A recent formulation for generating light beams with intensity and phase guided along 3D curves is implemented with electron beams. General design and fabrication methodologies, and potential applications are discussed.
Since commercial aberration-corrected electron microscopes were introduced nearly a decade and a half ago, and with the advance of fabrication technology, new venues for the manipulation of electron beams have introduced themselves. It is directly linked to research in computer-generated holograms, with roots nearly 70 years old in light optics. Thus, we have recently implemented the first computer-generated hologram by using sculpted phase masks for electrons [1]. We proceeded to demonstrate that these phase masks, much like in light-optics, have the potential to be used as cheap aberration correcting elements [2]. In a recent paper dealing with light-optics [3] a method for the encoding of nearly-arbitrary 3D curves is described.
In this work, we present preliminary results showing how binary amplitude computer-generated holograms are designed and fabricated. We will discuss several methods of fabrication, and present examples of masks yielding curves such as the knotted trefoil and Archimedean spiral, see Fig. 1. Potential applications for such beams have already been investigated in light optics, such as particle manipulation; in electron-optics, this is also a possibility, and one could envision synthesis of 3D nano-structures using this method.
Fig.1: Examples of 3D curves. (a) Measured and (b) simulated (Fresnel propagation) Archimedean Spiral, (c) measured and (d) theoretical curve of knotted trefoil. Images taken at an arbitrary section on the z-axis. Contrast and brightness altered for visibility.
[1] "Sculpturing the electron wave function using nanoscale phase masks,” Ultramicroscopy 144 (2014).
[2] R. Shiloh*, R. Remez*, A. Arie, “Prospects for electron beam aberration correction using sculpted phase masks,” Ultramicroscopy, accepted (2/2016).
[3] José A. Rodrigo, Tatiana Alieva, Eugeny Abramochkin, and Izan Castro, "Shaping of light beams along curves in three dimensions," Opt. Express 21, 20544-20555 (2013).
