Towards far-field fluorescence nanoscopy

Summary form only given. Far-field microscopy has been plagued by the diffraction resolution limit. This is particularly restraining in the case of fluorescence imaging of biological specimens such as live cells. Here we report on the creation spots of excited molecules at the tens of nanometer scale, with focused red light and conventionally focusing optics. The underlying strategy is the engineering of the microscope´s point-spread-function by stimulated emission depletion and interference. Sub-diffraction spots enable for the first time far-field fluorescence microscopy with axial resolution at the scale of 30-50 nm.