Angularly-selective transmission imaging in a scanning electron microscope

• A modular aperture system for STEM-in-SEM imaging is described.
• A flexible cantilever sample holder that can maximize camera length is described.
• The aperture system and sample holder enable complete acceptance angle control.
• Most STEM imaging modes can be implemented without multi-segment detectors.

This work presents recent advances in transmission scanning electron microscopy (t-SEM) imaging control capabilities. A modular aperture system and a cantilever-style sample holder that enable comprehensive angular selectivity of forward-scattered electrons are described. When combined with a commercially available solid-state transmission detector having only basic bright-field and dark-field imaging capabilities, the advances described here enable numerous transmission imaging modes. Several examples are provided that demonstrate how contrast arising from diffraction to mass-thickness can be obtained. Unanticipated image contrast at some imaging conditions is also observed and addressed.