scanning near-field optical microscopy fluorescence scanning near-field optical microscopy CHMO:0000121 Microscopy where a probe consisting of a laser of a specific wavelength transmitted through a tapered optical fibre is positioned very close to (<10 nm from) the surface of the specimen. The tip is coated with metal (to prevent light from escaping from the sides) and near-field (or evanescent field) light is emitted through a small opening or 'aperture' (50–100 nm in diameter) at the apex of the probe. An image is produced by scanning the probe over the specimen and detecting the fluorescence intensity from fluorophores on the surface of the specimen as a function of position. A force feedback loop is used to maintain a fixed relationship between the probe and surface during scanning.