CONTRAST OF MICROWAVE NEAR-FIELD MICROSCOPY

Constant-height scanning is demonstrated to improve near-field microsc opy by eliminating artifacts connected with topography scanning, hence , to image the inherent electromagnetic contrast. Microwaves are chose n for this study because the long wavelength eliminates coherence arti facts, owing to a scale separation of wave and image frequencies. Meas ured amplitude and phase images of conductive films are quantitatively analyzed by considering the longitudinal electric near field. The obs erved spatial resolution of 200 nm equals the probing tip size and pro ves that the skin depth delta of the tip material (here, 1600 nm) pres ents no resolution limit to scanning optical microscopy. (C) 1997 Amer ican Institute of Physics.