THE 14 TYPES OF MICROSCOPES AND THEIR FUNCTIONS - SCIENCE - 2024

There are different types of microscopes: optical, compound, stereoscopic, petrographic, confocal, fruorescence, electronic, transmission, scanning, scanning probe, tunneling, ion in the field, digital and virtual.

A microscope is an instrument used to allow man to see and observe things that could not be seen with the naked eye. It is used in different areas of trade and research ranging from medicine to biology and chemistry.

18th century microscopes from the Musée des Arts et Métiers, Paris

A term has even been coined for the use of this instrument for scientific or research purposes: microscopy.

The invention and first records of the use of the simplest microscope (it worked through a magnifying glass system) dates back to the 13th century, with different attributions to who could have been its inventor.

In contrast, the compound microscope, closer to the models we know today, is estimated to have been used for the first time in Europe around the year 1620.

Even then, there were several who sought to claim the invention of the microscope, and different versions emerged that, with similar components, managed to meet the objective and magnify the image of a very small sample in front of the human eye.

Among the more recognized names attributed to the invention and use of their own versions of microscopes are Galileo Galilei and Cornelis Drebber.

The arrival of the microscope in scientific studies led to discoveries and new perspectives on essential elements for the advancement of different areas of science.

The sighting and classification of cells and microorganisms such as bacteria are one of the most popular achievements made possible under the microscope.

Since its first versions more than 500 years ago, today the microscope maintains its basic concept of operation, although its performance and specialized purposes have been changing and evolving until today.

Main types of microscopes

Optical microscope

Also known as a light microscope, it is the microscope with the greatest structural and functional simplicity.

It works through a series of optics that, together with the entry of light, allow the magnification of an image that is well located in the focal plane of the optics.

It is the oldest design microscope and its earliest versions are attributed to Anton van Lewenhoek (17th century), who used a single lens prototype on a mechanism that held the sample.

Compound microscope

The compound microscope is a type of light microscope that works differently from the simple microscope.

It has one or more independent optics mechanisms that allow a greater or lesser degree of magnification on the sample. They tend to have a much more robust composition and allow greater ease of observation.

It is estimated that its name is not attributed to a greater number of optical mechanisms in the structure, but to the fact that the formation of the magnified image occurs in two stages.

A first stage, where the sample is projected directly onto the objectives on it, and a second, where it is magnified through the ocular system that reaches the human eye.

Stereoscopic microscope

It is a type of low-magnification light microscope mainly used for dissections. It has two independent optical and visual mechanisms; one for each end of the sample.

Work with reflected light on the sample rather than through it. It allows to visualize a three-dimensional image of the sample in question.

Petrographic microscope

Used especially for the observation and composition of rocks and mineral elements, the petrographic microscope works with the optical foundations of previous microscopes, with the quality of including polarized material in its objectives, which allows reducing the amount of light and brightness that minerals they can reflect.

The petrographic microscope allows, through the magnified image, to elucidate the elements and composition structures of rocks, minerals, and terrestrial components.

Confocal microscope

This optical microscope allows the increase of the optical resolution and the contrast of the image thanks to a device or spatial "pinhole" that eliminates excess or out-of-focus light that is reflected through the sample, especially if it has a greater size than allowed by the focal plane.

The device or “pinole” is a small opening in the optical mechanism that prevents excess light (that which is not in focus on the sample) from being scattered over the sample, reducing the sharpness and contrast that it may present.

Because of this, the confocal microscope works with a fairly limited depth of field.

Fluorescence microscope

It is another type of optical microscope in which fluorescent and phosphorescent light waves are used for better detail on the study of organic or inorganic components.

They stand out simply for the use of fluorescent light to generate the image, not having to depend entirely on the reflection and absorption of visible light.

Unlike other types of analog microscopes, the fluorescent microscope can have certain limitations due to the wear that the fluorescent light component can present due to the accumulation of chemical elements caused by the impact of electrons, wearing down the fluorescent molecules.

The development of the fluorescent microscope earned scientists Eric Betzig, William Moerner and Stefan Hell the Nobel Prize in Chemistry in 2014.

Electronic microscope

The electron microscope represents a category in itself compared to previous microscopes, because it changes the basic physical principle that allowed the visualization of a sample: light.

The electron microscope replaces the use of visible light with electrons as a source of illumination. The use of electrons generates a digital image that allows a greater magnification of the sample than optical components.

However, large magnifications can cause a loss of fidelity in the sample image. It is mainly used to investigate the ultra-structure of microorganic specimens; capacity that conventional microscopes do not have.

The first electron microscope was developed in 1926 by Han Busch.

Transmission electron microscope

Its main attribute is that the electron beam passes through the sample, generating a two-dimensional image.

Due to the energetic power that electrons can have, the sample must be subjected to a previous preparation before being observed through an electron microscope.

Scanning electron microscope

Unlike the transmission electron microscope, in this case the electron beam is projected onto the sample, generating a rebound effect.

This allows the three-dimensional visualization of the sample due to the fact that information is obtained on the surface of this.

Scanning probe microscope

This type of electron microscope was developed after the invention of the tunneling microscope.

It is characterized by using a test tube that scans the surfaces of a sample in order to generate a high fidelity image.

The test tube scans, and by means of the thermal values ​​of the sample it is able to generate an image for its later analysis, shown through the thermal values ​​obtained.

Tunneling Microscope

It is an instrument used especially to generate images at the atomic level. Its resolution capacity can allow the manipulation of individual images of atomic elements, operating through an electron system in a tunnel process that works with different voltage levels.

A great control of the environment is needed for an observation session at the atomic level, as well as the use of other elements in optimal state.

However, there have been cases in which microscopes of this type have been built and used in a domestic way.

It was invented and implemented in 1981 by Gerd Binnig and Heinrich Rohrer, who were awarded the Nobel Prize in Physics in 1986.

Ion field microscope

More than an instrument, it is known by this name to a technique implemented for the observation and study of the ordering and rearrangement at the atomic level of different elements.

It was the first technique that made it possible to discern the spatial arrangement of the atoms in a given element. Unlike other microscopes, the magnified image is not subject to the wavelength of light energy passing through it, but has a unique ability to magnify.

It was developed by Erwin Muller in the 20th century, and has been considered the precedent that has allowed a better and more detailed visualization of elements at the atomic level today, through new versions of the technique and instruments that make it possible.

Digital microscope

A digital microscope is an instrument with a mostly commercial and generalized character. It works through a digital camera whose image is projected on a monitor or computer.

It has been considered a functional instrument for the observation of volume and context of the worked samples. In the same way, it has a physical structure that is much easier to manipulate.

Virtual microscope

The virtual microscope, more than a physical instrument, is an initiative that seeks the digitization and archiving of samples worked so far in any field of science, with the aim that any interested party can access and interact with digital versions of organic samples or inorganic through a certified platform.

In this way, the use of specialized instruments would be left behind and research and development would be promoted without the risks of destroying or damaging a real sample.

References

1. (2010). Retrieved from History of the Microscope: history-of-the-microscope.org
2. Keyence. (sf). Basics of Microscopes. Obtained from Keyence - Biological Microscope Site: keyence.com
3. Microbehunter. (sf). Theory. Obtained from Microbehunter - Amateur Microscopy Resource: microbehunter.com
4. Williams, DB, & Carter, CB (nd). Transmission Electron Microscopy. New York: Plenum Press.