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TEM alignment
STEM alignment
Wave interference
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Diffractive imaginging
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Learn about key concepts in electron wave theory - without lots of mathematics...
The electron wave
:
The corkscrew analogy
Wave interference
:
How electron waves add together and how we measure intensity
Phase threads
:
An easy way of measuring the phase of wave components
Elementary wave types
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Spherical waves and plane waves - we can build up any sort of wave out of such elementary waves.
Diffraction at an obstacle
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A simple water wave analogy
The calculus of wave interference
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How we add together several waves, according to the rules of geometry
Young's slits
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The simplest example of wave interference
Huygen's principle
:
The most useful concept in wave propagation
Fresnel fringes
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A qualitative description of something we see everywhere in electron images
The Fraunhofer and Fresnel approximations
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All to do with geometry...
The Fourier transform
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An essential element of electron optics explained in very simple terms using a mechanical analogy
The sinc function
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Used extensively in Fourier analysis theory: a geometrical explanation
The diffraction grating
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The first step in understanding diffraction from a crystal
The Fourier transform of the diffraction grating
:
The first step in understanding reciprocal space
Crystallography
:
A super-simple introduction to diffraction from 3D objects
3D waves and scattering
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The geometry of the scattering vector in diffraction, plus some thoughts on 3D plane waves
Bragg's law
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Scattering from planes of atoms in real space
Reciprocal space
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A qualitative Fourier approach to understand this source of great confusion
The Ewald sphere
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The main reciprocal-space construction for diffraction scattering in 3D
The convolution integral
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An essential concept in imaging theory
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