Figure 2.

OPD noise of the setup measured in the sample immersion medium. (a) Temporal noise histogram: black, no interferogram average, ${\sigma }_{N=1}^t=0.59$ nm; red, 20 averaged interferograms, ${\sigma }_{N=20}^t=0.11$ nm. (b) Spatial noise: black line, standard deviation noise as a function of the number of averaged interferograms; gray dashed line, OPD noise deduced from the coverglass roughness measured with AFM. To see this figure in color, go online.