Вариант 1
V семестр
I. Прочитайте и переведите текст (устно).
Design of a laser
Components of a typical laser:
1. Gain medium
2. Laser pumping energy
3. High reflector
4. Output coupler
5. Laser beam
A laser consists of a gain medium, a mechanism to supply energy to it, and something to provide optical feedback. The gain medium is a material with properties that allow it to amplify light by stimulated emission. Light of a specific wavelength that passes through the gain medium is amplified (increases in power).
For the gain medium to amplify light, it needs to be supplied with energy. This process is called pumping. The energy is typically supplied as an electrical current, or as light at a different wavelength. Pump light may be provided by a flash lamp or by another laser.
The most common type of laser uses feedback from an optical cavity—a pair of mirrors on either end of the gain medium. Light bounces back and forth between the mirrors, passing through the gain medium and being amplified each time. Typically one of the two mirrors, the output coupler, is partially transparent. Some of the light escapes through this mirror. Depending on the design of the cavity (whether the mirrors are flat or curved), the light coming out of the laser may spread out or form a narrow beam. This type of device is sometimes called a laser oscillator in analogy to electronic oscillators, in which an electronic amplifier receives electrical feedback that causes it to produce a signal.
Most practical lasers contain additional elements that affect properties of the emitted light such as the polarization, the wavelength, and the shape of the beam.
II. Выберите правильный вариант ответа на вопросы к тексту.
1. What is not a component of a typical laser?
a) high reflector;
b) output coupler;
c) inside coupler.
2. What is a gain medium?
| a)a material with properties to amplify light; b)a material without properties to allow it to amplify light; c) a material with properties that allow it conduct electricity. | b) 25 – 30 |
3. What foris the gain medium supplied with energy?
a) to power the laser;
b) to emit the rays;
c) to amplify light.
III. Закончите предложения по содержанию прочитанного текста.
4. Pump light may be provided by...
a) …a gain medium.
b) …a flash lamp.
c) … a waveguide.
5. The most common type of laser uses …
| a) … radiation; | b) …feedback from an optical cavity; | c) …solar energy. |
6. Light … the laser may spread out or form a narrow beam.
a) … coming out of…;
b) … coming into …;
c) … coming between….
IV. Подберите эквивалент к данному русскому слову или словосочетанию.
7. отражать
| a) insist | b) convert | c) reflect |
8. возбуждать, нагнетать, качать
| a)provide | b) pump | c) fuse |
| 9. увеличивать a) focus | b) amplify | c)substitute |
10. элемент связи
| a) coupler | b) scale | c) cube |
11. резонатор, канал
| a) cavity | b) copper | c) clave |
12. пучок (лучей)
| a)branch | b) beam | c) flat |
13. генератор(колебаний)
| a) wavelength | b) oscillator | c) invention |
V. Выберите соответствующее определение данным словам из текста.
| a) to result in; b) leap; c) to influence; d) plane; e) configuration; f) bent; g) characteristic; h) reaction. |
14. feedback
15. property
16. bounce
17. flat
18. tocause
19. curved
20. shape
21. to affect
VI. Прочитайте предложения и укажите соответствует ли данное утверждение действительности: если соответствует напишите после предложения T- true, если не соответствует то F-false, при этом письменно подтвердите ваш ответ примером из текста.
22. The most common type of laser uses feedback from an optical cavity—a pair of mirrors.
23. The energy is never supplied as an electrical current.
24. Very seldom one of the two mirrors is partially transparent.
VII. Выберите правильную видовременную форму глагола.
25. It needs_________ with energy.
| a) to be supplied | b) supplied | c) to supplied |
26. This process_______ pumping.
| a) will called | b) is called | c) have call |
27. Pump light may______ by a flash lamp.
| a) is provided | b) be provided | c) will be provided |
28. An electronic amplifier______ electrical feedback.
| a) receiving | b) receive | c) receives |
29. Most practical lasers _______additional elements.
| a) contain | b) contains | c) to contain |
30. The light coming out of the laser may ______.
a) spread out b) spreading out c) spreads out
VIII. Переведите текст письменно.
“Star Wars”,"Star Trek" - laser technology plays a pivotal role in science fiction movies and books. It's no doubt thanks to these sorts of stories that we now associate lasers with futuristic warfare and sleek spaceships.
But lasers play a pivotal role in our everyday lives, too. The fact is, they show up in an amazing range of products and technologies. You'll find them in everything from CD players to dental drills to high-speed metal cutting machines to measuring systems. Tattoo removal, hair replacement, eye surgery -- they all use lasers. But what is a laser? What makes a laser beam different from the beam of a flashlight? Specifically, what makes a laser light different from other kinds of light? How are lasers classified?
Although more modern views of the atom do not depict discrete orbits for the electrons, it can be useful to think of these orbits as the different energy levels of the atom. In other words, if we apply some heat to an atom, we might expect that some of the electrons in the lower-energy orbitals would transition to higher-energy orbitals farther away from the nucleus.
This is a highly simplified view of things, but it actually reflects the core idea of how atoms work in terms of lasers.
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