Experiments and Potentialities for the use of Bessel Beam in Superresolution STEM

In light optics holographic beam shaping has been largely used to obtain complicated wavefronts and vortex beams. In the last years holograms have been used in the electron vortex beam generation. We have recently improved the technology of hologram fabrication by means of "phase hologram" replacing the amplitude hologram so far used. Phase holograms appropriately change the phase of the incident wavefront by a modulation of thickness in a silicon nitride thin membrane. Beyond vortex generation, holograms can have a large range of applications. As an example in this work we eport on the production of a Bessel beam in the Fresnel diffraction regime.