|
|
|
Министерство Науки и Высшего Образования
Павлодарский Государственный Университет
Кафедра АиВТ
РЕФЕРАТ
Тема: Fiber Optics
Руководитель:
к.т.н.
Потапенко О.Г.
Даниярова Г.Ж.
Выполнили:
Кондратьева Е.Л.
Чепурнов А.А.
ПАВЛОДАР
1999
Введение.
Что такое Волоконная оптика , где используются оптоволоконные световоды, из чего они сделаны и как работают?
На все эти вопросы вы найдёте ответы в этом материале. А ещё для вас станет понятно, что человечество никогда не остановится на достигнутом, то есть не все “паровые двигатели” ещё изобретены, а компьютер сможет сделать намного больше, если не будет ограничен в информационных возможностях.
Мы сможем сэкономить большое количество цветного металла, из которого изготавливаются провода. Почему? Да потомку что, сейчас появилась реальная возможность и необходимость использования оптоволоконных световодов.
Ведь оптоволоконные световоды - это просто-напросто очень чистое стекло, а стекло - это песок. А чего больше на земле: меди или песка? К тому же на оптоволоконные световоды не действуют ни электрические, ни магнитные поля, а температура, при которой они плавятся, равна 2000С, а эта температура, близкая к околосолнечной.
Волоконная оптика интересна и тем, что носителем информации является не электромагнитный импульс, а закодированный пучок света.
Если же сравнивать пропускную способность, то оптоволоконный световод толщиной с человеческий волос равноценен пучку медной проволоки толщиной с руку человека.
И, наконец, ответьте на вопрос: что это такое, если оно быстрее, точнее, дешевле? Конечно же, это волоконная оптика!
Contents
1. What is Fiber Optics? 4
2. Where are Optical Fibers used? 6
3. How are Optical Fibers made? 10
4. How do Optical Fibers Work? 12
5. Fiber Optics in the future. 17
1
What is Fiber Optics?
In 1880, four years after he invented the telephone, Alexander Graham Bell tested another talking device. He called it the photophone.
"Photo" and "phone" come from the Greek words for "light" and "sound." Bell's telephone used pulses of electricity traveling over copper wires to carry sound. But the photophone used a beam of sunlight traveling through air to carry the human voice from one place to another.
Bell was very enthusiastic about the photophone. He wrote to his father, "I have heard a ray of sun laugh and cough and sing!"
However, the new invention did not prove to be very practical. Sunlight was only available during the daytime. And even then, bad weather such as fog, rain, or snow blocked the beam of light.
In spite of these problems, throughout his life, Alexander Graham Bell thought the photophone was his most promising idea. He felt certain that someday people would use beams of light to talk to each other.
For nearly one hundred years, scientists like Bell dreamed of using light to communicate. They knew that light and electricity traveled as vibrations or waves. And they knew that many more light waves could he transmitted in one second than electrical waves. For this reason, light could carry more information than electricity flowing in copper wires.
Not until the 1960s and 1970s did two inventions make the dream possible. During this time, scientists invented lasers. Lasers are powerful sources of a special kind of light. Other researchers developed optical fibers.
An optical fiber is a flexible
thread of very clear glassthinner than a cat's whisker and up to six miles long. Laser light can pass through the length of an optical fiber and still stay bright. Because optical fibers can serve as pipelines for light, they also are called lightguides.
In the mid-1970s, these inventions were teamed together. Now pulses of light flash through optical fibers carrying information and messages over great distances. This important new technology is called fiber optics.
Glass fibers are replacing copper wires for many reasons. The fibers are not as expensive for telephone companies to buy and install. They weigh a lot less than copper wires making them easier for workers to handle. A single four-and-one-half-pound spool of optical fiber can carry the same number of messages as two hundred reels of copper wire that weigh over sixteen thousand pounds!
Optical fibers also take much less space than copper wires. This is very important in crowded cities where bulging, overloaded telephone cables have little room for additional lines. Optical fibers can help unsnarl this telephone traffic jam.
The fibers are better, too, because light is nut affected by nearby electrical generators, motors, power lines, or lightning storms. These often are the cause of noisy static on telephones or information errors in computer systems connected by copper wires.
As electrical signals pass through copper wires, they become weakened. Devices called repeaters are used to strengthen the electrical signals about every mile along each line. In a fiber optic system, repeaters are needed only every six miles or so to boost the light signals. And experiments have shown that this distance can be stretched many more miles. This means that installation costs for a fiber optic system are less now and can be cut further in the future.
However, the most important reason for using glass fibers is that they can carry much more information than copper wires. A single pair of threadlike glass fibers can transmit thousands of telephone calls at once. A cable as thick as your arm and containing 256 pairs of copper wires would be needed to handle the same number of conversations.
Pairs of fibers (or wires) are used for two-way communication. One fiber carries your voice to the listener at the other end of the line. The other member of the pair transmits the other person's reply to you.
Optical fibers are less expensive, easier to install, and more dependable than copper wires. With tight from a laser, they can transmit thousands of times more information than electricity in copper wires. The new technology of fiber optics is a better and faster way to communicate.
2
Where Are Optical Fibers Used?
All over the world, the copper wires of telephone trunk lines are being replaced by modern glass optical fibers.
One of the first attempts to use an optical fiber system in the United States was in 1977 in Chicago. There, two offices of the Bell Telephone Company and a third building for customers were connected successfully by twenty-four light-carrying glass fibers. The fibers were threaded through telephone cables already under the city streets. The total length of the fibers was about 1.5 miles.
In 1978, Vista-United Telecommunications at Walt Disney World near Orlando, Florida was first to use fiber optics commercially in the United States. Telephones throughout the 28,000-acre park are linked by fiber optic trunk lines. Video transmissions by glass fibers are
1 2 3 4 ... последняя
|
|
|
|
 |
На сайте: |
, ,
|
