PROBLEM TO BE SOLVED: To provide an apparatus and method for quantifying concentration, and a program, by which concentration of an objective component in an arbitrary layer can be noninvasively and accurately quantified by distinguishing backscatter light from the arbitrary layer among observation objects from light from other layers.SOLUTION: The apparatus 300 for quantifying the concentration includes: an irradiation part 304； a light receiving part 305； an optical path length distribution memory part 302； an optical path length acquisition part 307； a time resolution waveform memory part 303； a measurement light intensity acquisition part 306； an interval of integration calculation part 309 to calculate an interval of integration corresponding to the light intensity distribution of the arbitrary layer on the basis of light intensity distribution acquired by the measurement light intensity acquisition part 306, optical length acquired by the optical path length acquisition part 307 and the light intensity model acquired by a non-absorption time light intensity acquisition part 308； a light absorption coefficient calculation part 310 to calculate the light absorption coefficient of the objective component of the arbitrary layer by varying the interval of integration； and a concentration calculation part 313 to calculate the concentration of the objective component of the arbitrary layer on the basis of the light absorption coefficient acquired by the light absorption coefficient calculation part 310.【課題】観測対象のうち任意の層からの後方散乱光を他の層からの光と区別することで、任意の層における目的成分の濃度を、非侵襲的にかつ精度良く定量することができる濃度定量装置及び濃度定量方法並びにプログラムを提供する。【解決手段】本発明の濃度定量装置300は、照射部304と、受光部305と、光路長分布記憶部302と、光路長取得部307と、時間分解波形記憶部303と、計測光強度取得部306と、計測光強度取得部306が取得した光強度分布と、光路長取得部307が取得した光路長と、無吸収時光強度取得部308が取得した光強度モデルとに基づいて任意の層の光強度分布に対応する積分区間を算出する積分区間算出部309と、積分区間を変化させて任意の層の目的成分の光吸収係数を算出する光吸収係数算出部310と、光吸収係数算出部310が取得した光吸収係数に基づいて任意の層の目的成分の濃度を算出する濃度算出部313とを備えている。【選択図】図９
