 Scanning transmission electron microscopy

Scanning transmission electron microscopy forms an image by scanning a focused electron probe across a thin specimen and recording transmitted or scattered electrons at each probe position. The detector's angular range determines which interaction contributes to the recorded brightness.

A detector including the direct beam gives a different image contrast mechanism from an annular detector collecting scattered electrons. High-angle annular dark-field imaging can emphasize composition and mass-thickness differences, but specimen thickness and channeling still affect interpretation. The probe size limits spatial detail, whereas the displayed-to-scanned length ratio sets magnification; increasing the latter cannot sharpen the probe.