The general aim of near-field optics is to extend optical microscopy beyond the diffraction limit. The introduction of the aperture probe for near-field microscopy has allowed fluorescence imaging below the diffraction limit and has stimulated interest in many disciplines, especially the material and biological sciences.

Using basic AFM scanning techniques, the introduction of a probe, which is illuminated with an external laser source, allows for the hybrid AFM - NSOM (Near Field Scanning Optical Microscope) to generate optical information from the sample on the order of 10's of nanometers.

Explanation of images:

(black and white pair, upper left) Simultaneous topographic image (top) and near-field two-photon excited fluorescence image (bottom) of J-aggregates of PIC dye in a PVS film on a glass substrate. The topographic cross-section along the dashed line (A-B) has a particular feature of 35-nm FWHM (indicated by arrows) and a corresponding 30 nm FWHM in the emission cross-section.

(pink, upper right) DNA strands. The DNA is on a flat mica substrate, imaged by a homemade shear force (optical free) feedback system.

(black, center right) Flourescence image of single immobilized RhB dye molecules in a 5µ X 5µ field taken with two-photon excitation (5 min acquisition time.) The molecules are dispersed on a glass substrate.

(schematic, bottom left) Basic concept of NSOM

(red pair, bottom right) Far Field Raman image (top) and Near Field Raman image (bottom)of single-walled carbon nanotubes.