Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix
| In STEM mode, the electron coherence is defined by the coherence length seen at the condenser aperture. Coherence length (Lc) is the propagation distance of a wave from a coherent source to a point where the wave (e.g. an electron wave) maintains a specified degree of coherence. Interference is strong within a coherence length of the source, but not beyond it. The coherence length is inversely proportional to the energy spread of the electron beam. It has a magnitude of the order of hundreds of nm in EMs (electron microscopes).
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