An Evanescent Field Optical Microscope

An Evanescent Field Optical Microscope (EFOM) is presented, which employs frustrated total internal reflection on a highly localized scale by means of a sharp dielectric tip. The coupling of the evanescent field to the sub-micrometer probe as a function of probe-sample distance, angle of incidence and polarization has been characterized quantitatively both experimentally and theoretically. The coupling efficiency of light into the tip agrees with a description based on complex Fresnel coefficients. By scanning the tip images have been obtained of non-conducting dielectric samples, periodic gratings and non periodic structures, containing both topographic and dielectric information which clearly demonstrate the capacity of the evanescent field optical microscope for nanometer scale optical imaging. The effect of field gradient, tip-sample distance, polarization direction and tip artifacts on the images has been investigated. Recent results are presented.