Specifications of a Scanning Electron Microscope (SEM)

Posted By Tom Cropper on 07 May 2014

Posted in Used Equipment Buyers Guides

A scanning electron microscope (SEM) is a sophisticated piece of equipment that uses electrons instead of the more traditional method of using light to acquire the image of a given specimen.  This permits image magnifications of up to 100,000x whereas with light microscopy you only obtain 2000x.  

Sample Sizes

The first thing to consider when looking at specifications for a scanning microscope is the size of the samples that will need to be worked on. The majority of used SEM units are made for samples that are a few centimetres in diameter but it is possible to find an SEM that can work with samples up to 18 centimetres in diameter.  

3-D Images

An SEM also allows for sharp and well-focused 3-D images that highlight details on a specimen that could not be shown with a normal microscope. One way to achieve 3-D images is through photogrammetry, using two or three images from a tilted specimen or through photometric stereo, using four images from a BSE detector.

Remote Viewing

With the wonders of modern technology it is now possible to purchase a scanning microscope equipped with remote viewing capabilities. Images can be sent via the internet instantly anywhere in the world allowing consultations from colleagues even if they happen to be out of the office, or, even the country.

Radiation

There are some radiation concerns when dealing with an SEM that relates to the electrons and x-rays that are created in the scanning process. Although the machines are made so that there is only a background radiation emitted, the equipment will need regular check-ups and maintenance. The scanning microscope will also need to be registered with the local health department or other relevant authority prior to installation.