Figure 2.

Imaginary and real part of the refractive index. (a) The optical density of a 6.5-μm-thick film of oxygenated hemoglobin (33 g dL⁻¹) and acid blue 9 (0.8 g dL⁻¹) in bovine serum albumin (33 g dL⁻¹). (b) The refractive index of oxygenated hemoglobin, horse serum albumin, and water. The two vertical lines show the wavelengths of the two LEDs at 412 and 630 nm. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]