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■ Chinese name
microscope
■ English name
microscope
■ Instrument overview
Microscope is an optical instrument composed of one lens or several lenses. It marks that mankind has entered the atomic age. An instrument used to enlarge tiny objects to the extent that people can see them with the naked eye. Microscope can be divided into optical microscope and electron microscope. 1590, Zhan Sen and his son in the Netherlands first invented the optical microscope. At present, the optical microscope can enlarge the object by 1500 times, and the minimum resolution is 0.2 micron.
There are many kinds of optical microscopes, except the general ones, which mainly include:
(1) Dark-field microscope, a microscope with a dark-field condenser, makes the illumination beam not enter from the central part, but shoot at the specimen from the periphery.
(2) fluorescence microscope, which uses ultraviolet light as light source to make the irradiated object emit fluorescence. The electron microscope was first assembled by Noel and Ha Roska in Berlin in 193 1. This microscope uses high-speed electron beams instead of light beams. Because the wavelength of electron flow is much shorter than that of light wave, the magnification of electron microscope can reach 800 thousand times, and the lowest resolution limit is 0.2 nm. 1963 uses a scanning electron microscope, which enables people to see the tiny structures on the surface of objects.
■ Main uses
Microscopes are used to enlarge images of tiny objects. Generally used in biology, medicine and microscopic particle observation.
Instrument structure
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■ Optical microscope structure
The structure of ordinary optical microscope is mainly divided into three parts: mechanical part, lighting part and optical part.
◆ Mechanical part
(1) mirror base: it is the base for the microscope to support the whole mirror body.
(2) Mirror column: it is an upright part above the mirror base, which is used to connect the mirror base and the mirror arm.
(3) Mirror arm: one end is connected to the lens column, and the other end is connected to the lens barrel, which is the hand-held part when taking and placing the microscope.
(4) Lens barrel: connected to the front upper part of the lens arm, with an eyepiece at the upper end and an objective lens converter at the lower end.
(5) The objective lens converter (rotator) is connected to the lower part of the prism housing and can rotate freely. There are 3-4 round holes on the disc, which is where the objective lens is installed. By rotating the converter, the objective lens with different multiples can be replaced. When you hear a knock, you can observe it. At this time, the optical axis of the objective lens is just aligned with the center of the aperture, and the optical path is connected.
(6) stage (stage): There are two shapes under the lens barrel, square and round, and there is a light hole in the center. The microscope we use has a slide specimen pusher (slide pusher) on the stage, a spring clip on the left side of the pusher is used to clamp the slide specimen, and a propeller adjusting wheel is arranged below the stage, which can make the slide specimen move back and forth left and right.
(7) Regulator: There are two kinds of screws installed on the mirror column, which make the mirror table move up and down during adjustment.
① coarse adjuster (coarse adjustment screw): The large screw is called coarse adjuster, which can make the stage move quickly and greatly, so the distance between the objective lens and the specimen can be adjusted quickly, so that the object image appears in the field of vision. Usually, when using a low-power lens, you can quickly find the object image by using the coarse tuner first.
② Fine adjuster (thin screw): Small screw is called fine adjuster, which can make the stage slowly rise and fall when moving. It is mostly used when using high-power lens to obtain clearer images of objects and observe the structures of specimens at different levels and depths.
(8) Converter: The objective lenses with different multiples can be converted when used. After replacing the objective lens, it is not allowed to use the coarse adjuster, but only the fine adjuster to make the image clear.
◆ Lighting part
It is installed under the mirror stage and comprises a reflector and a light collector.
(1) reflector: installed on the mirror base and can rotate in any direction. It has flat and concave sides, and its function is to reflect the light emitted by the light source to the condenser, and then illuminate the specimen through the light hole. Concave mirror has a strong condensing effect and is suitable for use in weak light, while the flat mirror has a weak condensing effect and is suitable for use in strong light.
(2) The light collector (condenser) is located on the light collector frame below the stage and consists of a condenser and an aperture. Its function is to focus light on the sample to be observed.
(1) condenser: It consists of one or several lenses, which can collect light, enhance the illumination of the specimen, and make the light enter the objective lens. There is an adjusting screw next to the lens column, which can rotate to lift the condenser and adjust the brightness of light in the field of view.
(2) Aperture (iridescent aperture): Below the condenser, it consists of more than a dozen pieces of metal, and a handle extends out. Press it to adjust the size of the opening, thus adjusting the amount of light.
◆ Optical part
(1) spectacle lens: it is installed at the upper end of the lens barrel, and usually has 2-3 eyepieces, on which symbols of 5×, 10× or 15× are engraved to indicate its magnification. General installation 10× eyepiece.
(2) Objective lens: installed on the rotating body at the lower end of the lens barrel, there are generally 3-4 objective lenses, of which the shortest one engraved with the symbol "10X" is a low-power mirror, the longer one engraved with the symbol "40X" is a high-power mirror, and the longest one engraved with the symbol "10x" is an oil mirror. Besides,
The magnification of microscope is the product of the magnification of objective lens and the magnification of eyepiece. For example, if the objective lens is 10× the eyepiece is 10×, the magnification is10×/kloc-0 =100.
■ Electron microscope structure
An electron microscope consists of a lens barrel, a vacuum system and a power cabinet. The lens barrel is mainly composed of an electron gun, an electron lens, a sample holder, a fluorescent screen and a camera mechanism, which are usually assembled in a row from top to bottom; The vacuum system consists of a mechanical vacuum pump, a diffusion pump and a vacuum valve, and is connected with the lens barrel through an air extraction pipeline; The power cabinet is composed of high voltage generator, excitation current stabilizer and various adjustment control units.
◆ Electronic lens
The electron lens is the most important part of the electron microscope barrel. It uses a space electric field or magnetic field symmetrical to the axis of the lens barrel to bend the electron trajectory to the axis to form a focus, which is similar to the role of a glass convex lens in focusing light beams, so it is called an electron lens. Most modern electron microscopes use electromagnetic lenses, and very stable DC excitation current focuses electrons through the strong magnetic field generated by coils with pole shoes.
◆ Electron gun
The electron gun is a component composed of tungsten filament hot cathode, grid and cathode. It can emit and form an electron beam with uniform speed, so the stability of accelerating voltage is required to be not less than one ten thousandth.
Imaging principle
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■ Imaging principle of optical microscope
When the observed object is placed out of the focus of the objective lens near the focus, the real image formed behind the objective lens is just in the focus of the eyepiece near the focus, and it is enlarged into a virtual image again through the eyepiece. What is observed is the inverted image virtual image after two enlargements.
■ Imaging principle of electron microscope
Electron microscope is an instrument that uses electron beam and electron lens instead of light beam and optical lens according to the principle of electron optics, so that the fine structure of matter can be imaged at a very high magnification.
The resolving power of an electron microscope is expressed by the minimum distance between two adjacent points that it can resolve. In 1970s, the resolution of transmission electron microscope was about 0.3 nm (human eye resolution was about 0. 1 mm). At present, the maximum magnification of electron microscope is more than 3 million times, while the maximum magnification of optical microscope is about 2000 times, so some heavy metal atoms and ordered atomic lattices in crystals can be directly observed through electron microscope.
Repair and maintenance
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■ Maintenance of microscope
1, regular maintenance
(1) Moisture-proof If the room is humid, the optical lens is prone to mildew and fog. Once the lens is moldy, it is difficult to take it out. Because the lens inside the microscope is not easy to wipe, humidity does more harm to it. Mechanical parts are easy to rust when they are wet. In order to prevent moisture, when storing the microscope, in addition to choosing a dry room, the storage place should also be far away from walls, floors and moisture sources. 1 ~ 2 bags of silica gel should be put in the microscope box as a desiccant. And silica gel is often baked. When it turns pink, it should be baked in time and then used again.
(2) Dust falls on the surface of dustproof optical elements, which not only affects the passage of light, but also produces large color spots after being amplified by the optical system, which affects observation. Dust and sand fall into mechanical parts, which will increase wear and tear, cause movement obstruction and do great harm. Therefore, the microscope must always be kept clean.
(3) The anti-corrosion microscope cannot be put together with corrosive chemical reagents. Such as sulfuric acid, hydrochloric acid, strong alkali, etc.
(4) The main purpose of heat protection is to prevent the lens from opening and falling off due to thermal expansion and contraction.
2. Wipe the optical system
Usually, clean the surface of each optical part of the microscope with a clean brush or wipe it with mirror paper. When there are indelible dirt, oil stains or fingerprints on the lens, the lens is moldy and foggy, and it needs to be wiped after long-term use.
(1) wiping range The eyepiece and condenser are allowed to be disassembled for wiping. Due to the complex structure of the objective lens, special instruments are needed for calibration during assembly, and it is forbidden to disassemble and wipe it.
When removing the eyepiece and condenser, pay attention to the following points:
First, be careful.
B, when disassembly, to mark the relative position of each component (can be marked on the shell), the relative order and the front and back of the lens, in case of error when reassembling.
C, the operating environment should be kept clean and dry. When taking off the eyepiece, just unscrew the upper and lower lenses from both ends. The field stop in the eyepiece cannot be moved. Otherwise, the boundary of the field of vision will be blurred. After the condenser is unscrewed, it is forbidden to further decompose the lens above. Because the lens on it is oil-immersed, it is well sealed when it leaves the factory, and then decomposition will destroy its sealing performance and damage it.
2. Wipe method First, use a clean brush or hair dryer to remove the dust on the lens surface. Then use a clean flannel to make a spiral one-way motion from the center to the edge of the lens. After wiping, wipe the flannel in another place until it is clean. If there are indelible oil stains, dirt or fingerprints on the lens, you can wrap absorbent cotton with willow branches and wipe it with a small amount of alcohol and ether mixture (80% alcohol and 20% ether). If there are serious mildew spots or mildew spots that can't be removed, you can dip a cotton swab in water and then stick calcium carbonate powder (content above 99%) to wipe it. After wiping, the powder should be removed. Whether the lens is wiped clean can be observed and checked by the reflected light on the lens. It should be noted that dust must be removed before wiping. Otherwise, the sand in the dust will stain the mirror. Do not use towels, handkerchiefs, clothes, etc. Wipe the lens. Alcohol-ether mixture should not be used too much, so as to avoid liquid entering the bonding part of the lens and degumming the lens. There is a purple-blue transparent film on the lens surface, so don't mistake it for dirt to wipe it off.
3. Wipe the mechanical parts
The painted part of the surface can be wiped with a cloth. However, organic solvents such as alcohol and ether cannot be used to avoid paint stripping. If there is rust on the unpainted part, you can wipe it off with a cloth dipped in gasoline. After wiping, apply protective grease again.
■ Troubleshooting of mechanical equipment
1, troubleshooting of rough adjustment part
The main problem of coarse tuning is that the tightness is different when it slides down or rises and falls automatically. The so-called automatic sliding refers to the phenomenon that the lens barrel, the lens arm or the stage automatically falls slowly without adjustment under the action of its own weight. The reason is that the gravity of the lens barrel, the lens arm and the stage itself is greater than the static friction. The solution is to increase the static friction force to be greater than the gravity of the lens barrel or the lens arm itself.
For the coarse adjustment mechanism of inclined cylinder and most binocular microscopes, when the mirror arm slides down automatically, you can hold the stop pulley inside the coarse adjustment handwheel with both hands and tighten it clockwise to stop the sliding. If it doesn't work, find a professional to fix it.
The automatic sliding of the lens barrel often gives people an illusion that it is caused by the loose fit between the gear and the rack. So I put a washer under the shelf. Although this can temporarily stop the sliding of the lens barrel, the rack and pinion are in an abnormal meshing state. As a result of this movement, the gear and rack are deformed. Especially when the cushion is abnormal, the rack is deformed more severely, resulting in some biting tightly and some biting loosely. Therefore, this method is not suitable.
In addition, because the coarse adjustment mechanism is in disrepair for a long time, the lubricating oil is dry, which will cause uncomfortable feeling when lifting, and even the friction sound of parts can be heard. At this point, the mechanical device can be removed for cleaning, lubrication and reassembly.
2, fine-tuning part of the troubleshooting
The most common faults in the fine tuning part are stuck and faults. The fine-tuning part is installed inside the instrument, and its mechanical part is small and compact, which is the most delicate and complicated part of the microscope. The fault of the fine-tuning part should be repaired by professional technicians. If you are not sure enough, don't open it casually.
3. Troubleshooting of objective lens converter
The main fault of the objective lens converter is the fault of the positioning device. Generally, it is caused by the damage of the positioning spring (deformation, fracture, loss of elasticity, loosening of the spring fixing screw, etc.). ). When replacing a new spring, do not tighten the fixing screw temporarily, and first correct the optical axis according to "3 (2) 2" in this section. After the shafts are equal, tighten the screws again. If it is an internal positioning converter, before replacing the positioning spring, unscrew the big head screw in the center of the turntable and remove the turntable. The method of optical axis correction is the same as before.
4. Troubleshooting of hoisting mechanism of concentrator
The main fault of this part is also automatic sliding. The elimination method is as follows:
(1) The lifting mechanism of the condenser of the straight microscope is shown in figure 10-3-2: 1. 5. Celluloid washing machine 2. Big head screw 3. Eccentric rack sleeve 4. The sixth one. Lift handwheel 7. Binocular nut.
During adjustment, one hand uses a double-hole nut wrench to insert the double-hole nut at the end face of the handwheel, and the other hand uses a screwdriver to insert the notch of the big head screw at the other end, and the sliding can be stopped by tightening it hard.
(2) The lifting mechanism of the condenser of the inclined tube microscope is shown in Figure 10-3-3:
When adjusting, first unscrew the fixing screw 2 in the middle of the eyebolt by 1 ~ 2 turns with a screwdriver. The bearing washer 3 is closely matched with the fixing screw 2, so it will also be pulled out together with it and separated from the end face of the toothed bar 10. Then, screw the barrel nut 1 into the adjusting seat 5 with a barrel nut wrench. At the same time, turn the handwheel with the other hand to test until the lifting mechanism is tight enough to stay in any position, and then stop tightening the eye nut. Finally, screw in the parking screw again, so that the bearing washer touches the toothed bar 10.
Since the inner hole of the adjusting seat 5 is tapered, this adjustment can eliminate the fault. The tapered shaft sleeve 4 has a notch in the axial direction, as shown in figure 10-3-4. When the double-barrel nut 1 is screwed in, the conical sleeve is pushed in, so that when the conical sleeve advances, the notch becomes smaller, the inner hole shrinks, the toothed bar 10 is clamped more tightly, and the friction resistance of gear rotation increases, thus preventing automatic descent.
Application mode
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■ How to use a low-power mirror?
(1) microscope access: microscopes are usually stored in cabinets or boxes. When in use, take it out of the cabinet. Hold the mirror arm with the right hand and the mirror base with the left hand. Put the microscope on the experimental platform in front of the left shoulder. The back end of the mirror seat is 1-2 inches away from the table, which is convenient for sitting and operating.
(2) aiming: move the rotator with your thumb and middle finger (never move the objective lens by hand) so that the low-power lens is aimed at the light hole of the stage (knocking sound is heard when rotating, indicating that the optical axis of the objective lens is aimed at the center of the lens barrel). Open the aperture, raise the light collector, turn the reflector to the light source, observe with the left eye on the eyepiece (the right eye is open), and adjust the direction of the reflector at the same time until the light in the field of vision is uniform and bright.
(3) Placement of slide specimen: Place a slide specimen on the objective table, make sure that the side with the cover glass faces upwards, and do not turn upside down, clamp it with the spring of the push rod, and then rotate the push rod screw to adjust the position to be observed to the center of the light hole.
(4) Adjusting the focal length: Turn the coarse adjuster counterclockwise with your left hand, so that the objective table slowly rises to a position where the objective lens is about 5 mm away from the specimen. Be careful not to observe on the eyepiece when you climb the stage. Be sure to observe that the stage rises from the right to avoid excessive rise and damage to the lens or sample. Then, open your eyes at the same time, put your left eye on the eyepiece for observation, slowly turn the coarse adjuster clockwise with your left hand, and slowly lower the stage until a clear object appears in the field of vision.
If the image is not in the center of the field of view, adjust the film pusher to center it (note that the direction of moving the slide is opposite to the direction of moving the image in the field of view). If the brightness in the field of view is not suitable, it can be adjusted by raising and lowering the position of the light collector or opening and closing the aperture. If the lens table falls out of the working distance when adjusting the focal length (>: 5.40mm), and no image is seen, it means that the operation has failed, and it should be re-operated, and the table must not be raised blindly.
■ How to use a high power mirror?
(1) Select the target: you must first center the part that needs further observation under the low-power lens, and at the same time adjust the object image to the clearest degree before you can observe it under the high-power lens.
(2) Turn the converter and replace the high-power lens. Turn the high-power lens slowly and observe it from the side (to prevent the high-power lens from touching the slide). If the high-power lens touches the glass slide, it means that the focal length of the low-power lens has not been adjusted well, and it needs to be operated again.
(3) Adjust the focal length: after switching the high-power lens, observe with the left eye on the eyepiece. At this time, you can usually see an unclear object image. You can turn the screw of the trimmer counterclockwise about 0.5- 1 turn to get a clear image of the object (don't use the coarse trimmer! )
If the brightness of the visual field is not suitable, it can be adjusted by the light collector and aperture. If it is necessary to replace the slide sample, the coarse adjuster must be turned clockwise (not in the wrong direction) to lower the stage, and then the slide sample can be removed.
If you want to make the image bigger, you should keep the objective lens close to the object and the eyepiece away from the objective lens, while if the image becomes smaller, the opposite is true. ...
Matters needing attention
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■ When holding the mirror, you must hold the handrail in your right hand and the bracket in your left hand, and you can't take it out with one hand to avoid parts falling off or colliding with other places.
■ Handle with care. Don't put the microscope on the edge of the experimental platform to avoid knocking it over.
■ Keep the microscope clean. The optical and lighting parts can only be wiped with mirror paper, and it is forbidden to wipe with hands or cloth. The mechanical parts can be wiped with cloth.
■ Do not touch the lens and stage with water drops, alcohol or other drugs, and wipe it immediately if it is polluted.
■ When placing the slide specimen, aim at the center of the light hole, and don't put the slide upside down to avoid crushing the slide or damaging the objective lens.
■ Develop the habit of opening your eyes at the same time. Observe your vision with your left eye and draw with your right eye.
■ Do not disassemble the eyepiece at will to prevent dust from falling into the objective lens, and do not disassemble various parts at will to prevent damage.
■ After use, it must be restored before it can be put back in the mirror box. The steps are as follows: take down the specimen, rotate the rotator to make the lens leave the aperture, lower the stage, level the reflector, lower the light collector (but don't touch the reflector), close the diaphragm, return the push rod, cover the silk cover, and put it back in the test bench cabinet. Finally, fill in the use registration form. (Note: Generally, the reflector should be placed vertically, but sometimes the aperture will be damaged when the stage descends because the light collector does not rise to its due height, so it is placed horizontally here. )
Instrument classification
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Microscope can be divided into optical microscope and electron microscope.
■ Optical microscope
It was originally created by Zhan Sen and his son in the Netherlands in 1590. At present, the optical microscope can enlarge the object by 1500 times, and the minimum resolution is 0.2 micron. There are many kinds of optical microscopes, except general ones, mainly dark-field microscopes, which have a dark-field condenser, so that the illumination beam does not enter from the central part, but shines on the specimen from the periphery. The fluorescence microscope uses ultraviolet light as the light source to make the irradiated object emit fluorescence.
■ Electron microscope
It was first assembled by Knohl and Ha Roska in Berlin in 193 1 year. This microscope uses high-speed electron beams instead of light beams. Because the wavelength of electron flow is much shorter than that of light wave, the magnification of electron microscope can reach 800 thousand times, and the lowest resolution limit is 0.2 nm. 1963 uses a scanning electron microscope, which enables people to see the tiny structures on the surface of objects.
Major instrument manufacturers
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Foreign countries: Zeiss, Lycra, Olympus, Nikon
Domestic: Shanghai Yuguang Instrument Co., Ltd., Shanghai Yanrun Enterprise, Shanghai Optical Instrument Factory, Jiangnan Yongxin, Shanghai Rectangular Optical Instrument, Mike Audi, Chongqing Optical.
The history of musical instruments
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As early as the first century BC, people have found that when observing tiny objects through spherical transparent objects, the images can be enlarged. Later, I gradually realized that the surface energy of spherical glass magnifies the image of an object.
In 1590, Dutch and Italian glasses manufacturers have built magnifying instruments similar to microscopes.
16 1 1 year
Kepler: Put forward the manufacturing method of compound microscope.
1655
Hooke: The origin of the word "cell" comes from Hooke's observation of tiny pores in a certain area on a cork with a compound microscope.
1674
Levin Hooke (Wenli Heck): The report of discovering protozoology came out. Nine years later, he became the first person to discover the existence of "bacteria".
1833
Brown: He observed violets under a microscope, and then published his detailed discussion on the nucleus.
1838
Shriden and Schwann (Shelley and Schwann): Both of them advocate the principle of cytology, and their main idea is that "nucleated cells are the basic elements of all animal and plant tissues and functions".
1857
Kolliker: Mitochondria were found in muscle cells.
1876
Abbe: Analyze the diffraction phenomenon when the image is imaged under the microscope, and try to design the most ideal microscope.
1879
Flrmming (Fleming): It is found that when an animal cell is undergoing mitosis, its chromosome activity is clearly visible.
188 1 year
Retziue (Ruizu): The animal organization report came out, and no one could surpass this publication at that time. However, 20 years later, a group of histologists led by Cahal developed the microscopic staining observation method, which laid the foundation for the future microscopic anatomy.
1882
Kirk: He dyed the microbial tissues with benzene dye and found cholera and mycobacterium tuberculosis. In the next 20 years, other bacteriologists, such as Kleber and Pasteur, confirmed the causes of many diseases by examining staining drugs under the microscope.
1886
Zeiss (Chua's): Breaking the theoretical limit of general visible light, his invention-abbey lens and a series of other lenses opened up a new world for microscopists to interpret images.
1898
Golgi: The first microscopist to find Golgi in bacteria. He used silver nitrate to dye cells, which made a big step in the study of human cells.
1924
Lakseni (Lancashire): He and his experimental partner * * * developed radiography together. This invention uses radioactive polonium to detect biological specimens.
1930
Lebedev: Design and match the first interference microscope. In addition, zernike invented the phase difference microscope in 1932, and the phase difference observer developed by them expanded the traditional optical microscope, enabling biologists to observe various details on stained living cells.
194 1 year
Kuhns: Fluorescent dye was added to the antibody to detect cell antigen.
1952
Normaski: Invented the interference phase difference optical system. This invention is not only patented, but also named after the inventor himself.
198 1 year
Allen and Inoue (Allen and Ainiu): The images in the principle of optical microscope are enhanced and compared, and the development tends to be perfect.
1988
Confocal scanning microscope is widely used in the market.
Brief introduction of several special microscopes
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■ dark field microscope
Because the dark field microscope does not inject transparent light into the direct observation system, the field of view is dark when there is no object, so it is impossible to observe any object. When there is an object, the diffracted light and scattered light of the object are bright and visible in the dark background. When observing an object in a dark field, most of the illumination light is reflected back. Because of the different position, structure and thickness of the object (specimen), the scattering and refraction of light have great changes.
■ phase contrast microscope
Structure of phase contrast microscope;
The phase contrast microscope is a microscope that uses the phase contrast method. Therefore, the microscope should add the following accessories:
(1) objective lens with phase plate (phase annular plate), phase difference objective lens.
(2) A condenser with a phase ring (annular slit plate) and a phase difference condenser.
(3) Monochrome filter-(green).
Performance description of various components
(1) The phase plate shifts the phase of direct light by 90 degrees, absorbing and weakening the intensity of light. The brightness of the phase plate must be ensured when it is installed in the appropriate position of the back focal plane of the objective lens. In order to reduce the influence of diffracted light, the phase plate is made into a ring shape.
(2) The phase ring (annular aperture) can be replaced by a turntable according to the magnification of each objective lens.
(3) The monochromatic filter is a green filter with a central wavelength of 546nm (nanometer). Usually monochromatic filters are used for observation. The phase plate moves 90 degrees at a specific wavelength to see the phase of the direct light. When a specific wavelength is needed, the appropriate filter must be selected, and the contrast will be improved after inserting the filter. In addition, the center of the phase ring seam must be adjusted to the correct orientation to operate, and the centering telescope is the component that plays this role.
■ Video microscope
Traditional microscope is combined with camera system, display or computer to achieve the purpose of magnifying and observing the measured object.
The earliest prototype should be a camera microscope. Through the principle of pinhole imaging, the images obtained under the microscope are projected onto the photosensitive photos, so as to get the picture. Or directly dock the camera with the microscope to take pictures. With the rise of CCD camera, microscope can transmit real-time images to TV or monitor for direct observation, or shoot them through camera. In the mid-1980s, with the development of digital industry and computer industry, the function of microscope has been improved through them, making it simpler and easier to operate. By the end of 1990s, with the development of the semiconductor industry, the wafer demanded that the microscope could bring more coordination functions. The combination of hardware and software makes the microscope more intelligent and humanized, and makes the microscope have a greater development in industry.
■ fluorescence microscope
In the fluorescence microscope, excitation light with a specific wavelength must be selected from the illumination light of the sample to generate fluorescence, and then the fluorescence must be separated from the mixed light of excitation light and fluorescence for observation. Therefore, the filter system plays an extremely important role in the selection of specific wavelengths.
The principle of fluorescence microscope:
(a) Light source: A light source emits light of various wavelengths (from ultraviolet to infrared).
(b) Excitation filter light source: transmits light with a specific wavelength that can make the sample emit fluorescence, and at the same time blocks light that is useless for excitation fluorescence.
(c) Fluorescent specimens: generally stained with fluorescent pigments.
(d) Blocking filter: blocking the excitation light that is not absorbed by the specimen, so that the fluorescence is selectively transmitted, and some wavelengths in the fluorescence are also selectively transmitted.
■ Polarizing microscope
Polarizing microscope is a kind of microscope used to study so-called transparent and opaque anisotropic materials. Under the polarizing microscope, all substances with birefringence can be clearly distinguished. Of course, these substances can also be observed by dyeing, but some of them are impossible, and a polarizing microscope must be used.
Characteristics of (1) polarizing microscope
A method of changing ordinary light into polarized light, which is used for microscopic examination to identify whether a substance is single refraction (isotropic equivalence) or birefringence (anisotropy). Birefringence is the basic characteristic of crystals. Therefore, polarizing microscope is widely used in the fields of minerals, chemistry, biology and botany.
(2) The basic principle of polarizing microscope
The principle of polarizing microscope is complicated, so I won't introduce it too much here. Polarizing microscope must have the following accessories: polarizer and analyzer.