Match the fields of laser applications with their definitions.

1. dental drills     2. tattoo removal     3. high-speed metal cutting     4. hair replacement     5. eye surgery

a. To put hair back to its proper place b. Medical operation on people’ s eyes c. A small, high-speed tool used in dentistry to remove decayed tooth material prior to the insertion of a dental filling d. The process of taking away a permanent picture drawn on a part of your body by putting ink into your skin with a needle. e. Very quick operations aimed at dividing metal material into pieces

4.5 Match the words similar in the meaning.

1. extremely 2. efficient 3. extraordinary 4. move in step 5. tight 6. diffuse 7. randomly

a. straight b. dispersed c. unplanned d. pivotal e. amazing f. operate in conformity g. effective

Read the text 4.3 again and answer the following questions.

1. What is a laser?

2. What fields of human activity are the lasers used in?

3. What is the difference between regular and laser light?

4. What types of lasers have you learned about from the text?

5. What do you think about the prospects of laser applications?

 

 

Unit 5

Before you read

Read and memorize the following terms.

1. fiber/fibre (n) 2. fiber optics 3. loss (n) 4. immune (adj) 5. interference (n) 6. bandwidth (n) 7. sensor (n) 8. remote sensing 9. bundle (n) 10. network k(n, v) 11. propagate (v) 12. attenuation (n) 13. repeater (n) 14. duct (n) 15. cross-talk (n) 16. pick up of smth 17. ignition (n) 18. modulate (v) 19. light guide (n) 20. imaging device 21. gain medium 22. route (v)

волокно оптоволоконная техника потери устойчивый помехи, интерференция ширина полосы пропускания датчик дистанционное считывание пучок, группа сеть; создавать/подключаться к сети распространять(ся) затухание ретранслятор канал помехи, перекрестные искажения улавливание (зд.шума) воспламенение, возгорание модулировать, понижать частоту световод устройство изображения рабочая среда лазера направлять

5.2 Match the words with their definitions.

1.fibre a. to change something, especially in order to achieve some effect

2.fibre optics b. a very thin piece of natural or artificial substance

3 sensor c. the reduction of strength, amount or size of something

4 bundle d. the use of long fibres of glass or plastic to carry

information as light signals

5 immune e. a piece of equipment that reacts to physical changes

such as amount of heat, light, etc.

6 loss f. a group of things that have been tied or connected together

7 network g. not influenced or affected by something

8 attenuation h. to connect computers together so that each computer can

send and receive information

9 modulate i. the state of having less of something than before.

 

Read the text and find the answers to the following questions.

1. What is an optical fibre?

2. Where can optical fibres be used?

3. What are the advantages of optical fiber over electrical cables?

Optical Fiber and Its Use

A

An optical fiber (or fibre) is a glass or plastic fiber that carries light along its length. Fiber optics belongs to both applied science and engineering and is concerned with the design and application of optical fibers. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths than other forms of communications. Fibers are used instead of metal wires because signals travel along them with less loss, and they are also immune to electromagnetic interference. Fibers are also used for illumination. Specially designed fibers are used for a variety of other applications, including sensors and fiber lasers etc.

B

Optical fiber can be used as a medium for telecommunication and networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. This allows using few repeaters over long distances. For short distance applications, such as creating a network within an office building, fiber-optic cabling can be used to save space in cable ducts. This is because a single fiber can often carry much more data than many electrical cables. Fiber is also immune to electrical interference. There is no cross-talk between signals in different cables and no pickup of environmental noise. They can also be used in environments where explosive fumes are present, without danger of ignition.

C

Fibers have many uses in remote sensing. In some applications, the sensor is itself an optical fiber. In other cases, fiber is used to connect a non-fiberoptic sensor to a measurement system. Depending on the application, fiber may be used because of its small size, or the fact that no electrical power is needed at remote location. Optical fibers can be used as sensors strain, temperature, pressure and other quantities by modifying a fiber so that the quantity to be measured modulates the intensity, phase, polarization, wavelength or transit time of light in the fiber. Sensors that vary the intensity of light are the simplest, since only a simple source and detector are required. A particularly useful feature of such fiber-optic sensors is that they can, if required, provide distributed sensing over distances of up to one meter.

D

Fibers are widely used in illumination applications. They are used as light guides in medical and other applications where bright light needs to be shone on a target. In some buildings, optical fibers are used to route sunlight from the roof to other parts of the building. Optical fiber illumination is also used for decorative applications, including signs, art, and artificial Christmas trees. Swarovski boutiques use optical fibers to illuminate their crystal showcases(витрины) from many angles while only employing one light source. Optical fiber is an intrinsic (существенный) part of the light-transmitting concrete building product, LiTraCon.

E

Optical fibers can be used in many other applications. For example, in imaging devices called endoscope, which is used to view objects through a small hole. In spectroscopy, optical fiber bundles are used to transmit light from a spectrometer to a substance which cannot be placed inside the spectrometer itself, in order to analyze its composition.

An optical fiber with certain rare-earth (редкоземельный) elements can be used as the gain medium o f a laser or optical amplifier. Sometimes it is used to supply a low level of power (around 1 watt) to electronics situated in a difficult electrical environment. Examples of this are electronics in high-power antenna elements and measurement devices used in high voltage transmission equipment.

Thus we see that the application of optical fiber is enormous and, no doubt, it will increase with further development of engineering.

Comprehension