%0 Generic
%A Schmidt, Roman
%D 2008
%F heidok:9396
%K isoSTED, 4Pi, STED, Nanoskopie, MikroskopieisoSTED, 4Pi, sub-diffraction, nanoscopy, microscopy
%R 10.11588/heidok.00009396
%T 3D fluorescence microscopy with isotropic resolution on the nanoscale
%U https://archiv.ub.uni-heidelberg.de/volltextserver/9396/
%X The resolution of any linear imaging system is given by its point-spread-function (PSF) quantifying the blur of an object point in the image. The sharper the PSF, the better is the resolution. In standard fluorescence microscopy, however, diffraction dictates a PSF with a cigar-shaped main maximum, called the focal spot which extends over at least half the wavelength of light (L = 400-800 nm) in the focal plane and > L along the optic axis (z). While concepts have evolved to sharpen the focal spot both laterally and axially, none of them has reached their ultimate goal: a spherical spot that can be arbitrarily downscaled in size. Herein, I introduce such a fluorescence microscope and demonstrate the creation of spherical focal spots of 40-45 nm (~ L/16) diameter that is pushed down to 21-30 nm (~ L/30) under suitable conditions. Fully relying on focused light, this lens-based fluorescence nanoscope unravels the interior of cells noninvasively, uniquely dissecting their sub-L sized organelles. Further fields of application open up, such as the characterization of novel nanomaterials.