Electron Microscope: What Is It and How Does It Work?

Our eyes are engineered to see things in a more ‘bigger picture’ manner. When we look at objects we only see the whole and not the parts that go into making the whole. Looking at a piece of paper on your desk you are only able to discern that it is paper. Your eyes are lacking in the ability to look within the paper and see the different elements that go into making that paper.

Our sight from an evolutionary standpoint is enough for our needs. The human race simply needs to have the ability to discern between two objects in order to survive. We have no need of delving into molecular, atomic, and subatomic realms in order to carry out everyday tasks. However, we are a curious species. We have an endless need to learn about that which is around us.  It is for this reason that gadgets such as electron microscopes exist in the world today. If you are looking to buy microscope in Singapore, you might want to learn a thing or two about an electron microscope.

What is a Microscope?

A microscope simply put is a device that helps to make small objects that would otherwise not be visible to the naked eye large enough for the human eye to see. Most microscopes achieve this by distorting light beams with the help of lenses. Our microscope of interest achieves this magnification in a slightly different manner. Instead of distorting light, it distorts electrons, hence its name.

How an Electron Microscope Works?

The functionality of an electron microscope is based on two principles — the magnetism of electrons and the Louis de Broglie hypothesis. The hypothesis simply states that the electrons contain wave properties. These wave properties of electrons combined with their magnetic properties allow electron microscopes to magnify objects at a resolution of up to 5000 times greater than that of a light microscope.

To put things into perspective, allow us to use a simple illustration. Imagine having to make two drawings of the same landscape. To achieve the first drawing, you are presented with a pencil whose tip is the size of a baby carrot. The second drawing requires you to employ the use of a pencil with the tip the size of a hair follicle. Which of the two drawings will be richer in detail? The second one right?

This is the same case with electron vs light microscopes. Light microscopes, also known as optical microscopes, are your baby carrot tips while electron microscopes are your hair follicle pencils. Electrons possess a wavelength that is about 100,000 times less than that of visible light. The short wavelength of the electrons is what gives the electron microscope the ability to detail objects at such high resolutions. Electrons are simply able to permeate objects to depths not achievable by light particles.

Going back to our analogy, it would be difficult to show differences in color gradation within spaces close to each other using the baby carrot tip than it would be using the fine tip. In the same way, magnification using a light microscope provides fewer pixels in the resultant image as compared to an electron microscope. Images from the latter have finer details and are more pixelated.  This allows you to observe the finest of details about the sample being viewed.

For an electron microscope to work, electrons have to be supplied. This is done from the gun (otherwise known as the source). Since electrons possess magnetic properties, it is important that no other particles are present within the electron column. Light microscopes use lenses to converge light beams to focus on the object under scrutiny.

Electron microscopes take a different approach. They make use of magnets to converge the electrons. This happens in a vacuum in order to keep any larger particles from diverging the electrons and thus compromising the effectiveness of the microscope. The similarity between an electron and light microscope lies in the presentation of the image. For both, a coated fluorescent screen is used to light up the specimen for it to be properly visible.

Types of Electron Microscopes

Different electron microscopes will present the final images differently. The Transmission Electron Microscope is known to have a resolution of about 5 million times. It presents images in greyscale and is useful in investigating individual cell components as well as deep-lying structures. It is, however, limited in its field of view.

Scanning Electron Microscopes have a higher resolution than that of the Transmission Electron Microscope. While like the latter they produce images in greyscale, the images given of are in three dimensions. They are, therefore, easier to use than their counterparts. Another advantage to these microscopes is their wide field of view that allows researchers to study multiple sample aspects at once.

Before you buy a microscope, explore the pros and cons of the various electron microscopes in order to make an informed decision and check this guide on how to buy a microscope.

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