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The Symmetry Advantage - High Angular Resolution at High Speeds

Ever since CCD-based EBSD detectors became commercially available about 15 years ago, the live acquisition speeds of EBSD
systems have progressively increased. The latest CCD-based detectors can now acquire diffraction patterns at astonishing rates
in excess of 1500 patterns per second (pps). However, this speed comes with a penalty: these rates are achieved by extreme pixel
binning, with patterns from a 640 x 480 pixel camera reduced down to a mere 40 x 30 pixels and this can affect the quality of the resulting data.

Utilising a customised CMOS-sensor, Symmetry does not require extreme pixel binning to achieve high acquisition rates. The
highest speeds, in excess of 3000 pps, are achieved with a relatively high pattern resolution of 156 x 128 pixels. Even 622 x 512 pixel patterns can be collected and indexed at speeds well in excess of 500 pps. The advantages of this additional pattern information are not only improved hit rates and better phase discrimination, but also a significant improvement in angular resolution.

This technical bulletin explains the effect of this unique combination of speed and pattern detail: the Symmetry advantage.

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