Fig. 4.

Diffusion of red and blue food dyes through layered planar phantoms. In A, the reference phantom is shown with no added dye. In B, the dye-containing phantom is shown on day 2. In C, the dye-containing phantom is shown on day 7. These images show the red dye layer at the top, the middle has no added coloring, and the bottom layer has blue dye added. In D the diffuse reflectance is shown for the 6 measurement points (at days 1, 2, 3, 4, 6, and 7). The independent axis (position) is shown corresponding to a vertical cross section through the images. Arrows show the trends with time for the series of traces.