Fig. 4 – (a) Red channel image under red illumination of 45nm Au film with protein coatings of different thicknesses measured by ellipsometry. The coded colors represent reflected intensities. (b) CSPT–SPR curves extracted from ROIs selected from (a) and averaged over 10 images acquired in identical conditions. A 6 degrees polynomial fitting is used to identify each SPR curve (solid lines). (c) CSPT–SPR shift in pixels and degrees vs. protein thickness in nm. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)