October 22, 2022
SEM selfie : weekend SEM pornDid you know that you can make Scanning Electron Microscope to see itself? At right acceleration voltage electron beam can charge tiny dielectric sphere or plate to potential of ~30kV, at which point it starts reflecting electrons of lower energies back and allow microscope to see itself. Bright donut in the middle is backscattered electron detector (BSE, all 4 segments are enabled), tiny dark spot in the middle is output aperture where electrons are coming out. BSE detector is brightest here as it directly sees reflected electrons, everything else needs multiple reflections to hit detector.
At clock position 12 - there is energy-dispersive detector aperture, at 2 - secondary electron detector and bias electrode, and 10 - photomultiplier.
Let's see how other detectors looks like:
Photomultiplier (some components show long cathodoluminescence):