Российской Федерации Федеральное агентство по образованию

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Название	Российской Федерации Федеральное агентство по образованию
страница	3/25
Тип	Учебное пособие

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Exercise 1. True or false?

Images can’t be generated sequentially by point-by-point scanning, they can be produced only simultaneously.
To the ancients, the processes of image formation were full of mystery.
In the 19^th century scientists discovered that rays of light traveled in straight lines.
Today’s concept of an image is more convenient to regard an image as being composed of overlapping patterns of varying frequencies and contrasts.
Gauss published his classical book on geometrical optics, in which he expounded the concept of the theory of relativity.

Exercise 2. Choose the correct answer.

Who published a book on optics in which some important principles of geometrical optics were postulated? When did it happen?
1. Johannes Kepler did it in 1604.
2. James Gregory did it in 1663.
3. Christian Dopler did it in 1842.
4. Roger Bacon did it in 1262.

What is the today’s concept of an image?
1. An image is considered as innumerable separate points of light.
2. An image is formed when something reaches from the eye to the object and vice versa.
3. An image is considered as a combination of real and virtual images.
4. An image is being composed of overlapping patterns of different frequencies.

Who and how laid the foundation for the formal procedures of lens design?
1. Isaac Newton having created the corpuscular theory of light.
2. Gauss having made the geometrical theory of light, which was later extended to the calculation of five principal aberrations.
3. Maxwell having found the equations for electromagnetic field, that helped to identify optics with electromagnetism.
4. Gabor having developed the theory of holography.

INCREASE YOUR VOCABULARY

Exercise 1. Give the definitions to the following.

An optical image is …
A real image is …
A virtual image …

Exercise 2. Compare two columns and choose the matching words and word-combinations.

1	2
1) bend	луч
2) cardinal points	излагать
3) converge	задержка
4) expound	действительный
5) extended object	отклоняться
6) external object	вычислять
7) focal length	поле зрения
8) field of view	изотропность
9) flicker	ощущение
10) intermittence	движение
11) nonuniformity	внешний объект
12) overlap	сходиться
13) principal aberrations	распространяться
14) real	мнимый
15) scan	отображение
16) sensation	фокусное расстояние
17) simultaneously	неравномерность
18) travel	протяжённый объект
19) virtual	просматривать
20) ray	мелькание
21) motion	основные аберрации
22) transmit	передавать
	кардинальные точки
	перекрываться
	одновременно

LANGUAGE ACTIVITY

Exercise 1. Choose the right form of pronouns.

Is this your/yours lens?
The improved telescope was my/mine.
I know their /theirs invention. But this one is our/ours.
They are her/hers glasses.
I gave him/his address to our/ ours friends.
I locked my/mine bike. And they locked their/theirs.

Exercise 2. Complete the sentences with the following verbs: burn, do, dry, concentrate, meet, blame, feel. Use myself/yourself, etc. only where necessary.

I really … well today, much better than yesterday.
Be careful. The pan is hot. Don’t … .
It isn’t her fault. She really shouldn’t … .
He climbed out of the pool and … .

5.I tried to study but I just couldn’t … .

6. Mary and Jack first … at a party five years ago.

7. “Do you want me to post this letter for you?” “No, I’ll … .”
Exercise 3. Insert prepositions of place: in, at, on.

That man standing…the window is a well-known professor.
I couldn’t hear the teacher very well. She was talking quietly and I was sitting …the back.
The water …the tank should be heated up to 50⁰C_.
St. Petersburg is situated …the Neva river.
Look at this beautiful clock …the wall over there.
We shall see a picture …the screen 0.1 sec after it actually has disappeared.
The device is …the corner of the room.
Our laboratory is located …the 3-rd floor of the main building of the University.
Kate isn’t …home, she must be …work.

Exercise 4. Put some, any, something, somebody, anything, anybody, somewhere, anywhere in the blanks.

I was looking for … a little cheaper.
A blind man cannot see … .
If you have no money, you can buy … .
May I offer you … tea?
… has parked his car right in front of mine.
I don’t like … in his family.
There isn’t … time for discussion.
I don’t see my glasses … .
He’s … in the garden.
There’s … on the phone for you.
I never eat … with sugar in it.
We’ll get … to eat at that snack bar.

Exercise 5. Read the following figures, dates, numerals, etc.

35; 700; 268; 4093l; 1175;
1954; 1961; from 1954 up to 1960; 1812; 2005;
1/4; 3/7; 2.58; 0.005; 3⁷; 5^-10;
90%; 1 cm; 140 km/h; 25°C.

Unit 2

WORD-STUDY

Exercise 1. Check the transcription in the dictionary and read words listed below.

Nouns

stimulus, vision, behavior, frequency, spectrum, roughness, incidence, ratio,

surface.

Verbs

perceive, exhibit, emerge, occur, vibrate.

Adjectives

fascinating, perpendicular, diffuse, mirror-like.
Exercise 2. Make nouns from the following verbs using suffixes -ation, -tion, -ion, and translate them.

Adsorb, demonstrate, diffract, direct, illuminate, oppose, propagate, polarize, reflect, refract.

UNDERSTANDING A PRINTED TEXT

List of Terms:

diffraction – дифракция

enlargement – увеличение

interference – интерференция

inverted image – перевернутое изображение

opaque – светонепроницаемый

pinhole – точечное отверстие

polarization – поляризация

propagation – распространение

refraction – преломление

scattering – рассеивание

thermal rays – тепловые лучи

virtual image – мнимое изображение

crest – гребень волны

trough – впадина волны

adsorb - всасывать

READING FOR PRECISE INFORMATION

Nature of Light and Color

We know the world through our senses: sight, hearing, touch, taste, and smell. Each sense responds to particular stimulus, and the sensations we experience give us information about our surroundings. Sight is the most important of the senses. Through sight we perceive the shape, size, and color of objects, also their distance, motions, and relationships to each other. Light is the stimulus for the sense of sight - the raw material of vision.

To understand the fascinating story of light, let us explore its nature, its behavior in lenses and prisms, and then its uses in science and art.

Nature. Electromagnetic waves carry energy in all directions through the universe. All objects receive, absorb, and radiate these waves which can be pictured as electric and magnetic fields vibrating at right angles to each other and also to the direction in which the wave is travelling. Light is one form of electromagnetic wave. All electromagnetic waves travel in space at the same speed - the speed of light.

Electromagnetic waves show a continuous range of frequencies and wavelengths. Frequency is the number of wave crests passing a point in one second. Electromagnetic wave frequencies run from about one per second to over a trillion per second. For light, the frequencies are four to eight hundred trillion waves per second. The higher the frequency, the shorter the wavelength.

Visible light is that portion of the electromagnetic spectrum that normally stimulates the sense of sight. Electromagnetic waves exhibit a continuous range of frequencies and wavelengths. In the visible part of the spectrum these frequencies and wavelengths are what we see as colors. The wavelengths of light range from 3,500 A to 7,500 Å. The wavelengths of infrared rays (7,500 Å - 10,000,000 Å), longer than light rays, are not detected by the eye, and do not appreciably affect ordinary photographic film. They are also called heat or thermal rays and give us the sensation of warmth.

Light behavior includes transmission, absorption, reflection, refraction, scattering, diffraction, interference and polarization. Transmission, absorption and reflection account for all the light energy when light strikes an object. In the course of transmission, light may be scattered, refracted or polarized. It can also be polarized by reflection. The light that is not transmitted or reflected is absorbed and its energy contributes to the heat energy of the molecules of the absorbing material. The modification of light through these processes is responsible for all that we see.

Reflection is of two kinds - diffuse and regular. Diffuse reflection is the kind by which we ordinarily see objects. It gives us information about their shape, size, color and texture. Regular reflection is mirror-like. We don't see the surface of the mirror; instead, we see objects that are reflected in it. When light strikes a mirror at an angle, it is reflected at the same angle. In diffuse reflection, light leaves at many different angles. The degree of surface roughness determines the proportion of diffuse and regular reflection that occurs. Reflection from a smooth, polished surface like a mirror is mostly regular, while diffuse reflection takes place at surfaces that are rough compared with the wavelength of light. Since the wavelength of light is very small (about 5,000 Å), most reflection is diffuse.

Laws of reflection:

Angle of reflection equals to angle of incidence.
Incident and reflected rays lie in the same plane.
Incident and reflected rays are on opposite sides of the normal - a line perpendicular to the reflecting surface and passing through the point of incidence.

Refraction is the bending of a light ray when it crosses the boundary between two different materials, as from air into water. This change in direction is due to a change in speed. Light travels faster in empty space and slows down upon entering matter. Its speed in air is almost the same as its speed in space, but it travels only 3/4 as fast in water and only 2/3 as fast in glass. The refractive index of a substance is the ratio of the speed of light in space (or in air) to its speed in the substance. This ratio is always greater than one.

When a beam of light enters a plane of glass perpendicular to the surface, it slows down, and its wavelength in the glass becomes shorter in the same proportion. The frequency remains the same. Coming out of the glass, the light speeds up again, the wavelength returning to its former size.

When a light ray strikes the glass at some other angle, it changes direction as well as speed. Inside the glass, the ray bends toward the perpendicular or normal. If the two sides of the glass are parallel, the light will return to its original direction when it leaves the glass, even though it has been displaced in its passage. If the two sides of the glass are not parallel, as in the case of a prism or a lens, the ray emerges in a new direction.