Fig. 3.
STED modes PSFs. (a) Nano-bead fluorescence xz-scans in different STED modes (same LUT display). The inset highlights the origin of the excited ghosts that are poorly depleted by the z-STED beam. (b) Left: gold bead scattering cross-section in 2D-STED and CH-STED with isophote lines defining saturation contours. White-to-red represent signal rescue in 2D-STED (depletion power change) and in CH-STED (ρ change). Red and white isophotes in the CH-STED panel are for the same intensity value and are therefore representative of an actual 2D- to CH-STED transition. Right: effective PSF in the two STED regimes. Red-blue images (same LUT) are log-intensity versions that highlight background noise.