Light always surrounds us in nature. Both sunlight, moonlight and starlight are the most important sources of light to human life. But also, due to the need for additional light, people have learned on our own create light. Understanding the fundamental difference between natural and artificial light is the starting point in describing natural and artificial light sources. Natural light sources exist in nature and are beyond the control of humans. They include sunlight, moonlight, starlight, various plant and animal sources, radioluminescence, and, of course, fire.
Artificial light sources can be controlled by people. Examples of such sources– flames from burning logs, oil flames or gas burner, electric lamps, light from photo chemical reactions, and others various reactions, for example light from reactions with explosives.
Because of their obvious advantages in terms of availability, safety, cleanliness, and remote control, electric lamps have replaced almost all other artificial sources of lighting in human life. However, since the energy required to operate such artificial light sources is provided mainly by consuming natural resources, we come to the idea that it is necessary to use natural light sources to the maximum extent possible.
Operation natural sources light remains one of the most big problems in lighting.
Designers and architects put great effort into making maximum use of these types of light sources.
Do you know what characteristics they have? You can learn everything about them from our article.
And LED sources of ultraviolet radiation can be read. Try to figure out what areas such sources are used in?
From a practical point of view, light sources can be classified in terms of qualities of the light they produce. These qualities are critical to the lighting result and should be the first consideration when choosing a lighting source.
The most natural light comes from the sun, and moonlight is also natural. Its origin makes it absolutely pure and it does not consume natural resources. At the same time, artificial sources usually require the consumption of natural resources such as fossil fuels to convert stored energy into light energy. Electric lighting, on the one hand, is superior in all respects to ordinary flames from the combustion of wood, gas, oil, but is also a source of pollution. At the same time, electricity can be obtained from natural energy sources such as wind, hydro, geothermal and solar energy.
The operating principle of an electric incandescent lamp determines almost all parameters of the light created by such a lamp. In general, incandescent light bulbs produce light using the incandescent principle, which heats the metal until it glows.
At the same time, most other types of lamps emit light through complex system chemical reactions during which Electric Energy turns into light energy.
In this case, the release of thermal energy is always a side effect.
These processes usually occur in such lamps in terms of the light generated more efficiently than in incandescent lamps - due to complexity and other limitations. For example, a fluorescent lamp generates light by applying an electrical voltage to a gas, which in turn emits ultraviolet radiation, which is finally converted into visible light by a special substance, which provides the necessary glow. This process generates light for approximately 400 percent more efficient than is the case with conventional incandescent lamps.
For artificial lighting, electric lamps of two types are used - incandescent lamps (LN) and gas-discharge lamps (GL).
Incandescent lamps are thermal radiation light sources. Visible radiation (light) in them is obtained as a result of heating a tungsten filament by electric current.
In gas-discharge lamps, visible radiation arises as a result of an electrical discharge in an atmosphere of inert gases or metal vapors that fill the lamp bulb. Gas-discharge lamps are called fluorescent lamps, because the inside of the bulb is coated with a phosphor, which glows under the influence of ultraviolet radiation emitted by an electric discharge, thereby converting invisible ultraviolet radiation into light.
Incandescent lamps are the most widely used in everyday life due to their simplicity, reliability and ease of use. They are also used in production, organizations and institutions, but to a much lesser extent. This is due to their significant shortcomings: low luminous efficiency - from 7 to 20 lm/W (light output of a lamp is the ratio of the luminous flux of the lamp to its electrical power); short service life - up to 2500 hours; the predominance of yellow and red rays in the spectrum, which greatly distinguishes the spectral composition of artificial light from sunlight. In the marking of incandescent lamps, the letter B stands for vacuum lamps, G for gas-filled lamps, K for krypton-filled lamps, B for bispiral lamps.
Gas-discharge lamps have become most widespread in production, in organizations and institutions, primarily due to their significantly higher light output (40...PO lm/W) and service life (8000...12000 hours). Because of this, gas-discharge lamps are mainly used for street lighting, illumination, and illuminated advertising. By selecting a combination of inert gases, metal vapors filling lamp bulbs, and a phosphor, it is possible to obtain light in almost any spectral range - red, green, yellow, etc. For indoor lighting, fluorescent fluorescent lamps, the bulb of which is filled with vapors, are most widely used mercury The light emitted by such lamps is close in its spectrum to sunlight.
Gas-discharge lamps include various types of low-pressure fluorescent lamps with different luminous flux distributions across the spectrum: white light lamps (LB); cold white lamps
(LHB); lamps with improved color rendering (LDC); warm white light lamps (WLT); lamps close in spectrum to sunlight (LE); cool white light lamps with improved color rendering (LCWH).
For gas discharge lamps high pressure include: high-pressure mercury arc lamps with corrected color (CHR); xenon (DKST), based on the radiation of an arc discharge in heavy inert gases; high pressure sodium (HPS); metal halide (MHA) with the addition of metal iodides.
Lamps LE, LDTs are used in cases where high requirements to determine the color, in other cases - LB lamps, as the most economical. DRL lamps recommended for production premises, if the work is not related to the distinction of colors (in high workshops of machine-building enterprises, etc.), and external lighting. DRI lamps have high luminous efficiency and improved color, and are used to illuminate rooms of large height and area.
Light sources have different brightnesses. The maximum brightness tolerated by humans during direct observation is 7500 cd/m2.
However, gas-discharge lamps, along with their advantages over incandescent lamps, also have significant disadvantages that so far limit their distribution in everyday life.
This is a pulsation of light flux that distorts visual perception and negatively affects vision.
When illuminated by gas-discharge lamps, a stroboscopic effect may occur, which consists in an incorrect perception of the speed of movement of objects. The danger of the stroboscopic effect when using gas-discharge lamps is that rotating parts of the mechanisms may appear motionless and cause injury. Illumination pulsations are also harmful when working with stationary surfaces, causing rapid visual fatigue and headaches.
Limiting ripple to harmless values is achieved by uniformly alternating power supply to the lamps from different phases three-phase network, special connection diagrams. However, this complicates the lighting system. Therefore, fluorescent lamps have not found widespread use in everyday life. The disadvantages of gas-discharge lamps include: the duration of their combustion, the dependence of their performance on temperature environment, creating radio interference.
Another reason, apparently, is the following circumstance. The psychological and partly physiological impact on humans of the color of radiation from light sources is undoubtedly largely related to the light conditions to which humanity has adapted during its existence. A distant and cold blue sky, creating high illuminance during most of the daylight hours, in the evening - a close and hot yellow-red fire, and then the “combustion lamps” that replaced it, but similar in color, creating, however, low illuminance, - these are the light regimes, adaptation to which probably explains the following facts. In humans there is more operational state During the day, in the light of predominantly cold shades, and in the evening, in warm reddish light, it is better to relax. Incandescent lamps produce a warm, reddish-yellow color that promotes calm and relaxation; fluorescent lamps, on the contrary, create a cool white color that excites and gets you ready to work.
The correct color rendering depends on the type of light sources used. For example, dark blue fabric appears black under incandescent light, yellow flower- off-white. That is, incandescent lamps distort the correct color rendition. However, there are objects that people are accustomed to seeing mainly in the evening under artificial lighting, for example, gold jewelry looks “more natural” under the light of incandescent lamps than under the light of fluorescent lamps. If correct color rendering is important when performing work - for example, in drawing classes, in the printing industry, art galleries, etc. - it is better to use natural lighting, and if it is insufficient, artificial lighting from fluorescent lamps.
Thus, right choice Colors for the workplace significantly contribute to increased productivity, safety and overall well-being of workers. Finishing of surfaces and equipment located in work area, also contributes to creating a pleasant visual experience and a pleasant working environment.
Ordinary light consists of electromagnetic radiation with different wavelengths, each corresponding to a specific range of the visible spectrum. By mixing red, yellow and blue light we can create most visible colors, including white. Our perception of the color of an object depends on the color of the light that illuminates it and on the way the object itself reflects the color.
Light sources are classified into the following three categories based on the color of light they emit:
- * “warm” color (white reddish light) - recommended for lighting residential premises;
- *intermediate color (white light) - recommended for lighting workplaces;
- *"cold" color (white bluish light) - recommended when performing work that requires high level illumination or for hot climates.
Thus, important characteristic light sources is the color of the light emitted. To characterize the color of radiation, the concept of color temperature was introduced.
Color temperature is the temperature of a black body at which its radiation has the same color as the radiation in question. Indeed, when a black body is heated, its color changes from warm orange-red to cool white tones. Color temperature is measured in degrees Kelvin (°K). The relationship between degrees on the Celsius scale and on the Kelvin scale is as follows: °K = °C + 273. For example, O °C corresponds to 273 °K.
Introduction
1. Types of artificial lighting
2 Functional purpose of artificial lighting
3 Sources of artificial lighting. Incandescent lamps
3.1 Types of incandescent lamps
3.2 Incandescent lamp design
3.3 Advantages and disadvantages of incandescent lamps
4. Gas discharge lamps. general characteristics. Application area. Kinds
4.1 Sodium discharge lamp
4.2 Fluorescent lamp
4.3 Mercury discharge lamp
Bibliography
Introduction
The purpose of artificial lighting is to create favorable visibility conditions, maintain a person’s well-being and reduce eye fatigue. Under artificial light, all objects look different than in daylight. This happens because the position, spectral composition and intensity of the radiation sources changes.
The history of artificial lighting began when man began to use fire. The fire, torch and torch became the first artificial sources of light. Then came oil lamps and candles. At the beginning of the 19th century, they learned to release gas and refined petroleum products, and a kerosene lamp appeared, which is still used today.
When the wick is lit, a luminous flame appears. A flame only emits light when solid heated by this flame. It is not combustion that generates light, but only substances brought to a red-hot state that emit light. In a flame, light is emitted by hot soot particles. You can verify this by placing the glass over the flame of a candle or kerosene lamp.
Oil lamps appeared on the streets of Moscow and St. Petersburg in the 30s of the 18th century. Then the oil was replaced with an alcohol-turpentine mixture. Later, kerosene and, finally, illuminating gas, which was produced artificially, began to be used as a flammable substance. The luminous output of such sources was very small due to the low color temperature of the flame. It did not exceed 2000K.
In terms of color temperature, artificial light is very different from daylight, and this difference has long been noticed by the change in the color of objects during the transition from daytime to evening artificial lighting. The first thing that was noticed was a change in the color of the clothes. In the 20th century, with the widespread use of electric lighting, color changes with the transition to artificial lighting decreased, but did not disappear.
Today rare person knows about factories that produced illuminating gas. The gas was obtained by heating coal in retorts. Retorts were large metal or clay hollow vessels that were filled with coal and heated in a furnace. The released gas was purified and collected in structures for storing illuminating gas - gas holders.
More than a hundred years ago, in 1838, the St. Petersburg Gas Lighting Society built the first gas plant. By the end of the 19th century, gas holders appeared in almost all major cities of Russia. Gas was used to illuminate streets, railway stations, businesses, theaters and residential buildings. In Kyiv, engineer A.E. Struve installed gas lighting in 1872.
The creation of direct current electric generators driven by a steam engine made it possible to widely use the capabilities of electricity. First of all, the inventors took care of light sources and paid attention to the properties of the electric arc, which was first observed by Vasily Vladimirovich Petrov in 1802. The blindingly bright light made it possible to hope that people would be able to give up candles, torches, kerosene lamps and even gas lamps.
In arc lamps, it was necessary to constantly move the electrodes placed “nose” towards each other - they burned out quite quickly. At first they were moved manually, then dozens of regulators appeared, the simplest of which was the Arshro regulator. The lamp consisted of a fixed positive electrode mounted on a bracket and a movable negative electrode connected to a regulator. The regulator consisted of a coil and a block with a weight.
When the lamp was turned on, current flowed through the coil, the core was drawn into the coil and diverted the negative electrode from the positive one. The arc was ignited automatically. As the current decreased, the retracting force of the coil decreased and the negative electrode rose under the influence of the load. This and other systems were not widely used due to low reliability.
In 1875, Pavel Nikolaevich Yablochkov proposed a reliable and simple solution. He placed carbon electrodes in parallel, separating them with an insulating layer. The invention was a tremendous success, and the “Yablochkov candle” or “Russian light” became widespread in Europe.
Artificial lighting is provided in rooms where there is not enough natural light, or to illuminate the room during hours of the day when there is no natural light.
1.Types of artificial lighting
Artificial lighting can be general(all production premises are illuminated by the same type of lamps, evenly located above the illuminated surface and equipped with lamps of the same power) and combined(to general lighting, local lighting of work areas is added by lamps located near the apparatus, machine, instruments, etc.). Using only local lighting is unacceptable, since the sharp contrast between brightly lit and unlit areas tires the eyes, slows down the work process and can cause accidents.
2.Functional purpose of artificial lighting
According to their functional purpose, artificial lighting is divided into: working , duty , emergency .
Work lighting mandatory in all rooms and illuminated areas to ensure normal work of people and traffic flow.
Emergency lighting included outside working hours.
Emergency lighting is provided to ensure minimum illumination in the production area in case of sudden shutdown of working lighting.
In modern multi-bay one-story buildings without skylights with one side glazing in daytime days, natural and artificial lighting are used simultaneously (combined lighting). It is important that both types of lighting are in harmony with one another. In this case, it is advisable to use fluorescent lamps for artificial lighting.
3. Sources of artificial lighting. Incandescent lamps.
In modern lighting installations intended for lighting industrial premises, incandescent, halogen and gas-discharge lamps are used as light sources.
Incandescent lamp- an electric light source, the luminous body of which is the so-called incandescent body (the incandescent body is a conductor heated by the flow of electric current before high temperature). Currently, almost exclusively tungsten and alloys based on it are used as a material for the manufacture of filament bodies. IN late XIX- first half of the 20th century The filament body was made of a more affordable and easier to process material - carbon fiber.
3.1 Types of incandescent lamps
The industry produces various types of incandescent lamps:
vacuum , gas-filled(filler mixture of argon and nitrogen), coiled, With krypton filling .
3.2 Incandescent lamp design
Fig.1 Incandescent lamp
Design of a modern lamp. In the diagram: 1 - flask; 2 - flask cavity (vacuumed or filled with gas); 3 - filament body; 4, 5 - electrodes (current inputs); 6 - hooks-holders of the filament body; 7 - lamp leg; 8 - external link of current lead, fuse; 9 - base body; 10 - base insulator (glass); 11 - contact of the bottom of the base.
The designs of incandescent lamps are very diverse and depend on the purpose of the specific type of lamp. However, the following elements are common to all incandescent lamps: filament body, bulb, current leads. Depending on the characteristics of a particular type of lamp, filament holders can be used various designs; lamps can be made baseless or with bases various types, have an additional external flask and other additional structural elements.
3.3 Advantages and disadvantages of incandescent lamps
Advantages:
Low cost
Small sizes
The uselessness of ballasts
When turned on they light up almost instantly
Lack of toxic components and, as a consequence, no need for collection and disposal infrastructure
Ability to operate on both direct current (any polarity) and alternating current
Possibility of manufacturing lamps for a wide variety of voltages (from fractions of a volt to hundreds of volts)
No flickering or buzzing when running on AC
Continuous emission spectrum
Electromagnetic pulse resistance
Possibility of using brightness controls
Normal operation in low ambient temperatures
Flaws:
Low luminous efficiency
Relatively short service life
Sharp dependence of luminous efficiency and service life on voltage
The color temperature lies only in the range of 2300-2900 K, which gives the light a yellowish tint
Incandescent lamps represent fire danger. 30 minutes after turning on the incandescent lamps, the temperature of the outer surface reaches, depending on the power, the following values: 40 W - 145°C, 75 W - 250°C, 100 W - 290°C, 200 W - 330°C. When the lamps come into contact with textile materials, their bulb heats up even more. Straw touching the surface of a 60 W lamp will ignite in approximately 67 minutes.
The luminous efficiency of incandescent lamps, defined as the ratio of the power of visible spectrum rays to the power consumed from the electrical network, is very small and does not exceed 4%
Welcome to my blog again. I’m in touch with you, Timur Mustaev. I would like to congratulate all Muslims on the holy holiday of Kurban Bayram, wish clear skies above their heads, sincere love and health! Take care of the people close to you!
Today we will look at artificial and natural light sources. Because the important aspect Photography is lighting, without which photography is generally impossible. Let's start analyzing the concepts.
Sources are divided into two types:
- Natural;
- Artificial.
Daylight
Sources of natural light:
- Sun;
- The moon replaces the sun at night;
- Bioluminescence is the glow of living organisms;
- Atmospheric electrical charges, such as thunderstorms.
The first two sources are ordinary and constant, the next two can serve the photographer only in special conditions.
Natural lighting is less controllable because it depends on many factors:
1. Weather
- Solar
Everyone knows that you shouldn't take photographs on a sunny day, as the resulting photos will have hard shadows and clearly defined contours, which will not be in the photographer's favor. On a sunny day, it is better to take pictures in deep shade, where the sun's rays do not reach, for example, the shadow of a large building, gazebo, etc.
- Cloud
Cloudy weather is the most preferable for filming, since clouds provide soft lighting and the image is constructed in such a way that the colors blend smoothly into one another in tone.
Unfortunately, cloudiness may not always be uniform, and often its density fluctuates, which affects the intensity of light.
- Other unusual weather conditions
Is it possible to take photographs in unusual conditions? During hurricanes, thunderstorms and storms, a black sky will add drama to your photo.
Shooting in fog will help the viewer better sense the depth of the image and build a good perspective.
2. Time of day
To get the perfect result when shooting portraits or landscapes, choose sunrise or sunset. 30 minutes before sunset and after dawn is considered the golden time for photography. The advantage is that the lighting changes quickly. This allows you to get whole line unique and varied photographs.
The only drawback is the possibility of missing the perfect shooting moment. At sunset, the shadows lengthen and become less bright, and in the morning everything is exactly the opposite.
3. Geographical location
4. Air pollution
Contaminated particles scatter light rays, making it softer and less bright.
Advantages:
- Free source;
- Color rendering is excellent because the solar spectrum is continuous throughout the entire visibility range.
Flaws:
- Cannot be used in dark time days;
- Inconsistent color temperature, requiring frequent adjustments;
- Difficult to use for construction complex circuits lighting;
- Low brightness requires a long shutter speed, which cannot be achieved when shooting handheld.
Artificial lighting
The situation is different with the control of artificial light. The photographer becomes the master of the lighting and regulates all parameters:
- Quantity;
- Corner;
- Location;
- Intensity;
- Rigidity;
- Color temperature;
- White balance.
Why do you need to set white balance? So that the color rendition does not have distortions or has only minimal errors.
Colorful temperature
Let's take a closer look at this parameter. What it is? Well, if you rely on theory, then this is a characteristic that determines the temperature of a black object that emits its color. This characteristic is measured in Kelvin (K).
Constant lighting
What are examples of continuous lighting sources? The most common are halogen lamps, as well as sodium lamps, cold daylight and incandescent lamps. They all have different parameters color temperature.
For example, if you take tungsten lamps, they emit a reddish tint, and halogen lamps emit a cool blue light.
Benefits of use:
- Reasonable price;
- Full control over light;
- You can build the necessary lighting schemes to your liking, obtaining different light and shadow patterns.
Flaws:
- High energy consumption, correspondingly, high financial costs;
- When shooting, you need a long one (not in all cases);
- High heat transfer heats the air and objects in the room, which can affect their deformation.
Pulsed lighting
What are impulse color sources? Built-in and external flashes, monoblocks and generator systems.
How does the shooting process work? In studios, in addition to the flash lamp, a pilot light is installed, that is, a constant source. It acts as an auxiliary parameter and helps to correctly construct a cut-off pattern. When the photographer presses the shutter button, the flash fires and at the same moment the modeling light goes out and comes back on when the flash finishes firing.
Advantages:
- Energy consumption is less than that of constant artificial sources;
- Heat dissipation is low;
- Allows you to use the effect of “freezing objects” when shooting, for example, splashes or falling drops;
- You can come up with complex lighting schemes that will help take your work to a higher level.
Flaws:
- High cost of acquisition;
- If there is no pilot light, you will have to look for the “golden” frame among the probes;
- Requires a connection to the camera, so may slow down shooting when taking photos with multiple cameras.
Which light source should you choose?
If you are shooting portraits or photographing subjects, use artificial lighting to adjust all settings.
If you photograph landscapes or wildlife, then there is no choice. Only natural light.
Before you start shooting, choose the right mood and feelings that you want to convey in your photo. After that, select the desired lighting scheme.
Finally, watch the video course “” or “ My first MIRROR" It will help you understand the basics of photography and become irreplaceable helpers in your endeavors as a photographer.
My first MIRROR- for CANON DSLR supporters.
Digital SLR for a beginner 2.0- for NIKON DSLR supporters.
This concludes our course on types of light sources. You can combine all sources together if necessary to realize a creative idea. You just need to take into account different temperatures, which affects color rendering. For example, photographing a person at sunset requires artificial lighting if you want to get the model’s face illuminated and a beautiful sunset.
This combination is also typical when shooting black and white photography. Share this article with your friends on in social networks and subscribe to the blog to become a professional in photography.
All the best to you, Timur Mustaev.
Never before has the small town of Menlo Park known such excitement. On New Year's Eve 1880, it seemed that the population of the entire state of New Jersey, and perhaps several neighboring states, had gathered there. The Pennsylvania Railroad could not cope with the flow of people, and they had to run additional trains. People came for the sole purpose of seeing how one hundred electric suns, incandescent lamps, illuminated the station, streets and Edison's laboratory.
Thus began the era of mass electric lighting
Of course, even before the invention of electric lighting, people realized the need for artificial light and tried to “disperse the darkness.” “If you are asked: what is more beneficial, the sun or the month? - answer: month. For the sun shines during the day, when it is already light; and the month is at night,” said Kozma Prutkov. The brightness of sunlight is so great that very few artificial light sources can compete with it. But at night you have to be content with the pitiful reflection of sunlight from the lunar surface (and even then not always). So humanity has to invent substitutes.
Gift of Prometheus
The first artificial source of light was fire, which, as we know, was given to humanity by Prometheus. A fire was used as a stationary light source, and torches were used as portable ones, the design of which changed over time: from a simple firebrand taken from the fire to a handle wrapped in tow and soaked in oil, grease or oil. Despite the fact that the torch is a very ancient invention (it is believed that it is about a million years old!), it is still used today: its distant descendants, powered by gas, light the Olympic flame, and flares and rockets are used by the military for night marking and signaling. hunters and tourists.
In addition to the torch, in the Stone Age, humanity invented a lamp - a jug filled with fat or oil, with a wick (rope or fabric) immersed in it. In the third millennium BC, the first candles appeared - bars of melted solid animal fat (lard) with a wick inside. In the Middle Ages, whale oil and beeswax were used as materials for candles; currently paraffin is used for these purposes.
Torches, candles and lamps provide very weak light. The spectrum of open fire is very different from the solar spectrum, under which nature “sharpened” the human eye. A significant portion of the radiation occurs in the thermal (IR) range. Visible light is emitted mainly by carbon particles heated by a flame to a high temperature (it is these unburned particles that form soot). The spectrum of fire in the visible range covers only part of the yellow and red regions. It is almost impossible to work in such light, and many medieval craft guilds foresightedly prohibited work at night in artificial light, since the quality of the products would drop sharply.
Step on the gas!
In the 19th century, gas lighting became widespread. In 1807, the first gas lamps were lit on one of the central streets of London - Pall Mall. And by 1823, the streets of London, with a total length of 215 miles, were illuminated by forty thousand gas lamps (which were commonly called horns). They were lit every evening manually by special people - lamplighters. By the way, this position was elective and very honorable in some countries.
However, gas lighting was not very effective. the main problem was that a gas flame burning with an insufficient supply of oxygen produces a bright light, but at the same time produces a lot of smoke, while a clean, non-smoking flame (with an excess of oxygen) is practically invisible. But in 1885, Welsbach proposed using a heating grid, which was a fabric bag soaked in a solution of inorganic substances (various salts). When heated, the fabric burned, leaving a thin “skeleton” that glowed brightly when heated by the flame.
At the end of the 19th century, kerosene lamps appeared, and they can still be found. Many of them are equipped with heating grids (now metal or asbestos).
The first steps of electricity
The first electric light source was, oddly enough, a “battery-powered flashlight.” True, the light was not emitted by an incandescent lamp, but by an electric arc between carbon electrodes, and the batteries occupied an entire table. In 1809, Sir Humphry Davy demonstrated arc light at the Royal Academy of Sciences in London. There were no generators at that time (Faraday discovered the phenomenon of electromagnetic induction only in 1832), and batteries were the only source of power.
In 1878, our compatriot Pavel Yablochkov improved the design by placing the electrodes vertically and separating them with a layer of insulator. This design was called the “Yablochkov candle” and was used all over the world: for example, the Paris Opera House was illuminated with the help of such “candles”.
The electric arc produced a bright and fairly balanced spectrum of light, which made it possible to use it very widely. By 1884, large American cities were illuminated by more than 90 thousand arc lamps.
Hot threads
Most people associate the invention of incandescent lamps with the name of Edison. However, despite all his merits in this field, he was not the inventor of the lamp.
The first incandescent lamp was more like a piece of jewelry or a work of art, both in labor intensity and in cost. Long before Edison, in 1820, Warren De la Rue placed a platinum wire in glass vessel, from which the air was pumped out, and a current was passed through it. The lamp turned out to be successful, but... platinum! It was so expensive that its widespread use was out of the question.
Many inventors have experimented with various materials, but it was not until 1879 that Joseph Swan and Thomas Edison independently developed the carbon filament incandescent lamp. For his invention, Edison made a massive grand presentation: on New Year's Eve 1880, he used 100 of his lamps to illuminate the streets, laboratory and station of the town of Menlo Park (New Jersey). Trains were crowded with people wanting to see this miracle, and the Pennsylvania railway we even had to send additional trains. Edison's lamps worked for about a hundred hours, consumed 100 W and produced a luminous flux of 16 candelas (for comparison, a modern 100-watt incandescent lamp produces light of about 100-140 candelas).
Further improvement of the lamps took place in two directions: the carbon filament was replaced in 1907 by tungsten, and since 1913 the lamps became gas-filled (at first they were filled with nitrogen, then they switched to argon and krypton). Both improvements were made in the laboratories of General Electric, founded by Thomas Edison.
The modern incandescent lamp, well known to readers of our magazine, is cheap and widely used in everyday life, but it cannot be said that its light is ideal: it is shifted towards the red and infrared regions of the spectrum. Efficiency also leaves much to be desired: its efficiency is only 1−4%. In this sense, an incandescent lamp is more of a heating device than a lighting device.
Filled lamps
Conventional incandescent lamps, in addition to low efficiency, have another serious drawback. During operation, tungsten gradually evaporates from the hot surface of the filament and settles on the walls of the flask. The bulb takes on a “tinted” appearance, which impairs light output. And due to the evaporation of tungsten from the surface of the filament, the life of the lamp is reduced.
But if you add vapor, for example, iodine, to the gas filling the flask, the picture changes. Atoms of evaporated tungsten combine with iodine atoms, forming tungsten iodide, which does not settle on the walls of the flask, but decomposes on the hot surface of the filament, returning tungsten to the filament and iodine vapor back to the flask. But there is one condition: the temperature of the walls of the flask must also be quite high - about 2500C. This is why the bulbs of halogen lamps are so compact and, naturally, hot!
Halogen lamps, due to the high temperature of the filament, give whiter light and have more long time life compared to conventional incandescent lamps.
Cold light
These lamps are direct descendants of the electric arc. Only the discharge in them occurs between two electrodes in a container filled with various gases. Depending on the pressure (low - Spotlight beams
Another type of gas-discharge lamps is HID (High Intensity Discharge - high-intensity gas-discharge lamps, or gas-light arc lamps). Here, no phosphor is used, and the gas, when an electric current flows and an arc discharge occurs, emits light in the visible region of the spectrum. Mercury, sodium vapor or metal halides are usually used as fill gas.
High-pressure mercury arc lamps are used in floodlights to illuminate stadiums and other large objects; they produce very bright white-blue light (UV is filtered out by filters). The power of mercury lamps can be tens of kilowatts. Metal halide lamps are a type of mercury lamp, they have corrected color rendition
and increased efficiency.
Low-pressure sodium arc lamps are well known to all of us: they are the ones that are used street lamps, giving a warm “amber” glow. They are good because they have excellent efficiency, a long lifetime (more than 25 thousand hours) and are very cheap.
By the way, “xenon”, which is well known to motorists (which is equipped in modern luxury cars), is an ultra-high-pressure gas-discharge lamp.
Advertising lights
Traditionally, advertising signs made from bent gas-filled pipes are called neon. These are also gas-discharge lamps, but with a different type of discharge - glow. The intensity of the glow in them is not very high. Depending on the gas pumped inside, they can glow different colors(actually neon ones are red-orange).
LEDs
Speaking about autonomous light sources, one cannot fail to mention LEDs (read more about LEDs in the same issue. - Ed. “PM”). These are semiconductor devices that generate (when electric current passes through them) optical radiation. The emission of an LED is perceived by the human eye as monochromatic. The color of the emission is determined by the semiconductor material and dopants used.
Due to their high efficiency and low operating currents and voltages, LEDs are an excellent material for manufacturing autonomous sources Sveta. In compact flashlights, they have no equal and over time, most likely, will completely displace incandescent lamps from this sector.
Laser
The laser was developed independently by the American physicist Townes and our compatriots Basov and Prokhorov in 1960.
The laser produces a powerful narrow beam of monochromatic (single wavelength) radiation. The laser is not used for general lighting, but for special applications (for example, light shows) it has no equal. Depending on the type of working fluid used and principles, laser radiation can have different colors. In everyday life, semiconductor lasers are most often used - close relatives of LEDs.
Light exotica
Artificial light can be not only electric. Chemiluminescent (so-called chemical) markers - plastic transparent tubes - are widely used. To “turn on” the glow, you need to mix two substances separated by a thin membrane. Such a marker is completely autonomous, gives a dim soft light, but “burns” for a short time and, of course, is not restored.
And finally, one of the most exotic sources is bioluminescent. If you put fireflies in a glass jar, the light they emit is enough to tell the time on your wristwatch. Although this source is not artificial, but 100% of natural origin.
