A microscope is a device designed to magnify the image of objects of study in order to view details of their structure hidden to the naked eye. The device provides magnification of tens or thousands of times, which allows you to conduct research that can not be obtained using any other equipment or device.
Microscopes are widely used in medicine and laboratory research. They are used to initialize dangerous microorganisms and viruses in order to determine the treatment method. The microscope is irreplaceable and is constantly being improved. The first semblance of a microscope was created in 1538 by the Italian doctor Girolamo Fracastoro, who decided to install two consecutive optical lenses, similar to those used in glasses, binoculars, spyglasses and magnifiers. Galileo Galilei worked on improving the microscope, as well as dozens of world-famous scientists.
There are many types of microscopes that differ in their design. Most models share a similar design, but with minor technical features.
In the vast majority of cases, microscopes consist of a rack on which 4 main elements are fixed:
The lens is a complex optical system that consists of glass lenses that follow each other. The lenses are made in the form of tubes, inside which up to 14 lenses can be fixed. Each of them magnifies the image by removing it from the surface of the lens in front of it. Thus, if it increases the object by 2 times, the next one will increase the projection even more, and so on until the object is displayed on the surface of the last lens.
Each lens has its own focusing distance. In this regard, they are firmly fixed in the tube. If any of them are moved closer or further away, you will not be able to get a clear magnification of the image. Depending on the characteristics of the lens, the length of the tube that encloses the lens may differ. In fact, the higher it is, the more enlarged the image will be.
The eyepiece of a microscope also consists of lenses. It is designed so that the operator who works with a microscope can put his eye to it and see the enlarged image on the lens. The eyepiece has two lenses. The first is located closer to the eye and is called the ocular, and the second field. With the help of the latter, the image magnified by the lens is adjusted for its correct projection on the retina of the human eye. This is necessary in order to remove defects in vision perception by adjusting, since each person focuses at a different distance. The field lens allows you to adjust the microscope to this feature.
To view the subject under study, it is necessary to illuminate it, since the lens covers the natural light. As a result, looking into the eyepiece, you can always see only black or gray images. The lighting system was developed specifically for this purpose. It can be made in the form of a lamp, led or other light source. The simplest models receive light rays from an external source. They are directed to the subject of study using mirrors.
The last important and easiest part of the microscope is the slide table. The lens is directed at it, because it is on it that the subject is fixed for study. The table has a flat surface, which allows you to fix the object without fear that it will move. Even the minimal movement of the research object under magnification will be huge, so it will not be easy to find the original point that was studied again.
Over the vast history of this device, several microscopes have been developed that differ significantly in the principle of operation.
Among the most frequently used and popular types of this equipment are the following types:
The optical microscope is the most inexpensive and simple device. This equipment allows you to increase the image by 2000 times. This is a fairly large indicator that allows you to study the structure of cells, the surface of tissue, find defects on artificially created objects, and so on. It is worth noting that to achieve such a large increase, the device must be very high-quality, so it is expensive. The vast majority of optical microscopes are made much simpler and have a relatively small magnification. Educational types of microscopes are represented by optical ones. This is due to their lower cost, as well as not too large multiplicity of increase.
Usually an optical microscope has several lenses that are fixed to the rack movable. Each of them has its own degree of magnification. Looking at the subject, you can move the lens to the working position and study it under a certain multiplicity. If you want to zoom in even more, you just need to switch to an even more magnifying lens. These devices do not have ultra-precise adjustment. For example, if you only need to zoom in a little, then switching to a different lens, you can zoom in dozens of times, which will be excessive and will not allow you to correctly perceive the enlarged image and avoid unnecessary details.
Electronic is a more advanced design. It provides an image magnification of at least 20,000 times. The maximum magnification of such a device is possible in 106 times. The peculiarity of this equipment is that instead of a beam of light like an optical one, they direct a beam of electrons. The image is obtained by using special magnetic lenses that respond to the movement of electrons in the column of the device. The beam direction is adjusted using a magnetic field. These devices appeared in 1931. In the early 2000s, computer equipment and electron microscopes began to be combined, which significantly increased the magnification factor, the range of settings, and made it possible to capture the resulting image.
Scanning probe microscope allows you to get an image from an object by examining it with a special probe. The result is a three-dimensional image with accurate data on the characteristics of objects. This equipment has a high resolution. This is a relatively new equipment that was created several decades ago. Instead of a lens, these devices have a probe and a system for moving it. The image obtained from it is registered by a complex system and recorded, after which a topographic picture of enlarged objects is created. The probe is equipped with sensitive sensors that respond to the movement of electrons. There are also probes that work on the optical type by magnifying through the installation of lenses.
Often, probes are used to obtain data about the surface of objects with complex terrain. Often they are lowered into the pipe, holes, and small tunnels. The only condition is that the diameter of the probe corresponds to the diameter of the object of study.
This method is characterized by a significant measurement error, since the resulting 3D picture is difficult to decipher. There are many details that are distorted by the computer during processing. The original data are processed mathematically with the help of specialized software.