Innovative Phase Plates for Beam Shaping

In light optics the use of holographic beam shaping has been largely used to obtain complicated wavefronts and vortex beams but recently holograms have been used in the electron vortex beam generation . We show here our recent improvement in the technology of hologram fabrication by means of "phase hologram" replacing the amplitude hologram so far used. Phase hologram appropriately changes the phase of the wavefront by a modulation of thickness in a Silicon nitride thin membrane.