Nanoscopy with Focused Light

Abstract

Since the 19th century it has been widely accepted that a light microscope cannot see details that are finer than half the wavelength of light (>200 nm). However, in the 1990s it was discovered that this diffraction resolution barrier can be effectively overcome, such that fluorescent features can be resolved virtually down to molecular dimensions. Here we discuss the simple yet powerful physical principles that allowed us to break the resolution limit, with special emphasis on STED and RESOLFT microscopy. We exemplify the relevance of this ‘optical nanoscopy’ to the neurosciences.1-3