Estimate of the contribution of localized light absorption by blood vessels to the optical properties of biological tissue

A simple analytical procedure of considering localized light absorption by blood vessels and its effect on the absorption characteristics of multicomponent biological tissue is proposed. The final results are presented in the form of a single integral of elementary functions. A comparison of the estimates obtained with data in the literature shows their good agreement. The limiting cases of random and ordered arrangement of vessels are considered. It was shown that, in the blue spectral range, the absorption coefficient of biological tissues can reach saturation when it ceases to be dependent on the optical characteristics of blood and is determined only by the diameter of vessels and their volume concentration. The depth of light penetration into tissue and the reflection coefficient of tissue are estimated for both a localized and a homogeneously distributed absorber. Possible biomedical applications of the results obtained are illustrated. (C) 2004 MAIK "Nauka/Interperiodica".