Scanning Electron Microscopy – What is it all About?

This process involves using a scanning electron microscope which is used as an analytical tool to scan high resolution images

How Does it Work?

The electron microscope projects and then scans a focused stream of electrons across a surface and then creates an image. The images are high resolution and produce detailed images of surfaces that can be used to provide information about the subject’s topography and it’s composition.

The Process

The scanning electron microscope operates as follows:

  1. Electrons are produced at the very top of the column, they are then accelerated down and passed through various lenses and apertures eventually producing a beam of electrons which strike the surface of the subject sample.
  2. The sample, itself is placed (mounted) on a stage found n the chamber area of the microscope; both the column and the chamber are subject to evacuation by a combination of pumps with the intensity of the vacuum depending on the design of the microscope.
  3. The electron beam is positioned on the subject sample, controlled by scan coils sitting above the objective lens; these then allow the beam to be scanned across the surface area of the sample. The result is the production of a number of signals, which are then detected by relevant detectors.
  4. The scanning electron microscope produces images by scanning the subject sample with high energy beams of electrons. When the electrons hit the sample, secondary electrons, backscattered electrons and X-rays are produced. These signals are then picked up by detectors to develop images which are then transmitted to a computer screen.
  5. The high resolution produced by scanning electron microscopy depends on multiple factors such as the electron spot size and volume of the electron beam itself.

Uses for the Technology

The technology is used for a vast range of commercial and research applications.

It is particularly useful in medical science. Medical advice engineers, for example, use scanning electronic microscopy to characterize the finish of surfaces, chemical compositions or defects. Materials can be evaluated, and surface finishing methods fine-tuned along with production processes.

It is very useful as a problem-solving tool. It offers a number of advantages  for manufacturers. Little or sometimes no preparation of the sample is needed; large samples can also be accommodated. Surface contamination Is easily identified.

One of the largest advantages is the ability to investigate large samples; these can be rotated and translated into near-three dimensional images, even at high magnification.

In the areas of research, the technology is used for investigations into climate change, identification of new bacteria and viruses, finding new species, and genetic work.

It is also popular in the field  of criminal investigations – examining gunshot residue, handwriting analysis, jewellery examination, fibre examination, paint examination  are just a few examples.

With an increasing emphasis and focus on quality control, the science of scanning electron microscopy is proving to be an essential tool. High resolution imagery is can provide a level of detail that is indispensable.

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