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Illumination

the Science and technics
 
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People have learnt to use fire for illumination about 500 000 years ago. Confluence of centuries the design of fixtures more and more became complicated, and today one click of a knife switch it is possible to fill in with light the whole streets and houses.

Hollowed of a chalk and sandstone primitive lamps are dated scientists about 80 000 BC, and ceramic fixtures have been found in Iraq by age about 10 000 years. The bible testifies that the candles made from this animal fat burnt in a temple of Solomona in X century BC Since then without them any divine service, but wide application in a life they did not manage have found only during Middle Ages epoch.


Lampy Argana

The Century of modern illumination has begun with invention of oil lamps which in 1784 have got the most a perfect form diligence of Swiss Ami Argana. Its lamp has been supplied by a tubular match; air was soaked up from sides through the tube middle, providing bright and almost bezdymnoe a flame. Later in a lamp of Argana have started to use kerosene that has even more raised quality of a flame. On kerosene type lamps "ых=ѕёр  мышь".

to this day work

Success of gas

In 1798 Scot William Merdok has started to use coal gas for illumination of a cave nearby to its house in Kornuelle. Later 12 years it has arranged gas illumination of the house in Redrute, and then has tried to create gas lighting system at factory near Birmingham. In 1807 London Pell-Mell became the first-ever street with gas illumination. Despite difficulties with soot removal, by 1830 of street of big cities of Europe and the North America were already shined with gas lanterns.

The First gas fixtures gave enough languid flame, and only after occurrence in 1885 of a mesh lamp of Velsbaha gas have started to apply to internal illumination widely. Over an atomizer in which coal gas mixed up with air, Velsbah has fixed kalilnuju a grid. When gas lighted, the grid was brightly heated, radiating warm this world. The design has appeared so successful that till the end of 1930th years gas remained the strong contender of an electricity.


the Century of an electricity

The Very first electrolamps - coal arc - have been created by Hemfri of the Davy in 1809. Two coal cores were connected to plugs of the huge battery. In things in common these cores were heated until white. When them planted on distance about 10 sm, between them flashed it is dazzling a white light arch.

However these lamps have found practical application only in 1831, with the advent of generators. In 1850th years arc lamps have started to use for time illumination of streets in London, Paris, Berlin and New York, and in 1862 the first stationary arc lamp has been established on a beacon of Dandzheness.


the First electrolamps

In 1878 Joseph Suon has placed a thin thread of the charred cellulose in a tight glass flask, has heated up it to remove gases from coal, and then has pumped out from a flask air for vacuum creation.

A year later after Suona American Thomas Atva Edison has made a lamp with a thin thread from karbonizirovannogo a bamboo, and in 1882 has constructed in New York the first power station which supplied with energy of 10 000 lamps. So rapid development of a century of an electricity has begun.


Electrolamps of our days

In flasks of modern electrolamps the tungsten spiral is shone. An electric current, passing through a spiral, heats up it approximately to 2700°С, forcing to radiate bright this world.

Light Radiated by a lamp is measured in lumens. The parity between quantity of light and a consumed electricity is called as light efficiency. Light efficiency of a lamp with a tungsten spiral is equal about 12 lumen/watt. Differently, it nizkoeffektivnyj a light source. The most part of radiation of a spiral is in invisible infra-red, or thermal, a spectrum. Other problem consists that atoms of tungsten evaporate from a spiral surface, being besieged on an internal surface of a flask. The flask gradually blackens, and the quantity of radiated light decreases. Eventually, tungsten evaporates so that the spiral fuses, and the lamp dies away.

To slow down evaporation of a spiral, flasks of lamps fill with argon and nitrogen, but to prevent this process completely it is impossible. The above spiral temperature, the faster evaporation, but also the more brightly radiated light. Manufacturers managed to achieve some compromise, and modern lamps are issued with a resource approximately 1000 hours, but also in a spectrum radiated by them more than yellow colour, than in the solar.


Halogens

In another way to slow down spiral evaporation there was use volframovo-galogennyh lamps. Halogen is entered into a lamp flask - iodine or bromine. They form an unstable chemical compound which is besieged on a spiral, instead of on flask walls with tungsten.

However iodine and bromine too have chemical influence on glass, therefore a flask it is necessary to do of expensive quartz. Volframovo-galogennye lamps suppose heats of heat and without damage to durability radiate brighter this world close to a natural spectrum.

Gas-discharge lamps are applied from the beginning of 1930th years. The first lamps instead of pumped out air were filled with a neon small amount. The high voltage moved on the electrodes placed in both ends of a tube.

Between electrodes there was an electric category, and the lamp started to radiate a reddish luminescence. These tubes could be bent, forming various forms or letters, and they soon began to be applied in advertising. So the era of the neon fires sparkling almost in all city centers has begun.

Experiments with other gases have opened a wide spectrum of different colours. Natrievye lamps of low pressure radiate yellow light and are used for illumination of streets. At the beginning their efficiency did not exceed 70, but now she has grown to 200 lumen/watt.


Green light

Application and to mercury lamps with efficiency nearby 45 lumen/watt was found. However, in their greenish though and not monochrome, light subjects and people seem a bit illusive-flat.

By the end of 1930th years of a lamp began to cover phosphoric ljuminoforom which has added a mercury spectrum with a missing red shade. It were the first steps of luminescent illumination. The majority of office premises are shined with mercury gas-discharge lamps with a small impurity of argon. Pressure of steams remains low that it was radiated more ultra-violet, rather than visible light. The internal surface of a tube is covered by phosphorus. Ultra-violet radiation raises ljuminofor, and that starts to fluoresce, i.e. To absorb ultra-violet beams, publishing instead of them visible light. By means of various phosphoric mixes it is possible to achieve almost any colour of a luminescence.


a little red

In the middle of 19b0 th years in a covering of mercury lamps of a high pressure began to add rare-earth connection vanadat ittrija. The red luminescence published by him has allowed to compensate for the deficiency red colour in a spectrum of mercury lamps. They were much more compact than luminescent lamps and at corresponding configuration were easily connected to usual electroarmature. They consume one quarter energy, than a lamp nakalivanija, radiating much less than heat, and an impurity of certain metals - thallium, disprozija, indija and sodium - in mercury steams of a high pressure improve a colour rendition. Metallogaloidnye lamps efficiency 80-85 lumen/watt radiate this world close to a natural spectrum. 1000-vattnye metallogaloidnye lamps in tight reflectors from the pressed glass are applied to illumination of stadiums and have come in the stead of out-of-date arc lamps at illumination of shootings in the open air.

One of ways of improvement of a colour rendition is increase of pressure of steams in natrievyh lamps. However at a high pressure the glass cylinder of a lamp can not sustain chemical attack of the ionised sodium formed at temperatures above 700°С. Some variants of the decision of this problem Have been found. It is possible to apply aljuminievo-ceramic or quartz lamps, or to cover their internal surface with a powder dusting.

Manufacturers develop the xenon gas-discharge lamps giving polihromnyj light, almost identical to a natural solar spectrum. However the future, apparently, belongs to an electroluminescence - to the phenomenon, forcing to be shone surfaces of walls and ceilings.


Fiber optics

Workings out and in other directions of light engineering Are conducted. In the industry lamps with the special spectrum of a luminescence causing certain chemical reactions are applied. Under beams of infra-red lamps drying of the painted surfaces is accelerated, and in medicine infra-red lamps have found application both ultra-violet, and. Into an organism of the patient are entered endoskopy with the illumination, reducing to a minimum surgical intervention and allowing to see an operational field without large cuts. Fiber-optical optical paths shine places in which it is impossible to use a usual lamp. Moreover, endoskop with a fiber conductor on which tip the most thin laser beam sparkles, it is capable to heal an internal. By means of lasers treat many illnesses - stop a bleeding of gastric ulcers, delete the damaged sites of a brain, disconnect the painful centers and burn out cancer cages on a uterus neck.


Killing lasers

Designers try to transform lasers into the effective destructive weapon, without being content with that they are already used in systems of prompting and information networks. We will tell, bombs with laser prompting hit the mark, than at visual navodke much more precisely, and the rockets directed by an absent-minded laser beam, are capable to hit the target with the highest accuracy. War in Persian gulf has well shown value of these kinds of arms. However for the lasers capable directly to destroy the military purposes, it is required immeasurably to more energy, than presumes any state.