Determination of absorption coefficients in highly scattering media from changes in attenuation and phase.

The accurate, quantitative analysis of absorption and scattering properties in tissue is a central problem in biochemical optics, in particular for the determination of hemoglobin and oxyhemoglobin concentrations. Because of light scattering, the absolute concentrations of these chromophores (i.e., the absorption coefficient) cannot easily be inferred. A new method for the estimation of the absorption coefficients in scattering media, based on measurements obtained from an intensity-modulated optical spectrometer, is proposed. The ratios of the changes in attenuation and phase that are induced by changes in the absorption coefficient give a good approximation of the absorption coefficient.