Apertureless near field optical microscopy by local perturbation of a diffraction spot

Using a vibrating opaque metallic tip, which periodically and locally modifies the electromagnetic field distribution of a diffraction spot focused onto the sample surface through a microscope objective lens, we have observed a clear improvement of the optical resolution compared to the diffraction limit both with topographical and with purely optical features. This procedure simultaneously generates a reflection mode near field optical signal and a ''tapping mode'' Atomic Force Microscope (AFM) signal, and thus enables control of the effects of the local topography. The study of several samples has revealed a 50-100 nm optical resolution and the independence of the AFM and the near field optical signals.