Contrast in STEM lattice images is shown to arise from the interference between overlapping convergent beam discs at the STEM detector. For certain points this intensity is shown to be independent of the focus and aberrations of the probe-forming (objective) lens. The implications of this for determining the optimum detector shape for bright and dark field STEM lattice images are discussed. An estimate of the loss of contrast with increasing detector size for two-beam lattice fringes in STEM is also given.
|Original language||English (US)|
|Number of pages||14|
|State||Published - Jan 1 1978|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering