−９…円、１９−１，１９−２…白色光源、２０−１，２０−１…硝子フィルタ、２１−１，２１−１…レンズ、２２−１，２２−２…分光器。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a biological optical measurement device, and in particular, non-invasively measures a change in concentration of a light absorbing substance in a living body using light.And can measure concentration changes in deeper parts of the body with high detection sensitivity.The present invention relates to a biological light measurement device.
[0002]
[Prior art]
A device for simply and non-invasively measuring the inside of a living body is desired in clinical medicine, and living body optical measurement is very effective against this demand. The first reason is that the oxygen metabolism function in the living body corresponds to the concentration of a specific dye (hemoglobin, cytochrome aa3, myoglobin, etc.) in the living body, ie, the concentration of a light absorbing substance, and the concentration of the dye is light (visible to near red). This is because it is determined from the amount of absorption in the outer region). The second and third reasons why optical measurement is effective are that light is easy to handle with an optical fiber and that it does not harm the living body when used within the safety standards.
[0003]
Utilizing the advantages of the above-described optical measurement, a living body optical measurement device that irradiates a living body with light having a wavelength from visible to near infrared and measures the inside of the living body from reflected light at a position about 10 to 50 mm away from the irradiation position is known. For example, it is described in JP-A-63-277038 and JP-A-5-30087.
[0004]
[Problems to be solved by the invention]
In living body measurement using light, the irradiated light largely spreads inside the living body due to the strong light scattering characteristics of the living body (scattering coefficient = about 1.0 [1 / mm]). A wide range of absorbent concentrations will be included. In particular, the spatial characteristics of the detection sensitivity have a problem in that the sensitivity of the shallow part of the living body near the light irradiation and detection position is larger than the sensitivity of the deep part of the living body. Therefore, it is difficult to accurately measure a change in the concentration of an absorbent substance in a deep part of a living body. For example, when measuring the hemodynamic change of the living brain from above the scalp, there is a problem that the hemodynamic change of the skin or the skull greatly reflects on the measured value for the above-described reason.
[0005]
Hereinafter, an example in which the relative sensitivity distribution of a change in the concentration of an absorbing substance in a deep part of a living body is obtained using the above-described conventional technique will be described. Assuming that the surface of the living body is a plane, a plane parallel to the surface of the living body is defined as an XY plane, and light is irradiated from the position of x = 32.5 mm and y = 17.5 mm on the surface of the living body, and 30 mm from the light irradiation position. FIG. 11 shows the relative sensitivity distribution at the position of 2.5 mm in depth when the light was condensed at the position x = 32.5 mm and y = 47.5 mm at the distant positions. FIG. 12 shows the sensitivity distribution, and FIG. 13 shows the relative sensitivity distribution at a position of 12.5 mm in depth. In these figures, the influence of the surface of the living body is very large, and it is difficult to measure the concentration change of the absorbent in the deep part of the living body with high accuracy.
[0006]
An object of the present invention is to provide a biological light measurement device that measures a change in the concentration of an absorbing substance in a deep part of a living body with high accuracy.
[0007]
[Means for Solving the Problems]
A typical configuration of the present invention is as follows.
(1) From the first irradiation position in an area as small as the surface of the head of the subject according to claim 1, which can be regarded as a plane, into the inside of the head in the depth direction of the area. First light irradiating means for irradiating the first irradiation light, second light irradiating means for irradiating the inside of the head with second irradiation light from a second irradiation position in the area, and First detection means for detecting the first irradiation light transmitted through the inside of the head at a first detection position; and second detection means for transmitting the second irradiation light inside the head at a second detection position in the region Second detection means for detecting the irradiation light of
A first signal based on a first transmitted light signal of irradiation light from the first light irradiation unit detected by the first detection unit; and a second light irradiation detected by the second detection unit. Means for multiplying or adding the second signal based on the second transmitted light signal of the irradiation light from the means in the arithmetic unit,
The optical path of the first transmitted light from the first irradiation position to the first detection position and the optical path of the second transmitted light from the second irradiation position to the second detection position are equal to the head. The first and second irradiation positions and the first and second detection positions are positioned so as to overlap in a specific region inside the unit,
A first straight line connecting the first irradiation position and the first detection position and a second straight line connecting the second irradiation position and the second detection position are non-parallel. Characteristic biological light measurement device.
(2) Claim Two The head surface of the subject described in the description, the surface is regarded as a plane, and the first point is located at a point symmetric position such that the center of a circle having a diameter of a predetermined size is the point symmetric center on the surface area. Light irradiating means and the first light detecting means are arranged, and the second light irradiating means and the first light detecting means are arranged at a position different from the position where the first light irradiating means and the first light detecting means are arranged at the point symmetric position. A light irradiation means and a second light detection means are arranged, a first straight line connecting the first light irradiation means and the first light detection means, the second light irradiation means and the second light The second straight line connecting the detection means is non-parallel,
A first signal based on a first transmitted light signal of irradiation light from the first light irradiation unit detected by the first detection unit; and a second light irradiation detected by the second detection unit. A biological light measurement device comprising means for multiplying or adding a second signal based on a second transmitted light signal of irradiation light from the means in an arithmetic unit.
(3) Claim Four The head surface of the subject described above, the surface is regarded as a flat surface, and the first and second light irradiating means and the second light irradiating means are arranged at regular intervals on a circle having a diameter of a predetermined size on the flat surface area. A first straight line connecting the first light irradiating means and the first light detecting means passes through a center of the circle, and the second light irradiating means and the second light detecting means A second straight line connecting to the second light detecting means passes through the center of the circle, and the first straight line and the second straight line are non-parallel,
A first signal based on a first transmitted light signal of irradiation light from the first light irradiation unit detected by the first detection unit; and a second light irradiation detected by the second detection unit. Means for multiplying or adding a second signal based on a second transmitted light signal of the irradiation light from the means in the arithmetic unit,
The optical path of the first transmitted light from the first irradiation position to the first detection position and the optical path of the second transmitted light from the second irradiation position to the second detection position are equal to the head. A biological light measuring device characterized in that it overlaps in a specific area inside a part.
(4) Claim 6 The surface of the head of the subject described in the description, the surface is regarded as a plane, and the first and second light irradiations are equally spaced on a first circle having a diameter of a predetermined size on the plane area. Means and first and second light detecting means are arranged, and a first straight line connecting the first light irradiating means and the second light detecting means passes through the center of the first circle and the second straight line. A second straight line connecting the light irradiating means and the first light detecting means passes through the center of the first circle, and the first straight line and the second straight line pass through the first straight line. Non-parallel to the line,
The third and fourth light irradiating means and the first and second light irradiating means have the same diameter as the first circle and are equally spaced on a second circle on the plane area. A light detection means is disposed, and a third straight line connecting the third light irradiation means and the second light detection means passes through the center of the second circle, and the fourth light irradiation means and the first light A fourth straight line connected to the light detecting means passes through the center of the second circle, and the third straight line and the fourth straight line are non-parallel,
A first signal based on a first transmitted light signal of irradiation light from the second light irradiation unit detected by the first light detection unit and the first light detected by the second light detection unit The light from the third light irradiating means is multiplied or added in the arithmetic unit by a second signal based on the second transmitted light signal of the irradiating light from the irradiating means, and detected by the second light detecting means. A third signal based on a third transmitted light signal of light, a fourth signal based on a fourth transmitted light signal of irradiation light from the fourth light irradiation unit detected by the first light detection unit, and Is configured to be multiplied or added in the arithmetic device.
(5) Claim 8 When a specific small area of the surface of the subject's head described above is regarded as a plane, the first area having a predetermined diameter on the plane area is firstly spaced at equal intervals. A first straight line connecting the first light irradiating means and the first light detecting means, wherein the second and third light irradiating means and the first, second and third light detecting means are arranged; A second straight line connecting the second light irradiation means and the second light detection means and a third straight line connecting the third light irradiation means and the third light detection means are respectively the first straight line. Passing through the center of the circle, the first to third straight lines are non-parallel to each other,
Fourth, sixth, and second light irradiating means having the same diameter as the first circle, and at equal intervals on a second circle on the plane area, and 6 and the first light detection means are arranged, and a fourth straight line connecting the second light irradiation means and the fifth light detection means, the fourth light irradiation means and the first light detection A fifth straight line connecting means and a sixth straight line connecting the sixth light irradiating means and the sixth light detecting means respectively pass through the center of the second circle, and the fourth to sixth straight lines pass through the center of the second circle. The straight lines are non-parallel to each other,
A first signal based on a first transmitted light signal of irradiation light from the first light irradiation unit detected by the first light detection unit; and a second signal detected by the second light detection unit. A second signal based on a second transmitted light signal of irradiation light from the light irradiation unit, and a third transmitted light signal of irradiation light from the third light irradiation unit detected by the third light detection unit And a third signal based on the fourth transmitted light signal of the irradiation light from the fourth light irradiation means detected by the first light detection means. , A fifth signal based on a fifth transmitted light signal of irradiation light from the second light irradiation means detected by the fifth light detection means, and a signal detected by the sixth light detection means. The arithmetic unit multiplies or multiplies a sixth signal based on a sixth transmitted light signal of the irradiation light from the sixth light irradiation unit in the arithmetic unit. Living body light measuring device, characterized in that it is configured to add.
(6) The wavelength λ in the visible to infrared region from the first irradiation position on the subject surface to the inside of the subject according to claim 13. 1 Frequency of light f1 And the above-mentioned λ 1 Wavelength λ different from Two The light of the f1 Different frequency from f2 First light irradiating means for irradiating a first irradiation light having an intensity-modulated light,
The wavelength λ is introduced into the subject from a second irradiation position different from the first irradiation position on the subject surface. 1 The light of the f1 and f2 Different frequency from f3 And the wavelength λ Two The light of the f1 ~ f3 Different frequency from f4 A second light irradiating means for irradiating a second irradiation light having an intensity-modulated light,
The transmitted frequency of the first irradiation light transmitted through the inside of the subject at a first detection position on the surface of the subject corresponding to the first irradiation position. f1 And the frequency modulated at f2 And first light detection means for individually selecting and detecting the intensity-modulated ones,
Of the transmitted light transmitted through the subject of the second irradiation light at a second detection position different from the first detection position on the subject surface corresponding to the second irradiation position, frequency f3 And the frequency modulated at f4 Select and detect individually the intensity modulated by Second light detection means;
The frequency detected by the first light detection means f1 A first signal based on the first transmitted light intensity of the signal and the frequency detected by the second light detecting means. f3 Multiplying or adding a second signal based on the second transmitted light intensity of the second signal and the second signal based on the second transmitted light intensity in the arithmetic unit, and the frequency detected by the first light detecting means. f2 A third signal based on the third transmitted light intensity of the signal and the frequency detected by the second light detecting means. f4 Multiplying or adding a fourth signal based on a fourth transmitted light intensity of the signal in the arithmetic unit,
An optical path of first transmitted light in the subject from the first irradiation position to the first detection position, and a light path in the subject from the second irradiation position to the second detection position. The first and second irradiation positions and the first and second detection positions are positioned such that the optical path of the transmitted light 2 and the optical path of the transmitted light overlap each other in a predetermined measurement area in the subject.
A first straight line connecting the first irradiation position and the first detection position and a second straight line connecting the second irradiation position and the second detection position are non-parallel. Characteristic biological light measurement device.
The following configuration related to the present invention will be described.
Irradiation light emitted from multiple irradiation units is condensed as transmitted light transmitted through the object at multiple detection positions of the object, and transmitted so that the optical paths of the irradiation light emitted from each irradiation unit overlap each other. A biological light measurement device that collects light, improves the sensitivity of detecting an optical parameter in a first predetermined region of a subject, and calculates the intensity of transmitted light.
[0008]
Next, matters related to the present invention will be described.
A light irradiating unit having a plurality of irradiation units for irradiating irradiation light of a plurality of wavelengths to a plurality of irradiation positions of the subject; A light unit, a light collecting unit having a plurality of light collecting units for collecting transmitted light so that respective light paths of irradiation light emitted from the respective irradiation units overlap, and a plurality of light irradiation positions from the transmitted light. Detecting means for detecting the light intensity of the transmitted light for each wavelength, and arithmetic processing means for calculating the transmitted light intensity by improving the sensitivity for detecting the optical parameter of the first predetermined region of the subject. Biological light measuring device.
Irradiation light may be subjected to intensity modulation at different frequencies for each wavelength, and light having a predetermined intensity modulation frequency may be detected from transmitted light, or the intensity of light having a predetermined intensity modulation frequency may be calculated from transmitted light. May be. Further, the transmitted light may be separated for each wavelength, and light of a predetermined intensity modulation frequency may be detected from the separated transmitted light, or light of a predetermined intensity modulation frequency may be detected from the separated transmitted light. The strength may be calculated. The optical parameter is an absorption coefficient.
[0009]
Next, matters related to the present invention will be described.
A transmitted light signal having an intensity modulation frequency or transmitted light of a predetermined wavelength having a predetermined intensity modulation frequency is converted by photoelectric conversion into a transmitted light intensity signal having the predetermined intensity modulation frequency, and a transmitted light intensity signal is input. A signal corresponding to an intensity modulation frequency given to light of a predetermined wavelength at the light irradiation position is input to the phase detection unit, and an output signal from the phase detection unit is subjected to predetermined intensity modulation. Detected as intensity of transmitted light with frequencyConstitution. Alternatively, it has an analog-to-digital converter to which a transmitted light intensity signal is input, and inputs the transmitted light intensity signal to the analog-to-digital converter to perform Fourier transform to obtain a biologically transmitted light intensity signal in a frequency space, and A predetermined reference frequency is obtained by inputting a signal corresponding to an intensity modulation frequency given for each predetermined wavelength of a position or for each predetermined light irradiation position to an analog-digital conversion unit and performing Fourier transform to obtain a predetermined reference frequency. Is calculated as the intensity of transmitted light having a predetermined intensity modulation frequency.Configuration.
[0010]
Next, matters related to the present invention will be described.
The irradiating unit and the condensing unit are on at least one circle centered on a point where a straight line passing through the approximate center of the first predetermined region and the surface of the subject intersect, and on a circle having a predetermined diameter. The irradiation unit and the light condensing unit are arranged at equal intervals and the point of symmetry is such that the center of the circle is the center of point symmetry. Detected at each light condensing position, select the transmitted light intensity for each wavelength from the irradiation position at a point symmetrical position with the light condensing position from the transmitted light intensity for each of multiple wavelengths from each of the light irradiation positions, and select the selected transmission The transmitted light intensity detected on the same circle is selected from the light intensities, and the transmitted light intensity of the transmitted light having a predetermined wavelength detected on the same circle is multiplied or integrated to perform an arithmetic process. . Further, the transmitted light condensed by the condensing portion provided on the circle having a small diameter is used as information on the shallow portion of the subject, and the transmitted light condensed by the condensing portion provided on the circle having a large diameter. The transmitted light is arithmetically processed using the light as information on the deep part of the subject.
[0011]
The irradiating unit and the condensing unit are arranged in a square lattice shape. And the rows of the square lattice on which the condensing portions are arranged are arranged alternately. Alternatively, the irradiating unit and the condensing unit are arranged in a regular hexagonal lattice shape, and are alternately arranged at each lattice point of the regular hexagonal lattice.
[0012]
The irradiation light is light having a wavelength of about 805 nm. From the intensity of the transmitted light, the change in oxyhemoglobin concentration, the change in reduced hemoglobin concentration, and the change in total hemoglobin concentration calculated from the sum of the change in oxyhemoglobin concentration and the change in reduced hemoglobin concentration are calculated. It is characterized by displaying the time change of the total hemoglobin concentration change. Alternatively, the change in total hemoglobin concentration may be determined from the intensity of the transmitted light, and the irradiation light may be irradiation light of at least two wavelengths in a range from 700 nm to 1100 nm.
[0013]
The change in total hemoglobin concentration, the change in oxyhemoglobin concentration or the change in reduced hemoglobin concentration over time calculated from the sum of the change in oxyhemoglobin concentration and the change in reduced hemoglobin concentration is calculated from the sum of the change in oxyhemoglobin concentration and the change in reduced hemoglobin concentration. The color, the type of line, or the thickness of the line is changed for each change in the total hemoglobin concentration, oxyhemoglobin concentration, or reduced hemoglobin concentration. Changes in oxyhemoglobin concentration may be displayed in red or orange, changes in reduced hemoglobin concentration may be displayed in blue, indigo or green, and changes in total hemoglobin concentration may be displayed in black or brown. Further, an image of the total hemoglobin concentration change, the oxyhemoglobin concentration change or the reduced hemoglobin concentration change calculated from the sum of the oxyhemoglobin concentration change and the reduced hemoglobin concentration change may be displayed in a color or luminance corresponding to the concentration change. When the density change is positive, the display is displayed in darker red or higher brightness as the absolute value of the density change is larger, and when the density change is negative, the blue is lower or darker as the absolute value of the density change is smaller. It may be displayed with luminance.
[0014]
Rotate the transmitted light intensity of the transmitted light having a predetermined wavelength detected on the same circle, a predetermined range region of a predetermined depth of the subject on a perpendicular line passing through the center of the circle and perpendicular to the surface of the subject, or rotating the perpendicular. It is considered to reflect the change in total hemoglobin concentration, the change in oxyhemoglobin concentration, or the change in reduced hemoglobin concentration calculated from the sum of the change in oxyhemoglobin concentration and the change in reduced hemoglobin concentration in a predetermined range region of the predetermined rotating body with respect to the center. The diameter of the circle is from 25 mm to 35 mm, and the depth is from 12 mm to 25 mm. By covering the contact surface between the irradiating unit or the condensing unit and the subject using a flexible and highly transmissive member for irradiation light, the stimulation given to the subject by the irradiating unit or the condensing unit can be reduced.
[0015]
Next, matters related to the present invention will be described.
A plurality of irradiating parts and condensing parts are arranged on a circle of a predetermined diameter so that the respective optical paths of the irradiating light emitted from the irradiating part overlap each other. By selectively detecting only the transmitted light and multiplying the detected transmitted light by the transmitted light intensity, it is possible to improve the sensitivity at a predetermined depth from the center position of the circle.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
1 shows an embodiment according to the present invention. In the present embodiment, a case where two wavelengths are used as irradiation wavelengths and two light irradiation positions and light detection positions are set for the purpose of measuring changes in the concentration of oxidized and reduced hemoglobin in a living body will be described. It is easy to increase the position and the light detection position. In addition, by increasing the number of wavelengths, it is possible to measure the change in the concentration of other light absorbing substances such as cytochrome and myoglobin in addition to the change in the concentration of oxidized and reduced hemoglobin.
[0017]
FIG. 1 shows an apparatus configuration according to the present invention.
Light of a specific wavelength is emitted from the light sources 1-1, 1-2, 1-3, 1-4, and is incident on the optical fibers 2-1, 2-2, 2-3, 2-4, respectively. Here, the wavelength from the light sources 1-1 and 1-3 is λ1, and the wavelength from the light sources 1-2 and 1-4 is λ2, which is selected from the range of 400 nm to 2400 nm. In particular, when measuring hemodynamics in a living body, it is desirable to select from the range of 700 nm to 1100 nm such that the wavelength difference is within 50 nm. Further, the light sources 1-1, 1-2, 1-3, and 1-4 have different frequencies f1, f2 between 100 Hz and 10 MHz by the light source driving circuits 4-1, 4-2, 4-3, and 4-4, respectively. , F3, f4. The frequency signals from the light source driving circuits 4-1, 4-2, 4-3, and 4-4 are used as reference frequency signals, and are sent to the phase detectors 10-1, 10-2, 10-3, and 10-4, respectively. Has been entered.
[0018]
The optical fibers 2-1 and 2-2 are connected to the optical directional coupler 3-1, and the optical fibers 2-3 and 2-4 are connected to the optical directional coupler 3-2. The light from -2 is mixed and made incident on the irradiation optical fiber 5-1. The light from the light sources 1-3 and 1-4 is mixed and made incident on the irradiation optical fiber 5-2. The irradiation optical fibers 5-1 and 5-2 and the condensing optical fibers 8-1 and 8-2 are fixed by an optical fiber holder 6.
[0019]
The subject 7 is irradiated with light from the irradiation optical fibers 5-1 and 5-2, and the light transmitted through the living body is collected by the collection optical fibers 8-1 and 8-2. Here, the irradiation optical fibers 5-1 and 5-2 and the condensing optical fibers 8-1 and 8-2 are arranged at equal intervals on a circle of the optical fiber holder 6, and the irradiation optical fibers 5-1 and 5-2 are arranged. The condensing optical fibers 8-1 and 8-2 are arranged at positions opposite to. The optical fiber holder 6 is desirably coated with a black material or a black material in order to enhance the light blocking effect, and has a hollow structure. It is also desirable that the irradiation optical fibers 5-1 and 5-2 and the condensing optical fibers 8-1 and 8-2 are also coated with a black material on the surface other than the subject contact surface. Further, the irradiation surfaces of the optical fibers 5-1 and 5-2 and the converging optical fibers 8-1 and 8-2 are irradiated with, for example, a vinyl resin for the purpose of reducing pain caused by the contact. It is coated with a material having a good transmission with respect to the wavelength.
[0020]
The living body transmitted light condensed by the condensing optical fibers 8-1 and 8-2 is incident on the photodetectors 9-1 and 9-2, respectively, and the living body transmitted light at each light condensing position is photoelectrically converted and amplified. You. A photomultiplier tube or an avalanche photodiode is used for the photodetectors 9-1 and 9-2. After the output signal from the photodetector 9-1 was split into two, it was input to the phase detectors 10-1 and 10-2, and the output signal from the photodetector 9-2 was split into two. Thereafter, the signals are input to the phase detectors 10-3 and 10-4.
[0021]
The signals input to the respective phase detectors are mixed with the irradiated biological transmitted light of all the wavelengths. The phase detectors 10-1, 10-2, 10-3, and 10-4 respectively include light source driving circuits. Since the reference frequencies are input from 4-1 to 4-2, 4-3 and 4-4, the phase detector 10-1 determines the intensity of the transmitted light from the light source 1-1 and the phase detector 10-2. , The intensity of the transmitted light from the light source 1-2, the phase detector 10-3 indicates the intensity of the transmitted light from the light source 1-3, and the phase detector 10-4 indicates the intensity of the transmitted light from the light source 1-4. Separate and detect.
[0022]
Each of the biological transmitted light intensity signals detected by the phase detectors 10-1 and 10-3 (the biological transmitted light intensity of the same wavelength λ1 emitted from the opposing position) is input to the multiplier 11-1 and multiplied, thereby performing phase detection. The biological transmitted light intensity detected by the devices 10-2 and 10-4 (the biological transmitted light intensity of the wavelength λ2 emitted from the opposing position) is input to the multiplier 11-2 and multiplied. The output signal from 11-2 is input to log amplifiers 12-1 and 12-2, respectively. Further, output signals from the respective log amplifiers are input to analog-digital converters (hereinafter abbreviated as A / D converters) 13-1 and 13-2, converted into digital signals, and taken into the arithmetic unit 14.
[0023]
The arithmetic unit 14 calculates the sum of the change in the oxyhemoglobin concentration, the change in the reduced hemoglobin concentration, and the change in the oxyhemoglobin concentration and the change in the reduced hemoglobin concentration representing the blood volume from the time-series signals of the transmitted light intensities of the two wavelengths taken in. Then, it is displayed on the display device 15 as a time series graph. When multipoint measurement is performed by the same device, the image is displayed on the display device 15 as an image. When displaying the change of each hemoglobin concentration as a time series graph, if the display device is capable of displaying color, it is displayed with a different color for each change of hemoglobin concentration, and if the display device is not capable of displaying color, The line type or line thickness is changed and displayed for each change in each hemoglobin concentration. For example, changes in oxygenated hemoglobin concentration are displayed in red or orange, changes in reduced hemoglobin concentration are displayed in blue, indigo or green, and changes in total hemoglobin concentration are displayed in black, gray or brown. When an image is displayed, it may be displayed as a contour image, or may be displayed in a different color or brightness in accordance with a change in the density change value. For example, the larger the absolute value of the positive density change value, the deeper the color becomes red or dark gray, and the larger the absolute value of the negative density change value becomes the deep blue or pale white.
[0024]
Various combinations of the data collection units from the photodetector 9 to the arithmetic unit 14 shown in FIG. FIG. 2 to FIG. 6 show an example of a device configuration relating to a data collection unit from the photodetector 9 to the arithmetic unit 14.
[0025]
FIG. 2 shows a first example of the device configuration related to the data collection unit. In the figure, symbols A, B, C and D with circles represent reference frequency signals as in the example of the device configuration shown in FIG. Further, for simplicity, the components from the light source 1 to the condensing optical fiber 8 in FIG. An example of an apparatus configuration relating to the present data collection unit includes photodetectors 9-1 and 9-2, phase detectors 10-1, 10-2, 10-3, and 10-4, and an A / D converter 13-1. , 13-2, 13-3, 13-4 and the arithmetic unit 14.
[0026]
The configuration up to each of the phase detectors 10-1, 10-2, 10-3, and 10-4 is the same as that shown in FIG. -4 are converted into digital signals by A / D converters 13-1, 13-2, 13-3, and 13-4, respectively, and then input to the arithmetic unit 14. The arithmetic unit 14 multiplies the inputted biological transmitted light signals of all the same wavelengths and then performs a natural logarithm calculation on the result of the multiplication. Add the operation results. Here, the combination of the bio-transmitted light signals of the same wavelength is determined by a set of output signals from the A / D converter 13-1 and the A / D converter 13-3 and a combination of the A / D converter 13-2 and the A / D converter. There are two sets of output signals from the D converter 13-4.
[0027]
FIG. 3 shows a second example of the device configuration relating to the data collection unit. In the figure, symbols A, B, C and D with circles represent reference frequency signals as in the example of the device configuration shown in FIG. Further, for simplicity, the components from the light source 1 to the condensing optical fiber 8 in FIG. Examples of the device configuration relating to the present data collection unit include photodetectors 9-1 and 9-2, phase detectors 10-1, 10-2, 10-3, and 10-4, and multipliers 11-1 and 11-. 2, the A / D converters 13-1 and 13-2, and the arithmetic unit 14. The configuration up to the multipliers 11-1, 11-2, 11-3, and 11-4 is the same as that shown in FIG. 1, except that the output signals from the multipliers 11-1 and 11-2 are A After being converted into digital signals by the / D converter 13-1 and the A / D converter 13-2, they are input to the arithmetic unit 14. The arithmetic unit 14 performs a natural logarithmic operation on the signals from the A / D converters 13-1 and 13-2.
[0028]
FIG. 4 shows a third example of the device configuration related to the data collection unit. In the figure, symbols A, B, C, and D with circles represent reference frequency signals as in the example of the device configuration shown in FIG. Further, for simplicity, the components from the light source 1 to the condensing optical fiber 8 in FIG. An example of a device configuration relating to the present data collection unit includes photodetectors 9-1 and 9-2, phase detectors 10-1, 10-2, 10-3, and 10-4, and log amplifiers 12-1 and 12-. 2, 12-3, 12-4, adders 16-1, 16-2, A / D converters 13-1, 13-2, and an arithmetic unit 14. The configuration up to the phase detectors 10-1, 10-2, 10-3, and 10-4 is the same as that shown in FIG. 1, but each of the phase detectors 10-1, 10-2, 10-3, and 10- 4 are input to log amplifiers 12-1, 12-2, 12-3, and 12-4, respectively. Each of the biological transmitted light intensity signals (the biological transmitted light intensity of the same wavelength λ1 emitted from the opposing position) from the log amplifier 12-1 and the log amplifier 12-3 is input to the adder 16-1 and added, and added. Each of the biological transmitted light intensity signals (the biological transmitted light intensity of the same wavelength λ2 emitted from the opposing position) from the log amplifier 12-2 and the log amplifier 12-4 is input to the adder 16-2 and added to each other. -1 and 16-2 are input to A / D converters 13-1 and 13-2, respectively. The signals are converted into digital signals by the A / D converters 13-1 and 13-2, and then input to the arithmetic unit 14.
[0029]
FIG. 5 shows a fourth example of the device configuration related to the data collection unit. In the figure, symbols A, B, C, and D with circles represent reference frequency signals as in the example of the device configuration shown in FIG. Further, for simplicity, the components from the light source 1 to the condensing optical fiber 8 in FIG. An example of a device configuration relating to the present data collection unit includes photodetectors 9-1 and 9-2, phase detectors 10-1, 10-2, 10-3, and 10-4, and log amplifiers 12-1 and 12-. 2, 12-3, 12-4, A / D converters 13-1, 13-2, 13-3, 13-4, and an arithmetic unit 14. The configuration up to the phase detectors 10-1, 10-2, 10-3, and 10-4 is the same as that shown in FIG. 1, but each of the phase detectors 10-1, 10-2, 10-3, and 10- 4 are input to log amplifiers 12-1, 12-2, 12-3, and 12-4, respectively. After the output signals from the log amplifiers 12-1, 12-2, 12-3, and 12-4 are converted into digital signals by A / D converters 13-1, 13-2, 13-3, and 13-4, respectively. Input to the arithmetic unit 14. The arithmetic unit 14 adds the inputted biologically transmitted light signals of all the same wavelengths. Here, the combination of the bio-transmitted light signals of the same wavelength is determined by a set of output signals from the A / D converter 13-1 and the A / D converter 13-3 and a combination of the A / D converter 13-2 and the A / D converter. There are two sets of output signals from the D converter 13-4.
[0030]
FIG. 6 shows a fifth example of the device configuration related to the data collection unit. Symbols A, B, C, and D with circles in the figure represent reference frequency signals as in the example of the device configuration shown in FIG. Further, for simplicity, the components from the light source 1 to the condensing optical fiber 8 in FIG. An example of an apparatus configuration relating to the data collection unit includes photodetectors 9-1 and 9-2 and A / D converters 13-1, 13-2, 13-3, 13-4, 13-5, and 13-6. And the arithmetic unit 14. The configuration up to the photodetectors 9-1 and 9-2 is the same as that shown in FIG. 1, but the output signals from the photodetectors 9-1 and 9-2 are respectively converted into A / D converters 13-1. -1 and input to the A / D converter 13-2. Output signals from the A / D converters 13-1 and 13-2 are input to the arithmetic unit 14. The reference frequency signals A, B, C, and D given to the irradiation light are input to the A / D converters 13-3, 13-4, 13-5, and 13-6, and are converted into digital signals and then operated. Input to the device 14. In the arithmetic unit, the signals from the A / D converters 13-1, 13-2, 13-3, 13-4, 13-5, and 13-6 are Fourier-transformed. The signals from the A / D converters 13-3, 13-4, 13-5, and 13-6 are Fourier-transformed, and the obtained highest-intensity frequencies are denoted by f1, f2, f3, and f4, respectively. From the result of the Fourier transform of the signal from the A / D converter 13-1, the signal strengths corresponding to the frequencies f1 and f2 are defined as I (f1) and I (f2). Out of the result of the Fourier transform of the signal of (1), signal strengths corresponding to the frequencies f3 and f4 are defined as I (f3) and I (f4). Here, I (f1) and I (f3) are biologically transmitted optical signals of the same wavelength (light from the light sources 1-1 and 1-3 in FIG. 1) emitted from the opposing positions, so that they are multiplied by each other. Then, natural logarithm operation is performed, and I (f2) and I (f4) are biological transmitted light signals of the same wavelength (light from the light sources 1-2 and 1-4 in FIG. 1) irradiated from the opposite position. , And perform a natural logarithmic operation.
[0031]
The case where two irradiation optical fibers and two light collecting optical fibers are arranged on one circle has been described above. Hereinafter, an embodiment in which a large number of irradiation optical fibers and a large number of light collecting optical fibers are arranged will be described.
[0032]
FIG. 7 shows a first example of the arrangement of the irradiation optical fiber and the light collecting optical fiber. In this arrangement example, three irradiation optical fibers and three condensing optical fibers are arranged on each concentric circle on a double concentric circle. However, the irradiation optical fiber and the condensing optical fiber are multiplexed on the concentric circle. With this arrangement, the sensitivity of the measurement can be increased at various predetermined depths.
[0033]
The irradiation optical fibers 5-1 5-2, and 5-3 are disposed on the concentric circle 17-1 at every 120 degrees, and the condensing optical fibers 8-1 and 8-2 are located at positions facing the respective irradiation optical fibers. , 8-3. The irradiation optical fibers 5-4, 5-5, and 5-6 are arranged at intervals of 120 degrees on a concentric circle 17-2 provided inside the concentric circle 17-1, and opposing (180 degrees) positions of the irradiation optical fibers. The optical fibers 8-4, 8-5, and 8-6 for condensing light are arranged at the same time. Such an arrangement position fixing means is performed using the optical fiber holder 6. The multiplied biological transmitted light intensity detected on the concentric circle 17-2 is calculated by assigning the multiplied biological transmitted light intensity detected on the concentric circle 17-1 as deep information, and the multiplied biological transmitted light intensity detected on the concentric circle 17-2 is calculated. The change in hemoglobin concentration inside the living body can be calculated by assigning the information as the information of the shallow part. The hemoglobin concentration change calculated from the multiplied biological transmitted light intensity detected on the concentric circle 17-2 is multiplied by a predetermined weighting factor estimated from the sensitivity distribution, and the multiplication detected on the concentric circle 17-1 is calculated. By subtracting from the change in the hemoglobin concentration calculated from the obtained transmitted light intensity of the living body, it is possible to further improve the relative sensitivity at a predetermined depth.
[0034]
FIG. 8 shows a second example of the arrangement of the irradiation optical fibers and the condensing optical fibers. In this arrangement example, an efficient arrangement example in the case where measurement is performed at various positions of the living body based on the present invention is shown. In this example, an arrangement example of two sets of irradiation optical fibers and light collecting optical fibers on one circle is shown.
[0035]
When two sets of irradiation optical fibers and condensing optical fibers are arranged on one circle and the measurement area is extended, as shown in FIG. 8, the irradiation optical fibers and the condensing optical fibers are placed on the square lattice vertices. The grating is arranged so that the irradiation optical fiber and the condensing optical fiber are located in the diagonal direction of each grating. Here, when nine measurement positions are set, that is, nine from the circle 18-1 to the circle 18-9, as shown in FIG. 8, from the irradiation optical fiber 5-1 to the irradiation optical fiber 5-12, The light collecting optical fiber 8-1 to the light collecting optical fiber 8-12 are arranged on the square lattice apex. With this arrangement, the irradiation optical fiber and the condensing optical fiber arranged at the intersections of different circles function with respect to the same number of measurement positions as the number of circle intersections, so that measurement can be performed with a smaller number of optical fibers. Since a wider area is measured, it is easy to increase the measurement position. An image of hemodynamics in a deep part of a living body can be obtained from the result obtained by widening the measurement region.
[0036]
FIG. 9 shows a second example of the arrangement of the irradiation optical fibers and the light collecting optical fibers. In this arrangement example, an efficient arrangement example in the case where measurement is performed at various positions of the living body based on the present invention is shown. In this example, an example of arrangement of three sets of irradiation optical fibers and light collecting optical fibers on one circle is shown.
[0037]
When three sets of optical fibers for irradiation and optical fibers for condensing are arranged on one circle and the measurement area is extended, as shown in FIG. The optical fibers are arranged such that the irradiation optical fiber and the condensing optical fiber are located at the vertices opposite to the lattice vertices. Here, when four measurement positions are set, that is, four from the circle 18-1 to the circle 18-4, as shown in FIG. 8, from the irradiation optical fiber 5-1 to the irradiation optical fiber 5-8, The light collecting optical fibers 8-1 to 8-8 are arranged on the vertices of a regular hexagonal lattice. With this arrangement, the irradiation optical fiber and the condensing optical fiber arranged at the intersections of different circles function with respect to the same number of measurement positions as the number of circular intersections, so that measurement can be performed with a small number of optical fibers. Since a wider area is measured, it is easy to increase the measurement position. From the result obtained by widening the measurement area, an image of the biological hemodynamics can be obtained.
[0038]
(Reference example)
FIG.According to the reference exampleThe device configuration is shown.
Light having a continuous wavelength spectrum is emitted from the white light sources 19-1 and 19-2, passes through the glass filters 20-1 and 20-2, and a wavelength range necessary for measurement is selected. , 21-2 to be incident on the irradiation optical fibers 5-1 and 5-2. Here, the wavelength from the light source 19-1 and the light source 19-2 is in the range of 400 nm to 2400 nm. In particular, when measuring hemodynamics in a living body, it is desirable to select the glass filter 20-1 and the glass filter 20-2 so as to be in the range of 700 nm to 1100 nm. The light sources 19-1 and 19-2 are intensity-modulated at different frequencies f1 and f2 between 100 Hz and 10 MHz by the light source driving circuits 4-1 and 4-2, respectively. The frequency signals from the light source driving circuits 4-1 and 4-2 are input to the phase detectors 10-1, 10-2, 10-3 and 10-4 as reference frequency signals, respectively. The irradiation optical fiber 5-1 and the irradiation optical fiber 5-2 are fixed by the optical fiber holder 6 together with the light collecting optical fiber 8-1 and the light collecting optical fiber 8-2.
[0039]
The subject 7 is irradiated with light from the irradiation optical fibers 5-1 and 5-2, and the light transmitted through the living body is collected by the collection optical fibers 8-1 and 8-2. Here, the irradiation optical fibers 5-1 and 5-2 and the condensing optical fibers 8-1 and 8-2 are arranged on the optical fiber holder 6 at equal intervals on a circle, and the irradiation optical fibers 5-1 and 5-2 are arranged. The optical fibers 8-1 and 8-2 for condensing light are arranged at positions facing each other.
[0040]
The living body transmitted light condensed by the condensing optical fibers 8-1 and 8-2 is incident on spectroscopes 22-1 and 22-2, respectively, and is split at predetermined wavelengths. Here, the wavelength λ1 and the wavelength λ2 are selected from a plurality of split wavelengths. The biological transmitted light of wavelength λ1 from the spectroscope 22-1 is transmitted to the photodetector 9-1, the biological transmitted light of wavelength λ2 from the spectrometer 22-1 is transmitted to the photodetector 9-2, and the spectrometer 22-2. Is input to the photodetector 9-3, and the biologically transmitted light having the wavelength λ2 from the spectroscope 22-2 is input to the photodetector 9-4, and is photoelectrically converted and amplified by each photodetector. You. As the photodetectors 9-1, 9-2, 9-3, and 9-4, photomultiplier tubes or avalanche photodiodes are used. The output signal from the photodetector 9-1 is input to the phase detector 10-1, the output signal from the photodetector 9-2 is input to the phase detector 10-2, and the output signal from the photodetector 9-3. The output signal is input to the phase detector 10-3, and the output signal from the photodetector 9-4 is input to the phase detector 10-4.
[0041]
The signals input to each of the phase detectors are mixed with biologically transmitted light having the same wavelength and different intensity modulation frequencies, but each of the phase detectors 10-1, 10-2, 10-3, and 10-4 has Since the reference frequency is input from each of the light source driving circuits 4-1 and 4-2, the phase detector 10-1 determines the intensity of the living body transmitted light having the wavelength λ1 from the light source 19-1 by using the phase detector 10-2. , The biological transmitted light intensity of the wavelength λ2 from the light source 19-1, the phase detector 10-3 the biological transmitted light intensity of the wavelength λ1 from the light source 19-2, and the phase detector 10-4 from the light source 19-2. Can be separated and detected.
[0042]
Each of the biological transmitted light intensity signals detected by the phase detector 10-1 and the phase detector 10-3 (the biological transmitted light intensity of the wavelength λ1 emitted from the opposing position) is input to the multiplier 11-1 and multiplied. Each of the biological transmitted light intensities detected by the phase detector 10-2 and the phase detector 10-4 (the biological transmitted light intensity of the wavelength λ2 emitted from the opposing position) is input to the multiplier 11-2 and multiplied. The output signal from the multiplier is input to log amplifier 12-1 and log amplifier 12-112-2, respectively. Further, output signals from the respective log amplifiers are input to analog-digital converters 13-1 and 13-2, converted into digital signals, and then taken into the arithmetic unit 14.
[0043]
The arithmetic unit 14 calculates the change in the oxyhemoglobin concentration, the change in the reduced hemoglobin concentration, and the sum of the change in the oxyhemoglobin concentration and the change in the reduced hemoglobin concentration representing the blood volume from the time-series signals of the transmitted light intensities of the two wavelengths taken in. The calculation is performed and displayed on the display device 15 as a time series graph.
[0044]
In the apparatus configuration shown in FIG. 1, the number of pairs of irradiation optical fibers and light collecting optical fibers may be further increased and installed in the optical fiber holder 6. For example, FIG. 14, FIG. 15, and FIG. 16 show the measurement results obtained by providing four sets of an optical fiber for irradiation and an optical fiber for condensing. Assuming that the surface of the living body is a plane, a plane parallel to the surface of the living body is defined as an XY plane. Four sets of irradiation optical fibers and condensing optical fibers were arranged so that the center of the circle was a point symmetric center. The measurement results are shown as relative sensitivity distribution at a position of 2.5 mm depth (FIG. 14), relative sensitivity distribution at a position of 7.5 mm depth (FIG. 15), and relative sensitivity distribution at a position of 12.5 mm depth. (FIG. 16). Comparing the measurement results (FIGS. 11, 12 and 13) of the conventional example with the measurement results of the present invention (FIGS. 14, 15 and 16), it was possible to improve the measurement sensitivity in a predetermined deep part of the living body .
[0045]
In the present embodiment, the configuration has been described in which the bio-transmitted light intensity from the opposing position on the predetermined circle is all multiplied for each of the same wavelengths. Although the physical meaning is reduced, it is possible to improve the relative sensitivity in the deep part. In addition, the sensitivity of the target measurement area may be improved by using an apparatus configuration that performs four arithmetic operations on the transmitted light intensity of the living body measured at a plurality of positions. Further, according to the present invention, as a measurement requiring a sensitivity distribution in a deep part, a change in hemodynamics due to brain function activity can be measured from above the scalp.
[0046]
【The invention's effect】
According to the present invention, it is possible to accurately measure the concentration of an absorbent at a predetermined depth in a living body.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an optical measurement device according to the present invention.
FIG. 2 is another configuration diagram of a data collection unit in the optical measurement device according to the present invention.
FIG. 3 is another configuration diagram of a data collection unit in the optical measurement device according to the present invention.
FIG. 4 is another configuration diagram of a data collection unit in the optical measurement device according to the present invention.
FIG. 5 is another configuration diagram of the data collection unit in the optical measurement device according to the present invention.
FIG. 6 is another configuration diagram of a data collection unit in the optical measurement device according to the present invention.
FIG. 7 is a diagram showing an arrangement of an irradiation optical fiber and a condensing optical fiber in the optical measurement device according to the present invention.
FIG. 8 is a diagram showing another arrangement of an irradiation optical fiber and a condensing optical fiber in the optical measurement device according to the present invention.
FIG. 9 is a diagram showing another arrangement of an irradiation optical fiber and a condensing optical fiber in the optical measurement device according to the present invention.
FIG. 10 shows the present invention.Reference exampleThe figure which shows the other structure of the optical measuring device which concerns on FIG.
FIG. 11 is a diagram showing a sensitivity distribution at a biological body depth of 2.5 mm according to the related art.
FIG. 12 is a diagram showing a sensitivity distribution at a biological body depth of 7.5 mm according to the related art.
FIG. 13 is a diagram showing a sensitivity distribution at a biological body depth of 12.5 mm according to the related art.
FIG. 14 is a diagram showing a sensitivity distribution at a biological body depth of 2.5 mm obtained by the apparatus of the present invention.
FIG. 15 is a diagram showing a sensitivity distribution at a biological body depth of 7.5 mm obtained by the apparatus of the present invention.
FIG. 16 is a diagram showing a sensitivity distribution at a biological body depth of 12.5 mm obtained by the apparatus of the present invention.
[Explanation of symbols]
1-1, 1-2, 1-3, 1-4 ... light source, 2-1, 2-2, 2-3, 2-4 ... optical fiber, 3-1, 3-2 ... light directional coupler, 4-1, 4-2, 4-3, 4-4: Light source driving device, 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7, 5- Reference numeral 8: irradiation optical fiber, 6: optical fiber holder, 7: subject, 8-1, 8-2: condensing optical fiber, 9-1, 9-2: photodetector, 10-1, 10-2, 10-3, 10-4 ... phase detectors, 11-1, 11-2 ... multipliers, 12-1, 12-2 ... log amplifiers, 13-1, 13-2, 13-3, 13-4 ... Analog-digital converter, 14 arithmetic unit, 15 display unit, 16-1, 16-2 adder, 17-1, 17-2 concentric circles, 18-1, 18-2, 18-3, 18 -4,18-5,18 6, 18-7, 18-8, 18-9 circle, 19-1, 19-2 white light source, 20-1, 20-1 glass filter, 21-1, 21-1 lens, 22 1,22-2 ... Spectroscope.

Claims

A first irradiating light from a first irradiation position on a surface of the head of the subject in a small area where the surface can be regarded as a plane to the inside of the head in a depth direction of the area; 1 light irradiating means, second light irradiating means for irradiating the inside of the head with second irradiation light from a second irradiation position in the area, and the head at a first detection position in the area. First detection means for detecting the first irradiation light transmitted through the inside of the head, and second detection for detecting the second irradiation light transmitted through the inside of the head at a second detection position in the region. Detecting means;
A first signal based on the first transmitted light signal of the irradiation light from said detected by the first detecting means first light irradiating means, said second light irradiation detected by the second detecting means a second signal and means for multiplying or adding in a computing device based on the second transmission light signal of the irradiation light from the unit,
The optical path of the first transmitted light from the first irradiation position to the first detection position and the optical path of the second transmitted light from the second irradiation position to the second detection position are equal to the head. The first and second irradiation positions and the first and second detection positions are positioned so as to overlap in a specific region inside the unit ,
A first straight line connecting the first irradiation position and the first detection position and a second straight line connecting the second irradiation position and the second detection position are non-parallel. Characteristic biological light measurement device.

The first light irradiation is performed on the surface of the head of the subject, where the surface is regarded as a plane and the center of a circle having a diameter of a predetermined size becomes the center of point symmetry on the surface area. means and a first light detecting means is disposed, the second light irradiating means at a different position from the position where the a the point symmetrical position the first light emitting device and the first light detecting means is disposed When the second light detecting means is disposed, a first straight line connecting the said first light irradiation means first light detecting means, and said second light irradiation means and the second light detecting means It is non-parallel to the second straight line connecting a first signal based on the first transmitted light signal of the irradiation light from the first light emitting means detected by the first detecting means, the second a second signal based on the second transmission light signal of the irradiation light from the second light emitting means detected by the detection means Living body light measuring device, characterized that you have a means for multiplying or adding in a computing device.

The detection sensitivity of the concentration change of the absorbing substance inside the head below the center of the circle by the light detecting means is detected by the light detecting means of the concentration change of the absorbing substance at another part inside the head. The biological optical measurement device according to claim 2, wherein the sensitivity is higher than the sensitivity.

A head surface of the subject, considers the surface and a plane, equally spaced first and second light emitting means and the first and in the plane region on a circle having a diameter of predetermined size Two light detecting means are arranged, and a first straight line connecting the first light irradiating means and the first light detecting means passes through the center of the circle, and the second light irradiating means and the second light A second straight line connected to the light detection means passes through the center of the circle, and the first straight line and the second straight line are non-parallel,
A first signal based on the first transmitted light signal of the irradiation light from said detected by the first detecting means first light irradiating means, said second light irradiation detected by the second detecting means Means for multiplying or adding a second signal based on a second transmitted light signal of the irradiation light from the means in the arithmetic unit ,
The optical path of the first transmitted light from the first irradiation position to the first detection position and the optical path of the second transmitted light from the second irradiation position to the second detection position are equal to the head. A biological light measuring device characterized in that it overlaps in a specific area inside a part.

The detection sensitivity of the concentration change of the absorbing substance inside the head below the center of the circle by the light detecting means is detected by the light detecting means of the concentration change of the absorbing substance at another part inside the head. The biological light measurement device according to claim 4, wherein the sensitivity is higher than the sensitivity.

A head surface of the subject, which surface is regarded as a plane, and the first and second light irradiating means and the second light irradiating means are arranged at equal intervals on a first circle having a diameter of a predetermined size on the plane area; A first straight line connecting the first light irradiating means and the second light detecting means passes through a center of the first circle and irradiates the second light detecting means; A second straight line connecting the means and the first light detection means passes through the center of the first circle, and the first straight line and the second straight line are non-parallel;
The third and fourth light irradiating means and the first and second light irradiating means have the same diameter as the first circle and are equally spaced on a second circle on the plane area. A light detection means is disposed, and a third straight line connecting the third light irradiation means and the second light detection means passes through the center of the second circle, and the fourth light irradiation means and the first light A fourth straight line connected to the light detecting means passes through the center of the second circle, and the third straight line and the fourth straight line are non-parallel,
The first of the first light detected by the first signal and the second light detecting means based on the first transmitted light signal of the irradiation light from the second light emitting means detected by the light detecting means a second signal based on the second transmission light signal of the irradiation light from the irradiation means to multiply or add in computing devices, illumination from said detected by the second photodetector means the third light emitting means a fourth signal based on the third signal and the fourth transmitted light signal of the irradiation light from the first of the fourth detected by the light detecting means of the light irradiation means based on the third transmitted light signals of light Is configured to be multiplied or added in the arithmetic device.

The detection sensitivity of the light detecting means for the concentration change of the absorbing substance inside the head below the center of the first and second circles is different from the concentration change of the absorbing substance at another part inside the head. The biological light measurement device according to claim 6 , wherein the detection sensitivity is higher than the detection sensitivity of the light detection unit.

When a specific small area on the surface of the head of the subject is regarded as a plane, the first and second circles are equally spaced on a first circle having a predetermined diameter on the plane area. A first straight line connecting the first light irradiating means and the first light detecting means, and a first straight line connecting the first light irradiating means and the first light detecting means; the second straight line and the third third straight line each of the first circle connecting the light irradiation means and said third photodetector means connecting the light irradiation means and the second light detecting means through the center, it first to third linear et al are not parallel to each other,
Fourth, sixth, and second light irradiating means having the same diameter as the first circle, and at equal intervals on a second circle on the plane area, and 6 and the first light detection means are arranged, and a fourth straight line connecting the second light irradiation means and the fifth light detection means, the fourth light irradiation means and the first light detection passes through the center of the fifth straight and the sixth sixth straight line each of the second circle connecting the light irradiation means and said sixth light detection means for connecting the unit, it et fourth to sixth linear is non-parallel to each other,
A first signal based on the first transmitted light signal of the irradiation light from the first light emitting means detected by the first light detecting means, the second detected by the second light detecting means A second signal based on a second transmitted light signal of irradiation light from the light irradiation unit, and a third transmitted light signal of irradiation light from the third light irradiation unit detected by the third light detection unit and a third signal based on multiplying or adding in the arithmetic unit, and a fourth that is based on the fourth transmitted light signal of the irradiation light from said detected by the first light detecting means fourth light emitting means and signals detected by the fifth and the fifth signal based on the fifth transmission light signals of the irradiation light from the second light emitting means detected by the light detecting means, said sixth light detection means multiplying the sixth signal based on the sixth transmitted light signals of the irradiation light from the sixth light emitting means in said computing device also Living body light measuring device, characterized in that it is configured to add.

The detection sensitivity of the light detecting means for the concentration change of the absorbing substance inside the head below the center of the first and second circles is different from the concentration change of the absorbing substance at another part inside the head. The living body light measurement device according to claim 8 , wherein the detection sensitivity is higher than the detection sensitivity of the light detection means.

A first surface and a second light irradiating unit at equal intervals on a first circle having a diameter of a first size on a plane area of the head surface of the subject when the surface is regarded as a plane; First and second light detecting means are disposed, and a first straight line connecting the first light irradiating means and the first light detecting means passes through the center of the first circle, and the second straight line passes through the center of the first circle. A second straight line connecting the light irradiation means and the second light detection means passes through the center of the first circle, and the first straight line and the second straight line are non-parallel,
A third circle having a larger diameter than the first circle, the center of which is the same point as the center of the first circle, and the third and third circles being equally spaced on a second circle on the plane area; 4 light irradiating means and third and fourth light detecting means are arranged, and a third straight line connecting the third light irradiating means and the third light detecting means is located at the center of the second circle. As described above, the fourth straight line connecting the fourth light irradiation means and the fourth light detection means passes through the center of the second circle, and the third straight line and the fourth straight line are non-parallel. And
It said first of said second light detected by the first signal and the second light detecting means based on the first transmitted light signal of the irradiation light from the first light emitting means detected by the light detecting means with multiplying or adding the second signal based on the second transmission light signal of the irradiation light from the irradiation means in the arithmetic unit, from the third light emitting means detected by the third light detecting means A third signal based on a third transmitted light signal of the irradiation light and a fourth signal based on a fourth transmitted light signal of the irradiation light from the fourth light irradiation unit detected by the fourth light detection unit The biological light measurement device is configured to multiply or add in the arithmetic device.

The detection sensitivity of the light detecting means for the concentration change of the absorbing substance inside the head below the center of the first and second circles is different from the concentration change of the absorbing substance at another part inside the head. The living body light measurement device according to claim 10 , wherein the detection sensitivity is higher than the detection sensitivity of the light detection means.

The biological light measurement device according to claim 11, wherein the portion having the high detection sensitivity is located under the first and second circles and at two different positions in a depth direction.

From the first irradiation position on the surface of the subject to the inside of the subject, light having a wavelength λ1 in the visible to infrared region is intensity-modulated at a frequency f1 and light having a wavelength λ2 different from the λ1 at a frequency f2 different from the f1. First light irradiation means for irradiating a first irradiation light having an intensity-modulated one;
The light of the wavelength λ1 from the second irradiation position different from the first irradiation position on the surface of the subject to the inside of the subject is intensity-modulated at a frequency f3 different from the frequencies f1 and f2, and the wavelength λ2 A second light irradiating means for irradiating a second irradiation light having a light intensity modulated at a frequency f4 different from the f1 to f3,
At a first detection position on the surface of the subject corresponding to the first irradiation position, of the transmitted light of the first irradiation light transmitted through the inside of the subject, one of which intensity is modulated at the frequency f1; and a first light detecting means for detecting individually selected those intensity modulated at said frequency f2,
Of the transmitted light transmitted through the subject of the second irradiation light at a second detection position different from the first detection position on the subject surface corresponding to the second irradiation position, Second light detection means for selectively detecting individually the intensity-modulated frequency f3 and the intensity-modulated frequency f4,
A first signal based on a first transmitted light intensity of the signal of the frequency f1 detected by the first light detecting means and a second transmitted light of the signal of the frequency f3 detected by the second light detecting means The second signal based on the intensity is multiplied or added in the arithmetic unit, and the third signal based on the third transmitted light intensity of the signal of the frequency f2 detected by the first light detection means and the third signal are used . A second signal based on a fourth transmitted light intensity of the signal of the frequency f4 detected by the second light detection means is configured to be multiplied or added in the arithmetic device ;
An optical path of first transmitted light in the subject from the first irradiation position to the first detection position, and a light path in the subject from the second irradiation position to the second detection position. The first and second irradiation positions and the first and second detection positions are positioned such that the optical path of the transmitted light 2 and the optical path of the transmitted light overlap each other in a predetermined measurement area in the subject .
A first straight line connecting the first irradiation position and the first detection position and a second straight line connecting the second irradiation position and the second detection position are non-parallel. Characteristic biological light measurement device.