Parts of a microscope and what they do. Main parts of the microscope: mechanical, optical and lighting
The term "microscope" has Greek roots. It consists of two words, which when translated mean “small” and “I 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 in history about who was the inventor of the microscope. According to some sources, it was designed in 1590 by the father and son Janssens, eyeglass makers. Another contender for the title of inventor of the microscope is Galileo Galilei. In 1609, these scientists presented an instrument with concave and convex lenses to the public 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 width of the field of view. In addition, compared to the design of modern instruments, Huygens eyepieces have an inconvenient location for the eyes.
A special contribution to the history of the microscope was made by the manufacturer of such devices, Anton Van Leeuwenhoek (1632-1723). It was he who attracted the attention of biologists to this device. Leeuwenhoek produced small-sized products equipped with one, but very strong lens. Such devices were inconvenient to use, but they did not double the image defects that were present in compound microscopes. The inventors were able to correct this shortcoming only 150 years later. Along with the development of optics, image quality in composite devices has improved.
Improvement of microscopes continues to this day. Thus, in 2006, German scientists working at the Institute of Biophysical Chemistry, Mariano Bossi and Stefan Hell, developed a new 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.
Classification of microscopes
Currently exists great variety instruments designed to examine small objects. Their grouping is based on various parameters. This may be the purpose of the microscope or the illumination method adopted, the 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 the light type. There is a wide selection of them in optical stores. With the help of such devices, the main tasks of studying a particular object are solved. All other types of microscopes are classified as specialized. They are usually used in a laboratory setting.
Each of the above types of devices has its own subtypes, which are used in one area or another. In addition, today it is possible to buy a school microscope (or educational), which is an entry-level system. Professional devices are also offered to consumers.
Application
What is a microscope for? The human eye, being a special optical system biological type, has a certain level of resolution. In other words, there is a smallest distance between observed objects when they can still be distinguished. For a normal eye, this resolution is within 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 different types of microscopes come to the aid of people. For example, optical devices make it possible to distinguish structures in which the distance between elements is at least 0.20 microns.
How does a microscope work?
A device with which to the 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. There is also an object table on it.
Modern types of microscopes are usually equipped with a lighting system. This, in particular, is a condenser with an iris diaphragm. A mandatory set of magnifying devices includes micro- and macroscrews, which are used to adjust the sharpness. The design of microscopes also includes 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 describing the microscope with a story about one of its main parts, that is, 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, but also two or three lenses glued together.
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, the most complex microscope has up to fourteen lenses.
The lens consists of the front part and the systems following it. What is the basis for constructing an image of the required quality, as well as determining the working condition? 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, such functions are only possible in combination with a front lens. It is also worth mentioning that the design of the subsequent 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 construct the necessary microscopic image on the surface of the retina of the observer's eye. The eyepieces contain two groups of lenses. The one closest to the researcher’s eye is called the ocular one, and the farthest one is the field one (with its help, the lens builds an image of the object being studied).
Lighting system
The microscope has complex design from 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, rays from the sun or lamp 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 examination are placed on a flat surface. This is the object table. Various types microscopes may have this surface, designed in such a way that the object of study will be rotated towards the observer horizontally, vertically or at a certain angle.
Operating principle
In the first optical device, a system of lenses gave an inverse image of micro-objects. This made it possible to discern the structure of the substance and the smallest details that were subject to study. The principle of operation of a light microscope today is similar to the work carried out by refracting telescope. In this device, light is refracted as it passes through the glass part.
How do modern light microscopes magnify? After a beam of light rays enters the device, they are converted into a parallel stream. Only then does the refraction of light occur in the eyepiece, due to which the image of microscopic objects is magnified. Next, this information arrives in the form necessary for the observer in his
Subtypes of light microscopes
Modern ones classify:
1. By complexity class for research, work and school microscopes.
2. By area of application: surgical, biological and technical.
3. By types of microscopy: devices of reflected and transmitted light, phase contact, luminescent and polarization.
4. In the direction of the light flux into inverted and direct.
Electron microscopes
Over time, the device designed to examine microscopic objects became more and more sophisticated. Such types of microscopes appeared in which a completely different operating principle, independent of the refraction of light, was used. In the process of using the newest types of devices, electrons were involved. Similar systems They allow you to see individual parts of matter so small that light rays simply flow around them.
What is an electron microscope used for? It is used to study the structure of cells at the molecular and subcellular levels. Similar devices are also used to study viruses.
The device of electron microscopes
What underlies the operation of the latest instruments for viewing microscopic objects? How is an electron microscope different from a light microscope? Are there any similarities between them?
The operating principle of an electron microscope is based on the properties that electrical and magnetic fields. Their rotational symmetry can 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?” It, unlike an optical device, does not have 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 that of a light device. The only difference is that optical elements replaced by similar electric ones.
Magnification of an object in electron microscopes occurs due to the process of refraction of a beam of light passing through the object under study. At various angles, the rays enter the plane of the objective lens, where the first magnification of the sample occurs. Next, the electrons travel their 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 material under study is produced by the projection lens. From it the image hits the fluorescent screen.
Types of electron microscopes
Modern types include:
1. TEM, or transmission electron microscope. In this installation, an image of a very thin object, up to 0.1 microns 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 lens.
2. SEM, or scanning electron microscope. Such a device makes it possible to obtain an image of the surface of an object with high resolution, on the order of several nanometers. When using additional methods such a microscope provides information that helps determine the chemical composition of near-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 being studied. In this case, a distance of only a few angstroms is maintained. Next, a small potential is applied to the needle, resulting in a tunnel current. In this case, the observer receives a three-dimensional image of the object under study.
Microscopes "Leevenguk"
In 2002, it appeared in America new company, engaged in the production of optical instruments. Its product range includes microscopes, telescopes and binoculars. All these devices are distinguished by high quality images.
The company's head office and development department are located in the USA, in Fremond (California). But as for production facilities, they are located 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 offer the required option. The company's range of optical equipment includes digital and biological devices for magnifying the object being studied. In addition, the buyer is offered designer models in a variety of colors.
The Levenhuk microscope has extensive functionality. For example, educational device entry-level can be connected to a computer, and it is also capable of video recording of ongoing research. The Levenhuk D2L model is equipped with this functionality.
The company offers biological microscopes various levels. These include simpler models and new items that are suitable for professionals.
The study of the morphological characteristics of microbes - their shape, structure and size of cells, ability to move, etc. - is carried out using an optical instrument - a microscope (from the Greek “micros” - small, “skopeo” - I look). Of the biological microscopes produced, the best are MBI-1, MBI-2, MBI-3, MBR-1 and some others.
The main parts of a microscope are: the optical system (lens and eyepiece), the illuminating optical system (condenser and mirror) and the mechanical part. The optical system creates a magnified image of the object. The mechanical part provides movement optical system and the observed object (subject). Main parts mechanical system microscope (Fig. 60) are: a tripod, a stage, a tube holder with a revolver and screws for moving the tube - macrometric and micrometric.
A macrometric screw (crackle, or gear) is used for rough aiming of the microscope. The micrometer screw is a fine feed mechanism and serves for the final, precise focusing of the microscope on the specimen. Full turn The microscrew moves the microscope tube by 0.1 mm. The micrometer screw is one of the most fragile parts of the microscope and must be handled with extreme care. The sharpest and clearest image is obtained by moving the tube using macro- and micrometer screws with appropriate lighting settings. The microscope tube is fixed in the upper part of the tripod in a tube holder. The object stage is also mounted at the top of the tripod. In modern microscopes, the stage is almost always made movable. It is driven by two screws located on both sides of the table. With the help of these screws, the preparation, together with the table, moves into different directions, which greatly facilitates the examination of the drug at its various points. The drug is secured to the table with two terminals (clamps).
In addition to movable stages, some microscopes are equipped with cross-shaped stages. In this case, the drugs are moved in two mutually perpendicular directions. Two scales on the table allow you to mark areas of interest to the researcher so that they can be easily found during repeated microscopy.
At the bottom of the tube holder there is a revolver with holes equipped with threads. Lenses are screwed into these holes. Objectives make up the most important and expensive part of a microscope. This complex system biconvex lenses enclosed in a metal frame. Lenses magnify the subject being viewed, producing a truly magnified reverse image.
All lenses are divided into achromats and apochromats. Achromats are more common due to their simplicity and low cost. They have six lenses made from optical glass. The image obtained with achromats is sharpest in the center. The edges of the field due to chromatic aberration are often colored blue, yellow, green, red and other colors. Apochromats consist of more lenses (up to 10). For their manufacture, glass of various types is used. chemical composition: boric, phosphoric, fluorite, alum. In apochromats, chromatic aberration is largely eliminated.
Typically, microscopes are equipped with three objectives, which indicate the magnification they provide: 8X (low magnification), 40X (medium magnification) and 90X (high magnification) objectives. 8X and 40X lenses are dry systems, since when working with them there is a layer of air between the drug and the lens. Rays of light, passing through media of different densities (refractive index of air n = 1, glass n = 1.52) and getting from a denser medium (glass) to a less dense one (air), are strongly deflected and do not completely enter the microscope lens. Therefore, dry lenses can only be used at relatively low magnifications (up to 500-600 times).
The higher the magnification, the smaller the diameter of the lenses. Therefore, at high magnifications, too little of the rays enter the objective lens and the image is not clear enough. To avoid this, they resort to immersion (immersion) of the lens in a medium having a refractive index close to the refractive index of glass. Such an immersion, or submersible, objective in biological microscopes is the 90X objective. When working, a drop of immersion (most often cedar) oil, the refractive index of which is 1.51, is placed between this lens and a glass slide. The lens is immersed directly in oil, light rays pass through a homogeneous system without refraction or scattering, which helps to obtain a clear image of the object in question.
IN top part An eyepiece is inserted into the microscope tube. The eyepiece consists of two converging lenses: one facing the objective and one facing the eye. Between them in the eyepiece there is a diaphragm that blocks side rays and transmits rays parallel to the optical axis. This provides a higher contrast intermediate image. The eye lens of the eyepiece magnifies the image received from the objective. Eyepieces are manufactured with their own magnification of 7X, 10X, 15X times. The total magnification of a microscope is equal to the magnification of the objective multiplied by the magnification of the eyepiece. By combining eyepieces with objectives, various magnifications can be obtained - from 56 to 1350 times.
The condenser is a biconvex lens that collects light reflected from the mirror into a beam and directs it into the plane of the preparation, which provides the best illumination of the object. By raising and lowering the condenser, you can adjust the degree of illumination of the preparation. At the bottom of the condenser there is an iris diaphragm, through which you can also change the brightness of the lighting, narrowing it or, conversely, fully opening it.
The mirror, which has two reflective surfaces - flat and concave, is mounted on a swinging lever, with which it can be installed in any plane. The concave side of the mirror is rarely used - when working with weak lenses. The mirror reflects light rays and directs them into the lens through the condenser iris, the condenser and the object being viewed. At the bottom of the condenser frame there is a folding frame, which is used for installing light filters.
A microscope is a complex optical device; it requires careful and careful handling and appropriate operating skills. Proper care of the device and careful adherence to the instructions for use guarantee its impeccable and long-term service. Microscope image quality is highly dependent on illumination, so adjusting the illumination is an important preparatory step.
Work with a microscope can be carried out both under natural and artificial lighting. For responsible work they use artificial lighting, using the OI-19 illuminator. In natural light, you need to use diffused side light rather than direct sunlight.
Modern microscopes MBI-2, MBI-3 are equipped with binocular attachments of the AU-12 type, which have their own magnification of 1.5x, and a direct replaceable tube (Fig. 61). When using a binocular attachment, microscopy is facilitated, since observation is carried out with both eyes and vision does not become tired.
Bright field microscopy
The study of microbial cells invisible to the naked eye, whose dimensions do not exceed tens and hundreds of micrometers (1 μm = 0.001 mm), is possible only with the help of microscopes (from the Greek. mikros - small, skopeo - I'm watching). These devices make it possible to obtain hundreds of times (light microscopes) and tens to hundreds of thousands of times ( electron microscopes) enlarged image of the objects under study.
Using a microscope, they study the morphology of microorganism cells, their growth and development, and carry out primary identification (from Lat. IDENIFICARE- identification) of the studied organisms, monitor the nature of the development of microbial cenoses (communities) in the soil and other substrates.
The microscope consists of two parts: mechanical (auxiliary) and optical (main).
Mechanical part of the microscope. It includes a tripod, a stage and a tube (tube).
Tripod has a horseshoe-shaped base and a column (tube holder) in the shape of an arc. Adjacent to it is a mechanism box, a system gear wheels to regulate the position of the tube. The system is driven by rotation of macrometric and micrometric screws.
Micrometer screw(rack, gear, macroscrew) serves for preliminary approximate installation of the image of the object in question.
Micrometer screw(microscrew) is used for subsequent clear focusing. When the microscrew is fully rotated, the pipe moves 0.1 mm (100 µm).
When the screws are rotated clockwise, the pipe lowers towards the preparation; when rotated counterclockwise, it rises away from the preparation.
The object table is used to place the preparation with the object of study on it. The object stage rotates and moves in mutually perpendicular planes using screws. In the center of the table there is a round hole for illuminating the specimen from below with rays of light directed by the microscope mirror. Two clamps are built into the table (terminals)- springy metal plates designed to secure the drug.
If it is necessary to examine the surface of the specimen without allowing gaps (which is important when counting), or if during work it is necessary to re-examine any specific area on the specimen, the object table will be drug manager It has a system of rulers - verniers, with the help of which you can assign coordinates to any point of the object under study. To do this, when installing the slide, you should align the center of rotation of the stage and the optical axis of the microscope system with the centering plate of the slide (hence the stage with the slide is sometimes called cross-shaped).
Tube (pipe)- a frame that encloses the elements of the optical system of the microscope. A revolver (lens holder) with sockets for lenses is attached to the bottom of the tube. Modern models microscopes have an inclined tube with an arched tube holder, which ensures a horizontal position of the object stage.
Optical part microscope consists of a main optical unit (lens and eyepiece) and an auxiliary lighting system (mirror and condenser). All parts of the optical system are strictly centered relative to each other. In many modern microscopes, the mirror and condenser are replaced by an adjustable light source built into the device.
Lighting system located under the stage. Mirror reflects the light incident on it into the condenser . One side of the mirror is flat , other - concave. When working with a condenser, you must use only flat mirror. A concave mirror is used when working without a condenser with low magnification lenses . Condenser(from Lat. . condenso- compact, thicken), consisting of 2-3 short-focus lenses, collects rays coming from the mirror , and direct them to the object. A condenser is necessary, first of all, when working with an immersion system. The condenser lenses are mounted in a metal frame connected to a gear mechanism that allows the condenser to be moved up and down by a special screw. To adjust the light intensity in the condenser there is iris(petal) diaphragm, consisting of steel crescent plates
Colored preparations are best viewed with an almost fully open diaphragm, uncolored preparations are best viewed with a reduced diaphragm opening. .
Below the condenser is located ring holder for light filters (usually blue and white frosted glasses are included with the microscope). When working with an artificial light source, filters create the impression of daylight , making microscopy less taxing on the eyes.
Lens(from lat. objectum- object) is the most important part of the microscope. This is a multi-lens short-focus system, the quality of which mainly determines the image of the object. The outer lens facing the preparation with its flat side is called the frontal lens. It is she who provides the increase . The remaining lenses in the objective system perform primarily the functions of correcting optical deficiencies that arise when studying objects .
One of these disadvantages is the phenomenon spherical aberration. It is associated with the property of lenses to unevenly refract peripheral and central rays. The former are usually refracted to a greater extent than the latter, and therefore intersect at a closer distance to the lens. As a result, the image of the point takes on the appearance of a blurry spot.
Chromatic aberration occurs when a beam of rays with different wavelengths passes through a lens . Refracted differently , The rays intersect at more than one point. Blue-violet rays with short length waves refract more strongly than red ones with a longer wavelength. As a result, a color appears in a colorless object.
Lenses that eliminate spherical and partially chromatic aberration include achromats. They contain up to 6 lenses and correct primary spectrum(yellow-green part of the spectrum) without eliminating the secondary spectrum. The image obtained with the help of achromats is not colored, but its edges have a red or bluish halo. In modern achromats this defect is almost imperceptible. Best material for achromat lenses - flint glass - old types of glass with high content lead oxide.
Lenses that eliminate chromatic aberration and for the secondary spectrum are called apochromats. They can contain from 1 to 12 lenses. Apochromat lenses for better correction secondary spectrum is made from fluorspar, rock salt, alum and other materials. Apochromats make it possible to eliminate coloration of the object and obtain an equally sharp image from rays different colors. Maximum effect when working with apochromats, this can only be achieved when they are combined with compensation eyepieces that compensate for the optical deficiencies of the lenses. In compensating eyepieces, the chromatic error is the opposite of the chromatic error of the objective, and as a result, the chromatic aberration of the microscope is almost completely compensated.
Planachromats - a type of apochromat with a flat field of view. Planachromat lenses completely eliminate curvature of the field of view, which causes uneven focusing of an object (with curvature of the field of view, only part of the field is focused). Planachromats and planapochromats are used in microphotography.
Lenses can be dry or submersible (immersion). When working with dry With lenses, there is air between the front lens of the lens and the object of study. Optical calculation immersion lenses provides for their operation when the front lens of the lens is immersed in a liquid homogeneous medium. When working with a dry lens, due to the difference between the refractive indices of glass (1.52) and air (1.0), some of the light rays are deflected and do not enter the observer’s eye (Fig. 1).When working with an immersion objective, it must be placed between the cover glass and the objective lenses. cedar
oil, whose refractive index is close to the refractive index of glass (Table 1).
Rays in an optically homogeneous homogeneous medium do not change their direction. Immersion lenses on the frame have a black circular cut and designations: I - immersion, HI - homogeneous immersion, OI - oil immersion, MI - oil immersion. Lenses are distinguished by their magnification.
Native lens magnification (V) determined by the formula
Where l- optical length of the tube or the distance between the focal plane of the lens and the image plane, which is 128-180 mm for different lenses; f- focal length lens: the larger it is, the lower the lens magnification.
The magnification value of the lenses is indicated on their frame (8x, 40x, 9x). Each lens is also characterized by a certain working distance in millimeters.
For low magnification lenses, the distance from the front lens of the objective lens to the specimen is greater than for high magnification lenses. Thus, lenses with magnifications of 8 x, 40 x and 90 x have respectively working distances of 13.8; 0.6 and 0.12 mm. Depending on what lens you are working with, a macrometric and micrometric screw is selected to focus it. An oil immersion lens has a working distance of 0.12 mm, so it is often called “myopic”.
1 Cedar oil obtained from the seeds of Virginia juniper Juniperus virginiana or Zeravshan archa Juniperus seravschana. Currently, synthetic products that match the optical properties of cedar oil are more often used as immersion liquids.
There are various models of educational and research light microscopes. Such microscopes make it possible to determine the shape of microorganism cells, their size, mobility, the degree of morphological heterogeneity, as well as the ability of microorganisms to differentiate staining.
The success of observing an object and the reliability of the results obtained depend on a good knowledge of the optical system of the microscope.
Let's consider the structure and appearance of a biological microscope, model XSP-136 (Ningbo teaching instrument Co., LTD), and the operation of its components. The microscope has mechanical and optical parts (Figure 3.1).
Figure 3.1 – Design and appearance of the microscope
Mechanical part biological microscope includes a tripod with a stage; binocular attachment; coarse sharpness adjustment knob; sharpness fine adjustment handle; handles for moving the object table right/left, forward/backward; revolving device.
Optical part The microscope includes a lighting apparatus, a condenser, objectives and eyepieces.
Description and operation of the microscope components
Lenses. The lenses (achromat type) included in the microscope kit are designed for a mechanical length of the microscope tube of 160 mm, a linear field of view in the image plane of 18 mm, and a cover glass thickness of 0.17 mm. Each lens body is marked with a linear magnification, for example, 4x; 10x; 40x; 100x and, accordingly, the numerical aperture is indicated as 0.10; 0.25; 0.65; 1.25, as well as color coding.
Binocular attachment. The binocular attachment provides visual observation of the image of the object; is installed in the tripod socket and secured with a screw.
Setting the distance between the axes of the eyepieces in accordance with the eye base of the observer is carried out by turning the bodies with eyepiece tubes in the range from 55 to 75 mm.
Eyepieces. The microscope kit includes two wide-angle eyepieces with 10x magnification.
Revolving device. The four-socket revolving device ensures that the lenses are installed in the working position. Lenses are changed by rotating the corrugated ring of the revolving device to a fixed position.
Condenser. The microscope kit includes a bright-field Abbe condenser with an iris diaphragm and a filter, numerical aperture A = 1.25. The condenser is installed in a bracket under the microscope stage and secured with a screw. The brightfield condenser has an iris aperture diaphragm and a hinged frame for mounting a filter.
Lighting device. To obtain a uniformly illuminated image of objects, the microscope has an LED lighting device. The illuminator is turned on using a switch located on the rear surface of the microscope base. By rotating the lamp filament adjustment dial, located on the side surface of the microscope base to the left of the observer, you can change the brightness of the illumination.
Focusing mechanism. The focusing mechanism is located in the microscope stand. Focusing on an object is done by moving the height of the object table by rotating the handles located on both sides of the tripod. Coarse movement is carried out by a larger handle, fine movement by a smaller handle.
Subject table. The object table ensures movement of the object in the horizontal plane. The table movement range is 70x30 mm. The object is mounted on the surface of the table between the holder and the clamp of the drug guide, for which the clamp is moved to the side.
Working with a microscope
Before starting to work with drugs, it is necessary to properly set up the lighting. This allows you to achieve maximum resolution and image quality of the microscope. To work with a microscope, you should adjust the opening of the eyepieces so that the two images merge into one. The diopter adjustment ring on the right eyepiece should be set to “zero” if the visual acuity of both eyes is the same. Otherwise, it is necessary to perform general focusing, then close the left eye and achieve maximum sharpness for the right one by rotating the correction ring.
It is recommended to start studying the drug with a lens of the lowest magnification, which is used as a search lens when choosing an area for more detailed study, then you can move on to working with stronger lenses.
Make sure the 4x lens is ready for use. This will help you install slide into place, as well as place an object for research. Place the slide on the stage and gently clamp it using the spring holders.
Connect the power cord and turn on the microscope.
Always start your study with a 4x lens. To achieve clarity and sharpness of the image of the object under study, use the coarse and fine focusing knobs. If the weak 4x objective produces the desired image, rotate the nosepiece to the next higher 10x setting. The revolver should lock into place.
While viewing the object through the eyepiece, turn the (large diameter) coarse focusing knob. To get the clearest image, use the (small diameter) focus knob.
To control the flow of light passing through the condenser, you can open or close the iris diaphragm located under the stage. By changing the settings, you can achieve the clearest image of the object under study.
When focusing, do not allow the lens to come into contact with the object of study. When the lens is magnified up to 100x, the lens is very close to the slide.
Rules for handling and caring for a microscope
1 The microscope must be kept clean and protected from damage.
2 To save appearance microscope, it must be periodically wiped with a soft cloth lightly soaked in acid-free petroleum jelly, after removing dust, and then wiped with a dry, soft, clean cloth.
3 Metal parts of the microscope must be kept clean. To clean the microscope, use special non-corrosive lubricants.
4 To protect the optical parts of the visual attachment from dust, it is necessary to leave the eyepieces in the eyepiece tubes.
5 Do not touch the surfaces of optical parts with your fingers. If dust gets on the lens, remove the dust using a fan or brush. If dust has penetrated inside the lens and a cloudy coating has formed on the inner surfaces of the lenses, you must send the lens to an optical workshop for cleaning.
6 To avoid misalignment, it is necessary to protect the microscope from shocks and impacts.
7 To prevent dust from getting on the inner surface of the lenses, the microscope must be stored under a cover or in packaging.
8 You should not disassemble the microscope and its components yourself to troubleshoot problems.
Security measures
When working with a microscope, the source of danger is electric current. The design of the microscope eliminates the possibility of accidental contact with live parts that are energized.
The first concepts about a microscope are formed at school during biology lessons. There, children learn in practice that with the help of this optical device they can examine small objects that cannot be seen with the naked eye. The microscope and its structure are of interest to many schoolchildren. Continuation of these interesting lessons for some of them the whole future becomes adult life. When choosing some professions, it is necessary to know the structure of a microscope, since it is the main tool in the work.
Microscope structure
The design of optical instruments complies with the laws of optics. The structure of a microscope is based on its components. The components of the device in the form of a tube, an eyepiece, a lens, a stand, a table for placing the object of study, and an illuminator with a condenser have a specific purpose.
The stand holds a tube with an eyepiece and lens. An object stage with an illuminator and a condenser is attached to the stand. An illuminator is a built-in lamp or mirror that serves to illuminate the object under study. The image is brighter with an electric lamp. The purpose of the condenser in this system is to regulate illumination and focus the rays on the object being studied. The structure of microscopes without condensers is known; a single lens is installed in them. IN practical work It is more convenient to use optics with a movable table. 
The structure of a microscope and its design directly depend on the purpose of this device. For scientific research X-ray and electron optical equipment with more complex device than lighting devices.
The structure of a light microscope is simple. These are the most affordable optical devices and are most widely used in practice. Eyepiece in the form of two magnifying glasses, placed in a frame, and a lens, which also consists of magnifying glasses tucked into a frame, are the main components of a light microscope. This entire set is inserted into a tube and attached to a tripod, in which a stage with a mirror located under it, as well as an illuminator with a condenser, is mounted.
The main principle of operation of a light microscope is to magnify the image of an object of study placed on the stage by passing light rays through it and then hitting them on the objective lens system. The same role is played by the eyepiece lenses, which are used by the researcher in the process of studying the object.
It should be noted that light microscopes are also not the same. The difference between them is determined by the number of optical units. There are monocular, binocular or stereomicroscopes with one or two optical units.
Despite the fact that these optical instruments have been in use for many years, they remain incredibly in demand. Every year they improve and become more accurate. Not said yet last word in the history of such useful instruments as microscopes.
