Scanning Diffraction Microscopy: far-field microscopy by interferometry and diffraction combination

We have realized a novel optical microscope that uses the coherent superposition of diffused and diffracted beams. A laser emitting at 670nm is illuminating at oblique incidence the sample surface while a sharp metallic tip is partially obstructing the beam. The coherent superposition of diffracted radiation, coming from the tip sample region, and the reference beam, diffused by the whole surface, is collected in the far field during XY scan, obtained moving the sample only. The aperture between the tip, kept fixed at a working distance of the order of 20?m, and the local surface topography realizes a variable diffracting aperture, producing an intensity variations at the detector plane. We show clear images of a test structure with a resolution better than ?/10. A simple model is used and it is shown to be able to explain the obtained results.