electron backscatter diffraction
If you want to know how the crystals in a piece of metal are oriented — which way each grain's lattice points, and how the grains differ from their neighbours — across a whole polished surface, electron backscatter diffraction (EBSD) is the standard tool. It lives not in the transmission microscope but in the ordinary scanning electron microscope (SEM), and it maps orientation grain by grain over areas of millimetres, something no thin-foil technique can do at that scale.
The setup is distinctive: the flat, polished specimen is tilted steeply, about 70 degrees away from horizontal, so the electron beam grazes the surface. Electrons that scatter back out of the top few tens of nanometres then diffract off the crystal planes on their way out, and — just like Kikuchi lines in the TEM — form a pattern of bright bands (an electron backscatter pattern, or EBSP) on a phosphor screen and camera set beside the sample. Each band corresponds to one set of lattice planes, and the geometry of the whole set of bands is a fingerprint of the crystal's orientation. Software recognises the bands, indexes them against the known crystal structure, and reports the orientation at that point in a fraction of a second. Now raster the beam across the surface, index a pattern at every point, and you build an orientation map — a coloured picture where each grain's colour encodes which way its lattice faces.
From such maps you read grain size and shape, the misorientation across every boundary (distinguishing low-angle from high-angle boundaries and identifying special coincidence-site-lattice boundaries), the overall texture or preferred orientation of the material, and even a rough sense of stored strain (which blurs the bands). EBSD can also tell apart phases with different crystal structures. The honest limits: it is a surface technique that samples only a shallow near-surface layer, so it demands careful polishing — a deformed or contaminated surface layer wrecks the patterns. It maps orientation and phase, not the full atomic structure, and it struggles to separate phases whose lattices are nearly identical.
An EBSD scan of a rolled aluminium sheet produces a colour map in which large regions share the same colour — meaning many grains share a preferred orientation left by rolling. The software also flags boundaries where the misorientation exceeds 15 degrees as high-angle boundaries, drawing the true grain structure and its texture in one automated pass.
EBSD indexes a Kikuchi-band pattern at every point of an SEM raster to map grain orientation, boundaries, and texture.
EBSD samples only a shallow near-surface layer, so surface preparation is everything: a mechanically deformed or oxidised top layer degrades the Kikuchi bands and can make indexing fail. It maps orientation and phase, not the full crystal structure.