Near-field optical microscopy of fractal structures

Using a photon scanning tunnelling microscope combined with a shear-force f eedback system, we image both topographical and near-field optical images ( at the wavelengths of 633 and 594 nm) of silver colloid fractals. Near-fiel d optical imaging is calibrated with a standing evanescent wave pattern. Ne ar-held optical images exhibit spatially localized (within 150-250 nm) inte nsity enhancement (by up to 20 times) in the form of round bright spots, wh ose positions and brightness are found to be sensitive to the light wavelen gth, polarization and angle of incidence. The observed phenomenon is relate d to the localization of resonant dipolar eigenmodes in random surface nano structures.