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What Is an Electron Microscope?

Last Updated: 09.12.21


While you may use an iPhone microscope to observe things such as hair, bugs, and specs of dust, if you want to see objects that are millions of times smaller such as bacteria, molecules, and viruses, you will need an electron microscope.

In the informative article below we will explore this extraordinary instrument, and afterward, you can also read some of our other articles if you want to look for more information about the types of microscopes you can purchase for yourself or for your kids.

What is an electron microscope?

When our eyes see the objects in the world around us, they do so because of light rays, be it from the Sun or from another artificial or natural light source, like a lamp or a candle. The classic microscope sees using these particles of light, known as photons, too, and it works great as long as the objects you are observing are large enough.

Things get tricky when you wish to observe things that are smaller since in that situation using photons to observe things can be quite difficult, and gives you pictures that are clumsy and often times useless.

The photons of light that an ordinary light microscope uses are equivalent to a wavelength of around 400-700 nanometers. This is more than enough for studying the human hair, bugs, or a spec of dust which can be hundreds of times bigger than the wavelength of the microscope.

Bacteria, on the other hand, is around 200 nanometers across, and a protein can be as small as 10 nanometers long. To examine these specimens you will need an instrument that can use particles that have an even shorter wavelength, and the perfect tools for this job are the electrons.

As you’ve probably learned in school, electrons are the minute charged particles that can be found in the outer regions of atoms. An electron microscope, as you can probably already deduce from its name, uses a stream of electrons instead of a beam of light.

What makes an electron microscope so powerful is the fact that unlike an ordinary light microscope, its wavelength is hundreds of times shorter at just over 1 nanometer. This allows this nifty instrument to see objects that are, as crazy as it may seem, smaller than even light itself.


How does an electron microscope work?

Even though this instrument is much more advanced, if you’ve used a classic microscope before, the idea behind it is very similar and you will find it quite easy to understand how the whole thing works.

With an ordinary microscope, there are four important parts: the source of light, the specimen, the lenses that help make the specimen appear bigger, and the final magnified image of the specimen that you end up seeing.

With an electron microscope, there are still four steps involved but they are just slightly different. First, the light source is now replaced by a beam of fast-moving electrons. Then, the specimen will need to be prepared specially and held inside a vacuum chamber since electrons can’t travel very far in air.

There are no lenses present in an electron microscope, as these are replaced by a series of coil-shaped electromagnets. The electrons will travel through these electromagnets, and the coils in the electromagnets will bend electron beams just as the glass lenses bend the light beams that pass through them to produce magnification. In this sense, they work very similarly.

Finally, the end result is produced as a photograph, also known as an electron micrograph, or most commonly, as an image that you can observe on the screen of a computer monitor or TV.


The two types of electron microscopes

If you want to learn even more about this device, you should know that there are currently two different types of electron microscopes and even though they both work using the same basic concept, they offer different results and are used for different applications.

First, we have the Transmission Electron Microscope, also known as TEM, which is the original form of this instrument as it was developed in 1931. It has the most in common with an optical microscope. The TEM fires a beam of electrons through a specimen and that helps it produce the magnified image of the object

The TEM requires a very thick solid as a detector and its resolution is usually about 1 nanometer. Furthermore, high voltage and antivibration TEMs are so powerful that they can even resolute individual atoms.

The other type is the Scanning Electron Microscope, SEM, which has a resolution of around 2 nanometers. Unlike a TEM, an SEM will scan a beam of electrons over a specimen in order to produce the magnified image of the object. Thus, the beam of electrons won’t go right through the specimen.

SEMs are used to make images of the surfaces of tiny objects. This is why most of the electron microscope images you can see in books such as wasps holding microchips in their mouths and what not, are made using SEMs.



Where are electron microscopes used?

Electronic microscopes are most commonly used in universities, research laboratories, and nanotechnology centers but the way that this instrument can be used is quite varied. Apart from the many scientific discoveries this nifty instrument can help uncover, it can also be used in industry, forensic science, and natural resources.

For industrial purposes, the electron microscope can help in developing new products by providing high-resolution images for the developing and manufacturing of small electronics such as semiconductors.

Perhaps the most exciting application for the average person is in forensic science where an electron microscope can be used to analyze clothing fibers, blood, biological substances and even the residues from a gunshot.

Electron microscopes can also be used to analyze and characterize organic materials, which is very important especially for mining companies since it lets them see objective, automated and quantitative information about the environment very fast.



Ioana Moldovan

Ioana’s professional experience in the optics field has helped her understand the value of passing her knowledge forward. Her curious personality helps her gather useful information for her readers and her goal is to make technical information fun and accessible to everyone.

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