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Light Transport in Tissue Experimental results Experiments were done on different thicknesses of human dermis. The first set consists of nine measurements on five different samples ranging 200-400$\mu$m thick. The second set used 24 samples (including twelve 20$\mu$m samples) on thin microtomed sections varying from 20-100$\mu$m thick. The attenuation coefficient $\mu_t=\mu_a+\mu_s$ was obtained by making total attenuation measurements on all samples and averaging the results. The total attenuation measurement so obtained is 190cm-1 and was used to convert all sample thicknesses into optical depths. These optical depths were used to calculate the correction factors. A typical fit is shown in Figure 5.10. Figure 5.10: Experimental data and fitted phase function for 100$\mu$m thick human dermis. Solid line is the fitted phase function. Squares and error bars indicate measured values and uncertainty in measurements. Figure: The measured anisotropy factor $g_{\protect\mathrm{HG}}$ for human dermis as a function of sample thickness. The solid line indicates the dependence of the measurement technique on sample thickness. The limiting value of $g_{\protect\mathrm{HG}}$ is 0.92. Error bars indicate the standard deviation of the data. Figure 5.12: The measured isotropy factor $\beta$ for human dermis as a function of sample thickness. The limiting value of $\beta$ is 0.05. Error bars indicate the standard deviation of the data. The Henyey-Greenstein phase function parameter gHG as a function of thickness is shown in Figure 5.11. The limiting value for the anisotropy factor was gHG=0.92. The error bars are the standard deviation of the fitted values of gHG for each sample thickness. The increased error for the thinnest samples $(\tau=0.38)$ is caused by tearing occurring during the tissue preparation process. The solid curve is identical to that in Figure 5.7 and is included to indicate the dependence of the fitted value of gHG on the thickness of the sample. Figure 5.12 shows corrected values for the isotropy $\beta$ as a function of thickness.

S. A. Prahl."Light Transport in Tissue," PhD thesis, University of Texas at Austin, 1988.