Absorption information measuring method and apparatus of scattering medium

A method of measuring absorption information of a scattering medium, said method comprising:

• applying a plurality of modulated light beams to form a spot shape incident on a surface of a scattering medium comprising a measured object, each of said plurality of modulated light beams having a predetermined modulation frequency component and a different wavelength at which scattering coefficients of said measured object are substantially equal to one another;
• acquiring respective measurement signals for said different wavelengths by receiving said modulated light beams having propagated inside said measured object at a predetermined position on said surface of said scattering medium;
• detecting, from each of said respective measurement signals, respective signals of said modulation frequency component;
• obtaining, from said respective signals of said modulation frequency component, amplitude components and phase component slopes against modulation angular frequency;
• and
• calculating a difference between absorption coefficients of said measuring object at said respective wavelengths based upon a predetermined relation among said amplitude components, said phase component slopes against modulation angular frequency, and said difference between absorption coefficients of said measured object at said respective wavelengths.

An apparatus for measuring absorption information of a scattering medium, said apparatus comprising:

• a light source, configured and arranged to apply modulated light having a predetermined modulation frequency component to form a spot shaped incident on a surface of a scattering medium comprising a measured object;
• a photodetector, configured and arranged to acquire respective measurement signals by receiving said modulated light having propagated inside said measured object at one or both of a plurality of different times and a plurality of positions on said surface of said scattering medium;
• a signal detector, configured and arranged to detect, from said respective measurement signals, respective signals of said modulation frequency component;
• a first arithmetic section, configured and arranged to calculate, from said respective signals of said modulation frequency component, amplitude components and phase component slopes against modulation angular frequency;
• and
• a second arithmetic section for calculating a difference between absorption coefficients of said measuring object based upon a predetermined relation among said amplitude components, said phase component slopes against modulation angular frequency, and said difference between absorption coefficients of said measuring object.

An apparatus for measuring absorption information of a scattering medium, said apparatus comprising:

• a light source, configured and arranged to apply a plurality of modulated light beams to form a spot shaped incident on a surface of a scattering medium comprising a measured object, each of said plurality of modulated light beams having a predetermined modulation frequency component and having a predetermined different wavelength at which scattering coefficients of said measured object are substantially equal to one another;
• a photodetector, configured and arranged to acquire respective measurement signals for said different wavelengths by receiving said modulated light beams having propagated inside said measured object at a predetermined position in said surface of said scattering medium;
• a signal detector, configured and arranged to detect, from said respective measurement signals, respective signals of said modulation frequency component;
• a first arithmetic section for obtaining, from said respective signals of said modulation frequency component, amplitude components and phase component slopes against modulation angular frequency;
• and
• a second arithmetic section for calculating a difference between absorption coefficients of said measuring object based upon a predetermined relation among said amplitude components, said phase component slopes against modulation angular frequency, and said difference between absorption coefficients.