Unit 7. Optical Instruments.

Active vocabulary

1. Aperture ['æpətjuə] апертура

2. Binoculars [bɪ'nɔkjuləz] бінокль

3. Camera ['kæm(ə)rə] фотоапарат

4. Charge-coupled device (CCD) прилад із зарядовим зв’язком

[ʧɑːʤ'kʌpld dɪ'vaɪs]

5. Curved mirror ['kɜːvd'mɪrə] сферичне дзеркало

6. Digital camera [ˌdɪʤɪt(ə)l'kæmərə] цифровий фотоапарат, цифрова камера

7. (To) digitize ['dɪʤɪtaɪz] перетворювати у цифрову форму

8. Enlarged [ɪn'lɑːʤd ], [en-] збільшений

9. Exposure time [ɪk'spəuʒəˌtaɪm] витримка (затвора)

10. Eyepiece ['aɪˌpiːs] окуляр (оптичного приладу)

11. Inverted image [ɪn'vɜːtɪd'ɪmɪʤ] перевернуте зображення

12. Light-tight chamber світлонепроникна касета

['laɪtˌtaɪt 'ʧeɪmbə]

13. Magnification [ˌmægnɪfɪ'keɪʃən] збільшення

14. Magnifier magnifier ['mægnɪfaɪə] збільшувальне скло, лупа

15. Microscope ['maɪkrəskəup] мікроскоп

16. Objective [əb'ʤektɪv] об'єктив

17. Optical instrument оптичний прилад, інструмент

['ɔptɪk(ə)l 'ɪnstrəmənt]

18. Reflecting telescope дзеркальний телескоп, [rɪ'flektɪŋ'telɪskəup] телескоп-рефлектор

19. Refracting telescope лінзовий телескоп, телескоп- [rɪ'fræktɪŋ'telɪskəup] рефрактор

20. Shutter [ʃʌtə] затвор (фотооб'єктива)

21. Spherical aberration сферична аберація

['sferɪk(ə)lˌæbə'reɪʃ(ə)n]

Pre-reading task

Exercise 76. Work in small groups. Discuss the following question.

There are many optical gadgets we buy and use for fun, but many are an essential part of our lives. Make a list of as many optical gadgets as you can.

Reading

Exercise 77. Read, translate the text below.

Optical instruments

Optical instruments that use lenses include the camera, the telescope (and binoculars), and the compound microscope.

The Camera

The photographic camera is a simple optical instrument whose essential components are light-tight chamber, a converging lens that produces a real image, and a film behind the lens to receive the image. The lens in a camera forms a real, inverted image on the film or chip. One focuses the camera by varying the distance between lens and film. For proper focusing – which is necessary for the formation of sharp images – the lens-to-film distance depends on the object distance as well as on the focal length of the lens. The shutter, positioned behind the lens, is a mechanical device that is opened for selected time intervals, called exposure times. One can photograph moving objects by using short exposure times or photograph dark scenes by using long exposure times.

More expensive cameras have an aperture of adjustable diameter to control the intensity of the light reaching the film. When an aperture of small diameter is used, only light from the central portion of the lens reaches the film; in this way spherical aberration is reduced.

Digital cameras are similar to these cameras except that the light does not form an image on photographic film. The image in a digital camera is formed on a charge-coupled device (CCD), which digitizes the image, turning it into binary code. The digital information is stored on a memory chip for playback on the screen of the camera, or it can be downloaded to a computer and sent through the Internet.