The scanning electron microscope

The SEM is used to produce three-dimensional images of the surface of specimens. Electron are reflected from the surface of a specimen stained with a heavy metal. This enables the SEM to produce images of whole specimens: cells, tissues, or even organisms.

Although electron microscopes have revolutionized cell biology, they have The scanning electron microscope not completely replaced light microscopes. Light microscopes are used to examine living and unstained specimens. Preparation of specimens for electron microscopy is complicated and time-consuming. Electron microscopes are very expensive and can be used only to study dead specimens stained with heavy metal, which might well produce The scanning electron microscope artifacts.

■ Glossary of essential terms for you to know.

English term Russian equivalent
magnified увеличенный
specimen эталон, особь
to explore изучить
toinvent изобретать
lens линза
to refract преломлять
magnification повышение
apparent видимый
compound составной, непростой
blurred смазанный
to distinguish различать
resolution разрешение
wavelength длина волны
clarity ясность, четкость The scanning electron microscope
beam луч, пучок лучей
ray луч
internal внутренний
sample эталон
to impregnate оплодотворять, пропитывать, насыщать
stain пропитка
readily просто
to reflect отражать
to enable позволять
tissues ткани
to replace подменять

■ Your Essential Assignments

I. Quick check

1. How is the magnification varied in:

a) a light microscope

b) an electron microscope?

2. Why The scanning electron microscope is the resolving power of an electron microscope so much better than of a light microscope?

3. What is the approximate size of the smallest structure that can be observed with a light microscope?

II. Fill in the missing words:

Term (verb) Noun Adjective
magnify ....... .......
multiply ....... .......
reflect ....... .......
absorb ....... .......
prevent ....... .......

III. Use monolingual English The scanning electron microscope dictionary and write down what could the words given below mean:

microscope, to refract, magnification, sample, ray.

IV. Match these words with their definitions:

1. beam A. a piece of curved glass which makes things look bigger or smaller
2. toinvent B. the power of a microscope to give a clear The scanning electron microscope picture of things, or a measure of this
3. eyepiece C. to change the position of the lens on a microscope so that you can see something clearly
4. lens D. to make a substance spread completely through something
5. resolution E. a shining line of light from the sun, a lamp The scanning electron microscope
6. to фокус F. a picture of a subject in a mirror or in the lens of a camera
7. specimen G. easily noticed
8. to impregnate H. to make, design, or produce something new for the first time
9. image I. мейд up of two or more parts or The scanning electron microscope substances
10. apparent J. a small amount or piece of something that is taken from a plant or animal, so that can be tested or examined
11. compound K. the glass piece that you look through in a microscope

V. Find English equivalents to the following word combinations:

Russian term English equivalent
1. научное внедрение The scanning electron microscope микроскопов
2. электрический микроскоп
3. стеклянные линзы
4. окуляр
5. видимый размер объекта
6. зависеть от ч.-л.
7. длина волны света
8. без утраты четкости
9. сканирующий электрический микроскоп
10. внутренняя структура клеточки
11. просто проходить через ч.-л.
12. трехмерное изображение
13. поверхность эталона

VI. Give Russian equivalents to the following English terms:

English term Russian equivalent The scanning electron microscope
a magnified image of sth.
a compound light microscope
to pass through
to refract (bend) the light
structures lying close together
the resolving power
to be limited by sth.
a beam of light
thetransmission electron microscope
to фокус an image
to produce clear images
complicated and time-consuming
dead specimens
pass The scanning electron microscope readily through the lightly stained parts
to be impregnated with sth.

VII. Find synonyms among the pool of words:

Pool of words Synonyms
1)1. multiply /2. sample /3.increase /4. specimen
2)1. image / 2. visible / 3. apparent / 4. picture
3)1.beam/2.refract/3.examine/4.bend/5.explore/6. ray
4)1.organism/2.compound/ thing/4. complex

VIII. Answer the following questions. Use The scanning electron microscope all information given before:

1. What are microscopes used for?

2. What types of microscopes are most commonly used today?

3. What is a compound light microscope?

4. What does the magnificationof an instrument depend on?

5. How do electron microscopes differ from compound light microscopes?

6. What are the main types of electron microscopes The scanning electron microscope?

7. What is the difference between thetransmission electron microscope and the scanning electron microscope?

IX. Match the sentence halves. Make complete centences: