A dual interpretation of experimental data concerning the propagation of laser light through tissue-like turbid media

摘要

The propagation is investigated of a continuous laser beam through homogeneous tissue-like turbid media such as diluted emulsions of Intralipid or milk having presumably sharply forward directed Henyey-Greenstein or Gaussian indicatrices. The cross sectional radial distributions of the detected forward-propagating light power at different depths along the beam axis in each medium of interest are experimentally determined. The detected-power spatial distribution, for both the types of indicatrices, is also described analytically by a solution of the radiative transfer equation in the so-called small-angle approximation. The experimental results are consistent with the analytical expressions obtained that are shown to allow one to estimate the extinction (a_t), reduced-scattering (a_(rs)) and absorption (a_a) coefficients and the g-factor of the investigated media. The values obtained of a_l, a_(rs) and g of the dilutions of concern are quite reasonable and behave, depending on the dilution turbidity, in a way observed formerly in other similar experiments. The comparative analysis of the estimated characteristics of the dilutions shows that in the case of Henyey-Greenstein indicatrix we have a smaller value of the g-factor and larger value of a_(rs) with respect to the case of Gaussian indicatrix. At equal g-factors, in the former case we shall have a narrower forward-propagating scattered-light beam with higher on-axis intensity as compared with the latter case.