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.