The concept of a microscope. Research project “What is a microscope? The device of electron microscopes

MICROSCOPE
an optical instrument with one or more lenses for obtaining magnified images of objects not visible to the naked eye. Microscopes are simple and complex. A simple microscope is one lens system. A simple magnifying glass can be considered a simple microscope - a plano-convex lens. A compound microscope (often referred to simply as a microscope) is a combination of two simple ones. A compound microscope gives a greater magnification than a simple one, and has a higher resolution. Resolution is the ability to distinguish the details of the sample. An enlarged image, in which details are indistinguishable, provides little useful information. The compound microscope has a two-stage scheme. One lens system, called the objective, is brought close to the specimen; it creates an enlarged and resolved image of the object. The image is further magnified by another lens system, called an eyepiece, which is placed closer to the observer's eye. These two lens systems are located at opposite ends of the tube.

Working with a microscope. The illustration shows a typical biological microscope. The tripod stand is made in the form of a heavy casting, usually a horseshoe shape. A tube holder is attached to it on a hinge, carrying all the other parts of the microscope. The tube, in which the lens systems are mounted, allows you to move them relative to the sample for focusing. The lens is located at the lower end of the tube. Typically, the microscope is equipped with several objectives of different magnification on the turret, which allows you to set them in working position on the optical axis. The operator, when examining a sample, usually starts with the lowest magnification objective and the widest field of view, finds the details of interest, and then examines them using a high magnification objective. The eyepiece is mounted on the end of a retractable holder (which allows you to change the length of the tube when necessary). The entire tube with the objective and eyepiece can be moved up and down to bring the microscope into sharp focus. The sample is usually taken as a very thin transparent layer or section; it is placed on a rectangular glass plate, called a glass slide, and covered on top with a thinner, smaller glass plate, called a coverslip. The sample is often stained chemicals to increase contrast. The glass slide is placed on the stage so that the sample is above the center hole of the stage. The stage is usually equipped with a mechanism for smooth and precise movement of the sample in the field of view. Under the object stage is the holder of the third lens system - the condenser, which concentrates the light on the sample. There can be several condensers, and an iris diaphragm is located here to adjust the aperture. Even lower is an illuminating mirror mounted in a universal joint, which casts the light of the lamp onto the sample, due to which the entire optical system of the microscope creates visible image. The eyepiece can be replaced with a photo attachment, and then the image will be formed on the film. Many research microscopes are equipped with a dedicated illuminator, so an illuminating mirror is not necessary.
Increase. The magnification of a microscope is equal to the magnification of the objective lens times the magnification of the eyepiece. For a typical research microscope the magnification of the eyepiece is 10, and the magnification of the objectives is 10, 45 and 100. Therefore, the magnification of such a microscope is from 100 to 1000. The magnification of some microscopes reaches 2000. Increasing the magnification even more does not make sense, since the resolution does not improve; on the contrary, the image quality deteriorates.
Theory. A consistent theory of the microscope was given by the German physicist Ernst Abbe at the end of the 19th century. Abbe found that the resolution (the smallest possible distance between two points that are visible separately) is given by

where R is the resolution in micrometers (10-6 m), l is the wavelength of light (produced by the illuminator), µm, n is the refractive index of the medium between the sample and the objective, and a is half the entrance angle of the objective (the angle between the extreme rays of the conical light beam entering the lens). Abbe called the quantity numerical aperture (it is denoted by the symbol NA). It can be seen from the above formula that the resolvable details of the object under study are the smaller, the larger NA and the shorter the wavelength. Numerical aperture not only determines the resolution of the system, but also characterizes the aperture ratio of the lens: the light intensity per unit area of ​​the image is approximately equal to the square of NA. For a good lens, the NA value is about 0.95. The microscope is usually designed so that its total magnification is approx. 1000NA.
Lenses. There are three main types of lenses that differ in the degree of correction of optical distortions - chromatic and spherical aberrations. Chromatic aberrations are due to the fact that light waves with different wavelengths are focused at different points on the optical axis. As a result, the image is colored. Spherical aberrations are caused by the fact that the light passing through the center of the lens and the light passing through its periphery are focused at different points on the axis. As a result, the image is fuzzy. Achromatic lenses are currently the most common. In them, chromatic aberrations are suppressed due to the use of glass elements with different dispersions, which ensure the convergence of the extreme rays of the visible spectrum - blue and red - in one focus. A slight coloration of the image remains and sometimes appears as faint green bands around the object. Spherical aberration can only be corrected for one color. Fluorite lenses use glass additives to improve color correction to such an extent that coloration in the image is almost completely eliminated. Apochromatic lenses are the lenses with the most complex color correction. They not only almost completely eliminated chromatic aberrations, but also corrected for spherical aberrations not for one, but for two colors. Increase apochromats for of blue color slightly larger than for red, and therefore they require special "compensating" eyepieces. Most lenses are "dry", ie. they are designed to work in such conditions when the gap between the objective and the sample is filled with air; the NA value for such lenses does not exceed 0.95. If a liquid (oil or, more rarely, water) is introduced between the objective and the sample, an "immersion" objective is obtained with an NA value as high as 1.4, with a corresponding improvement in resolution. The industry is currently producing various kinds special lenses. These include flat-field objectives for microphotography, stress-free (relaxed) objectives for working in polarized light, and objectives for examining opaque metallurgical specimens illuminated from above.
Capacitors. The condenser forms a light cone directed at the sample. Typically, a microscope is provided with an iris to match the aperture of the light cone with the aperture of the objective, which ensures maximum resolution and maximum image contrast. (Contrast in microscopy has the same importance, as in television technology.) The simplest condenser, quite suitable for most general purpose microscopes, is the two-lens Abbe condenser. Larger aperture objectives, especially oil immersion objectives, require more complex corrected condensers. Oil objectives with maximum aperture require a special condenser having immersion oil contact with bottom surface glass slide on which the sample is placed.
specialized microscopes. In connection with different requirements science and technology have developed microscopes of many special kinds. A stereoscopic binocular microscope designed to obtain a three-dimensional image of an object consists of two separate microscopic systems. The device is designed for a small increase (up to 100). Commonly used for assembly of miniature electronic components, technical control, surgical operations. The polarizing microscope is designed to study the interaction of samples with polarized light. Polarized light often makes it possible to reveal the structure of objects that lies beyond the limits of conventional optical resolution. A reflective microscope is equipped with image-forming mirrors instead of lenses. Since it is difficult to make a mirror lens, there are very few fully reflective microscopes, and mirrors are currently used mainly only in attachments, for example, for microsurgery of individual cells. Fluorescent microscope - with ultraviolet or blue light illumination of the sample. The sample, absorbing this radiation, emits visible luminescence light. Microscopes of this type are used in biology, as well as in medicine - for diagnosis (especially cancer). The dark-field microscope makes it possible to circumvent the difficulties associated with the fact that living materials are transparent. The sample in it is viewed under such "oblique" illumination that direct light cannot enter the objective. The image is formed by light diffracted from the object, and as a result, the object appears very light against a dark background (with very high contrast). The phase contrast microscope is used to examine transparent objects, especially living cells. Thanks to special devices, part of the light passing through the microscope is shifted in phase by half a wavelength relative to the other part, which is the reason for the contrast in the image. The interference microscope is a further development of the phase contrast microscope. Two light beams interfere in it, one of which passes through the sample, and the other is reflected. With this method, colored images are obtained, which provide very valuable information in the study of living material. see also
ELECTRONIC MICROSCOPE ;
OPTICAL INSTRUMENTS ;
OPTICS.
LITERATURE
Microscopes. L., 1969 Design of optical systems. M., 1983 Ivanova T.A., Kirillovsky V.K. Design and control of microscope optics. M., 1984 Kulagin S.V., Gomenyuk A.S. etc. Optical-mechanical devices. M., 1984

Collier Encyclopedia. - Open Society. 2000 .

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Microscope ... Spelling Dictionary

MICROSCOPE- (from Greek mikros small and skopeo look), optical instrument to study small objects that are not directly visible to the naked eye. There are simple M., or a magnifying glass, and complex M., or a microscope in the proper sense. Magnifying glass… … Big Medical Encyclopedia

microscope- a, m. microscope m.gr. mikros small + skopeo look. An optical instrument with a system of highly magnifying glasses for viewing objects or parts of them that are not visible to the naked eye. BAS 1. Microscope, small lens. 1790. Kurg. // Maltseva 54.… … Historical Dictionary of Gallicisms of the Russian Language

MICROSCOPE (Microscopus), a small constellation in the southern sky. Its brightest star has a magnitude of 4.7. MICROSCOPE An optical instrument that allows you to get an enlarged image of small objects. The first microscope was created in 1668 ... ... Scientific and technical encyclopedic Dictionary

- (Greek, from mikros small, and I look at skopeo). A physical projectile for examining the smallest objects, which are presented, through it, in an enlarged form. Dictionary foreign words included in the Russian language. Chudinov A.N.,… … Dictionary of foreign words of the Russian language

- (from micro ... and ... scope) a tool that allows you to get an enlarged image of small objects and their details that are not visible to the naked eye. The magnification of the microscope, reaching 1500 2000, is limited by diffraction phenomena. Unarmed... ... Big Encyclopedic Dictionary

Microtextile, orthoscope Dictionary of Russian synonyms. microscope noun, number of synonyms: 11 biomicroscope (1) … Synonym dictionary

MICROSCOPE, ah, husband. A magnifying device for viewing objects that are indistinguishable with the naked eye. Optical m. Electronic m. (giving an enlarged image using electron beams). Under a microscope (into a microscope) examine what n. |… … Explanatory dictionary of Ozhegov

- (from the Greek mikros small and skopeo look), optical. a device for obtaining highly magnified images of objects (or details of their structure) that are not visible naked eye. Various types of M. are intended to detect and study bacteria, ... ... Physical Encyclopedia

MICROSCOPE, microscope, husband. (from Greek mikros small and skopeo look) (physical). An optical instrument with a system of highly magnifying glasses for viewing objects that cannot be seen with the naked eye. Explanatory Dictionary of Ushakov. ... ... Explanatory Dictionary of Ushakov

An optical device for obtaining an enlarged image of objects that are not visible to the naked eye. In microbiol. light and electronic M. is used. One of the main indicators of M. is resolution - the ability to distinguish between two neighboring objects ... ... Dictionary of microbiology

A microscope is a device designed to magnify the image of objects of study in order to view the details of their structure hidden to the naked eye. The device provides an increase of tens or thousands of times, which allows you to conduct research that cannot be obtained using any other equipment or device.

Microscopes are widely used in medicine and laboratory research. With their help, dangerous microorganisms and viruses are initialized in order to determine the method of treatment. The microscope is indispensable and is constantly being improved. The first similarity of a microscope was created in 1538 by the Italian physician Girolamo Fracastoro, who decided to install two optical lenses in series, similar topics that are used in glasses, binoculars, spyglasses and magnifiers. Galileo Galilei worked on improving the microscope, as well as dozens of world famous scientists.

Device

There are many types of microscopes, which differ in design. Most models share a similar design, but with minor technical features.

In the vast majority of cases, microscopes consist of a stand on which 4 main elements are fixed:

• Lens.
• Eyepiece.
• Lighting system.
• Subject table.

Lens

The lens is a complex optical system, which consists of glass lenses going one after another. The lenses are made in the form of tubes, inside which up to 14 lenses can be fixed. Each of them enlarges the image by taking it from the surface of the lens in front. Thus, if one magnifies the object by 2 times, the next one will increase the given 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 tightly fixed in the tube. If any of them is moved closer or farther, it will not be possible to obtain a distinct increase in the image. Depending on the characteristics of the lens, the length of the tube in which the lens is enclosed may vary. In fact, the higher it is, the more magnified the image will be.

Eyepiece

The eyepiece of a microscope also consists of lenses. It is designed so that the operator who works with the microscope can put his eye on it and see the enlarged image on the objective. The eyepiece has two lenses. The first is located closer to the eye and is called the eye, and the second is the field. With the help of the latter, the image magnified by the lens is adjusted for its correct projection onto the retina of the human eye. This is necessary in order to remove defects in the perception of vision by adjusting, since each person focuses at a different distance. The field lens allows you to adjust the microscope to this feature.

Lighting system

To view the object under study, it is necessary to illuminate it, since the lens covers natural light. As a result, looking through the eyepiece, you can always see only a black or gray image. A lighting system has been specially developed for this. 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 with the help of mirrors.

Subject table

The last important and easiest part of the microscope to manufacture is the stage. The lens is pointed at it, since it is on it that the object for study is fixed. The table has a flat surface, which allows you to fix the object without fear that it will move. Even the smallest movement of the object of study under magnification will be huge, so it will not be easy to find the original point that was studied again.

Types of microscopes

Over the long history of the existence of this device, several microscopes have been developed that differ significantly from each other in terms of the principle of operation of microscopes.

Among the most commonly used and sought-after types of this equipment are the following types:

• Optical.
• Electronic.
• Scanning probes.
• X-ray.

Optical

An optical microscope is the most budgetary and simple device. This equipment allows you to magnify 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 in artificially created objects, etc. It is worth noting that in order to achieve such a large increase, the device must be of very high quality, therefore it is expensive. The vast majority of optical microscopes are made much simpler and have a relatively low magnification. Educational types of microscopes are represented precisely by optical ones. This is due to their lower cost, as well as not too high magnification.

Usually optical microscope has several lenses that are fixed on the rack movable. Each of them has its own degree of magnification. When examining an object, you can move the lens to its working position and examine it at a certain magnification. If you want to get even closer, you just need to switch to an even larger lens. These devices do not have ultra-precise adjustment. For example, if you only need to zoom in a little, then by switching to another 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.

Electron microscope

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 by 10 6 times. The peculiarity of this equipment lies in the fact that instead of a beam of light, like optical ones, they send a beam of electrons. Image acquisition is carried out through the use of special magnetic lenses that respond to the movement of electrons in the column of the device. The beam direction is adjusted using . These devices appeared in 1931. In the early 2000s, they began to combine computer equipment and electron microscopes, which significantly increased the magnification factor, the adjustment range, and made it possible to capture the resulting image.

Electronic devices, for all their merits, have a high price, and require special conditions for operation. To obtain a high-quality clear image, it is necessary that the subject of study be in a vacuum. This is due to the fact that air molecules scatter electrons, which disturbs the clarity of the image and does not allow for fine adjustment. For this reason, this equipment is used in laboratory conditions. Also an important requirement for the use of electron microscopes is the absence of external magnetic fields. As a result, the laboratories in which they are used have very thick insulated walls or are located in underground bunkers.

Such equipment is used in medicine, biology, as well as in various industries.

Scanning probe microscopes

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 according to the optical type by increasing due to the installation of lenses.

Probes are often used to obtain data on the surface of objects with complex relief. Often they are lowered into a pipe, holes, as well as small tunnels. The only condition is that the diameter of the probe corresponds to the diameter of the object under 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 initial data is processed mathematically using specialized software.

X-ray microscopes

The X-ray microscope is laboratory equipment used to study objects whose dimensions are comparable to the X-ray wavelength. Enlargement efficiency this device located between optical and electronic devices. X-rays are sent to the object under study, after which sensitive sensors react to their refraction. As a result, a picture of the surface of the object under study is created. Due to the fact that x-rays can pass through the surface of an object, such equipment allows not only to obtain data on the structure of the object, but also its chemical composition.

X-ray equipment is commonly used to assess the quality of thin coatings. It is used in biology and botany, as well as for the analysis of powder mixtures and metals.

The term "microscope" has Greek roots. It consists of two words, which in translation mean "small" and "look." The main role of the microscope is its use in examining very small objects. At the same time, this device allows you to determine the size and shape, structure and other characteristics of bodies invisible to the naked eye.

History of creation

There is no exact information about who was the inventor of the microscope in history. According to some sources, it was designed in 1590 by the father and son of Janssen, a master in the manufacture of glasses. Another contender for the title of inventor of the microscope is Galileo Galilei. In 1609, these scientists presented a device with a concave and convex lens on public display at the Accademia dei Lincei.

Over the years, the system for viewing microscopic objects has evolved and improved. A huge step in its history was the invention of a simple achromatically adjustable two-lens device. This system was introduced by the Dutchman Christian Huygens in the late 1600s. The eyepieces of this inventor are still in production today. Their only drawback is the insufficient breadth of the field of view. In addition, compared with the design of modern devices, Huygens eyepieces have an uncomfortable position for the eyes.

Anton van Leeuwenhoek (1632-1723), a manufacturer of such instruments, made a special contribution to the history of the microscope. It was he who drew the attention of biologists to this device. Leeuwenhoek made small-sized products equipped with one, but very strong lens. It was inconvenient to use such devices, but they did not double the image defects that were present in compound microscopes. The inventors were able to correct this shortcoming only after 150 years. Along with the development of optics, the image quality in composite devices has improved.

Improving microscopes continues to this day. So, in 2006, the German scientists working at the Institute of Biophysical Chemistry, Mariano Bossi and Stefan Hell, developed the latest optical microscope. Due to the ability to observe objects with dimensions of 10 nm and three-dimensional high-quality 3D images, the device was called a nanoscope.

Microscope classification

Currently, there is a wide variety of instruments designed to examine small objects. Their grouping is based on various parameters. This may be the purpose of a microscope or accepted way lighting, structure used for the optical design, etc.

But, as a rule, the main types of microscopes are classified according to the resolution of microparticles that can be seen using this system. According to this division, microscopes are:
- optical (light);
- electronic;
- x-ray;
- scanning probes.

The most widely used microscopes are of the light type. Their wide selection is available in optics stores. With the help of such devices, the main tasks of studying an object are solved. All other types of microscopes are classified as specialized. They are usually used in the laboratory.

Each of the above types of devices has its own subspecies, which are used in a particular area. In addition, today there is an opportunity to buy a school microscope (or educational), which is a system entry level. Offered to consumers and professional devices.

Application

What is a microscope for? The human eye, being a special biological type optical system, has a certain level of resolution. In other words, there is the smallest distance between observed objects when they can still be distinguished. For a normal eye, this resolution is in the range of 0.176 mm. But the sizes of most animals and plant cells, microorganisms, crystals, microstructure of alloys, metals, etc. are much less than this value. How to study and observe such objects? This is where people come to help different kinds microscopes. For example, optical type devices make it possible to distinguish structures in which the distance between elements is at least 0.20 μm.

How is a microscope made?

The device with which human eye consideration of microscopic objects becomes available, has two main elements. They are the lens and the eyepiece. These parts of the microscope are fixed in a movable tube located on a metal base. It also has an object table.

Modern types of microscopes are usually equipped with a lighting system. This is, in particular, a condenser having an iris diaphragm. A mandatory set of magnifying devices are micro and macro screws, which serve to adjust the sharpness. The design of microscopes also provides for the presence of a system that controls the position of the condenser.

Specialized, more complex microscopes often use other additional systems and devices.

Lenses

I would like to start the description of the microscope with a story about one of its main parts, that is, from the lens. They are a complex optical system that increases the size of the object in question in the image plane. The design of the lenses includes a whole system of not only single lenses, but also lenses glued in two or three pieces.

The complexity of such an optical-mechanical design depends on the range of tasks that must be solved by one or another device. For example, in the most complex microscope, up to fourteen lenses are provided.

The lens consists of the front part and the systems that follow it. What is the basis for building an image the right quality, as well as determining the operating state? This is a front lens or their system. Subsequent parts of the lens are necessary to provide the required magnification, focal length and image quality. However, the implementation of such functions is only possible in combination with a front lens. It is worth mentioning that the design of the next part affects the length of the tube and the height of the lens of the device.

Eyepieces

These parts of the microscope are an optical system designed to build the necessary microscopic image on the surface of the retina of the observer's eyes. The eyepieces contain two groups of lenses. The closest to the eye of the researcher is called the eye, and the farthest is called the field (with its help, the lens builds an image of the object under study).

Lighting system

The microscope has a complex design of diaphragms, mirrors and lenses. With its help, uniform illumination of the object under study is ensured. In the very first microscopes this function carried out As optical instruments improved, they began to use first flat and then concave mirrors.

With the help of such simple details, the rays from the sun or lamps were directed to the object of study. In modern microscopes more perfect. It consists of a condenser and a collector.

Subject table

Microscopic preparations requiring study are placed on a flat surface. This is the subject table. Various types of microscopes can have this surface designed in such a way that the object of study will turn into the observer horizontally, vertically or at a certain angle.

Operating principle

In the first optical device, the lens system provided an inverse image of microobjects. This made it possible to see the structure of matter and the smallest details that were to be studied. The principle of operation of a light microscope today is similar to the work carried out by a refractor telescope. In this device, light is refracted as it passes through the glass part.

How do modern light microscopes? After a beam of light rays enters the device, they are converted into a parallel stream. Only then does the refraction of light in the eyepiece, due to which the image of microscopic objects increases. Further, this information arrives in the form necessary for the observer in his

Subspecies of light microscopes

Modern classify:

1. According to the class of complexity for a research, working and school microscope.
2. According to the field of application for surgical, biological and technical.
3. By types of microscopy for reflected and transmitted light, phase contact, luminescent and polarizing devices.
4. In the direction of the light flux to inverted and direct.

Electron microscopes

Over time, the device designed to examine microscopic objects became more and more perfect. Such types of microscopes appeared in which a completely different principle of operation, independent of the refraction of light, was used. In use latest types devices involved electrons. Such systems make it possible to see individual parts of matter so small that light rays simply flow around them.

What is a microscope for? electronic type? It is used to study the structure of cells at the molecular and subcellular levels. Also, similar devices are used to study viruses.

The device of electron microscopes

What is the basis of the work the latest appliances to view microscopic objects? How is an electron microscope different from a light microscope? Are there any similarities between them?

The principle of operation of an electron microscope is based on the properties that electrical and magnetic fields. Their rotational symmetry is able to have a focusing effect on electron beams. Based on this, we can answer the question: “How does an electron microscope differ from a light microscope?” In it, unlike an optical device, there are no lenses. Their role is played by appropriately calculated magnetic and electric fields. They are created by turns of coils through which current passes. In this case, such fields act similarly. When the current increases or decreases, the focal length of the device changes.

As for the circuit diagram, for an electron microscope it is similar to the diagram of a light device. The only difference is that the optical elements are replaced by electric ones similar to them.

An increase in an object in electron microscopes occurs due to the process of refraction of a beam of light passing through the object under study. At different angles, the rays enter the plane of the objective lens, where the first magnification of the sample takes place. Then the electrons pass the way to the intermediate lens. In it there is a smooth change in the increase in the size of the object. The final image of the studied material is given by the projection lens. From it, the image falls on a fluorescent screen.

Types of electron microscopes

Modern species include:

1. TEM, or transmission electron microscope. In this setup, an image of a very thin object, up to 0.1 µm thick, is formed by the interaction of an electron beam with the substance under study and its subsequent magnification by magnetic lenses located in the objective.
2. SEM, or scanning electron microscope. Such a device makes it possible to obtain an image of the surface of an object with a high resolution of the order of several nanometers. Using additional methods such a microscope provides information that helps to determine chemical composition surface layers.
3. Tunneling Scanning Electron Microscope, or STM. Using this device, the relief of conductive surfaces with high spatial resolution is measured. In the process of working with STM, a sharp metal needle is brought to the object under study. At the same time, a distance of only a few angstroms is maintained. Next, a small potential is applied to the needle, due to which a tunnel current arises. In this case, the observer receives a three-dimensional image of the object under study.

Microscopes Leeuwenhoek

In 2002, America appeared new company engaged in the production of optical instruments. Its product range includes microscopes, telescopes and binoculars. All these devices are distinguished by high image quality.

The head office and development department of the company are located in the USA, in the city of Fremond (California). But as regards production capacity then they are in China. Thanks to all this, the company supplies the market with advanced and high-quality products at an affordable price.

Do you need a microscope? Levenhuk will suggest the required option. The range of optical equipment of the company includes digital and biological devices for magnifying the object under study. In addition, the buyer is offered and designer models, executed in a variety of colors.

Levenhuk Microscope has extensive functionality. For example, an entry-level training device can be connected to a computer and is also capable of capturing video of ongoing research. Levenhuk D2L is equipped with this functionality.

The company offers biological microscopes different levels. This and more simple models, and novelties that will suit professionals.

The human eye is designed in such a way that it cannot see an object whose dimensions do not exceed 0.1 mm. In nature, there are objects whose dimensions are much smaller. These are microorganisms, cells of living tissues, elements of the structure of substances and much more.

Even in ancient times, polished natural crystals were used to improve vision. With the development of glassmaking, they began to produce glass lentils - lenses. R. Bacon in the XIII century. advised people with poor eyesight to put convex glasses on objects in order to better examine them. At the same time, glasses appeared in Italy, consisting of two connected lenses.

In the XVI century. craftsmen in Italy and the Netherlands, who made spectacle glasses, knew about the property of a two-lens system to give an enlarged image. One of the first such devices was made in 1590 by the Dutchman 3. Jansen.

Despite the fact that the magnifying power of spherical surfaces and lenses was known as early as the 13th century, until the beginning of the 17th century. none of the naturalists even tried to use them for observation smallest items inaccessible to the naked human eye.

The word "microscope", which comes from two Greek words - "small" and "look", was introduced into scientific use by a member of the Academy "Dei Lyncei" (Rynx-eyed) Desmikian at the beginning of the 17th century.

In 1609, Galileo Galilei, studying the telescope he had designed, also used it as a microscope. To do this, he changed the distance between the lens and the eyepiece. Galileo was the first to come to the conclusion that the quality of lenses for spectacles and telescopes must be different. He created a microscope, choosing such a distance between the lenses, at which not distant, but closely spaced objects increased. In 1614, Galileo examined insects with a microscope.

Galileo's student E. Torricelli adopted the art of grinding lenses from his teacher. In addition to making telescopes, Torricelli designed simple microscopes, consisting of one tiny lens, which he obtained from one drop of glass by melting a glass rod over a fire.

In the 17th century the simplest microscopes were popular, consisting of a magnifying glass - a biconvex lens mounted on a stand. The object table, on which the object in question was placed, was also fixed on the stand. At the bottom, under the table, there was a mirror of a flat or convex shape, which reflected Sun rays on an object and illuminated it from below. To improve the image, the magnifier was moved relative to the stage using a screw.

In 1665, the Englishman R. Hooke, using a microscope that used small glass balls, discovered cellular structure animal and plant tissues.

Hooke's contemporary, the Dutchman A. van Leeuwenhoek, made microscopes consisting of small biconvex lenses. They gave 150–300x magnification. With the help of his microscopes, Leeuwenhoek studied the structure of living organisms. In particular, he discovered the movement of blood in blood vessels and red blood cells, spermatozoa, described the structure of muscles, skin scales, and much more.

Leeuwenhoek opened new world the world of microorganisms. He described many types of ciliates and bacteria.

Many discoveries in the field of microscopic anatomy were made by the Dutch biologist J. Swammerdam. He studied the anatomy of insects in most detail. In the 30s. 18th century he produced a lavishly illustrated work entitled The Bible of Nature.

Methods for calculating the optical components of a microscope were developed by the Swiss L. Euler, who worked in Russia.

The most common scheme of the microscope is as follows: the object under study is placed on the object table. Above it is a device in which objective lenses and a tube are mounted - a tube with an eyepiece. The observed object is illuminated with a lamp or sunlight, inclined mirror and lens. Apertures installed between the light source and the object limit the luminous flux and reduce the proportion of scattered light in it. Between the diaphragms there is a mirror that changes the direction of the light flux by 90°. The condenser concentrates a beam of light on the subject. The lens collects the rays scattered by the object and forms an enlarged image of the object, viewed with the help of an eyepiece. The eyepiece works like a magnifying glass, giving extra magnification. The magnification limits of the microscope are from 44 to 1500 times.

In 1827, J. Amici used an immersion objective in a microscope. In it, the space between the object and the lens is filled with immersion liquid. As such a liquid, various oils (cedar or mineral), water or water solution glycerin, etc. Such lenses allow increasing the resolution of the microscope, improving the contrast of the image.

In 1850, the English optician G. Sorby created the first microscope for observing objects in polarized light. Such devices are used to study crystals, metal samples, animal and plant tissues.

The beginning of interference microscopy was laid in 1893 by the Englishman J. Sirks. Its essence is that each beam, entering the microscope, bifurcates. One of the received rays is directed to the observed particle, the second - past it. In the ocular part, both beams recombine, and interference occurs between them. Interference microscopy allows you to study living tissues and cells.

In the XX century. Various types of microscopes appeared with different purposes and designs, which made it possible to study objects in wide ranges of the spectrum.

So, in inverted microscopes, the objective is located under the observed object, and the condenser is on top. The direction of the rays is changed with the help of a system of mirrors, and they fall into the eye of the observer, as usual - from the bottom up. These microscopes are designed to study bulky objects that are difficult to place on the stage of conventional microscopes. With their help, tissue cultures, chemical reactions are studied, and the melting points of materials are determined. Such microscopes are most widely used in metallography for observing the surfaces of metals, alloys, and minerals. Inverted microscopes can be equipped with special devices for microphotography and microcine filming.

Replaceable light filters are installed on luminescent microscopes, which make it possible to select in the illuminator radiation that part of the spectrum that causes luminescence of the object under study. Special filters pass only luminescence light from the object. The light sources in such microscopes are ultrahigh-pressure mercury lamps that emit ultra-violet rays and rays of the short-wave range of the visible spectrum.

Ultraviolet and infrared microscopes are used to study areas of the spectrum that are inaccessible to the human eye. The optical schemes are similar to those of conventional microscopes. The lenses of these microscopes are made of materials that are transparent to ultraviolet (quartz, fluorite) and infrared (silicon, germanium) rays. They are equipped with cameras that capture an invisible image and electron-optical converters that turn an invisible image into a visible one.

A stereo microscope provides a three-dimensional image of an object. These are actually two microscopes, made in a single design in such a way that the right and left eyes observe the object from different angles. They have found applications in microsurgery and the assembly of miniature devices.

Comparison microscopes are two conventional combined microscopes with a single ocular system. In such microscopes, two objects can be observed at once, comparing their visual characteristics.

In television microscopes, the image of the drug is converted into electrical signals that reproduce this image on the screen of the cathode ray tube. In these microscopes, you can change the brightness and contrast of the image. With their help, you can study at a safe distance objects that are dangerous for viewing at close range, such as radioactive substances.

The best optical microscopes allow you to magnify the observed objects by about 2000 times. Further magnification is not possible because the light bends around the illuminated object, and if its dimensions are smaller than the wavelength, such an object becomes invisible. Minimum size an object that can be seen through an optical microscope is 0.2-0.3 micrometers.

In 1834, W. Hamilton established that there is an analogy between the passage of light rays in optically inhomogeneous media and the trajectories of particles in force fields. The possibility of creating an electron microscope appeared in 1924 after L. De Broglie put forward the hypothesis that all types of matter without exception - electrons, protons, atoms, etc. and waves. The technical prerequisites for creating such a microscope appeared thanks to the research of the German physicist X. Bush. He studied the focusing properties of axisymmetric fields and in 1928 developed a magnetic electron lens.

In 1928, M. Knoll and M. Ruska set about creating the first magnetic transmission microscope. Three years later, they captured an image of an object shaped by electron beams. In 1938 M. von Ardenne in Germany and in 1942 V.K. Zworykin in the USA built the first scanning electron microscopes operating on the principle of scanning. In them, a thin electron beam (probe) sequentially moved over the object from point to point.

In an electron microscope, unlike an optical one, electrons are used instead of light rays, and electromagnetic coils or electronic lenses are used instead of glass lenses. The electron gun is the source of electrons for illuminating the object. In it, the source of electrons is a metal cathode. Then the electrons are collected into a beam using a focusing electrode and, under the action of a strong electric field acting between the cathode and anode, gain energy. To create a field, a voltage of up to 100 kilovolts or more is applied to the electrodes. The voltage is regulated in steps and is very stable - in 1-3 minutes it changes by no more than 1-2 millionths of the original value.

Leaving the electron "gun", the electron beam is directed to the object with the help of a condenser lens, scattered on it and focused by the object lens, which creates an intermediate image of the object. The projection lens collects the electrons again and creates a second, even larger image on the fluorescent screen. On it, under the action of electrons hitting it, a luminous picture of the object arises. If you place a photographic plate under the screen, you can photograph this image.

Great Definition

Incomplete definition ↓

Tudupov Ayur

In his work, the student considers the history of the creation of the microscope. And also describes the experience of creating a simple microscope at home.

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MOU "Mogoytuy secondary school No. 1"

Research work on the topic

"What is a microscope"

Section: physics, technology

Completed by: 2nd grade student Ayur Tudupov

Head: Baranova I.V.

town Mogoytuy

year 2013

Performance

being put forward

student of the 2nd grade MOU MSOSH No. 1 p. Mogoytuy Tudupov Ayur

Research paper title

"What is a microscope?"

Work manager

Baranova Irina Vladimirovna

Brief description (topic) of the work :

This work belongs to experimental studies and is an experimental - theoretical study.

Direction:

Physics, applied research (technics).

Brief description of the research work

Name "What is a microscope?"

Made by Tudupov Ayur

Under the direction ofBaranova Irina Vladimirovna

Research work is devoted to the study of:making a microscope with a drop of water

Where did your interest in this issue come from?I always wanted to have a microscope to see the invisible world.

Where did we look for information to answer our questions?(indicate sources)

1. Internet
2. encyclopedias
3. Teacher consultation

What hypothesis was put forward?you can create a microscope with your own hands from a drop of water.

In the study, we usedthe following methods:

Experiments:

1. Experiment No. 1 "Creating a microscope."
2. Working with books.

Conclusions:

1. At home, you can make a simple microscope from improvised means.
2. I learned what a microscope is made of.
3. Creating your own thing is very interesting, especially since the microscope is an interesting thing.

We plan to use photographs to present the results of the study.

Participant Questionnaire

Work plan

1. Questionnaire of the author of the work - page 1
2. Table of contents - page 2
3. Brief description of the project - page 3
4. Introduction - page 4
5. Main body - pages 5 – 10
6. Microscope experiment. - pp. 11-14
7. Conclusion - page 15
8. Literature and sources - page 16

INTRODUCTION

From the early age every day, at home, in kindergarten and at school, coming from a walk and after the toilet, after games and before eating, I hear the same thing: “Don't forget to wash your hands!”. And so I thought: “Why wash them so often? Are they really clean?" I asked my mother: “Why do you need to wash your hands?”. Mom answered: “On the hands, as well as on all surrounding objects, there are many microbes that, if they get into the mouth with food, can cause illness.” I looked closely at my hands, but I did not see any germs. And my mother said that microbes are very small and cannot be seen without special magnifying devices. Then I armed myself with a magnifying glass and began to look at everything that surrounded me. But I still didn't see any microbes. My mother explained to me that microbes are so small that they can only be seen under a microscope. We have microscopes at school, but you can't take them home and look for germs. And then I decided to make my own microscope.

Purpose of my research: Assemble your microscope.

Project objectives:

1. Learn the history of the microscope.
2. Find out what microscopes consist of and what they can be.
3. Try to build your own microscope and test it.

My hypothesis : you can create a microscope with your own hands at home from a drop of water and improvised means.

Main part

The history of the creation of the microscope.

Microscope (from Greek - small and look) - an optical device for obtaining enlarged images of objects invisible to the naked eye.

It's fun to look at something through a microscope. No worse computer games and maybe even better. But who invented this miracle - a microscope?

Three hundred and fifty years ago, a spectacle master lived in the Dutch city of Middelburg. He patiently polished glasses, made glasses and sold them to anyone who needed it. He had two children - two boys. They were very fond of climbing into their father's workshop and playing with his instruments and glasses, although this was forbidden to them. And then one day, when the father went away somewhere, the guys made their way, as usual, to his workbench - is there anything new that you can have fun with? Glasses prepared for glasses lay on the table, and in the corner lay a short copper tube: from it the master was going to cut out rings - a frame for glasses. The guys squeezed spectacle glass into the ends of the tube. The older boy put a tube to his eye and looked at the page of an open book that was lying on the table here. To his surprise, the letters became huge. The younger looked into the phone and shouted, amazed: he saw a comma, but what a comma - it looked like a fat worm! The guys aimed the tube at the glass dust left after the glass was polished. And they saw not dust, but a bunch of glass grains. The tube turned out to be downright magical: it greatly enlarged all objects. The children told their father about their discovery. He did not even scold them: he was so surprised by the extraordinary property of the pipe. He tried to make another tube with the same glasses, long and extendable. The new tube increased even better. This was the first microscope. His

accidentally invented in 1590 by the spectacle master Zakharia Jansen, or rather, his children.

Similar thoughts about creating a magnifying device occurred to more than one Jansen: new devices were invented by the Dutchman Jan Lipershey (also a master of spectacles and also from Middelburg), and Jacob Metius. In England, the Dutchman Cornelius Drebbel appeared, who invented a microscope with two biconvex lenses. When rumors spread in 1609 that there was some kind of device for viewing tiny objects in Holland, Galileo understood the general idea of ​​\u200b\u200bthe design the very next day and made a microscope in his laboratory, and in 1612 he had already established the manufacture of microscopes. At first, no one called the created device a microscope, it was called a conspicillium. The familiar words "telescope" and "microscope" were first uttered in 1614 by the Greek Demiscian.

In 1697, the Great Embassy left Moscow from Moscow, which included our Tsar Peter the Great. In Holland, he heard that "a certain Dutchman Leeuwenhoek", who lives in the city of Delft, makes amazing devices at home. With their help, he discovered thousands of animals, more wonderful than the most outlandish overseas animals. And these small animals "nest" in the water, in the air and even in the human mouth. Knowing the king's curiosity, it is not difficult to guess that Peter immediately went to visit. The devices that the king saw were the so-called simple microscopes (it was a magnifier with high magnification). However, Leeuwenhoek managed to achieve a magnification of 300 times, and this exceeded the capabilities of the best compound microscopes of the 17th century, which had both an objective and an eyepiece.

For a long time, the secret of "flea glass", as Leeuwenhoek's device was dismissively called by envious contemporaries, could not be revealed. How could

it turns out that in the 17th century a scientist created devices that, according to some characteristics, are close to devices of the early 20th century? After all, with the technology of that time it was impossible to make a microscope. Leeuwenhoek himself did not reveal his secret to anyone. The mystery of "flea glass" was revealed only after 315 years, in the Novosibirsk State medical institute at the Department of General Biology and Fundamentals of Genetics. The secret had to be very simple, because Leeuwenhoek managed to make many copies of his single-lens microscopes in a short time. Maybe he never polished magnifying lenses? Yes, fire did it for him! If you take a glass thread and place it in the flame of a burner, a ball will appear at the end of the thread - it was Leeuwenhoek who served as a lens. The smaller the ball was, the greater the increase could be achieved ...

In 1697, Peter the Great spent about two hours at Leeuwenhoek - and looked and looked. And already in 1716, during his second trip abroad, the emperor purchased the first microscopes for the Kunstkamera. So a wonderful device appeared in Russia.

A microscope can be called an instrument that reveals secrets. microscopes in different years looked different, but every year they became more and more complex, and they began to have many details.

This is what Jansen's first microscope looked like:

The first large compound microscope was made by the English physicist Robert Hooke in the 17th century.

This is what microscopes looked like in the 18th century. There were many travelers in the 18th century. And they needed to have a travel microscope that would fit in a bag or jacket pocket. In the first half of the XVIII century. the so-called "hand" or "pocket" microscope, designed by the English optician J. Wilson, became widespread. This is how they looked:

What is a microscope made of?

All microscopes consist of the following parts:

There is also a backlight and clips.

I also learned what microscopes can be. IN modern world Allmicroscopescan be divided:

1. Educational microscopes. They are also called school or children's.
2. Digital microscopes. The main task of a digital microscope is not just to show an object in an enlarged form, but also to take a photo or shoot a video.
3. Laboratory microscopes. The main task of a laboratory microscope is to conduct specific research in various fields science, industry, medicine.

Building your own microscope

When we were looking for information about the history of microscopes, we found out on one of the sites that you can make your own microscope from a drop of water. And then I decided to try to conduct an experiment to create such a microscope. A small microscope can be made from a drop of water. To do this, take thick paper, pierce a hole in it with a thick needle and carefully place a drop of water on it. The microscope is ready! Bring this drop to the newspaper - the letters have increased. The smaller the drop, the greater the magnification. In the first microscope, invented by Leeuwenhoek, everything was done just like that, only the droplet was glass.

We found a book called "My first scientific experiments" and slightly complicated the model of the microscope. For work I needed:

1. Glass jar.
2. Metallized paper (baking foil).
3. Scissors.
4. Scotch.
5. Thick needle.
6. Plasticine.

When I collected all this, I started to create a microscope model. A little lower I will gradually sign all my work. Of course, I needed a little help from my mother and sister.