The blood was assumed to have a hematocrit of 43%, a hemoglobin concentration of blood, and a mean cell hemoglobin concentration of RBC. The wavelength-dependent absorption coefficients for oxygenated and deoxygenated blood ( and ) were derived from Ziljstra et al.23 A scattering coefficient of blood of at the laser wavelength (780 nm) was used, and at the same wavelength, a Gegenbauer kernel phase function with parameters and , resulting in an anisotropy factor of 0.991, was used.21 The oxygen saturation () was given by one parameter and was assumed to be equal in the two dermal layers. The absorption coefficient of blood in layer was calculated as Display Formula
(4)where is a factor compensating for the so called vessel-packaging effect. This factor is given by7,8,24Display Formula
(5)where is the average vessel diameter in layer (variable parameter twice as high for the deeper dermis layer). It can be realized that when or . The absorption coefficient of the two dermal layers was given by () Display Formula
(6)where was the volume fraction in the two dermis layers given by two parameters.