SEM challenge
This is a secondary electron image taken at 25kV. The specimen is randomly distributed fine aluminium particles embedded in polymer resin and polished to a flat cross-section.
The specimen is mounted flat and in focus.

Why do some particles have a sharp edge and other particles have a "fuzzy" edge. What type of electrons are causing this effect?
Note: SE1 are a type of secondary electron generated by the primary beam whereas SE2 are generated by backscattered electrons. The term SE includes all types of secondary electrons.

