Figure 2.

Fourier transformed spectrum |F(OPL)| of the original backscattering spectrum I(x, y, k) from (a) the Diff-Quik staining solution and (b) a cell nucleus stained with Diff-Quik stains. (a) The prominent peak at the low-spatial-frequency component of |F(OPL)| comes from the absorption profile of the Diff-Quik staining solution. (b) Evidently, the |F(OPL)| from the Diff-Quik-stained cell nucleus has a distinctly different peak, corresponding to the optical path length of the cell nucleus (as indicated by the black arrow). These results confirmed that our selected optical path length of interest is not affected by the absorption profile of the Diff-Quik staining solution.