Method for automatically aligning a scanning transmission electron microscope for precession electron diffraction data mapping

A method for automatically aligning a scanning transmission electron microscope (STEM) for acquiring precession electron diffraction (PED) mapping data at high spatial resolution, comprising:

• generating an incident electron beam aligned with the optic axis of the STEM and focused on a region of a sample and;
• acquiring a non-inclined signal spatial distribution from the sample region by scanning the incident beam across multiple discrete locations of the sample region while acquiring from at least one electron detector a signal associated with each location;
• further characterized by:
• inclining the incident electron beam to a fixed inclination angle θ with respect to the optic axis;
• acquiring an inclined signal spatial distribution from the sample region by scanning the inclined incident beam across the multiple discrete locations while applying a cyclic azimuthal scanning protocol to the inclined beam;
• and
• acquiring from the at least one electron detector a signal associated with each location;
• and determining an azimuthal spatial alignment correction by comparing the non-inclined and inclined signal spatial distributions.