Microscopy is a technical field that deals with the examination of invisible objects using a microscope or the examination of normal objects. The three most common branches of microscopy are optical microscopy, electron microscopy and scanning probe microscopy.
Optical microscopy and electron microscopy use the diffraction, scattering, or reflection of electromagnetic radiation or electron beams and form an image. The process takes place by continuing the large-scale irradiation of the sample taken or by scanning a beam over the sample.
In scanning probe microscopy, the contact where the scanning probe enters the surface of the object under investigation is also involved. The use of microscopy method has opened a new era in biology and has led to the birth of many important scientific fields such as histology.
Microscopes are tools for magnifying small objects. Microscopes come in various sizes and shapes, and they can create an image using many imaging methods (light, electron, ion, x-ray, mechanical probe, etc.) and signals. A microscope can be as simple as a hand-held magnifying glass, or it can be a complex research instrument worth millions of dollars.
The simple microscope is considered to be the first type of microscope. This microscope was invented by Antony van Leeuwenhoek in the 17th century, when Leeuwenhoek held a thin-edged (convergent) lens over the specimen with a handle, paving the way for the birth of a simple microscope.
This microscope can magnify the image 200-300 times and we can say that it is essentially a magnifying glass. Even though this microscope is a simple microscope, it has provided Antony van Leeuwenhoek with very important information about many biological samples, especially the differences between the shapes of red blood cells with this microscope.
Today, simple microscopes are not used as often as they used to be, as compound microscopes were invented by adding a second lens, replacing the simple microscope and giving a better image.
A compound microscope was created using two lenses and has much better magnification than a simple microscope. Thanks to the added second lens, the image can be enlarged much more than the first.
Compound microscopes are light field microscopes, which means that the sample under study is illuminated from below. These microscopes can be binocular or single eyed. The compound microscope can zoom the image up to 1000 times. These microscopes are very inexpensive but very useful and can be used in schools and research laboratories.
A stereo microscope can zoom the image up to 300 times. This microscope is single-eyed and is used to examine opaque objects and objects too large to be examined with a compound microscope as it does not require slide preparation.
Although it has a low magnification, it is a very useful microscope. It gives a very close and three-dimensional view of the surface of the sample and also allows the user to move the sample during imaging.
Stereo microscopes are used in biological and medical science applications as well as in the electronics industry, for example in the clock making and circuit board manufacturing industries these microscopes are often used.
Unlike the compound microscope and stereo microscope, the concentric microscope uses laser light, not straight light, to scan the sample and scans the stained sample. These samples are prepared and placed on slides, then, with the help of two-color mirrors, the microscope produces a magnified image of the sample and creates it on the computer screen.
It is also possible to obtain three-dimensional images using this microscope, requiring several scans. As with the compound microscope, the image is magnified at a very high rate in the concentric microscope, but a higher quality image is obtained compared to the compound microscope. These microscopes are frequently used in cell biology and medical research.
Scanning electron microscopes use electrons instead of light to create images. The samples are scanned in a vacuum or semi-vacuum state so that they can be specifically prepared by dehydrating first and coated in a thin layer with an auxiliary material such as gold.
After the sample is prepared and placed, the scanning electron microscope gives a three-dimensional, black and white image of the sample to the computer screen. They are used in physical, medical and biological sciences, as they give plenty of control over the magnification rate. It is possible to examine many samples from bones to insects with this microscope.
Like scanning electron microscopy, transmission electron microscopy uses electrons to magnify the image and samples are prepared by scanning them with a vacuum.
However, unlike scanning electron microscopy, transmission electron microscopy uses slide preparation method to obtain a two-dimensional image of the sample. Thus, it is possible to view objects that are transparent to a certain extent.
The transmission electron microscope is a highly efficient microscope in terms of both magnification and result. It is a type of microscope frequently used in physical and biological sciences, metallurgy, nanotechnology, and forensic analysis.