CHARACTERIZATION OF ABSORPTION AND SCATTERING PROPERTIES OF SMALL-VOLUME BIOLOGICAL SAMPLES USING TIME-RESOLVED SPECTROSCOPY

With time-resolved spectroscopy, we develop an experimental approach by sample substitution to measure the absorption (μa) and reduced scattering (μ′s) coefficients of small-volume biological samples. To investigate the method, small-volume control samples are substituted into a large-size host medium during increases in the absorber (or scatterer) concentration of the host. By characterizing the deviation of the spectra taken with and without the sample, we determine the matching points where the sample and surrounding medium are optically identical. We show that this method can result in correct values of the μa and μ′s for the sample within 6% error if the matching conditions for both the μa and the μ′s are fully realized. The results also indicate that this method can give approximate values of the μa and μ′s in a reasonable range if either the μa or the μ′s matching between the two media is realized. This method has been applied to the studies of absorption properties of a human finger and of scattering properties of yeast. © 1993 Academic Press, Inc.