Guiding light by internal reflection, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall, a physicist, demonstrated it during his public lectures in London, 12 years later.
The principle was first used for internal medical examinations by Heinrich Lamm in the 1930s. Modern optical fibers, where the glass fiber is coated with a transparent cladding to offer a more suitable refractive index, appeared later in the decade.
The term "fiber optics" was coined by Narinder Singh Kapany.
In 1965 Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables (STC) were the first to show that the loss of intensity in optical fibers could be reduced, making fibers a practical communication medium. They proposed that the defects in fibers available at the time was caused by impurities which could be removed. They pointed out the right material to use for such fibers, such as silica glass which has high purity. This discovery earned Kao the Nobel Prize in Physics in 2009.
An optical fiber is a long, thin strand of clear material. Its shape is usually similar to a cylinder. In the center, it has a "core". Around the core is a layer called the "cladding". The core and cladding are made of different kinds of glass or plastic, so that light travels slower in the core than it does in the cladding. If the light in the core hits the edge of the cladding at a shallow angle, it bounces off. Light can travel inside the core and bounce off of the cladding. No light escapes until it comes to the end of the fiber, unless the fiber is bent sharply or stretched.
If the cladding of the fiber is scratched, it may break. A plastic coating called the "buffer" covers the cladding to protect it. Often, the buffered fiber is put inside an even tougher layer, called the "jacket". This makes it easy to use the fiber without breaking it.
The main use of optical fiber is in communication (telecommunication). Fiber-optic communication transmits information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information. First developed in the 1970s, fiber-optic communication systems have revolutionized the telecommunications industry and have helped with the advent of the Information Age.
Early systems had short range but later ones used fibers that are more transparent. Since the light does not leak out of the fiber, the light can go a long distance before the signal gets too weak. This is used to send telephone and internet signals within and between cities. Because of its advantages over electrical transmission, optical fibers have largely replaced copper wire communications in core networks in the developed world.
Most optical communication systems have electrical connections. An electric signal controls a transmitter. The transmitter converts the electric signal to a light signal and sends it through the fiber to the receiver. The receiver converts the light signal back to an electric signal.
Fiber is sometimes used for shorter links too, such as to carry the sound signals between a compact disc player and a stereo receiver. The fibers used for these short links are often made of plastic which is less transparent. TOSLINK is the most common type of optical plug for stereos.
Optical fibers can be used as sensors. Special fibers are used for this, that change how they pass light through when there is a change around the fiber. Sensors like this can be used to detect changes in temperature, pressure, and other things. These sensors are useful because they are small and do not need any electricity at the place where the sensing happens.
These fibers are also used to carry light for humans to see. This is sometimes used for decoration, like fiber-optic Christmas trees. Sometimes it is used for lighting, when it is convenient to have the light bulb someplace other than where the light needs to be. This is sometimes used in signs and art for special effects.
A bundle of fibers can be used to make a device called an endoscope or a fiberscope. This is a long thin probe that can be put into a small hole, that will send an image of what is inside through the fiber to a camera. Endoscopes are used by doctors to see inside the human body, and are sometimes used by engineers to see inside tight spaces in machines.
Optical fibers (with special chemicals added) can be used as optical amplifiers. This allows an optical signal to travel further between endpoints, and without converting the optical signal to electrical and back, reducing the overall cost of the components. These optical amplifiers can also be used to create Lasers. These are called fiber lasers. They can be very powerful, because the long thin fiber is easy to keep cool, and makes a good quality light beam.
490s
390s
360s
Below is a list of events that happened in the years from 360 to 369.
60s
Population pyramid
A population pyramid is a graph. It has two back-to-back bars. These bars show the population in groups of ages, with woman in one side and man in the other side.
The pyramids show the age distribution of the place, which can help in understanding and predicting the development of a country.
There are three types of population pyramids:
In this type of graph, a wide base means a very high birth rate and a narrow base means a low birth rate.
To
To may mean:
And
And or AND may be any of the following:
Quarry
A quarry is a type of open pit mine that is used to get rocks and minerals from the ground. Quarries are often used to cut stone from the ground in large pieces or blocks. These are called dimension stones. They are used for building things. Some quarries fill with water to make small lakes when they are no longer being used for mining.
The largest granite quarry in the world is run by Rock of Ages Corporation in Vermont, USA..
Central Powers
The Central Powers were a group of nations fighting against the Allied Powers during World War I.
The members included Germany, Austria-Hungary, the Ottoman Empire, Bulgaria and their territories. In 1918 the breakaway republics of Azerbaijan, Finland and Lithuania also supported them. The Central Powers lost the war. The Allied Forces included Great Britain, Canada, Newfoundland, Russia, France, later the United States of America, Greece, Portugal, Brazil, Georgia, Armenia, Australia, Japan and Italy.
Soxhlet extractor
A Soxhlet extractor is a kind of laboratory equipment. It is made of glass. Franz von Soxhlet invented it in 1879. It has a flask, an extraction chamber, and a condenser. It can be used for solid-liquid extractions.
In this discontinuous extraction process, the extraction solvent inside the boiling flask is evaporated and re-condensed in the distillation column above. It then falls down onto the solid material requiring extraction. The chamber containing the solid material is connected to the boiling flask below by a syphoning mechanism seen in the Pythagorean cup, which allows the chamber to fill to a point, at which it will empty its contents and start to fill again and the extracted compounds will accumulate in the boiling flask below.
Chemists use it to remove a material from a solid. It is useful when removing materials that do not dissolve well in any solvent. Chemists use a solvent such as ether or alcohol in the extractor. The Soxhlet extractor applies the solvent repeatedly to the solid until enough of the material dissolves.
Italia
Italia may mean
Dream
Dreams are what a person sees and hears in their mind when they are sleeping. They are often similar to real life in some ways, but can also be very strange. Dreams can seem so real while they happen that the person might think that they are awake when actually they are asleep.