The 18 types of microscopes (and their characteristics)

A summary of the types of microscope used in the field of research, described.

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

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

Today we are going to discover the different types of microscopesand see what they are used for, what they are made of and how they work. Don't miss them.

The 18 types of microscopes (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 boosted since a Dutch merchant named Anton van Leeuwenhoek a Dutch merchant by the name of Anton van Leeuwenhoek, a rather bored good mana somewhat bored good man, decided to experiment with various magnifying glasses in the middle of the 17th century and invented, out of the blue, an instrument through which to observe things as small as red Blood cells or spermatozoa.

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

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

Optical microscope

The optical microscope was the first microscope in history.. This instrument marked a before and after in biology and medicine because this invention, despite its relative technological simplicity, made it possible to see cells for the first time.

The main characteristic of this instrument is that visible light is the element that makes it possible to see the sample. A beam of light illuminates the object to be observed, passing through it and being conducted to the eye of the observer who receives a magnified image thanks to a system of lenses. The optical microscope is useful for most microscopy tasks, as it allows us to see cells and tissue details that we would not be able to see with the naked eye.

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

Transmission electron microscope

The transmission electron microscope was invented during the 1930s and was a true revolution during the first half of the last century. This microscope allows a higher magnification than the optical microscope, since it does not use visible light as a visualization element, but rather uses electrons.

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

The mechanism of this microscope is based on shining electrons on an ultrafine sample, much finer than those normally prepared for observation in the optical microscope. The image is obtained from the electrons that pass through the sample and then impact on a photographic plate. To achieve the correct flow of electrons through the interior of these microscopes, they must be empty.

The electrons are accelerated towards the sample using a magnetic field. Once they hit the sample, some electrons will pass through it while others will bounce off it and be scattered. This results in images with dark areas, where the electrons have bounced off, and light areas, where the electrons have passed through.The microscope is a black-and-white image of the specimen.

Transmission electron microscopes are not limited by the wavelength of visible light, which makes them capable of magnifying 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.

Scanning electron microscope

The scanning electron microscope is based on shining electrons on the sample to visualize it, but it differs from the transmission electron microscope in that in this case the particles do not impact the entire sample at the same time, but rather travel through different points of the sample.. It could be said that it performs a scanning 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 on the sample undergo changes. A part of their initial energy is transformed into X-rays or heat emission. By measuring these changes it is possible to obtain all the information necessary 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 observed through them.. This sample is illuminated by a xenon or mercury vapor lamp. A traditional light beam is not used, but gases are used instead.

These substances illuminate the preparation with a very specific wavelength, which allows the elements that make up the sample to start emitting light of their own. In other words, it is the sample itself that emits light instead of illuminating it for observation. This instrument is widely used in biological and analytical microscopy, being a technique that provides high sensitivity and specificity.

5. Confocal microscope

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

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 three-dimensional images to be obtained.

7. X-ray microscope

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

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 between the atoms in the microscope probe and the atoms on the surface. This instrument detects the forces of attraction and repulsion of the atoms, at very low energies.This instrument detects the forces of attraction and repulsion of the atoms, at very low energies, which allows mapping the surface of the sample, thus obtaining three-dimensional images as if a topographic map were being made.

9. Stereo microscope

Stereo microscopes are a variant of traditional optical microscopes, although they have the peculiarity of allowing a three-dimensional visualization of the preparation. They are equipped with two eyepieces, unlike traditional microscopes, which have only one, and the image that reaches each of them is slightly different. The combination of what is captured by the two eyepieces creates the desired three-dimensional effect..

Although it does not reach as high a magnification as the traditional optical microscope, the stereo microscope is often used in areas where simultaneous manipulation of the sample is required.

10. Petrographic microscope

The petrographic microscope, also known as a polarized light microscope, is based on the principles of the optical microscope 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 brightness.

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

11. Field ion microscope

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

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 camera that can capture an image of the sample and project it.a. Although their resolution limit is lower than that of the traditional optical microscope, digital microscopes can be very useful for observing everyday objects and, because they are capable of preserving images of slides, this device is very interesting at the commercial level.

13. Reflected light microscope

In the case of reflected light microscopes, the light does not pass through the specimen but is reflected back to the specimen and directed towards the objective.. These microscopes are used when working with opaque materials that, despite being cut very thinly, do not allow light to pass through.

14. Ultraviolet light microscope

Ultraviolet light microscopes do not illuminate the preparation with visible light, but 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 able to detect a greater number of contrasts, making them especially useful when samples are too transparent and could not be seen with the traditional optical microscope.

15. Compound microscope

The compound microscope encompasses any optical instrument equipped with at least two lenses.. The original optical microscopes were usually simple, while most modern microscopes are compound, having several lenses in both the objective and the eyepiece.

16. Darkfield microscope

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

17. Transmitted light microscope

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

18. Phase contrast microscope

The phase contrast microscope works on the physical principle that light travels at different speeds depending on the medium through which it travels. Using this property, this instrument collects the velocities at which light has traveled while passing through the sample, makes a reconstruction and thus obtains an image of the sample.. This type of microscope allows working with live cells since it is not necessary to stain the sample.