List industrial laser equipment ~ ~ ~

It is very common to transmit information by light today. For example, ships communicate with signals, and traffic lights are dispatched with red, yellow and green. But all these ways of transmitting information by ordinary light can only be limited to a short distance. If you want to use light to transmit information directly to far places, you can't use ordinary light, you can only use laser.

So how do you deliver the laser? We know that electricity can be transmitted along copper wires, but light cannot be transmitted along ordinary metal wires. To this end, scientists have developed a kind of filament that can transmit light, called optical fiber, or optical fiber for short. Optical fiber is made of special glass material, and its diameter is thinner than that of human hair, usually 50 ~ 150 micron, which is very soft.

In fact, the inner core of optical fiber is transparent optical glass with high refractive index, while the outer sheath is glass or plastic with low refractive index. On the one hand, this structure can refract light along the inner core, just like water in the tap water pipe flows forward and electricity in the wire propagates forward, even if it is tortuous. On the other hand, the sheath with low refractive index can prevent light from leaking out, just as the water pipe will not leak and the insulation layer of the wire will not conduct electricity.

The appearance of optical fiber solves the transmission mode of light, but it doesn't mean that with it, any light can be transmitted to far places. Only the laser with high brightness, pure color and good directivity is the most ideal light source to transmit information. After input from one end of the optical fiber, it is output from the other end with almost no loss. Therefore, optical communication is essentially laser communication, which has the advantages of large capacity, high quality, wide source of materials, strong confidentiality and durability. It is praised by scientists as a revolution in the field of communication and one of the most brilliant achievements in the technological revolution.

Where is the advanced laser communication? The advantage of laser communication is firstly large capacity. What's its capacity? When we usually make a phone call, sometimes there will be irrelevant voices. This kind of fighting phenomenon is because only one telephone line can be used on a pair of telephone lines. If another telephone line is connected in series, the normal calls of both parties will be disturbed. If there are 10 pairs of people talking on a pair of telephone lines at the same time, it means that 20 people are talking at the same time and it is impossible to talk at all. In order to solve this problem, it is necessary to use carrier wave and other methods to make every mobile phone in every frequency band. Because the frequency range of ordinary telephone is 300 ~ 400 Hz, and the highest frequency on a pair of telephone lines is only 1500 kHz, so a pair of telephone lines can only pass through more than a dozen telephones at the same time. Obviously, such telecom capacity is far from meeting the requirements of today's information society.

If the transmission information of ordinary telephone is compared to a big car, then laser communication is a car. Because the frequency of laser is much higher than that of radio waves, the information capacity of laser communication is 65.438+0 billion times that of electric communication. An optical fiber thinner than a human hair can transmit tens of thousands of telephone calls or thousands of TV programs. The optical cable composed of 20 optical fibers is only as thick as a pencil and can make 76,200 calls every day. In contrast, the cable composed of 1800 copper wire is about 7.6 cm in diameter, but it can only make 900 calls every day.

Surprisingly, optical fiber communication is especially suitable for TV, image and digital transmission. It is reported that a pair of optical fibers can transmit a complete set of Encyclopedia Britannica in one minute.

In addition, optical fiber is made of sand that can be seen everywhere on the earth-timely. A few grams can be made into an optical fiber with a length of 1 km. In this way, not only the raw materials are inexhaustible, but also copper and aluminum can be greatly saved. Because of this, all developed countries in the world are competing to study laser communication. Therefore, laser communication has become the darling of competing development.

In the history of communication technology, the development of optical fiber communication technology is unprecedented. Looking at several milestones in the history of communication technology, it took about 60 years for the telephone to be invented and applied, and telephone communication is still widely used. Radio technology (such as telegraph) also took about 30 years from invention to application. Although TV technology has developed rapidly, it was born about 14 years ago. Laser communication, from the birth of the first low-loss optical fiber to its application, only takes five years. Nowadays, laser communication is not only widely used, but also forms a huge optical fiber market.

1977 in may, a big American company called telegraph and telephone company laid the world's first short-distance optical fiber communication line between two telephone offices in Chicago. Since then, short-distance laser communication lines with a total length of hundreds of kilometers have been established in nearly 100 places in the United States. This means that in a short distance, laser communication has begun to replace ordinary electrical communication. By 1983, 600 kilometers of optical fiber communication had been put into use between new york and Boston.

Japan follows the United States closely. 1984, Japan built a long-distance optical fiber communication trunk line from Sapporo, Hokkaido to Fukuoka, Kyushu, with a total length of 2,800 kilometers, connecting more than 30 cities in the middle. 199365438+In February, the Sino-Japanese optical cable across the East China Sea was successfully laid. A submarine optical cable with a length of 6,543,800 kilometers across the Pacific Ocean between Japan and the United States is also under design.

Due to the vigorous development of optical fiber communication, the United States, Japan, Britain, France and other industrialized countries have successively established optical fiber and cable production enterprises. The world's three famous optical fiber and cable companies-Nishiko, Corning and Sumitomo, have an annual optical fiber output of over1.2000 km.

In a word, industrialized countries have established a nationwide optical fiber communication network, completely replacing the current copper wire and cable. This huge technical project is expected to be completed in 2000. By then, laser communication will bring great changes to our planet. For example, you can use optical fiber network to process documents or attend meetings at home without leaving home; Or connect the optical fiber network at home to the shopping center, just like in the supermarket, you can buy the goods you need at home, and the payment only needs to be settled by the electronic financial shopping system. Medical centers all over the country can also check the patient's condition and laboratory reports from the screen, and prescribe prescriptions accordingly, so as to truly achieve "a scholar can know what's going on in the world without going out" and "plan in the air and win the battle thousands of miles away".

Laser and optical fiber can also transmit images. First of all, a single optical fiber with a diameter smaller than a human hair should be combined into an optical fiber bundle. In the process of transmitting information, there are two kinds of commonly used optical fiber bundles: one is called beam and the other is called image beam. The task of transmitting light beam is to transmit light from one end to the other. The structure of the beam is relatively simple. It is made by gluing a plurality of monofilaments, then polishing and grinding its end face to reduce the reflection and scattering loss when light enters the optical fiber, and then putting a plastic sheath on the outside of the light beam.

Because one optical fiber can only transmit one light spot, to transmit the whole image, the optical fibers must be arranged neatly one by one, and the optical fiber bundle formed in this way is called image transmission bundle.

In the image bundle, all the optical fibers are arranged neatly, and the positions of the two ends are strictly corresponding, which is not messy at all, just like a neat chopstick. For example, one end of the optical fiber is in the eighth row and the eighth column in the image beam, so the other end is also in the eighth and eighth positions.

When an image beam transmits an image, the image is first divided into grids, that is, an image is decomposed into countless pixels by countless optical fibers, and then transmitted. One optical fiber is responsible for transmitting one pixel, and countless optical fibers can transmit the whole image to the other end. If you want to transmit images clearly, you should use optical fiber with smaller diameter as much as possible, because the thinner the optical fiber, the more light beams an image transmission beam can hold, and thus more pixels can be transmitted. Obviously, the more pixels, the clearer the image.

The image beam used now consists of tens of thousands of optical fibers, and it is not easy to arrange so many optical fibers neatly. After the arrangement, use an organic adhesive called epoxy resin to stick the two ends together, so that the optical fibers can be bonded and fixed, ensuring that the optical fibers at both ends correspond to each other one by one. Both ends should be polished. As for the middle part, it doesn't need to be glued firmly, but it's as loose as the erhu string, just add a protective plastic sleeve outside, so that the image beam is very soft and can be bent at will.

In addition to transmitting images, image beams can also transmit general symbols or numbers to enlarge or reduce images.

If you want to enlarge the image, you can make one end of the image beam big and the other end small, just like a cone. When pixels are transmitted from small end to large end, the whole image is enlarged. On the contrary, if the image is sent from the big end to the small end, the whole image will be reduced.

In addition, images can be changed by using optical fibers. If the arrangement of optical fibers is intentionally disturbed as needed, the pixels at the exit end cannot fall on the original corresponding point, but on the main point of view, and the image will change. If the optical fiber at the entrance end of the pixel is square and the optical fiber at the exit end is round, then the square pixel can be turned into a round pixel.

In a word, optical fiber image bundle has great development potential and will show its unique role in the future optical information processing technology.

(2) Material processing

When machining metal materials, drilling, cutting, welding and quenching are the most commonly used operations. Since the advent of laser, a new situation has been created in the intensity, quality and scope of processing. In addition to metallic materials, laser can also process many non-metallic materials.

Laser drilling machine Before the emergence of laser drilling machine, all kinds of mechanical parts were drilled by electric drilling machine or punch. However, mechanical drilling is not only inefficient, but also the surface of drilling is not smooth enough.

The principle of laser drilling is to make the focus temperature of the metal surface rise rapidly by using laser beam focusing, and the temperature rise can reach/kloc-0.00000 degrees per second. Before the heat dissipates, the light beam melts the metal until it evaporates, leaving a small hole. Laser drilling is not limited by the hardness and brittleness of the processed material, and the drilling speed is extremely fast, and small holes can be drilled as fast as a few thousandths of a second or even a few millionths of a second.

For example, it is necessary to drill hundreds of tiny holes in a metal plate that are imperceptible to the naked eye, which is obviously not competent with an electric drilling machine, but it can be completed with a laser drilling machine 1 ~ 2 seconds. If you carefully examine these micropores with a magnifying glass, you can find that the surface of the micropores is very neat and clean.

Laser drilling can also be used to process watch diamonds. It can drill 20 ~ 30 holes per second, which is hundreds of times more efficient than mechanical processing and has high quality. At the same time, laser drilling is the same as the laser cutting we will talk about below, and the processing process is non-contact, that is, unlike mechanical processing, steel drills are not used to drill through metal materials gradually. Therefore, laser operation can play a role in automatic continuous machining or ultra-clean and vacuum special environment.

Knowing the principle of laser drilling, the laser cutting machine can easily understand why laser can cut metal materials: as long as the workpiece is moved or the laser beam is moved to make the drilled holes line up, the material can be cut naturally. Moreover, no matter what kind of material, such as steel plate, titanium plate, ceramic, timely, rubber, plastic, leather, chemical fiber, wood and so on. Laser is like a lightsaber, cutting iron like mud, cutting wood like ash, and the cutting edge is very smooth.

Laser welding machine Laser can be used for welding because of its high power density. The so-called high power density means that extremely high energy can be concentrated per square centimeter. How high is the power density of the laser? We can make a comparison: the acetylene flame commonly used for welding in factories can weld two steel plates together, and the power density of this flame can reach per square centimeter 1000 watt; The power density of argon arc welding equipment is higher, which can reach per square centimeter 10000 watt. But these two welding flames can't be compared with lasers at all, because the power density of lasers is ten million times higher than them. Such high power density can be used for welding not only ordinary metal materials, but also hard and brittle ceramics.

The traditional laser quenching method is very simple. Burn the blade red first, and then suddenly immerse it in cold water. After this cold and hot treatment, the hardness of the blade is greatly improved. However, this quenching is obviously inconvenient and the effect is not necessarily ideal.

Laser quenching is to use laser to scan the parts that need to be quenched, so that the temperature of the scanned area rises, while the parts that are not scanned remain at room temperature. Due to the rapid heat dissipation of metal, the temperature of this part drops sharply when the laser beam is swept away. The faster the temperature drops, the higher the hardness. If the scanned parts are sprayed with rapid cooling agent, the hardness is much better than that of ordinary quenching.

(3) Laser phototypesetting

In fact, phototypesetting introduces the principle of optical photography. Typesetting with movable type must be based on the original manuscript, and fonts and symbols of different sizes and fonts must be detected during typesetting. On the other hand, photo typesetting is much simpler. It changes the size and shape of the text through the lens on the typesetting machine. As for why you can change the size and shape of words with lenses, it is actually equivalent to taking a "ha ha mirror".

In phototypesetting, only the required characters and symbols need to be imaged on photographic paper through a lens, and then developed and fixed to form a photographic negative. Then, print it out like a photo.

Phototypesetting can use two kinds of light sources, just ordinary light sources, compared with laser typesetting, which saves time and effort. Because of the high brightness and good color of the laser, the clarity of the image can be greatly improved, and the quality of the printed book is naturally high. What is its principle? First, the computer turns the text into dots, and then the point-controlled laser scans the photosensitive film, so that a real hologram can be taken.

Holography and stereo photography are two different things. Although the stereoscopic color photo looks bright, layered and stereoscopic, it is still a one-sided image, and even the best stereo photo can't replace the real thing. For example, no matter how we change the viewing angle, we can only see the picture in the photo, but the hologram is different. By changing the observation angle, we can see the six faces of the square. Because holographic technology can record all the geometric features of objects on the negative, this is also the most important feature of holography.

The second important feature of holography is that you can know the whole leopard at a glance. When the hologram is damaged, even if most of it is damaged, we can still see the whole picture of the original object in this hologram from the remaining half. This is not good for ordinary photos, even if a corner is lost, you can't see the picture on that corner.

The third feature of holographic photos is that multiple holographic photos can be recorded in layers on a holographic negative without interfering with each other when displaying pictures. It is this layered recording that enables holograms to store a large amount of information. The negative of laser holography can be special glass, latex, crystal or thermoplastic. A small special glass can store all the contents of millions of books in a large library. Holography is more and more widely used.

Holography can record precious historical relics. In case the cultural relics are seriously damaged, even if nothing is left, we can still reconstruct them according to holography. Such scenic spots as the Yuanmingyuan in Beijing were burnt down by Eight-Nation Alliance in that year. Although reconstruction is planned now, it is difficult to fully recover because we don't know the original appearance. If holography was invented 100 years ago, things would be simple.

Holography can also be used for nondestructive testing in industry. What is nondestructive testing? In other words, laser holographic technology can not only check whether there are any tiny defects in products, but also won't damage these products at all.

More interestingly, at present, holography is also used to shoot holographic films and television, and soon the audience will see real-life images. That is, the laser "hits" the photosensitive coating on the negative film, leaving countless corresponding points, which are developed and fixed and then become words or images again. Here the laser beam is equivalent to the electron beam, and the photosensitive film is equivalent to the TV screen. Next, you can print books, newspapers and magazines with negatives containing words and images. The color TV can display red, green and blue because the screen is coated with tricolor phosphor, which will appear three colors under the impact of electrons. Laser phototypesetting can also use similar principles to print beautiful color pictures.

(4) The application of laser in medicine.

There have been many achievements in the application of laser in the field of medical devices, which can play a variety of roles, such as drill, scalpel, welding torch and so on.

Welding torch and electric drill in ophthalmology, laser is mainly used to treat retinal detachment. Retinal detachment is a very difficult disease. The patient's retina is separated from the inner wall of the eyeball and cannot produce vision. Before the advent of lasers, I was worried that patients would inevitably go blind.

Now, the doctor can aim the laser at the patient's fundus, let the laser emit a beam of laser, and recombine the retina with the inner wall of the eyeball by heating. The whole process takes less than a few minutes, and the laser beam welds the patient's retina like a welding gun.

Besides welding, laser welding guns can also be used for cutting.

Cataract is a common disease in the elderly. The convex lens in the front of the patient's eyeball gradually becomes turbid and inelastic from the original transparent elastic body, and the light can't pass through the lens and fall on the retina of the fundus, so the patient can't see things gradually. The traditional method of treating cataract is to cut an incision in front of the eyeball and then insert a thin metal needle through the incision. The temperature of this metal needle is extremely low, and the turbid lens is frozen and stuck to the needle, and then taken out of the small hole together. Obviously, the whole operation is more troublesome.

If medical laser is used for treatment, it is not only convenient but also effective. As long as the laser beam is aimed at the front or back of the intraocular lens, the chaotic film on the lens surface can be quickly removed.

In dentistry, laser can replace dental drill. According to the statistics of the World Health Organization, the incidence of dental caries in children is quite high, reaching about 75%. Using laser to treat teeth, patients will hardly feel uncomfortable, as long as they are not inflamed, one treatment can solve the problem. Dental laser is the youngest brother in laser. Its power is very small, only 3 watts, which is equivalent to an energy-saving lamp and hardly generates heat. Its transmitting end is actually an optical fiber as thin as a hair.

During the treatment, just put the emitting end of the optical fiber close to the caries focus, emit a laser beam, the caries tissue will decompose, and then rinse it with clean water. If dental caries only damage the surface of enamel, the laser beam will seal the tiny pores in the damaged area one by one, thus preventing the corrosion of lactic acid to dentin. If there is a cavity, the artificial enamel material can be filled into the cavity after drilling and cleaning with a laser beam, and then the joint can be heated with laser to make the artificial enamel material and enamel become a whole. Laser treatment of teeth is not only painless and rapid, but also effective after treatment.

If you want to operate on the patient's bladder, heart, liver, stomach, intestines and other important internal organs, it will be more difficult. How does laser enter human viscera? This depends on a treasure in the doctor's hand, that is, the laser fiber endoscope.

The so-called endoscope is an optical device that doctors use to insert into the human body to directly observe organs. The usual endoscope is relatively large and rough, and can only be inserted into the stomach from the patient's mouth along the esophagus for observation. Inserting into the stomach is very uncomfortable, and the patient will feel very painful. Laser fiber endoscope is completely different. Endoscopes made of optical fibers are soft, thin and flexible. When it is inserted into the patient's stomach, there will be no pain. In addition to the stomach, fiber optic endoscope can also enter other important organs. On the one hand, laser fiber endoscope can be used to check whether the patient's organs are diseased, and more importantly, it can input laser energy into the viscera to irradiate the diseased tissues, that is, remove the diseased tissues and play the role of a scalpel. Moreover, with laser knife cutting, the wound can stop bleeding automatically without ligating the bleeding point, which greatly shortens the operation time and prevents the wound from inflammation. If you use a laser knife to remove malignant tumors, you can also prevent cancer cells from spreading.

(5) Laser weapons

During the Laser Missile Gulf War, the multinational forces led by the United States launched a large-scale air strike in Iraq, destroying many important military targets in Iraq. Finally, the war ended in the failure of Iraq. Some people say that the Gulf War is a contest of advanced weapons, which is true.

American planes are equipped with laser sights, which can emit infrared lasers. When the reconnaissance plane found the ground target in the air, it circled in the air and fired a laser beam at the target with a laser sight. This kind of laser beam actually plays a guiding role. At this time, other planes carrying out the attack mission flew in and dropped laser-guided missiles on the target. These laser-guided missiles are equipped with an automatic tracking system. This automatic tracking system is equivalent to the eyes of a missile. When the missile pounces on the target, it can constantly correct the course in flight according to the guided laser reflected by the target, so as to hit the target accurately.

In fact, this laser-guided missile was used by the United States in the Vietnam battlefield as early as the 1970s. Now there are not only air-to-surface missiles, but also ground-to-ground, air-to-air, surface-to-air and other laser missiles.

Today, people have been able to combine radio search radar and lidar to form a combat system. For example, when a radio radar finds an air target (enemy plane or missile), it can accurately measure the height, orientation and speed of the target. As long as the target enters a certain range, the lidar will be turned on, emitting a very thin laser beam, keeping a close eye on it and accurately measuring the position of the target. Then the launched laser missile will accurately hit the target and destroy it according to the guiding laser beam provided by the laser radar. This laser missile can be easily deployed on trucks or converted into anti-tank missiles.

The anti-tank laser missile developed at present can be launched from the ground or from a helicopter. The missile is equipped with a semiconductor laser, which plays the role of automatically tracking the target, so that the missile hits the tank in every shot.

Although lidar has high precision, small size, dexterous operation and convenient transfer, it also has some shortcomings, that is, it is easily limited by meteorological conditions and is not suitable for searching targets in a large range. Therefore, it is generally used in conjunction with radio radar to learn from each other's strengths.

Laser guns and laser cannons The so-called laser guns and laser cannons belong to laser tactical weapons. They are shaped like guns and cannons, but instead of bullets and shells, they emit laser beams, causing enemy casualties or blindness. The power of this gun is related to its own energy and shooting distance. At present, the effective range of laser gun and laser gun is not far, so the power of death ray is limited.

However, the prospect of death ray weapons is incalculable. Once the energy of the laser beam increases and the effective distance increases, it will become a veritable dead light. For example, using a laser gun to hit a plane at an altitude of 10000 meters, because the speed of the laser beam is 300000 kilometers per second, it only takes 30000 seconds to hit a plane. In this brief moment, the plane can only move forward a few centimeters in the air. In this way, for the death ray, the moving plane has actually become a dead target and will die. According to this calculation, even if it is fired at a missile several meters away from Qian Qian, it will only take a few tenths of a second to die, and at this moment, the missile can only fly forward several tens of meters. So the death ray has enough time to destroy missiles in outer space.

In addition, laser can constantly change direction, aim at various targets and destroy them one by one. Economically speaking, it is much cheaper to manufacture laser cannons than intercontinental missiles.