A microscope is an apparatus or mechanism that enables better visibility of smaller elements or objects, obtaining an enlarged image of them. This instrument is characterized by increasing the image to the level of the retina in order to capture the information much better. The science that is responsible for the investigation of this series of small objects, using this instrument, is called microscopy.
What is the microscope
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Etymologically speaking, the word microscope comes from the Greek μικρός σκοπέω, which means "device or apparatus to observe small things that are not visible to the naked eye", a word formed by "micro" which means "small" and "scopian" refers to " apparatus for seeing or observing. '
In other words, the microscope is nothing more than an extremely valuable and relevant optical tool for science, because thanks to it, both microorganisms and tiny elements can be observed.
This tool is composed of lenses that are responsible for enlarging the small images that are being focused and that cannot be seen with the naked eye by the human eye.
The first microscope created in the history of mankind, was the optical one and is still in use due to its operation, as it is based on the property of various materials that achieve the change of direction of light rays.
From that moment, scientists began to create special lenses that allowed the light rays to converge, so that, with the combination of both, the magnified image of any type of object that was being studied could be generated. A practical example of this would be to use a single lens (like a magnifying glass, for example), to reproduce a more magnified image of a given sample.
When it comes to an optical microscope, the magnified image is generated from different lenses, some mounted on the objective of the tool and others on the eyepiece. It is important to note that the lenses located on the objective generate a real magnified image of the sample, then the image is enlarged through the eyepiece lenses, giving rise to a virtual sample with a size greater than the original.
It is also important to mention the fact that one of the essential elements of these devices is light, perhaps that is why microscopes are equipped with a focus and condenser, in this way, they manage to focus the light beam towards the samples. After the light passes through the sample, the lenses are responsible for correctly deflecting it to achieve a magnified image.
History of the microscope
A few centuries ago, long before the first microscope was created, people made use of different lenses that could magnify the image of the samples that were being studied, these lenses are known as magnifying glasses that, in fact, are still used in many parts of the world.
However, Roger Bacon, during the 13th century, was in charge of studying these magnifying glasses and giving their use a total twist, conducting effective research to change the use of magnifying glasses for other tools that would give better effectiveness to the enlargement of samples.
The origin of the microscope dates back to the year 1590, being its inventor Zacharias Janssen, born in Middelburg, in the Netherlands; and then Anton Van Leeuwenhoek, merchant and scientist of Dutch origin, in 1674 perfecting this creation, because thanks to him, red blood cells and bacteria were discovered in the blood. The optical microscope is the most widely used and the first to be created due to its technical simplicity, since it consists of one or more lenses that allow an enlarged image of the object or element under observation to be achieved.
It should be noted that these lenses can magnify an object up to 15 times through refraction. These lenses are glass, plastic or any other type of translucent circular materials, which change the direction of the light that falls on them. But around the same time, Galileo Galilei also made a microscope using a convex and a concave lens.
Therefore, even though many years have passed, there are doubts as to who is the true inventor of this very useful tool. The only thing that remains clear is that the first person to use the term microscope was Giovanni Faber in the year 1625.
Then, for what was part of the seventeenth century, the first investigations that documented observations made under the monitoring of a microscope began to appear. The first of these investigations has the title of Micrographia and was written by Robert Hooke, which was published in 1665. In this work, there are all kinds of illustrations of insects and plants. All of them taken by means of this optical tool.
Over the centuries, the technology of these tools was perfected until obtaining the devices that are being used today throughout the world, being Carl Zeiss one of the most famous microscope manufacturers of the 19th century because his company completely modernized the tools and incorporated many optical theories developed by Ernst Abbe, a renowned scientist. Later, the advances of the 20th century allowed the development of new microscopic techniques, obtaining as a result, new types of microscopes, among them, the electronic one, which will be fully explained later in this same post.
Microscope parts
Like any scientific tool, microscopes have several parts that make up their entire operation. Its parts can be classified according to those that belong to its mechanical system and those that belong to its optical system. Without these, it is impossible for the microscope to function properly.
Optical system
The optical microscope is one of the inventions that has marked a before and after in the history of science, especially medicinal and biological matters. Essentially it can be defined as an instrument that allows to observe in an enlarged size elements that are imperceptible to the naked eye and that, thanks to it, many other microscopes were created, which have an optical and a mechanical system. The optician includes a set of light manipulation elements and lenses that allow a more magnified image to be generated.
- Focus: it is responsible for emitting the light rays that are directed to the samples that are being studied.
- Condenser: its main function is to concentrate each of the light rays on the sample to be observed.
- Diaphragm: the condenser tends to be coupled with the diaphragm, which is responsible for regulating the amount of incident light used on the sample.
- Objective: this fundamental part of the tool is based on a set of lenses that receive the light that comes from the sample, in this way, it allows to increase the image of the sample that is being observed.
- Eyepiece: it is responsible for enlarging the image that comes from the objective, in fact, it is through this part that the sample can be fully observed.
Mechanic system
This system is based on the proportion of the structural support of all the elements that have been mentioned previously in this same section. Here it is exactly the same as with the optical system, if not all of them are present, then the microscope cannot function correctly.
It is classified as follows:
- Base: also known as the foot, it is responsible for keeping the microscope in a stable position.
- Arm: it is the main structure of the tool, in addition, it connects the base with its optical system.
- Stage: it is the horizontal part of the sample enlargement tool and, there, the sample to be observed is placed.
- Micrometric and coarse screws: since the stage is not firmly connected to the arm, it must regulate its position using the micrometric and coarse screws.
- Revolver: this is the part where the objectives are located, generally they are 3 or 4 and you can rotate to select the appropriate objective.
- Tube: is responsible for connecting the objectives with the eyepiece.
Types of microscopes
In addition to the optical, there are also other types of microscopes, with different functions and characteristics, among them are simple microscope, compound microscope, ultraviolet light, fluorescence, petrographic, dark field microscope, contrast, polarized light phase, electron confocal, transmission electron microscope, scanning electron microscope, among others. In this section, the most important ones in the world will be explained, as well as their dominant characteristics.
Compound microscope
This is categorized as being elementary for the optician. Its term "composite" refers to the fact that two or more lenses are used to obtain the magnified image of the sample. The name is used in contrast to a simple tool, since it refers to microscopes that work with a single lens, that is, magnifying glasses.
Monocular microscope
As its name implies, it has a single eyepiece that allows you to view the sample with just one eye.
Due to this simple feature, it is used by students or people who find their passion in microscopy. This tool is not comfortable, even less when the samples have to be analyzed by the hour, which is why professionals do not use it and make way for the binocular tool. This type of optical tool has two eyepieces, so both eyes can be used to analyze samples, it is more comfortable and the image of the objective is divided in two through an optical prism.
Trinocular microscope
Which has two eyepieces that allow the observation of the sample, but also includes an additional eyepiece to connect a camera that captures the images of the observations made.
There is also the digital one, instead of having an eyepiece, it has a camera, which allows the images of the sample to be digitally captured, which is viewed in real time through a screen, although it can also be transmitted to a PC through connections USB.
Inverted microscope
As the name implies, it reverses the position of the light source and the target, so the specimen is illuminated from the top and the target is positioned below the stage. The advantage of this tool is that you can see the elements that are in the bottom of the observation container. It is used to see the living tissues and cells that are inside the container and constantly hydrated.
Stereoscopic
It is a binocular tool, as it has two eyepieces, but with this optical tool, each eyepiece provides a different image. The combination of the two images provided by the eyepieces produces an effect of seeing the image in three dimensions. In order to obtain this effect, two objectives must be used, one different for each eyepiece. With conventional devices, the sample tends to be stained with substances, thus increasing the contrast in relation to a bright background.
When the sample is not stained, the contrast tends to be low and the details are not fully appreciated, so, to remedy these types of problems, these devices were created that are used with techniques of treatment of the light beam. These make it possible to observe the samples with the adequate levels of contrast. These microscopes are:
- Dark field microscope
- Petrographic or polarized light microscope
- Phase contrast microscope
- Differential interference contrast microscope
- Some also tend to include infrared, ultraviolet, and fluorescent lights.
Microscope images
In this section you will find a gallery of images of microscopes to see first-hand what each of those mentioned in this post looks like, starting with real photographs up to a drawing microscope.
