How did humans discover infrared rays?

Infrared ray is a kind of light that is invisible to the naked eye. In the past two or three decades, the nascent infrared technology has been widely used in various fields. It began to be applied to production and formed a brand-new technology - infrared technology.

In 1800, the British scientist Heschel conducted an experiment. After dividing the sunlight into colored light bands, he used a thermometer to measure the temperature of various lights, and discovered a strange phenomenon: the depth of light close to the sun The invisible part outside the red light is actually hotter than the red light. This was an unexpected discovery. Because in the past we only knew that sunlight has seven colors, it was not clear what substances existed in the darkness beyond the seven colors. Therefore, Heschel imagined that in addition to visible light, the sun's radiation must also contain a kind of radiation that is invisible to the naked eye. Later experiments proved that this radiation also exists in the radiation emitted by other objects. At that time, people called it "invisible radiation." Since this "invisible radiation" was found outside the red light, it was later called infrared radiation, or infrared rays.

In 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 needs of production practice, the development of various new technologies was promoted. Infrared science also came out of the laboratory and began to be applied to production, forming a brand-new technology-infrared technology.

In the past two or three decades, the nascent infrared technology has been widely used in various fields.

Infrared rays have a greater thermal effect than red light and have strong penetrating power. It can be used to dry things quickly and effectively. Therefore, 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 the paint, and the moisture inside could not escape, forming a bubble, which affected the quality of the paint. Using infrared rays to dry paint eliminates this drawback. Infrared rays have strong penetrating ability and can be used to dye synthetic fabrics. For example, after infrared high temperature penetrates into the interior of the nylon fabric, the structure of the nylon fabric will change, making it easy for the pigment to enter the inside of the fiber, fix the pigment on the fabric, and dry it. In this way, people can use infrared rays to dye nylon fabrics into various bright colors.

Infrared ray is a kind of light that is invisible to the naked eye. It can be used to form an invisible line of defense. In order to protect the warehouse, you can use a reflector to cleverly circle the infrared rays around the warehouse, and then project it onto a photoelectric tube that can only feel the infrared radiation, so that the photoelectric tube emits current. Hide reflectors, photoelectric tubes, etc. well to form an imperceptible line of defense. If someone dares to invade the warehouse, it will block the infrared rays. Once the infrared rays are blocked, the photoelectric tube will stop working. A switch connected to the photoelectric tube will be turned off immediately, and the alarm bell will sound.

Not long ago, scientific and technical personnel successfully developed an instrument called a pyroelectric camera, which is also an infrared TV. It can be used to detect fire sources, check fire hazards, monitor fires, and issue alarms in a timely manner. It is known as the "sentinel monitoring fires." Since infrared TV cameras rely on the infrared rays emitted by the subject to take pictures, the higher the temperature of the subject, the stronger the infrared rays emitted, and the clearer the captured image. Therefore, infrared TV can not be blocked by smoke, clouds, wind and rain, etc., and can check various fire conditions very sensitively and put out the fire when it has just emerged.

Infrared TV cameras, coupled with fire identifiers, automatic tracking systems, search mechanisms and telescopes, form a new type of automatic urban fire monitoring system. It can automatically search and find fire sources 2 to 3 square meters in size five or six kilometers away, and can automatically track and alarm. In this way, the automation of fire command and dispatch can be realized, providing modern technical means for timely detection and elimination of fires.

Infrared TV is also used in industry for monitoring darkroom operations, non-destructive, and thermal exploration of natural resources; in agriculture, it is used to detect fires in forests and pastures; and in transportation, it is used for fog-penetrating navigation. wait.

Infrared TV is still a "luminous eye"! It can effectively conduct reconnaissance on enemy positions and military facilities in complete darkness. Even cleverly concealed enemy lurking posts cannot escape its sharp eyes; it can also be used on border posts to monitor enemy positions and military facilities. Monitor a specific area; you can also "see" through the snow to see enemies hiding under the snow. There is also an infrared microscope. When people think of a microscope, they often think of it as an instrument used to magnify small objects. In fact, it is an instrument used to measure temperature. However, it is different from ordinary temperature measuring instruments and can be used to measure the temperature at very small points. Although the temperature at a tiny point can also be measured with a semiconductor point thermometer, since it is in direct contact with the surface of the object during measurement, it can easily affect the physical and chemical properties of the measured point; if measured with an infrared microscope, not only These shortcomings can be overcome and are much more accurate than semiconductor point thermometers.

Although infrared technology is just beginning to show its promise, we firmly believe that with the continuous development of science and technology, it will do many wonderful things for us that are predictable or even unexpected.

Infrared ray is also called "infrared light". In the electromagnetic spectrum, electromagnetic radiation with wavelengths between red light and microwaves. Outside the range of visible light, the wavelength is longer than red light and has a significant thermal effect. It can be measured with thermocouples, photoresistors and other instruments. The wavelength is 0.77-3 microns in the near-infrared region; 3-30 microns is the mid-infrared region. ; 30 to 1000 microns is the far infrared region. Infrared rays are easily absorbed by objects and converted into the internal energy of the objects; when passing through clouds and other substances filled with suspended particles, they are not easily scattered and have strong penetrating capabilities. Infrared rays are widely used and can be used to bake food and dry paint. and medical treatment, etc. The absorption spectrum of infrared rays by substances is of great significance to the study of the molecular structure of substances, chemical analysis and control in the chemical industry. Infrared detectors are commonly used in the military to detect targets and infrared communications.

Infrared TV is a system that uses the thermal radiation or reflected infrared rays of the subject itself to film and display movies. It is called infrared TV. Suitable for non-contact and non-destructive inspection, often used in industry, medicine, space development, military, etc.

The electromagnetic wave between the red end of visible light and microwaves has a wavelength range of approximately 7×10?7 meters to 1×10? meters. In 1800, British physicist Scheherr placed a thermometer outside the red light region of the solar spectrum and found that it still had a strong thermal effect. So this invisible ray is called infrared ray. All objects radiate infrared rays. The higher the temperature of an object, the wider the infrared band it emits. The mechanism of infrared ray generation is that the outer electrons of atoms are excited. The most significant feature of infrared rays is its thermal effect. The wavelength of infrared rays is longer than that of red light, so the diffraction phenomenon is more obvious. It can easily pass through clouds and smoke and be difficult to be absorbed by suspended particles in the air.

Use the thermal effect of infrared rays to heat objects, such as drying paint and grains and performing medical treatment. Films sensitive to infrared rays can be used for long-distance photography and high-altitude photography, and infrared rays can be used to photograph the ground from satellites. Objects on the ground can be clearly seen and are not restricted by day and night. Since all objects are constantly radiating infrared rays, and different objects radiate infrared rays with different wavelengths and intensities, infrared remote sensing technology can be used to survey geothermal energy on aircraft or satellites, find water sources, weather forecasts, etc. In modern warfare, night vision equipment such as infrared night vision devices are used to make the opponent's targets vividly visible. Infrared physics can be used to detect infrared radiation of high-temperature objects. Infrared sensors are now also used for anti-missile early warning.

Using thermometers to solve optical problems - the discovery of infrared rays

The sun is the most familiar celestial body in the universe. It rises in the east and sets in the west every day, leaving early and returning late. Sunlight shines on the earth, allowing all things to grow and multiply. In summer, the fiery red sunshine makes people feel unbearably hot. In winter, people want to bask in the sun as much as possible in order to use the heat of the sun to resist the cold. Human beings have known since ancient times that the sun brings light and heat to people, and the light and heat of the sun are always inseparable. But when humans generously accept the light and heat given by the sun, they never consider how light carries heat.

The Color of Sunlight With the development of science, in the 17th century, people began to conduct systematic research on the phenomenon of light. In 1666, the great scientist Newton discovered in an experiment that let sunlight pass through a glass prism. White sunlight was actually composed of seven colors of monochromatic light: red, orange, yellow, green, blue, indigo, and violet. This It is the famous "dispersion experiment of light" in physics. Newton made many contributions to optical research. His research achievements in many aspects such as the linear propagation of light, the refraction and reflection of light, the imaging of lenses, and the theory of color have become the most important part of the treasure house of human knowledge. But Newton himself and his contemporaries focused their attention on various optical phenomena or on the endless debates about the nature of light. Only no one cared about the light of the sun. It can be said that in the history of the development of optics, the light of the sun was an outcast of science for a long time.

The Priest’s Inspiration In 1738, a child named Hershall was born in England. Heshall was an ordinary child when he was a child, and he did not become a scientist when he grew up. He is a priest by profession, but he has a special love for sunlight. For this purpose, he specially bought a large glass prism and placed it on his desk, admiring the seven-colored ribbons formed by the sunlight passing through it from time to time. One morning in 1800, Heshall, who was over sixty years old, looked at the beautiful color bands and suddenly asked himself curiously like a child: "Sunlight has heat, but which of the seven monochromatic lights that make up sunlight has the most heat?" Which one carries the most heat?" No one knew about his seemingly simple question at the time, so Hershall began to think about this question and try to find the correct answer.

A few days later, Hershall found a solution to this problem. He thought that sunlight is divided into seven types of monochromatic light through a prism. If the temperature of each type of light is known, wouldn't it be possible to know which one of them carries more heat? Then, Heshur put a piece of white paper on the wall of his room as a light screen, and let the seven-color light strips passing through the prism shine on the paper screen. Then Hershall hung a thermometer at each strip of light. He was afraid that his observation was not comprehensive enough, so he hung a thermometer outside the red light band and a thermometer outside the purple light band.

After doing all this, Heshuer recorded the initial reading of each thermometer, then sat down on the chair next to the table and began to observe. The mercury on the thermometer rose slowly, and Hershall waited patiently. After about half an hour, all the thermometer readings stopped changing. Herschel found that the temperature in the green light area increased by 3°C, the temperature in the purple light area increased by 2°C, and the reading of the thermometer outside the purple light area almost did not change. However, what surprised him was that the reading of the thermometer outside the red light area actually increased by 7°C.

Although Heshall is a priest, he has the qualities of a scientist. After discovering this strange phenomenon, he immediately repeated the experiment. But the results of multiple experiments are the same: the reading of the thermometer outside the red light area rises the most. After detailed analysis, Heshuer believed that the spectrum of sunlight is actually wider than the seven monochromatic lights seen by people. There must be some kind of light invisible to the human eye outside the red light band, and this light carries has the most calories. Later, the scientific community named this invisible light infrared, and Heshall also made his name in the history of science for discovering it.

Where does infrared rays come from? After Herschel discovered infrared rays, because humans did not have a deep enough understanding of many natural phenomena at that time, and the overall level of scientific research was not high at that time, scientists engaged in infrared ray research did not not much. Later, with the development of physics and other scientific disciplines, it became clear that infrared rays, like other visible light, are part of electromagnetic waves. However, the wavelength range of visible light is 0.4-0.75 microns, while the wavelength range of infrared rays is 0.76-1000 microns, so it is invisible to the human eye.

Scientists later also learned about the mechanism of infrared rays. Infrared rays are also called infrared radiation. As long as the temperature of any object is higher than absolute temperature zero - -273°C, their molecules will have thermal motion. Accompanied by this The thermal motion of molecules causes the object to radiate infrared rays of different wavelengths.

The wonderful use of infrared rays. Human beings have discovered infrared rays for a long time, but it was not until this century with the rise and development of radio electronics and materials science that infrared rays became a hundred times more valuable and appeared in our world as high technology. before.

Everyone likes to watch CCTV’s “Animal World” column hosted by Zhao Zhongxiang, in which so many shots of animals’ nocturnal activities were obtained using infrared photography. Since any object radiates infrared rays, scientists have developed an infrared film that can specifically record infrared signals. By attaching this film to an ordinary camera and borrowing other equipment, you can shoot at night and far away from animals. Crocodiles are ferocious animals familiar to humans. In order to study the living habits of crocodiles and the process of raising their children, researchers placed automatic infrared cameras near crocodile nests in appropriate seasons. It can be seen from the footage that when the baby crocodiles are newly hatched, the mother crocodile sometimes licks them, sometimes moves them, and sometimes feeds them. The ferocity that we usually see is gone, and his compassion for children is no less than that of us humans.

Thermal infrared detection system is an important application of infrared. Since any object that radiates infrared rays is a heat source different from other surrounding objects, that is, there is a temperature difference between an object and the surrounding environment, the thermal infrared detection system discovers the target by detecting the temperature difference. For example, this device is used in the military to find enemies hiding in the bushes and enemy vehicles and tanks that are moving forward. We often see battle scenes like this in movies or TV. Two planes are chasing each other in the air. Suddenly, the plane behind shoots a missile, and the other plane sees this and immediately changes its flight direction, sometimes turning, and sometimes rolling up and down. , but was still hit by a missile seconds later. Why can't the plane get rid of the missile? This is because the exhaust pipe of a flying aircraft engine is a source of infrared radiation, and a missile equipped with an infrared detector will have no difficulty detecting it. Although the aircraft tried its best to get rid of the missile, the electronic navigation system on the missile caused the missile to always bite the heat source. In this way, the aircraft that was slower than the missile could not be hit.

Today, the application scope of infrared is becoming more and more extensive, and it has extremely important applications in many aspects such as industry, agriculture, military, food processing, and security work. But don't forget that the discovery of infrared rays was the one with the least investment and the simplest process in science - only relying on a glass prism and a few thermometers.

Infrared rays are electromagnetic waves with wavelengths between red light and microwaves in the electromagnetic spectrum. The wavelength is about 0.75 to 1000 microns and cannot cause vision. Infrared rays have significant thermal effects and can be detected with instruments such as thermocouples, photoresistors or photoelectric tubes. Infrared rays are easily absorbed by objects and converted into their internal energy; they have strong penetrating ability when passing through clouds and fog and other substances filled with suspended particles. Infrared rays can be used for communication, tracking and detecting targets in the military; in industry, they can be used to dry paint, baked foods, etc.; for long-distance targets and high-speed moving targets, infrared technology can be used for non-contact temperature measurement; in medicine, they can be used Infrared technology diagnoses disease. Infrared technology has become a rapidly developing emerging technology in the past 20 years.

[Infrared rays] are invisible to the human eye, but can pass through or penetrate many materials, such as thin wood chips, bakelite, trees, paper, mist, leather, etc. If the material is too thick, infrared rays cannot penetrate and can only penetrate to a certain extent.

Infrared rays can also interact with atoms, causing some changes in the motion of the atoms. Infrared rays have a thermal effect. It was discovered by the British astronomer Herschel in 1800 because of its significant thermal effect. We can find many uses for infrared rays by taking advantage of their invisible properties, strong penetrating power, thermal effects, and ability to deal with atoms. Such as infrared spectrum analysis, drying, infrared photography, detection, communication, etc.

Infrared waves The wavelength of infrared rays is longer than the wavelength of visible light we can see. Most heat waves are infrared waves, which is why when you put your hand on a friend's cheek, you can feel Warm, but no light waves visible.

What is infrared? In 1800, scientist William. Sir Herschel discovered that about two-thirds of the energy in sunlight comes from heat energy invisible to the naked eye, or infrared radiation. Objects heat up when exposed to sunlight, not because they absorb the visible sunlight we see, but because of the infrared radiation energy that accompanies visible sunlight. All heat sources contain infrared light, and astronomers can even detect some planets through infrared light instead of using visible light waves. This laser record player is activated by infrared light in the remote control, and the red indicator on the machine lets you know that the infrared light is working. In this detector or induction box, its sensing efficiency is obtained through an electric photoreceptor that can detect light waves. When the surrounding light is dim, the sensor will activate the infrared detector; during the day, when lighting is not needed, it will not activate.

Infrared receptors are special temperature receptors located on both sides of the face of snakes (Crotalidae, vipers, pit vipers, and rattlesnakes) that are only sensitive to infrared rays. In the dark night, venomous snakes detect the infrared rays emitted by each other, which acts like binocular vision. There are small holes under the eye sockets, also known as perforations. There is a membrane at the bottom similar to the tympanic membrane of the middle ear, and there is a cavity at the back that communicates with the outside world, which is very similar to the Eustachian tube. There are many mitochondria in the cytoplasm. On the membrane, trigeminal nerve fibers are densely networked to form terminal ends, surrounded by Schwann cells on the outside. Once infrared rays reach this film, the potential changes in proportion to the heat. Although the sensing mechanism of infrared rays is not very clear, it is very sensitive and can distinguish 0.002℃. There are also venomous snakes (king snakes) that do not have pores but have infrared sensitivity, but in this case the sensitivity is said to be very poor.

The discovery of ultraviolet light One day in 1801, a scientist who studied the solar spectrum suddenly wanted to know whether there were other invisible lights after the sunlight was decomposed into seven colors of light. At that time, he happened to have a bottle of silver chloride solution on hand. People already knew at that time that silver chloride would decompose and precipitate silver when heated or exposed to light. The precipitated silver appears black because the particles are small. This scientist wanted to use silver chloride to determine the components of sunlight other than the seven colors of light. He soaked a piece of paper with a little silver chloride solution and placed the paper on the outside of the purple light of the seven colors of light after the white light was dispersed by the prism. After a while, he indeed observed on the piece of paper that the lower part with silver chloride turned black, which showed that after the sunlight was dispersed by the prism, there was still an invisible light outside the purple light. The scientist took this This light is called ultraviolet light. This scientist is Ritter, who was born on December 16, 1776 in Silesia, Germany. When I was a child, my family was poor and I didn't go to school for several years. When he was 14 years old, he became an apprentice in a pharmacy. During his apprenticeship, Ritter read many books voraciously and learned a lot about chemistry and physics. With diligent self-study, he was admitted to the University of Jena at the age of 20 and later made many contributions in chemistry and electrophysiology. In 1799, he successfully electrolyzed copper from a copper sulfate solution using a Galvanic cell, and concluded that static electricity and Galvanic electricity were consistent. He also correctly pointed out that the cause of the Galvanic current is a chemical reaction inside the Galvanic battery, thus becoming the first person to correctly explain the cause of the Galvanic current. In 1802, Ritter produced the first dry battery, and in 1803 he successfully developed a storage battery. Ritter's major contribution to physics was the discovery of ultraviolet light. Ultraviolet radiation is radiation with a shorter wavelength than violet light and is part of the solar spectrum that is invisible to the naked eye. Strong ultraviolet light exposure is harmful to the human body and living things, but an appropriate amount of ultraviolet light can make you feel refreshed and promote the body's metabolism. Ultraviolet light is also used in medicine to sterilize. In addition, people have also created a new analysis method, namely fluorescence analysis, based on the "photoluminescence" phenomenon of ultraviolet rays (ultraviolet rays induce the luminescence of substances). It can not only detect the structure of substances, but also clearly detect what is difficult for the human eye to detect. Cracks found in machine parts. The discovery of ultraviolet light has brought good news to mankind, but its discoverer Ritter was from a poor family and lived a miserable life. When he was full of longing to climb to the peak of science, he was killed by lung disease. He was only 34 years old when he died. .

Ultraviolet light is also called "ultraviolet light". Electromagnetic radiation that lies between violet light and roentgen rays (X-rays) on the electromagnetic spectrum. The wavelength is about (4~39) × 10-6 cm, which cannot cause vision (that is, it is outside the visible light range). Materials that can transmit visible light will strongly absorb certain bands of ultraviolet light.

For example: glass has strong absorption of ultraviolet rays with wavelengths less than 35 × 10-4 cm; oxygen and ozone in the earth's atmosphere almost all absorb ultraviolet rays with wavelengths less than 29 × 10-6 cm in solar radiation; crystal (i.e. quartz) Absorbs ultraviolet rays with wavelengths less than 2 × 10-5 cm; ultraviolet rays with wavelengths less than 2 × 10-5 cm are strongly absorbed by the air. Therefore, the interior of the spectrometer that observes this ultraviolet band must be evacuated. This band is called vacuum ultraviolet, and the spectrometer suitable for this band is called a vacuum ultraviolet spectrometer. The light of mercury lamps and electric arcs contains strong ultraviolet radiation between (25~39) × 10-6 cm. They are commonly used ultraviolet light sources. Ultraviolet rays are usually detected using photoelectric components and photosensitive latex. Ultraviolet spectroscopy is an important means of studying atomic structure, and ultraviolet light also has important application value in industry and agriculture. Ultraviolet rays are commonly used in biology and medicine for sterilization, inducing mutations, and treating skin diseases and rickets.

Globally - Ultraviolet rays are increasing in densely populated areas. NASA recently published a survey report showing that ultraviolet rays are increasing in densely populated areas around the world. In the past 10 years, ultraviolet rays have increased by as much as 10%. Researchers used Earth observation satellites to observe the Earth's ozone layer and ultraviolet exposure for 13 years and drew corresponding maps. In addition, observation data provided by eight ground observation stations in Canada, New Zealand and the United States supplemented the above observations. Based on this, the researchers analyzed the distribution of the increase in ultraviolet exposure due to the reduction of the ozone layer along the Earth's latitudes. It was found that ultraviolet exposure increased significantly in densely populated areas in both the southern and northern hemispheres. The area near 55 degrees south latitude, including Argentina and Chile in South America. The amount of ultraviolet exposure increased by 9.9% in 10 years. Areas near 55 degrees north latitude such as the United Kingdom, Germany, and Russia increased by 6.8%; areas located between 30 degrees and 45 degrees north latitude such as Japan and the United States increased by 4%.

The "expert" in absorbing ultraviolet rays - the ozone atmosphere - the earth's gas shell, within which humans and all living things live. There is a layer in the atmosphere that is good at absorbing ultraviolet rays, 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, then all existing life on the earth would probably be gone. The ozone layer therefore acts as an impenetrable shield, protecting the environment from the sun's ultraviolet rays, which kill animals. The ozone molecule is composed of three oxygen atoms. It has very active chemical properties and has a special odor, hence its name. It is located in the stratosphere of the atmosphere, and its concentration is highest in the ozone layer, which is located at an altitude of twenty to thirty kilometers. It is this layer that absorbs most of the ultraviolet rays and plays a role in protecting life on earth. Ozone easily reacts with nitrogen oxides, thereby reducing the amount of ozone. The sources of nitrogen oxides include emissions from supersonic aircraft, nitrogen fertilizers that are widely used into the stratosphere, and freon, which is widely used as refrigerants and is the most ferocious "killer" of ozone. These "killers" are causing the ozone in the ozone layer to continue to decrease. Excessive and long-lasting ultraviolet radiation can cause a significant reduction in crop yields, damage human health, cause skin cancer, etc. We should take measures as soon as possible to protect the ozone layer!

Ultraviolet rays are at work. It turns out that factors such as Los Angeles' special geographical location, special climate conditions and strong sunlight are responsible for this smog. If any one of these links is missing, smoke cannot occur. Scientists have discovered that the smog that appears in Los Angeles is photochemical smog. This smog is an irritating light blue smog produced by the action of ultraviolet rays from sunlight on nitrogen oxides and hydrocarbons emitted into the atmosphere. It contains ozone, Various complex compounds such as peroxyacyl nitrates and aldehydes are secondary pollutants generated by photochemical reactions. Under certain geographical conditions, when encountering temperature inversion or unfavorable diffusion meteorological conditions, smog will accumulate and remain, causing air pollution events, irritating human eyes and respiratory tracts or inducing various respiratory tract inflammations, endangering human health.

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

Plants that are most tolerant of ultraviolet irradiation. There is a type of ultraviolet ray in the sun that affects almost all living things. Especially microorganisms will be killed in ten minutes if exposed to a certain dose of ultraviolet rays. Therefore, hospitals and some factories often use ultraviolet rays for sterilization. Higher plants are no exception. According to research by scientists, if the ultraviolet intensity equivalent to that on the surface of Mars is used as a standard to irradiate various plants, tomatoes, peas, etc. will die in just 3-4 hours; rye, wheat, corn, etc. can be killed if irradiated for 60-100 hours. Dead leaves; while the southern European black pine is still alive after being exposed to irradiation for 635 hours. This is the plant most tolerant of UV rays. Scientists estimate that plants like the black pine could live on Mars for a season. This fact proves that it is possible for life to exist on planets other than Earth, such as Mars. Ultraviolet electromagnetic radiation with wavelengths between the violet end of visible light and X-rays has a wavelength range of 400 to 500 nanometers and cannot cause human vision.

In 1801, German physicist Ritter discovered that a section outside the violet end of the sunlight spectrum could sensitize photographic films containing silver bromide, thus discovering the existence of ultraviolet light. The main source of UV light in nature is the sun. When sunlight passes through the atmosphere, ultraviolet rays with wavelengths shorter than 290×10?9 meters are absorbed by ozone in the atmosphere. Artificial ultraviolet light sources include arcs of various gases (such as low-pressure mercury arc, high-pressure mercury arc). Ultraviolet rays have chemical effects that can sensitize photographic films. They have strong fluorescent effects, such as fluorescent lamps, various fluorescent lamps, and black light lamps used in agriculture to trap pests. They all use ultraviolet light to excite fluorescent materials to emit light. Ultraviolet rays also have physiological effects and can sterilize, disinfect, and treat skin diseases and rickets. Ultraviolet rays are highly particle-like and can cause photoelectric effects on various metals. Ultraviolet rays are also called "ultraviolet light". Electromagnetic radiation that lies between violet light and roentgen rays (X-rays) on the electromagnetic spectrum. The wavelength is about (4~39) × 10-6 cm, which cannot cause vision (that is, it is outside the visible light range). Materials that can transmit visible light will strongly absorb certain bands of ultraviolet light. For example: glass has strong absorption of ultraviolet rays with wavelengths less than 35 × 10-4 cm; oxygen and ozone in the earth's atmosphere almost all absorb ultraviolet rays with wavelengths less than 29 × 10-6 cm in solar radiation; crystal (i.e. quartz) Absorbs ultraviolet rays with wavelengths less than 2 × 10-5 cm; ultraviolet rays with wavelengths less than 2 × 10-5 cm are strongly absorbed by the air. Therefore, the interior of the spectrometer that observes this ultraviolet band must be evacuated. This band is called vacuum ultraviolet, and the spectrometer suitable for this band is called a vacuum ultraviolet spectrometer. The light of mercury lamps and electric arcs contains strong ultraviolet radiation between (25~39) × 10-6 cm. They are commonly used ultraviolet light sources. Ultraviolet rays are usually detected using photoelectric components and photosensitive latex. Ultraviolet spectroscopy is an important means of studying atomic structure, and ultraviolet light also has important application value in industry and agriculture. Ultraviolet rays are commonly used in biology and medicine for sterilization, inducing mutations, and treating skin diseases and rickets.

[Ultraviolet] Electromagnetic radiation located between violet light and X-rays in the electromagnetic spectrum. Also called ultraviolet light. The wavelength is about 0.04 to 0.39 microns and cannot cause vision. The most prominent characteristic of ultraviolet rays is that many substances will fluoresce under its irradiation. The fluorescent lamps for lighting are made by utilizing the fluorescence effect of ultraviolet rays. Ultraviolet rays have a chemical effect that sensitizes photo negatives. Ultraviolet rays also have physiological effects and are widely used in medical care. Ultraviolet rays can also penetrate the epidermis and cause chemical changes in the internal tissue cells of the human body. Skin exposed to ultraviolet rays for a long time will change color, blood vessels will dilate, calcium and phosphorus in the blood will increase, and red blood cells and hemoglobin will also increase. In addition, it is particularly suitable for the treatment of rickets, childhood frailty, tuberculosis outside the lungs, and certain infectious skin diseases. Sunlight (most of the ultraviolet rays are absorbed by the air after passing through the atmosphere) does not contain much ultraviolet rays, but it is very beneficial to the human body. People who live in cities and work indoors for a long time often have weak constitutions and pale skin due to lack of ultraviolet rays. Especially those who work in mines or underground should often use sun lamps or mercury lamps. In addition, ultraviolet rays can dry paint and disinfect food, drinking water, clothes, utensils, etc.

The advent of anti-UV fabrics In recent years, the ozone hole caused by air pollution has caused more and more ultraviolet radiation to reach the surface of the earth, resulting in a sharp increase in skin cancer patients. Can you tolerate your healthy skin being destroyed? A scientific and technological invention from Ningxia has brought good news to mankind: fiber fabrics that resist ultraviolet rays and release far-infrared rays have been successfully developed in Ningxia and have recently passed technical appraisal. The environmentally friendly functional clothing produced has also initially achieved productivity. Tested by the National Institute of Metrology, this type of clothing has an ultraviolet shielding rate of 98.3% and a far-infrared emissivity of over 90%. It has been tested and certified by the health and epidemic prevention department as a "non-toxic, odorless, non-irritating, without any side effects" product. The application of anti-UV and far-infrared ray-releasing fabrics to clothing not only solves the technical factor of anti-UV radiation, but also has health care functions, adding a new concept to human clothing and becoming a wonder in the clothing series.

X-rays and ultraviolet waves External rays and X-rays (also called X-rays) have short wavelengths, and they can penetrate solid objects, such as human tissue. Short-term exposure to this type of light will not harm the body. For example, doctors can use X-rays to understand a person's physical condition. However, excessive exposure to these lights will cause great harm to the human body. Causes of Sunburn: Direct exposure to the sun for a long time, or overexposure to ultraviolet rays, will lead to sunburn.

People who have been exposed to the sun for many years may suffer from excessive ultraviolet rays