Background Reduction in STED-FCS Using a Bivortex Phase Mask

In brief

In this paper, we investigate how different STED confinement modes reduce the spurious background contributions from undepleted areas of the excitation in 3D FCS, thus increasing the signal quality and ultimately the resolution. By simulations as well as experiments with fluorescent probes in solution and in cells, we demonstrate that the coherent-hybrid (CH) depletion pattern created by a bivortex phase mask reduces background most efficiently and thus provides superior signal quality under comparable reduction of the observation volume.