Nanoscale mapping of refractive index by using scattering-type scanning near-field optical microscopy

The experimental s-SNOM results (Amplitude and Phase images) are correlated to the theoretical model of oscillating point-dipole. Together they lead to a 4D visual representation with nanoscale resolution of the sample (red blood cells). The topography is represented in three spatial dimensions, while the refractive index is coded using a colormap.169