Experimental research of diffraction of an linearly-polarized gaussian beam by binary microaxicon with the period close to wavelength

To compensate widening of the central light spot which inevitably arises at linear polarization of a beam illuminating high-aperture axicon, it is possible to insert asymmetry in axicon structure. Experimental research of diffraction of Gaussian beam by three types of binary microaxicon with the period close to wavelength is carry out by means of nearfield microscope. Diffractive optical elements with the period of 500 nanometers and various height of a microrelief have been made by a method of e-beam lithography. It is experimentally confirmed, that asymmetric microaxicons allow to reduce widening of the central light spot. Also it is shown, that in a near zone overcoming of the diffraction limit along one direction (down to FWHM=0.32 ) is provided.