How did humans discover infrared rays?

Infrared is a kind of invisible light. In recent twenty or thirty years, the rising infrared technology has been widely used in various fields. It began to be used in production and formed a brand-new technology-infrared technology.

1800, British scientist Haischer made an experiment. After he divided the sunlight into color bands, he measured the temperatures of all kinds of light with a thermometer and found a strange phenomenon: the invisible part near the crimson light of the sunlight was even higher than the red light. This is an unexpected discovery. Because we only know that sunlight has seven colors, it is not clear what other substances exist in the darkness besides these seven colors. Therefore, Haischer imagined that in the radiation of the sun, besides visible light, there must be a kind of radiation invisible to the naked eye. Later, it was proved by experiments that this kind of radiation still exists in the radiation emitted by other objects. At that time, people called it "invisible radiation" because this kind of "invisible radiation" was found outside red light, and it was later called infrared radiation, also called infrared ray.

1887, people successfully produced infrared rays in the laboratory, which made people realize that visible light, infrared rays and radio waves are essentially the same. In the 20th century, due to the need of production practice, the development of various new technologies was promoted, and infrared science also went out of the laboratory and began to be applied to production, forming a brand-new technology-infrared technology.

In recent twenty or thirty years, the rising infrared technology has been widely used in various fields.

The thermal effect of infrared light is greater than that of red light, and its penetration ability is also very strong. Use it to dry things quickly and well. So people often use it to dry the paint of airplanes, ships and cars. In the past, natural drying often formed a hard shell on the surface of paint, and the water inside could not be emitted, forming bubbles, which affected the quality of paint. Using infrared dry paint won't have this disadvantage. Infrared rays have strong penetrating power and can be used for dyeing synthetic fiber fabrics. For example, after infrared rays penetrate into nylon fabric at high temperature, the structure of nylon fabric will change, making it easy for pigments to enter the fiber, fixing the pigments on the fabric and drying them. In this way, people can dye nylon fabrics with various bright colors with infrared rays.

Infrared ray is a kind of invisible light, which can be used to form an invisible defense line. In order to protect the warehouse, infrared rays can be skillfully circled around the warehouse with the help of reflector, and then projected onto the photovoltaic cell that can only feel infrared rays, so that the photovoltaic cell can generate current. Reflector, photovoltaic cell, etc. It is well hidden and forms an imperceptible line of defense. If anyone dares to invade the warehouse, it will block infrared rays. Once the infrared ray is blocked, the photocell will stop working, a switch connected to the photocell will be turned off immediately, and an alarm will sound.

Not long ago, scientists and technicians successfully developed an instrument called pyroelectric camera, that is, infrared TV. It can be used to detect the fire source, check the fire hidden danger, monitor the fire and give an alarm in time, so it is known as the "sentry to monitor the fire". Because infrared TV cameras take pictures by the infrared rays emitted by the object being photographed, the higher the temperature of the object being photographed, the stronger the infrared rays emitted, and the clearer the images taken. So infrared TV will not be blocked by smoke, clouds, wind, rain, etc. It can detect all kinds of fires very sensitively and put them out when they first appear.

The infrared TV camera is equipped with a fire detector, an automatic tracking system, a search mechanism and a telescope, which constitutes a new automatic monitoring system for urban fires. It can automatically search and find the fire source with the size of 2 ~ 3 square meters five or six kilometers away, and can automatically track and alarm. In this way, the automation of fire command and dispatch can be realized, which provides a modern technical means for finding and eliminating fires in time.

Infrared TV is also used to monitor darkroom operation in industry, without destroying and exploring natural resources; Used in agriculture to detect fires in forests and pastures; Used for fog navigation in traffic, etc.

Infrared TV or "luminous eyes"! It can effectively detect enemy positions and military facilities in the dark, even if the enemy's ambush whistle is cleverly hidden, it can't escape its keen eyes; It can also be used at border posts to monitor specific areas; You can also "penetrate" the snow layer and "see" the enemies hiding under the snow. There is also an infrared microscope. When it comes to microscope, people often think that it is an instrument used to magnify tiny objects. In fact, it is an instrument for measuring temperature. However, it is different from ordinary temperature measuring instruments and can be used to measure the temperature of very tiny points. Although the temperature of micro-point can also be measured by semiconductor point thermometer, it is easy to affect the physical and chemical properties of the measured point because it is in direct contact with the surface of the object. If infrared microscope is used to measure, not only these shortcomings can be overcome, but also it is much more accurate than semiconductor point thermometer.

Although infrared technology has just begun to emerge, we are convinced that with the continuous development of science and technology, it will certainly do many wonderful things that can be expected or even unexpected for us.

Infrared light is also called "infrared". In the electromagnetic spectrum, electromagnetic radiation with a wavelength between red light and microwave. Outside the visible range, the wavelength is longer than that of red light, and the thermal effect is obvious, which can be measured by thermocouples, photoresistors and other instruments. The wavelength is in the near infrared region of 0.77 ~ 3 microns. 3 ~ 30 microns is the mid-infrared region; 30 ~ 1000 micron is the far infrared region. Infrared rays are easily absorbed by objects and converted into internal energy of objects; When passing through substances full of suspended particles, such as clouds, it is not easy to disperse, has strong penetration ability, and infrared rays are widely used, which can be used for baking food, drying paint, medical treatment and so on. The infrared absorption spectrum of substances is of great significance for studying their molecular structure, chemical analysis and chemical industry control. In the military, infrared detectors are often used to detect targets and infrared communication.

Infrared TV, also known as infrared TV, uses the thermal radiation or reflected infrared rays of the photographed scene to shoot and display movies. It is suitable for non-contact and nondestructive testing, and is often used in industry, medicine, space development, military and so on.

The electromagnetic wave between the red end of infrared visible light and microwave has a wavelength range of about 7× 10? 7 m ~ 1× 10? Between meters. 1800, the British physicist Sheikh put the thermometer outside the red region of the solar spectrum and found that it still had a strong thermal effect. So this invisible ray is called infrared ray. Everything radiates infrared. The higher the temperature of the object, the wider the emitted infrared band. The mechanism of infrared ray generation is that electrons in the outer layer of atoms are excited. The most striking feature of infrared ray is its thermal effect. The wavelength of infrared light is longer than that of red light, so the diffraction phenomenon is more obvious, and it is easy to pass through clouds and dust, and is not easily absorbed by suspended particles in the air.

Use infrared rays to heat objects, such as drying paint and grain, and carrying out medical treatment. We can take long-distance photography and high-altitude photography with infrared photographic film, and we can clearly see the objects on the ground with infrared photography from the satellite without being limited by day and night. Because all objects are constantly radiating infrared rays, different objects radiate infrared rays with different wavelengths and intensities, so we can use infrared remote sensing technology to survey geothermal energy on airplanes or satellites, find water sources, forecast weather and so on. In modern warfare, night vision equipment such as infrared night vision equipment is used to make opponents' targets lifelike. Infrared physics can be used to detect the infrared radiation of high-temperature objects. Now infrared sensors are also used for anti-missile warning.

The optical problem-the discovery of infrared ray was solved by thermometer.

The sun is the most familiar celestial body in the universe. It rises in the east and sets in the west every day, goes out early and returns late, and does not hesitate to sprinkle the sun on the earth, so that everything can grow and multiply. In summer, fiery red sunshine makes people feel hot and miserable. If it comes to winter, people should try to bask in the sun as much as possible in order to resist the cold with the help of the heat of the sun. Humans have known since ancient times that the sun brings light and heat to people, and the light and heat of the sun are inseparable forever. But when human beings generously accept the light and heat given by the sun, they never consider how light carries heat.

With the development of science,17th century began to systematically study the color of sunlight. 1666, Newton, a great scientist, found in the experiment that sunlight passed through a glass prism that white light was actually composed of monochromatic light of seven colors: red, orange, yellow, green, blue, indigo and purple. This is the famous "dispersion experiment of light" in physics. Newton has made many contributions to optical research, and his research achievements in many aspects, such as linear propagation of light, refraction and reflection of light, imaging of lens, color theory and so on, have become the most important part of human knowledge. But Newton himself and his contemporaries were all focused on various optical phenomena or endless debates about the nature of light, but no one cared about the light of the sun. It can be said that in the history of optical development, sunlight has been an outcast of science for a long time.

Pastor's inspiration 1738, a child named Herschel was born in England. Herschel was an ordinary child when he was a child, and he didn't become a scientist when he grew up. He is a priest by profession, but he has a unique love for sunshine. To this end, he bought a large glass prism and put it on his desk, enjoying the seven-color ribbons formed by sunlight through it from time to time. /kloc-One morning in 0/800, Herschel, who was over 60 years old, looked at the beautiful ribbons and suddenly asked himself curiously like a child, "Sunshine has heat, but which of the seven monochromatic lights that make up sunshine has the most heat?" At that time, no one knew his seemingly simple question, so Herschel began to think and try to find the right answer.

A few days later, Herschel found a solution to this problem. He believes that sunlight is divided into seven monochromatic lights through a prism. If we know the temperature of each light, don't we know which light has more heat? Then, Herschel put a piece of white paper on the wall of his room as a light curtain, so that the seven-color light band passing through the prism could shine on the paper curtain. Then, Herschel hung a thermometer at the position of each light band. I was afraid that my observation was not comprehensive enough, so I hung a thermometer outside the red belt and the purple belt.

After all this, Herschel recorded the first reading of each thermometer, and then sat in the chair next to the table and began to observe. The mercury column of the thermometer rose slowly, and Herschel waited patiently. After about half an hour, all the thermometer readings stopped changing. Herschel found that the temperature in the green area rose by 3℃, the temperature in the purple area rose by 2℃, and the thermometer reading outside the purple area hardly changed. However, to his surprise, the thermometer reading outside the red light district rose by 7℃.

Although Herschel is a priest, he has the qualities of a scientist. He repeated the experiment immediately after he found this strange phenomenon. But the results of many experiments are the same: the reading of thermometer rises the most outside the red light region. After detailed analysis, Herschel thinks that the spectrum of sunlight is actually wider than the seven kinds of monochromatic light that people see. There must be some invisible light outside the red band, and this light carries the most heat. Later, the scientific community named this invisible light infrared, and Herschel went down in the history of science because he discovered it.

Where does the infrared ray come from? After Herschel discovered infrared, there were not many scientists engaged in infrared research because the understanding of many natural phenomena was not deep enough and the overall level of scientific research was not high. Later, with the development of physics and other scientific disciplines, people clearly realized that infrared rays, like other visible light, are part of electromagnetic waves. Only the wavelength range of visible light is 0.4-0.75 micron, while the wavelength range of infrared light is 0.76- 1000 micron, so it is invisible to human eyes.

Scientists later learned about the mechanism of infrared rays, also known as infrared radiation. As long as the temperature of any object is higher than the absolute temperature of zero -273℃, their molecules have thermal motion. With the thermal motion of this molecule, the object radiates infrared rays with different wavelengths.

The wonderful use of infrared rays has a long history of human discovery of infrared rays, but it was not until this century with the rise and development of radio electronics and materials science that infrared rays became worth a hundred times and appeared in front of us as a high-tech identity.

Everyone likes to watch the "Animal World" column hosted by CCTV Zhao Zhongxiang, in which so many pictures of animals' nocturnal activities are obtained by infrared photography. Since everything radiates infrared rays, scientists have developed an infrared film that can record infrared signals specially. This kind of film can be mounted on an ordinary camera, and then taken at night with other equipment, away from animals. Crocodiles are ferocious animals familiar to human beings. In order to study the living habits of crocodiles and the process of raising children, researchers placed automatic infrared cameras near crocodile nests in appropriate seasons. As can be seen from the lens, when the baby crocodiles just hatch, the crocodile mother sometimes licks them, sometimes moves them and sometimes feeds them. Seeing the usual ferocity, Reiko Kobayakawa's heart is not worse than ours.

Thermal infrared detection system is an important application of infrared technology. Because any object that radiates infrared rays is a different heat source from other objects around it, that is, there is a temperature difference between the object and its surrounding environment, the thermal infrared detection system can find the target by detecting the temperature difference. For example, in the military, this device is used to find enemies hidden in bushes and moving vehicles and tanks. In movies or TV, we often see such a battle scene. Two planes chased each other in the air, and suddenly the plane behind them fired a missile, while the other plane immediately changed its flight direction, turned for a while, rolled up and down for a while, and was hit by a missile a few seconds later. Why can't planes get rid of missiles? This is because the exhaust pipe of the flying aircraft engine is an infrared radiation source, and missiles equipped with infrared detectors will find it easily. Although the plane tried to get rid of the missile, the electronic navigation system on the missile kept the missile biting the heat source, so how could the plane with a lower speed than the missile not be hit?

Today, the application scope of infrared ray is more and more extensive, and it has extremely important applications in industry, agriculture, military affairs, food processing and safety work. But don't forget, the discovery of infrared ray is the discovery with the least scientific investment and the simplest process-only by a glass prism and several thermometers.

Infrared in the electromagnetic spectrum, electromagnetic wave with wavelength between red light and microwave. The wavelength is about 0.75 ~ 1000 micron, which will not cause vision. Infrared ray has obvious thermal effect, which can be detected by thermocouple, photoresistor photocell and other instruments. Infrared rays are easily absorbed by objects and converted into their internal energy; It has strong penetration ability when it passes through substances full of suspended particles such as clouds. Infrared rays can be used for communication, tracking and detecting targets in the military; It can be used for drying paint and baking food in industry, and can be used for non-contact temperature measurement of long-distance targets and high-speed moving targets. In medicine, infrared technology can be used to diagnose diseases. Infrared technology is a new technology that has developed rapidly in recent 20 years.

[Infrared] Things invisible to human eyes can penetrate or penetrate many substances, such as sawdust, bakelite, trees, paper, mist and leather. If the material is too thick, infrared rays can't penetrate, only to a certain extent. Infrared rays can also process atoms and make some changes in the motion state of atoms. Infrared rays have a thermal effect. It was discovered by British astronomer Herschel in 1800 because of its remarkable thermal effect. Using the invisibility, strong penetration, thermal effect and ability to deal with atoms of infrared rays, we can find many uses for us. Such as infrared spectrum analysis, drying, infrared photography, detection and communication.

The wavelength of infrared light is longer than that of visible light that we can see. Most of the heat waves are infrared waves, which is why when you put your hand on your friend's cheek, you can feel the warmth, but you can't see the light waves.

What is infrared? /kloc-in 0/800, the scientist Sir William Herschel discovered that about two-thirds of the energy in sunlight comes from invisible heat energy, that is, infrared radiation energy. Objects will heat up in the sun, not because they absorb the visible sunlight we see, but because the visible sunlight is accompanied by infrared radiation energy. All heat sources contain infrared rays, and a writer can even find some planets through infrared rays instead of using visible light waves. This CD player is started by the infrared ray in the remote control. The red indicator light on the machine can let you know that the infrared ray is working. In this kind of detector or induction box, its induction efficiency is obtained by an electric photoreceptor capable of detecting light waves. When the surrounding light is dim, the sensor will start the infrared detector; It won't start when lighting is not needed during the day.

Infrared sensors are located on both sides of the face of Agkistrodon halys (Rattlesnakae) and snakes (Agkistrodon halys, rice spoons and rattlesnakes), and are special temperature sensors that are only sensitive to infrared rays. In the dark, poisonous snakes detect the infrared rays emitted by the other side, which plays the role of binocular vision. It is a small hole under the eye socket, also called the foramen device. Its bottom has a membrane similar to the tympanic membrane of the middle ear, and its back also has a cavity to communicate with the outside world, which is very similar to the eustachian tube. There are many mitochondria in the cytoplasm. Trigeminal nerve fibers are densely distributed in the membrane and surrounded by Schwann cells on the outside. Once the infrared ray reaches this film, the change of potential is directly proportional to the heat. Although the sensing mechanism of infrared ray is not very clear, it is very sensitive and can distinguish 0.002℃. There are also poisonous snakes (king snakes) that are infrared sensitive and nonporous, but in this case, it is said that the sensitivity is very poor.

The discovery of ultraviolet light 180 1 year One day, a scientist who studied the solar spectrum suddenly wanted to know whether there was any other invisible light after the sunlight was decomposed into seven colors. He happened to have a bottle of silver chloride solution at hand. At that time, it was known that silver chloride would decompose and precipitate silver when heated or illuminated, and the precipitated silver was black because of its small particles. Scientists want to determine the components of sunlight other than the seven colors by silver chloride. He soaked a little silver chloride solution in a piece of paper and dispersed the white light of seven colors outside the paper through a prism. After a while, he really observed that the low piece with silver chloride turned black on the paper, which showed that there was an invisible light outside the purple light after the sunlight was dispersed by the prism. Scientists call this light ultraviolet. This scientist is Riter,177665438+February 16. Riter was born in Silesia. When I was a child, I didn't study for a few years because my family was poor. 14 years old, went to a pharmacy as an apprentice. During his apprenticeship, Ritter greedily read many books and learned a lot about chemistry and physics. With hard self-study, he was admitted to Jena University at the age of 20, and later made many contributions to chemistry and electrophysiology. 1799, he successfully electrolyzed copper from copper sulfate solution with primary battery, from which he came to the conclusion that static electricity is consistent with galvanic electricity. He also correctly pointed out that the cause of galvanic current is the chemical reaction inside galvanic cell, thus becoming the first person to correctly explain the cause of galvanic current. Ritter made the first dry battery in 1802, and successfully developed the storage battery in 1803. Ritter's main contribution to physics is the discovery of ultraviolet light. Ultraviolet ray is radiation with shorter wavelength than violet light, which is part of the solar spectrum and invisible to the naked eye. Strong ultraviolet rays are harmful to human body and living things, but moderate ultraviolet rays can be used to refresh the mind and promote the metabolism of the body. Ultraviolet rays are also used for sterilization in medicine. In addition, people have created a new analysis method, namely fluorescence analysis method, according to the phenomenon of "light-excited light" of ultraviolet rays, which can not only detect the structure of substances, but also clearly find cracks in machine parts that are difficult to be found by naked eyes. The discovery of ultraviolet ray brought good news to mankind, but its discoverer Ritter was born in poverty and lived a poor life. When he climbed the peak of science hopefully, he was killed by lung disease. He died at the age of 34.

Ultraviolet rays are also called "ultraviolet rays". Electromagnetic radiation in the electromagnetic spectrum between violet light and x-rays. The wavelength is about (4 ~ 39) × 10-6 cm, which will not cause vision (that is, outside the visible range). Substances that can transmit visible light will strongly absorb ultraviolet rays in some bands. For example, glass has a strong absorption of ultraviolet light with a wavelength less than 35× 10-4 cm; Almost all the oxygen and ozone in the earth's atmosphere absorb ultraviolet rays with a wavelength less than 29× 10-6 cm. The crystal (i.e., in time) absorbs ultraviolet light with a wavelength less than 2× 10-5cm; Ultraviolet light with a wavelength less than 2× 10-5cm is strongly absorbed by air. Therefore, it is necessary to evacuate the interior of the spectrometer to observe this ultraviolet band, which is called vacuum ultraviolet, and the spectrometer suitable for this band is called vacuum ultraviolet spectrometer. Mercury lamp and arc lamp have strong ultraviolet radiation between (25 ~ 39) × 10-6 cm, and are commonly used ultraviolet light sources. Ultraviolet light is usually detected by photoelectric elements and photosensitive latex. Ultraviolet spectrum is an important means to study atomic structure, and ultraviolet light also has important application value in industry and agriculture. In biology and medicine, ultraviolet rays are often used to sterilize, induce mutation, and treat skin diseases and rickets.

Global-ultraviolet rays in densely populated areas increase. A recent survey report released by NASA shows that ultraviolet rays in densely populated areas around the world are increasing. In recent 10 years, the increase of ultraviolet rays is the largest, reaching 10%. Researchers used Earth observation satellites to observe the ozone layer and ultraviolet radiation on Earth for 13 years, and drew corresponding maps. In addition, the observation data provided by eight ground observation stations in Canada, New Zealand and the United States supplemented the above observation results. Based on this, the researchers analyzed the distribution of the increase of ultraviolet radiation caused by the decrease of ozone layer in the latitude of the earth. The results show that the amount of ultraviolet radiation in densely populated areas in the southern hemisphere and the northern hemisphere has increased significantly. Including Argentina and Chile in South America. During 10 years, ultraviolet radiation increased by 9.9%. Britain, Germany, Russia and other areas near 55 degrees north latitude increased by 6.8%; Japan and the United States, which are located between 30 and 45 degrees north latitude, have increased by 4%.

The "expert" who absorbs ultraviolet rays-the ozone atmosphere-the gas shell of the earth, in which human beings and all living things live. There is an expert in absorbing ultraviolet rays in the atmosphere, and that is the ozone layer. Although the content of this layer of material is very small, it is of great significance to life on earth. If all the ultraviolet rays radiated by the sun reached the ground unimpeded, the living things on the earth would have disappeared long ago. Therefore, the ozone layer is like an airtight shield, protecting the environment from the ultraviolet radiation of the sun that causes the death of animals. Ozone molecule is composed of three oxygen atoms, which is very active in chemistry and has a special smell, hence its name. It is located in the stratosphere of the atmosphere, and the highest concentration is the ozone layer, which is located at a height of 20 to 30 kilometers. It is this layer that absorbs most ultraviolet rays and plays a role in protecting life on earth. Ozone easily reacts with nitrogen oxides, thus reducing the content of ozone. The source of nitrogen oxides is supersonic aircraft emissions, and a large number of nitrogen fertilizers are used to enter the stratosphere; And freon, widely used as refrigerant, is the most fierce "killer" of ozone. These "killers" make the ozone in the ozone layer decrease continuously. Excessive and continuous ultraviolet radiation will reduce crop yield, damage human health and cause skin cancer. We should take measures to protect the ozone layer as soon as possible!

Ultraviolet light is at work. It turned out that the special geographical location, special climatic conditions and strong sunshine in Los Angeles caused this smog. Without any of them, smog is impossible. Scientists have found that the smog in Los Angeles is photochemical smog, which is an irritating light blue smog produced by nitrogen oxides and hydrocarbons discharged into the atmosphere under the action of solar ultraviolet rays, including ozone, peroxyacyl nitrates and aldehydes, all of which are secondary pollutants produced by photochemical reactions. Under certain geographical conditions, when encountering adverse weather conditions such as inversion or diffusion, smog will persist, causing air pollution events, irritating people's eyes and respiratory tract or inducing various respiratory tract inflammation, which is harmful to human health.

Forecasting ultraviolet rays: With the development of science and people's needs, the weather forecast has added a new content: ultraviolet index, that is, ultraviolet index. In the daily weather forecast program, in addition to temperature, humidity, air pressure, wind and other items, the National Weather Service also predicts ultraviolet radiation in 58 cities in the United States.

The plants that can tolerate ultraviolet radiation most have an ultraviolet ray in the sunlight, which affects almost all living things. Microorganisms, in particular, will be killed in ten minutes after a certain dose of ultraviolet radiation. Therefore, hospitals and some factories often use ultraviolet rays for disinfection. Higher plants are no exception. According to the research of scientists, if the ultraviolet intensity equivalent to the surface of Mars is used as the standard to irradiate various plants, such as tomatoes and peas. Will die within 3-4 hours; Rye, wheat, corn, etc. Irradiation for 60- 100 hours can kill the leaves; Pinus thunbergii survived 635 hours after irradiation. This is the plant with the strongest tolerance to ultraviolet rays. Scientists estimate that plants like southern European black pine can survive on Mars for one season. This fact proves that there may be life on planets other than the earth, such as Mars. Electromagnetic radiation with ultraviolet wavelength between visible light and X-ray, whose wavelength range is between 400-500 nanometers, cannot cause human vision. 180 1 year, German physicist Ritter discovered that the outer section of the ultraviolet end of the solar spectrum can make the photographic film containing silver bromide sensitive, thus discovering the existence of ultraviolet rays. The main ultraviolet light source in nature is the sun. When sunlight passes through the atmosphere, the wavelength is less than 290× 10? 9 meters of ultraviolet light is absorbed by ozone in the atmosphere. The artificial ultraviolet light source has arcs of various gases (such as low-pressure mercury arc and high-pressure mercury arc), and ultraviolet light can chemically make the photographic film sensitive and has a strong fluorescence effect. Fluorescent lamps, all kinds of fluorescent lamps and black lights used to trap and kill pests in agriculture, all use ultraviolet rays to excite fluorescent substances to emit light. Ultraviolet rays also have physiological functions, such as sterilization, disinfection, treatment of skin diseases, rickets and so on. Ultraviolet rays have strong particle properties and can produce photoelectric effects on various metals. Ultraviolet rays are also called "ultraviolet rays". Electromagnetic radiation in the electromagnetic spectrum between violet light and x-rays. The wavelength is about (4 ~ 39) × 10-6 cm, which will not cause vision (that is, outside the visible range). Substances that can transmit visible light will strongly absorb ultraviolet rays in some bands. For example, glass has a strong absorption of ultraviolet light with a wavelength less than 35× 10-4 cm; Almost all the oxygen and ozone in the earth's atmosphere absorb ultraviolet rays with a wavelength less than 29× 10-6 cm. The crystal (i.e., in time) absorbs ultraviolet light with a wavelength less than 2× 10-5cm; Ultraviolet light with a wavelength less than 2× 10-5cm is strongly absorbed by air. Therefore, it is necessary to evacuate the interior of the spectrometer to observe this ultraviolet band, which is called vacuum ultraviolet, and the spectrometer suitable for this band is called vacuum ultraviolet spectrometer. Mercury lamp and arc lamp have strong ultraviolet radiation between (25 ~ 39) × 10-6 cm, and are commonly used ultraviolet light sources. Ultraviolet light is usually detected by photoelectric elements and photosensitive latex. Ultraviolet spectrum is an important means to study atomic structure, and ultraviolet light also has important application value in industry and agriculture. In biology and medicine, ultraviolet rays are often used to sterilize, induce mutation, and treat skin diseases and rickets.

[Ultraviolet] The electromagnetic radiation between violet light and X-rays in the electromagnetic spectrum. Also called ultraviolet light. The wavelength is about 0.04 ~ 0.39 micron, which will not cause vision. The most prominent feature of ultraviolet light is that many substances will emit fluorescence under its irradiation, and fluorescent lamps for lighting are made of ultraviolet light. Ultraviolet light has a chemical effect, which can make the photographic film sensitive. Ultraviolet rays also have physiological functions and are of great use in medical care. Ultraviolet rays can also penetrate the epidermis and cause chemical changes in tissues and cells inside the human body. Long-term exposure of the skin to ultraviolet rays will lead to discoloration, vasodilation, increase of calcium and phosphorus in blood, and increase of red blood cells and hemoglobin. In addition, it is especially suitable for treating rickets, infantile weakness, extrapulmonary tuberculosis and some infectious skin diseases. Although there are not many ultraviolet rays in the sun (most of them are absorbed by the air after passing through the atmosphere), they are very beneficial to the human body. People who live in cities and work indoors for a long time are often weak and pale because of lack of ultraviolet rays, especially those who work in mines or underground. They should always use solar lamps or mercury lamps to illuminate. In addition, ultraviolet rays can also dry paint and disinfect food, drinking water, clothes and utensils.

In recent years, the ozone hole caused by air pollution has led to more and more ultraviolet radiation to the surface, and the number of skin cancer patients has risen sharply. Can you tolerate your healthy skin being poisoned? A scientific and technological invention from Ningxia has brought good news to mankind: a fiber fabric that can resist ultraviolet rays and release far infrared rays has been successfully developed in Ningxia, and recently passed the technical appraisal, and the environmental protection functional clothing made has also initially formed productivity. Tested by the National Institute of Metrology, the ultraviolet shielding rate of this kind of clothing is 98.3%, and the far infrared emissivity is over 90%. Tested by the health and epidemic prevention department, the product is considered as "non-toxic, tasteless, non-irritating and without any side effects". The application of fabrics that resist ultraviolet rays and release far infrared rays to clothing not only solves the technical elements of ultraviolet rays, but also has health care functions, adding a new concept to human clothing and becoming a wonderful flower in clothing series.

X-rays and ultraviolet rays have short wavelengths, and they can penetrate solids, such as human tissues. Exposure to this light for a short time is harmless to the body. For example, doctors can learn about people's physical condition through X-rays. However, excessive exposure to these rays will do great harm to the human body. The cause of sunburn is direct exposure to the scorching sun for a long time, and excessive exposure to ultraviolet rays will lead to sunburn. People who have been exposed to the sun for many years may be exposed to excessive ultraviolet rays.