Quasi non-diffractive electron Bessel beams using direct phase masks with applications in electron microscopy

This is the authors' abstract. We don't add key points for this paper.

Electron-beam shaping opens up novel imaging possibilities in electron microscopy (EM). The implementation of a phase or amplitude mask in the condenser lens system allows the generation of electron beams with various shapes. Non-diffractive Bessel beams (BBs) are of interest for numerous applications due to their extraordinary large depth of focus. We present an experimental demonstration of single high-intensity quasi non-diffractive electron BBs generated by direct phase masks (PMs). The PM fabrication by focused ion beam is optimized using custom scan routines. The propagation of the electron beam after transmission through several PMs is analyzed in detail. A sub nm-sized non-diffractive electron beam is realized in the object plane of a transmission electron microscope. The experiments agree well with simulations and a route towards a beneficial application of non-diffractive electron beams in EM is discussed.