Scanning electron microscopy is an advanced imaging tool with superb optical resolution, surpassing the magnification capabilities of conventional microscopes by several orders of magnitude. The power and precision of SEM microscopes offer process engineers and researchers that chance to visualize their samples beyond the resolving limits of visible light.
The empowering performance of SEM microscopy provides unprecedented insights into nanoscale surface topography and chemical composition. At Electron Optics Instruments, we offer industry-leading SEM technologies with unrivaled market quality.
In this article, we aim to offer a broad explanation of the working principles and applications of SEM microscopes, while highlighting some of our tried-and-trusted SEM solutions.
Working Principles of SEM Microscopes
SEM microscopes work using a focussed electron beam to create an image rather than visible light. This beam is created by a high-energy electron source at the top of a vacuum column containing a series of apertures and condenser lenses. The condenser defines the size of the electron beam while a final objective lens focusses the beam onto the sample. Within the column are scanning coils, also known as deflector coils, which continuously alter the beam path, causing it to scan the sample in a raster pattern.
Why Use Electrons Instead of Visible Light?
Conventional microscopes use visible light to illuminate and magnify samples with greater resolution than that of the human eye, yet this imposes an inherent magnification limit of approximately 1000x due to the wavelengths of light used for illumination. A compound microscope subsequently cannot resolve features within 200 nanometres (nm) of one another. SEM microscopes do not pose the same limitations.
When the electron beam of an SEM microscope interacts with the sample, it causes the surface to emit backscattered and secondary electrons. These are characteristic signals which offer detailed information into chemical composition, crystal structure, morphology, and so on. Separate detectors positioned in the sample chamber acquire these characteristic signals as the sample is scanned, enabling the SEM microscope to develop a three-dimensional (3D) chemical map of the sample’s surface. Not only does this offer enhanced chemical specificity, but it also allows for magnifications of up to 200,000x.
SEM Microscopes from Electron Optics Instruments
At Electron Optics Instruments, we provide a wide range of benchtop and tabletop SEM microscopes suitable for the broadest possible range of application areas, from high-resolution artwork to advanced materials science applications. If you would like information on our instrument specifications or existing areas of application, simply contact a member of the team today.