Optical Methods for Data Processing in Heat and Fluid Flow

Section 2 Laser Speckle and Holography

5

The Reflected Spectrum of Complex Multi-layered Inhomogeneous Highly Scattering Medium

I V Meglinsky and S J Matcher

Abstract

We use the optical/near-infrared (NIR) reflectance spectroscopy to non-invasively measure the haemoglobin saturation in living human skin. The difficulties in the clinical application of this technique for skin tissue oxygenation monitoring are due to the complexity of extracting the information of chromophore distribution and their concentrations from the reflectance spectra in the case of multiple scattering of light. We have developed a computational model of human skin and Monte Carlo technique for simulation of the reflectance spectra of skin in the visible and near-infrared spectral region. The computational model of skin contains several layers with wavy inter-layered boundaries corresponding to the structure of human skin. Our model takes into account probe geometry, variations of spatial distribution of blood vessels, various levels of blood oxygen saturation, volume fraction of water, oxy- and deoxy- hemoglobin, melanin content, and chromophores of interest. The small source-detector separation (250, 400, and 800 μm) required due to the shallow (100–150 μm under skin surface) spatial location of skin capillary loops is our main interest. Comparison of the results of spectra simulation and experimental results made in vivo are presented. As the experimental system we use the spectrometer in conjunction with ...