  A monolithic active pixel sensor based direct detector that is optimized for
the primary beam energies in scanning electron microscopes is implemented for
electron back-scattered diffraction (EBSD) applications. The high detection
efficiency of the detector and its large array of pixels allow sensitive and
accurate detection of Kikuchi bands arising from primary electron beam
excitation energies of 4 keV to 28 keV, with the optimal contrast occurring in
the range of 8-16 keV. The diffraction pattern acquisition speed is
substantially improved via a sparse sampling mode, resulting from the
acquisition of a reduced number of pixels on the detector. Standard inpainting
algorithms are implemented to effectively estimate the information in the
skipped regions in the acquired diffraction pattern. For EBSD mapping, a speed
as high as 5988 scan points per second is demonstrated, with a tolerable
fraction of indexed points and accuracy. The collective capabilities spanning
from high angular resolution EBSD pattern to high speed pattern acquisition are
achieved on the same detector, facilitating simultaneous detection modalities
that enable a multitude of advanced EBSD applications, including lattice strain
mapping, structural refinement, low-dose characterization, 3D-EBSD and dynamic
in situ EBSD.
