What is Electron Microscope?

What is Electron Microscope
Has anyone ever wondered how an electron microscope that can magnify millions of times works? We even have the opportunity to see atoms with electron microscopes. We can even see the structure of DNA with a microscope that can magnify this much.

Does anyone know what an electron microscope is?

My acquaintance with the microscope coincided with my childhood years. One day, my brother came out with a microscope. Maybe it was a birthday present, I don't remember now. But it was a simple microscope with three lenses.

The microscopes we know have a mirror at the bottom that reflects light, and they can magnify the object to be examined by 10 times or maybe a little more when you place it between thin glasses, which we call lamella, and adjust it according to your eye with the appropriate lens.

Of course, I think the lenses of professional microscopes today can magnify up to 2000 times. They cannot magnify any further, because the wavelength of light does not allow further magnification. The object being viewed then crystallizes due to the wavelength of natural light.

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When I was little, I looked at things with that simple microscope.

For example, when you look at the onion skin, the cell structure is literally visible.

By soaking straw in a small bottle for a while and waiting for a week, single-celled organisms would form in it. I remember when you dropped a drop between a thin piece of cotton with a pipette and looked at it with a microscope, I even observed slippery animals stuck between the cotton fibers.

I remember even looking at a drop of blood.

This interesting toy attracted my attention at the time.

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As I said, standard microscopes cannot show beyond a certain magnification capacity.

However, there is also a technology called electron microscopy.

Electron microscopes, on the other hand, have much higher magnification capacity. Today, we have the opportunity to see even atoms with electron microscopes.

Has anyone ever wondered how an electron microscope that can magnify millions of times works?

With a microscope that magnifies this much, you even have the chance to see the structure of DNA!

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In the 1590s, Dutch eyeglasses manufacturer Hans Janssen and his son Zacharias discovered that objects could be magnified much more with two lenses instead of a single lens.

These two, who discovered that small things can be seen magnified 10 times by placing two lenses in a tube, also discovered what we call the optical microscope for the first time in history.

In fact, knowledge of the magnifying feature of lenses dates back to the Roman Empire. However, it has taken this long in human history to discover that two consecutive lenses have greater magnification capacity.

In fact, the invention of the telescope coincides with these years. Another Dutch optician, Hans Lippershey, who further developed Janssen's discovery in the following years, in 1608, is known as the person who first discovered the telescope.

Galileo di Vincenzo Bonaiuti de Galilei, on the other hand, used the telescope technology he learned from Lippershey and turned his own telescope, which he improved further in the next year, to the sky and made his famous discovery, which caused conflict with the church.

Earth is not the center of the universe!

Despite everything, the world is turning!

Yes, telescope aside, the discovery of the microscope led to the discovery of many things, and nearly two centuries later, Louis Pasteur was even able to discover the rabies vaccine, thanks to his work with the microscope, which was further developed in this process.

I've talked a little bit about the French scientist Pasteur before.

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Let's talk about the electron microscope.

The electron microscope was first developed by German physicist Ernst Ruska in the 1930s.

In fact, the 1930s were the years when many things were discovered about the atom and it was known that the electron was a part of the atom.

Albert Einstein published his special theory of relativity in 1905. In 1915, he put forward the theory of general relativity.

Electron beams were discovered much earlier, in 1838, by Michael Faraday.

In the 1920s, Max Born, Werner Heisenberg and Wolfgang Paulil came to the fore with the theory of quantum mechanics, and the first form of the system was introduced to the scientific world in Born's article in 1924.

In other words, 1930 is a suitable date for historical development in terms of the use of electron beams in microscopes instead of light beams.

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So how do these electron microscopes work?

The general working principle of these microscopes is to first direct the electrons to the thing to be examined and examine the image that appears on a screen positioned behind the examined area.

But of course, everything is not that simple. These devices require very fine tuning.

Of course, in order to avoid the crystallization problem experienced in light, the electron beam must be accelerated very much.

In the latest model electron microscopes produced today, electrons are accelerated up to 70% of the speed of light and reflected onto the object being examined.

To do this, a series of electron accelerators are used within the microscope.

How can you accelerate a beam of electrons?

By creating an electric field of course!

Although most of the electrons passed through a high electric field such as 5000 Volts are damped at the anode end, the electrons escaping from a hole left in the middle of the anode three accelerate again in the next electric field, and the electrons escaping from the hole at the anode end of the following electric field to the next region are further accelerated. When they are accelerated and reach speeds of up to 70% of the speed of light, they are projected onto the thing to be examined.

Of course, this job requires quite fine adjustments, and there are a series of focusing units, magnetic lenses, in the device for these settings. These units, in a sense, work like lenses and prevent the electron beam from scattering around.

Of course, the electron beam must reach the sample under examination at the correct angle and the sample must be positioned exactly at the intersection of the electrons.

For this, the angle and position settings of the slide on which the sample is placed must be made.

At this stage, the image reflected on the screen behind the sample is magnified 50 thousand times.

Then, the image reflected on the rear screen is captured with a sensitive camera and the next enlargement operations are performed.

At this stage, the image is enlarged 2 million times.

These devices are so sensitive that even air molecules in the environment can cause these settings to be disrupted and a distorted image to be obtained.

That's why there are special vacuum units inside the device that evacuate the air in the environment and create a vacuum environment.

And finally, here is the atomic image of that natural wonder braid on the wings of a butterfly!

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Electron microscopes can now be produced with such sensitivity that they can even image atoms. 50 picometers is the size of a hydrogen atom, and these devices can image even such an atom.

In principle, there are two types of electron microscopes.

One is the type called “Transmission Electron Microscope”, or TEM in short. While this microscope serves to examine the internal structure of the sample, thanks to the electron beam passed through the sample examined point by point,

Another type, “Scanning Electron Microscope”, is used to scan the surface of larger samples and examine their top views. The abbreviated name of this type is SEM. What differentiates these types from TEMs in principle is that the image is positioned above the screen on which it is projected, rather than below it, and the image is obtained from the reflected electrons. Of course, this type of electron microscopes have the feature of scanning samples like the scanners we know, and although they have less magnification, they have different usage areas because they can image larger surfaces.

In the video I watched, it is said that a combination of these two is also possible. These devices are called STEM for short.

These devices are millions of dollars worth, that is, extremely high-tech devices.

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What do you think, can we produce an electron microscope?

Maybe we have the technology to produce such sensitive devices? Say what?

Or, you might say, someone else is producing it, so why should we produce it?

You may be thinking that buying would be a much simpler solution.

I think that if we want to be a pioneer in something, we should be able to make such sensitive devices ourselves.

In fact, our aim should not only be to do what others can do before.

We need to be discovering things ourselves, too.

In your opinion, how many patents are received for discoveries made in Turkey in a year?

The number of applications made to obtain patents in 2022 was 9009, and the number of patents registered was 3407.

Of course, there is no information about how many of these registered patents are technological patents or high technology patents in the report I looked at.

Nevertheless, the report has been prepared in great detail, covering many years on patent applications, including world-wide rankings, both on the basis of cities, sectors, companies and universities.

By the way, we are the 16th country in the world in terms of patents.

Let me end the article by saying that even this is a positive development.