Fig. 3.

Reflectance sensitivities with respect to (a, b) absorption and (c, d) reduced scattering coefficient for (a, c) bottom and (b, d) top layers, respectively, as a function of spatial frequency for a top layer thickness of $300\mu \mathrm{m}$. In each plot, the black line indicates the case where ${\mu }_{s,t}^{\prime }=0.4\times {\mu }_{s,b}$. The red line indicates ${\mu }_{s,t}=0.7\times {\mu }_{s,b}$, the blue indicates ${\mu }_{s,t}={\mu }_{s,b}$, the green indicates ${\mu }_{s,t}=1.3\times {\mu }_{s,b}$, and the magenta indicates ${\mu }_{s,t}=1.6\times {\mu }_{s,b}$.