Figure 1.
Microscope. (a) Excitation pulses are followed by stimulated emission depletion pulses for fluorescence inhibition. After passing dichroic mirrors and emission filters, fluorescence is detected through a confocal pinhole by a counting photodiode. (b) Measured excitation PSF. (c) Measured STED-beam-PSF featuring local minimum at the center and intense maxima above and below the focal plane. Z denotes optic axis. The measurements of b and c are carried out with the pinhole removed.