title: Generation and application of bessel beams in electron microscopy.
abstract: We report a systematic treatment of the holographic generation of electron Bessel beams, with a view to applications in electron microscopy. We describe in detail the theory underlying hologram patterning, as well as the actual electron-optical configuration used experimentally. We show that by optimizing our nanofabrication recipe, electron Bessel beams can be generated with relative efficiencies reaching 37±3%. We also demonstrate by tuning various hologram parameters that electron Bessel beams can be produced with many visible rings, making them ideal for interferometric applications, or in more highly localized forms with fewer rings, more suitable for imaging. We describe the settings required to tune beam localization in this way, and explore beam and hologram configurations that allow the convergences and topological charges of electron Bessel beams to be controlled. We also characterize the phase structure of the Bessel beams generated with our technique, using a simulation procedure that accounts for imperfections in the hologram manufacturing process.
authors.affiliation: CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy; CNR-IMEM, Parco Area delle Scienze 37/A, I-43124 Parma, Italy. Electronic address: vincenzo.grillo@cnr.it.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Grillo
authors.affiliation: Department of Physics, University of Ottawa, 25 Templeton St., Ottawa, Ontario, Canada K1N 6N5.
authors.forename: Jérémie
authors.initials: J
authors.lastname: Harris
authors.affiliation: CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy.
authors.forename: Gian Carlo
authors.initials: GC
authors.lastname: Gazzadi
authors.affiliation: CNR-IMM Bologna, Via P. Gobetti 101, 40129 Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Balboni
authors.affiliation: Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena, Italy.
authors.forename: Erfan
authors.initials: E
authors.lastname: Mafakheri
authors.affiliation: H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Dennis
authors.affiliation: CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy; Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Frabboni
authors.affiliation: Department of Physics, University of Ottawa, 25 Templeton St., Ottawa, Ontario, Canada K1N 6N5.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Boyd
authors.affiliation: Department of Physics, University of Ottawa, 25 Templeton St., Ottawa, Ontario, Canada K1N 6N5.
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Karimi
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D006696:Holography; D008027:Light; D008854:Microscopy, Electron / Q000379:methods; D012542:Scattering, Radiation
keywords: Bessel beams; Fresnel diffraction; Holographic beam shaping; STEM; Vortex beams