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Figure 2 Phase Retardation Plot

Phase retardation, , angles averaged over the width of the central region of interest (500 x 200 µm) in the 2 PSOCT images shown in Figures 1B and 1F are plotted as a function of depth. Least-squares fits over a depth of 200 µm for each plot show that PSOCT birefringence measured as the slope as the phase retardation plot is higher ( = 0.60°/µm) for the plaque constituting 88% collagen (displayed in Figs. 1A to 1D) compared with a lower birefringence ( = 0.04°/µm) for the plaque with depleted collagen (displayed in Figs. 1E to 1H). Abbreviations as in Figure 1.