Discuss and compare the advantages and disadvantages of electron microscopy versus optical microscop

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Resolving power is an important indicator of electron microscopy, which is expressed by the minimum distance between two adjacent points that it can resolve, and it is related to the angle and wavelength of the electron beam incident through the sample. The wavelength of visible light is about 300 700 nanometers, while the wavelength of the electron beam is related to the accelerating voltage. According to the principle of wave-particle duality, the wavelength of high-speed electrons is shorter than that of visible light, and the resolution of a microscope is limited by the wavelength it uses, so the resolution of an electron microscope (about 200 nanometers) is much higher than that of an optical microscope.

When the accelerating voltage is 50 100 kV, the wavelength of the electron beam is about nanometers. Since the wavelength of the electron beam is much smaller than that of visible light, the resolution of the electron microscope is far superior to that of the optical microscope, even if the cone angle of the electron beam is only 1% of that of the optical microscope. The maximum magnification of optical microscopes is about 2,000 times, while the maximum magnification of modern electron microscopes is more than 3 million times, so the atoms of certain heavy metals and the neatly arranged atomic lattices in crystals can be directly observed through electron microscopes.

Although the resolution of electron microscopes is far superior to that of optical microscopes, electron microscopes are difficult to observe living organisms because they need to work under vacuum conditions, and biological samples can also be damaged by irradiation due to the irradiation of electron beams. Other issues, such as the improvement of the brightness of the electron gun and the quality of the electronic lens, also need to be further studied.

Summary. Optical microscope uses optical principles to form clear images, which has the advantages of low cost, simple operation, moderate resolution, and no need for vacuum. Compared to electron microscopes, optical microscopes are easy to use and do not require complex sample preparation, handling techniques, and equipment maintenance.

At the same time, optical microscopes are suitable for the study of biology, medicine, materials science and other disciplines, and can observe living organisms, soft tissues, and samples that do not require conductivity. In addition, the optical microscope can be used with different imaging techniques, such as fluorescence microscope, speed microscope, etc., to further improve the performance of resolution and sensitivity, and broaden the scope of analysis.

Optical microscope uses optical principles to form clear images, which has the advantages of low cost, simple operation, moderate resolution, and no need for vacuum. Compared to electron microscopes, optical microscopes are easy to use and do not require complex sample preparation, manipulation and equipment maintenance. At the same time, optical microscopes are suitable for the study of biology, medicine, materials science and other disciplines, and can observe living organisms, soft tissues, and samples that do not require conductivity.

In addition, the optical microscope can be used with different imaging techniques, such as fluorescence microscope, spread-velocity microscope, etc., to further improve the resolution, sensitivity and other performance, and broaden the scope of analysis.

Extended Information: Optical microscopy has a significant disadvantage due to its lower resolution than electron microscopy. At present, with the continuous development of optical principles and imaging technologies, people have gradually overcome this difficulty and obtained super-resolution optical microscopes.

This microscope can be used to study biomolecules, cells, nanomaterials, slide bridges, macromaterials, and other fields.

The optical aberration microscope is an optical instrument that uses optical principles to magnify and image tiny objects that cannot be distinguished by the naked eye, so that people can extract microstructural information. After more than 50 years of development, electron microscope has become an indispensable and important tool in modern science and technology. The electron microscope consists of three parts: a lens tube, a vacuum device and a power cabinet.

Advantages: 1. High resolution, the resolution of the optical microscope is, the resolution of the transmission electron microscope is, that is to say, the transmission electron microscope is magnified 1000 times on the basis of the optical microscope.

2. Transmission electron microscope is often used to observe the structure of fine substances that cannot be distinguished by ordinary microscopes; Scanning electron microscope is mainly used to observe the morphology of solid surfaces, and can also be combined with X-ray diffractometer or electron spectrometer to form an electron microprobe for material composition analysis; Emission electron microscopy is used to study the surface of self-emitting electrons.

Disadvantages: 1. In the electron microscope, the sample must be observed in a vacuum, so the live sample cannot be observed. With the advancement of technology, environmental scanning electron microscopy will gradually realize the direct observation of living samples;

2. When processing the sample, it may produce structures that the sample does not have, which makes it more difficult to analyze the image later;

3. Due to the strong electron scattering ability, secondary diffraction is prone to occur;

4. Because it is a two-dimensional plane projection of a three-dimensional object, sometimes the image is not unique;

5. Since transmission electron microscopy can only observe very thin samples, it is possible that the structure of the surface of the substance is different from the structure inside the substance;

6. For ultra-thin samples (below 100 nm), the sample preparation process is complex and difficult, and the sample preparation is damaged;

7. The electron beam may destroy the sample through collision and heating;

8. In addition, the purchase and maintenance of electron microscopes are relatively high.

<> ordinary optical microscope refers to a microscope with a relatively simple structure.

The components of the compound microscope are collocated and have strong scalability.

Optical microscopes use light to observe objects, while electron microscopes use electron beams instead of light beams, with complex structures and high resolution.

Mitochondria, endoplasmic reticulum, centrosomes, chloroplasts, Golgi apparatus, ribosomes and other organelles can be seen under the electron microscope, and plastids and vacuoles can be seen under the light microscope.

Organelles are usually divided into: mitochondria; Chloroplast; Endoplasmic reticulum; Golgi apparatus; lysosomes; Vacuoles, ribosomes, centrosomes. Among them, chloroplasts are only found in plant cells, vacuoles are only found in plant cells and lower animals, and centrosomes are only found in lower plant cells and animal cells.

At the secondary level, the nucleus is not recognized as an organelle, whereas at the college level, the nucleus is considered to be the largest and most important organelle in the cell.

In addition, in cells, cytosol accounts for about 55% of the total volume of cells, in which thousands of enzymes are present. Most intermediate metabolism, including glycolysis, gluconeogenesis, and the synthesis of sugars, fatty acids, nucleotides, and amino acids, takes place in the cytosol.

The cytoplasmic matrix is essentially a highly organized system at different levels, rather than a simple solution. However, the tangible structures within the cytoplasmic matrix are not visible under ordinary transmission electron microscopy.

The function of the microscope is to study the structure and specific internal characteristics of the object by magnifying the specific shape of the object, which is mainly used in the physical, biological and medical aspects. Microscopes have optical microscopes and electron microscopes, what is the difference between the two? Let's take a look!

There are five main differences between electron microscopes and optical microscopes:

1.Optical microscopes (hereinafter referred to as light microscopes) use visible light as a light source, while electron microscopes (hereinafter referred to as electron microscopes) use high-precision short-wavelength electron coarse beams instead of visible light.

2.Depending on the magnification, the light microscope can generally magnify up to 2000 times, and the electron microscope can be as high as hundreds of thousands of times.

3.Optical lenses are used for focusing lenses for light mirrors, while electromagnetic lenses are used for electron microscopes.

4.The light microscope can only observe the surface microstructure, and the electron microscope can obtain the crystal structure, microstructure, chemical composition, and the distribution of electron filial piety stools.

5.The imaging system is different. Light microscopy can only see cells and some organelles, such as mitochondria and chloroplasts, but only their presence, not the specific structure of the organelles (such as the basal grains of chloroplasts, the ridges of mitochondria).

Electron microscopes can see the fine structure of organelles, even the smallest organisms like viruses, and even large molecules such as proteins.

The biggest difference between an optical microscope and an electron microscope is that the wavelengths used are different, the former uses visible light, the resolution is up to micron, the maximum effective magnification can only be about 1600 times, and the corresponding depth of field is also very small (micron). The latter uses electrons, which, according to the theory of wavelength of matter, can achieve a resolution of electron microscopes in the nanometer range, which is thousands of times higher than that of optical microscopes, under the acceleration of voltages ranging from tens of kilovolts to hundreds of kilovolts.

When the magnification of the electron microscope is small, its depth of field is large, and it can shoot a very three-dimensional **.

1. Optics tens of thousands to hundreds of thousands. Electronics, millions of dollars or more.

2. Optics is the use of light, and electron microscope is the use of electron beams to see things.

So it must be the magnification of the electron microscope.

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1. The development history is different.

The development of optical microscopy was the foundation of the development of electron microscopy. In the middle of the 17th century, Robert Hooke in England and Leeuwenhoek in the Netherlands both made outstanding contributions to the development of microscopy. Around 1665, Hooke incorporated coarse and micro-motion focusing mechanisms, illumination systems, and tables to carry specimens.

These components have been continuously improved and become a fundamental part of modern microscopes.

The development history of electron microscopy is relatively short, and in 1926 Hans Bush developed the first magnetic electron lens.

2. The principle is different.

Optical microscope uses the magnifying imaging principle of convex lens to magnify small objects that cannot be distinguished by the human eye to a size that can be distinguished by the human eye. Electron microscopy, on the other hand, mainly uses secondary electron signal imaging to observe the surface morphology of the sample, that is, to scan the sample with a very narrow electron beam, and the interaction between the electron beam and the sample produces an amplifying effect.

3. The composition is different.

The optical system of an optical microscope mainly consists of four parts: an objective lens, an eyepiece, a reflector, and a condenser. Broadly speaking, it also includes lighting sources, optical filters, coverslips and glass slides. The electron microscope consists of three parts: a lens tube, a vacuum device and a power cabinet.

4. The focus is different.

The focus of an optical lens is fixed, whereas the focus of an electron lens can be adjusted, so an electron microscope does not have a lens system that can be moved like an optical microscope.

5. The resolution is different.

The application of electron microscopy technology is based on the optical microscope, the resolution of the optical microscope is, the resolution of the transmission electron microscope is, that is to say, the transmission electron microscope is magnified by 1000 times on the basis of the optical microscope.