III Oral practice

Ex. 8. Examine the difference between CD-ROM and DVD-ROM.

Ex. 9 Explain what will increase the speed of telecommunication.

Ex. 10 Describe the importance of using CD-ROM and DVD-ROM

Ex. 11 Discuss the text according to the points:

1. Rapid progress of optical communication

2. High – capacity optical transmission system

3. The first digital optical discs.

4. Comparing of CD and DVD

IV Reading and comprehension

Ex. 12. Read the text and translate it

New words

to manipulate- маніпулювати

to attempt - намагатися

to make use - використовувати

fundamental building block – головний вбудований блок

non-linear index – не лінійний показник

voltage - вольтаж

repose - реакція

consumption - використання

data rate – норми даних

prospect - перспектива

dimension - об’єм

implement – виконувати

image processing – обробка зображення

Optical computers

1. An optical computer is a computer that uses light instead of electricity (i.e. photons rather than electrons) to manipulate, store and transmit data. Photons have fundamentally different physical properties than electrons, and researchers have attempted to make use of these properties, mostly using the basic principles of optics, to produce computers with performance and/or capabilities greater than those of electronic computers. Optical computer technology is still in the early stages: functional optical computers have been built in the laboratory.

2. The fundamental building block of modern electronic computers is the transistor. To replace electronic components with optical ones, an equivalent "optical transistor" is required. This is achieved using materials with a non-linear refractive index. In particular, materials exist where the intensity of incoming light affects the intensity of the light transmitted through the material in a similar manner to the voltage response of an electronic transistor. This "optical transistor" effect is used to create logic gates, which in turn are assembled into the higher level components of the computer's CPU.

3. Another claimed advantage of optics is that it can reduce power consumption, but an optical communication system will typically use more power over short distances than an electronic one. This is because the shot noise of an optical communication channel is greater than the thermal noise of an electrical channel which, from information theory, means that we require more signal power to achieve the same data capacity. However, over longer distances and at greater data rates the loss in electrical lines is sufficiently large that optical communications will comparatively use a lower amount of power. As communication data rates rise, this distance becomes shorter and so the prospect of using optics in computing systems becomes more practical

4. Light, which is an electromagnetic wave, can only interact with another electromagnetic wave in the presence of electrons in a material and the strength of this interaction is much weaker for electromagnetic wave light than for the electronic signals in a conventional computer. This results in the processing elements for an optical computer requiring high powers and larger dimensions than for a conventional electronic computer using transistors

5. There is one recent (2007) model of Optical Neural Network: the Programmable Optical Array/Analogic Computer (POAC). It had been implemented in the year 2000 and reported based on modified Joint Fourier Transform Correlator (JTC) and Bacteriorhodopsin (BR) as a holographic optical memory. Full parallelism, large array size and the speed of light are three promises offered by POAC . POAC is a general purpose and programmable array computer that has a wide range of applications including: image processing; pattern recognition; real-time video processing; document security; and optical switching.

Ex. 13 Find in the text where it is said about the points given below. Put down the number of the paragraph

1. Optics can reduce power consumption

2. The recent model of optical Neural Network

3. The optical transistor which is used to create logic gates.

4. The properties of photons

5. A computer that uses light instead of capacity.

Ex. 14 Find the synonyms to the following words in the text:

1. reaction (2) 5. representation (5)

2. using (3) 6. security (5)

3. information (3) 7. need (4)

4. capacity (4) 8. superiority (3)

Ex. 15. Find English equivalents to the following words and word –combination in the texts:

1. оптичний комп’ютер;

2. однак;

3. виконання;

4. здібності;

5. потребувати;

6. інформаційна теорія;

7. існувати

Ex.16 Define the abbreviations:

CPU, POAC, JTC, OCT

Ex. 17. Say if the following statements are true or false:

1. Photons have the same physical properties as electrons.

2. Optical computer technology is still in the last stages.

3. The fundamental building block of modern electronic computers is the transistor.

4. Advantage of optics is that it can reduce power consumption.

5. An optical communication system will not typically use more power over short distances than an electronic one.

Ex.18 Answer the following questions. Find answers in the text. Put down the number of the paragraph:

1. What is called an optical computer?

2. What is required to replace electronic components with optical ones?

3. What is optical transistor used for?

4. Why does optical computer require high powers and larger dimensions than for a conventional electronic computer?

5. Has POAC a wide range of applications?