The 18 types of microscope (and their characteristics)

There are things so small that the human eye simply cannot see them. For this, something is necessary that can increase them, and for that reason there are instruments as closely related to the scientific world as microscopes.

The first of them was invented by Anton van Leeuwenhoek and, since then, his invention has not only become more sophisticated, but also, Also, other types have been created that work to observe things that this Dutch trader would never have believed exist.

Today we are going to discover the different types of microscope, in addition to seeing what they are for, what they are made of and how they work. Do not miss them.

• Related article: "The 14 parts of the microscope, and their functions"

The 18 types of microscope (explained)

The microscope is an instrument that, had it never been invented, science would certainly not be as advanced as it is today. Science and technology have been strongly promoted since a Dutch merchant named Anton van Leeuwenhoek, a little boring the good man, he decided to experiment with various magnifying glasses in the middle of the seventeenth century and invented, as who does not want the thing, an instrument through which to observe things as small as red blood cells or sperm.

Four centuries have passed since this man invented the prototype of the microscope and scientists, in his desire to know what this tiny world is like the human eye cannot see with the naked eye, they have been designing new types of microscopes, some so sophisticated and powerful that they allow us to see even viruses and atoms. The technical improvements of the many microscopes that have been invented have led to improvements in both medicine and industrial technology and biology.

Throughout this article we are going to discover the 18 types of microscopes that exist, how they work and for which fields of knowledge they are used fundamentally.

1. Optical microscope

The light microscope was the first microscope in history. This instrument marked a before and after in biology and medicine as this invention, despite its relative technological simplicity, allowed us to see cells for the first time.

The main characteristic of this instrument is that visible light is the element that allows the sample to be seen. A beam of light illuminates the object to be observed, passing through it and being led to the observer's eye, who receives an enlarged image thanks to a lens system. The light microscope is useful for most microscopy tasks, as it allows us to see cells and tissue details that we cannot see with the naked eye.

However, this microscope is the simplest of all. Its resolution limit is marked by the diffraction of light, a phenomenon by which light rays are inevitably deflected through space. As a consequence, the maximum that can be obtained with an optical microscope is 1,500x magnification.

• You may be interested in: "17 curiosities about human perception"

2. Transmission electron microscope

The transmission electron microscope was invented during the 1930s and was a real revolution in the first half of the last century. This microscope allows to reach a higher number of magnifications than optical, since it does not use visible light as a display element but uses electrons.

Transmission electron microscopes are much more complex than optical ones, and this is evident in the way the samples are viewed.

The mechanism of this microscope is based on striking electrons on an ultra-fine sample, much finer than those normally prepared for observation in the light microscope. The image is obtained from the electrons that pass through the sample and subsequently impact on a photographic plate. To achieve the correct flow of electrons inside these microscopes, they need to be empty.

Electrons are accelerated towards the sample using a magnetic field. Once they hit it, some electrons will pass through it while others will bounce off it and scatter. This is the result images with dark areas, where the electrons have bounced, and light areas, which are where the electrons have passed, forming a black and white image of the sample.

Transmission electron microscopes are not limited by the wavelength of visible light, which means they have the ability to magnify an object up to 1,000,000 times. Thanks to this we can not only see bacteria with these instruments, but also much smaller bodies such as viruses.

• Related article: "The 15 types of research (and characteristics)"

3. Scanning electron microscope

The scanning electron microscope is based on striking electrons on the sample to achieve the visualization of the same, but it differs from the transmission by the fact that in this case the particles do not impact on the entire sample at once, but do so by traveling through different points. You could say that it performs a scan of the sample.

With this microscope the image is not obtained from the electrons that impact on a photographic plate after passing through the sample. Here its operation is based on the properties of the electrons, which after impacting the sample undergo changes. A part of its initial energy is transformed into X-rays or heat emission. By measuring these changes, all the necessary information can be obtained to make an enlarged reconstruction of the sample, as if it were a map.

4. Fluorescence microscope

Fluorescence Microscopes form an image thanks to the fluorescent properties of the sample seen through them. This sample is illuminated by a xenon or mercury vapor lamp. A traditional beam of light is not used but works with gases.

These substances illuminate the preparation with a very specific wavelength, which allows the elements that make up the sample to begin to emit their own light. In other words, here the sample itself is the one that emits light instead of illuminating it to be able to observe it. This instrument is widely used in biological and analytical microscopy, being a technique that provides great sensitivity and specificity.

5. Confocal microscope

The confocal microscope could be considered a type of fluorescence microscope in which the sample is not fully illuminated, but a scan is made as in the case of a scanning electron microscope. Its main advantage over traditional fluorescence is that the confocal allows a reconstruction of the sample obtaining three-dimensional images.

• Related article: "The 4 main types of science (and their fields of research)"

6. Tunneling Microscope

The tunneling microscope allows us to see the atomic structure of the particles. This instrument uses the principles of quantum mechanics, capturing electrons and achieving a high resolution image in which each atom can be distinguished from the others. It is a fundamental tool in the field of nanotechnology, being used to produce changes in the molecular composition of substances and allowing imaging three-dimensional.

7. X-ray microscope

The X-ray microscope, as its name suggests, uses neither traditional light nor electrons, but uses X-rays to see the sample. This radiation of very low wavelength is absorbed by the electrons of the sample, which allows to know the electronic structure of the preparation..

• You may be interested in: "Atomism: what is it and how has this philosophical paradigm developed"

8. Atomic force microscope

The atomic force microscope detects neither light nor electrons. Its operation is based on scanning the surface of the preparation to detect the forces that occur between the atoms of the microscope probe and the atoms on the surface. This instrument detects the attractive and repulsive forces of atoms, very low energies, which makes it possible to map the surface of the sample, thus obtaining three-dimensional images as if a topographic map were being made.

9. Stereoscopic microscope

Stereoscopic microscopes are a variant of traditional optical microscopes, although these have the peculiarity that they allow a three-dimensional visualization of the preparation. They are equipped with two eyepieces, unlike the traditional ones that only have one, and the image that reaches each of them is slightly different. By combining what is captured by the two eyepieces, the desired three-dimensional effect is formed.

Although it does not reach as many magnifications as the traditional optical, the stereomicroscope is often widely used in areas where simultaneous manipulation of the sample is required.

• Related article: "The 11 parts of the eye and their functions"

10. Petrographic microscope

The petrographic microscope, also known as a polarized light microscope, It is based on the principles of the optician but with the peculiarity that it has two polarizers, one in the condenser and the other in the eyepiece.. These parts of the microscope reduce the refraction of light and the amount of glare.

This instrument is used to observe minerals and crystalline objects, because if they were illuminated in a traditional way, the image obtained would be blurred and difficult to appreciate. It is also a very useful type of microscope when looking at tissues that can cause light refraction, such as muscle tissue.

11. Ion field microscope

The field ion microscope is used in materials science because allows you to see the arrangement of the atoms in the preparation. Its function is similar to the atomic force microscope, allowing the absorbed gas atoms to be measured by a metal tip to make a reconstruction of the surface of the sample at the atomic level.

• You may be interested in: "The 10 branches of Biology: their objectives and characteristics"

12. Digital microscope

The digital microscope is a tool capable of capturing an image of the sample and projecting it. Its main characteristic is that, instead of having an eyepiece, it has a camerato. Although its resolution limit is lower than that of the traditional optical microscope, digital ones can be very useful for observing everyday objects and, thanks to the fact that they are able to preserve the images of the preparations, this device is very interesting at the level commercial.

13. Reflected light microscope

In the case of reflected light microscopes, the light does not pass through the sample but is reflected when striking the preparation and is guided towards the objective. These microscopes are used when working with opaque materials that, despite having been cut very fine, do not allow light to pass through.

14. Ultraviolet light microscope

Ultraviolet light microscopes do not illuminate the preparation with visible light, but instead use ultraviolet light as the name suggests. This type of light has a shorter wavelength, making it possible to achieve a higher resolution..

In addition, they are capable of detecting a greater number of contrasts, making them especially useful. when the samples are too transparent and could not be seen with the light microscope traditional.

15. Compound microscope

The compound microscope encompasses any optical instrument equipped with at least two lenses. Normally the original optical microscopes used to be simple, while most of the modern ones are composite, having several lenses both in the objective and in the eyepiece.

16. Dark field microscope

Darkfield microscopes illuminate the sample obliquely. The rays of light that reach the objective do not come directly from the light source, but are scattered throughout the sample. In this case, it is not necessary to stain the sample to be able to visualize it, and these microscopes allow work with cells and tissues too transparent to be observed with classical techniques of illumination.

17. Transmitted light microscope

In the transmitted light microscope a beam of light passes through the preparation and is the most widely used illumination system in optical microscopes. Due to this method, the sample must be cut very thin to make it semi-transparent so that light can pass through it.

18. Phase contrast microscope

The phase contrast microscope works on the physical principle that makes light travel at different speeds depending on the medium through which it travels. Using this property, this instrument collects the speeds at which light has circulated while passing through the sample, makes a reconstruction and thus obtains an image. This type of microscope allows working with living cells since the sample does not need to be stained.