A scanning electron microscope (SEM) is a type of electron microscope used to scan microbial surfaces, which uses a low-energy moving electron beam to focus and scan the sample.
The development of electron microscopy was attributed to the inefficiency of optical microscopy wavelengths. Compared to light microscopes, electron microscopes have short vertical wavelengths and therefore achieve better resolution.
Principles of scanning electron microscopy
Unlike transmission electron microscopy, which uses transmitted electrons, scanning electron microscopy uses emitted electrons.
Scanning electron microscopy works by applying kinetic energy to produce signals about electron interactions. These electrons are secondary electrons, backscattered electrons and diffracted backscattered electrons, which are used to observe crystalline elements and photons. Secondary electrons and backscattered electrons are used to produce the image. The secondary electrons emitted from the sample play a major role in detecting the morphology and topography of the sample, while the backscattered electrons exhibit contrast in the elemental composition of the sample.
