Electron microscopes offer scientists an invaluable tool in probing matter at a very small
scale. Rapid advancements over the past several decades has allowed electron microscopes
to routinely image samples at the atomic scale. These advancements have been in all aspects
of electron microscope design – such as more stable control voltages and currents, brighter
and more coherent sources, beam aberration correction, and direct electron detectors, to
name a few. One very recent advancement is in shaping the electron beam to provide an
almost arbitrary set of possible beam profiles.
Following the demonstration of electron vortex beams in 2010, there has been a surge of
interest in the potential shaping electron beams. Utilizing holographic electron diffraction
gratings, an almost arbitrary set of electron beams can be generated. These diffraction
gratings are challenging to create due their tiny size and the precision with which they must
be fabricated.
We present a comprehensive study on the fabrication and design of electron diffraction
gratings with the aim of being able to produce optimal gratings that result in bright, well
separated beams which closely match a desired beam profile. We have developed and optimized
fabrication of these gratings with focused ion beam milling, and have been able to
use the fabricated gratings in a number of important experiments.
These electron diffraction gratings have allowed us to perform various experiments such
as aberration correction, electron helical dichroism, advanced phase-contrast imaging, and
multi-beam interferometric techniques. Holographic beam shaping will continue to be an
important tool for electron microscopists.
| Identifer | oai:union.ndltd.org:uoregon.edu/oai:scholarsbank.uoregon.edu:1794/24182 |
| Date | 11 January 2019 |
| Creators | Pierce, Jordan |
| Contributors | Taylor, Richard |
| Publisher | University of Oregon |
| Source Sets | University of Oregon |
| Language | en_US |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Rights | All Rights Reserved. |
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