A scanning electron microscope scans a focused Electron probe across a specimen and assigns a detector signal to each probe position. Secondary electrons leaving the irradiated region often reveal surface relief; backscattered electrons can provide composition-dependent contrast. Image brightness records the selected signal, rather than a transmitted projection enlarged by two lenses. Display enlargement is therefore set by the ratio of display width to scanned specimen width. Surface geometry and composition both affect brightness.[ref]
Articles by others on the same topic
The Scanning Electron Microscope by MaterialsScience2000 (2014)
Source. Shows operation of the microscope really well. Seems too easy, there must have been some extra setup before however. Impressed by how fast the image update, it is basically instantaneous. Produced by Prof. Dr.-Ing. Rainer Schwab from the Karlsruhe University of Applied Sciences.Mosquito Eye Scanning Electron Microscope Zoom by Mathew Tizard (2005)
Source. Video description mentions is a composite video. Why can't you do it in one shot?