Lesson four

I. Look through the list of English words and their Russian equivalents. You will need them for better understanding text C:

thermonuclear fusion – термоядерная реакция, термоядерный синтез; to condense – конденсировать; сгущать; evolvement – развитие; создание; exploration – исследование; target – мишень, цель; angle reflector – угловой отражатель; incident – падающий; reverse – обратный, противоположный; range – дальность; geodetic – геодезический; precision – точность.

II. Read the following text carefully. While you are reading look for the answers to the questions:

1. What idea have specialists of the quantum radiophysics laboratory suggested? 2. How is the distance to the Moon measured?

Text С

Laser at Work

1. In a department of the Lebedev Physics Institute of the USSR Academy of Sciences (FIAN) scientists from the quantum radiophysics laboratory have suggested the idea of laser-controlled thermonuclear fusion and obtained priority results in this field. Experiments in heating and condensing plasma to receive thermonuclear fusion are being conducted at one of the world's biggest laser thermonuclear installations "Delfin" (Dolphin).

2. The Institute carries out research in developing new types of lasers, studying the interaction of coherent radiation with matter, in laser thermonuclear fusion and in optoelectronics.

3. The results of this fundamental research find wide application in the development of new instruments and technological processes, in the evolvement of substances with new properties in medicine, in metrology and in the latest methods of information processing.

4. What's more, lasers are being used for very important and interesting explorations, such as measuring the distance to the Moon. Power lasers send very short light pulses to-the Moon. There are targets, or angle light reflectors, installed in five different places there, able to reflect the incident light in a precisely reverse direction. As with radar, the distance to the Moon is being established by measuring the time the signal takes to reach the target and return.

5. FIAN's station in the Crimea has built laser range finding complexes. They measure the distance to the Moon with an error of not more than one or two centimeters. This precision has allowed the laser measurement of distances to the Moon to become a new method for exploring the Earth-Moon system. Compared with other methods, laser measurements of many basic geometric and dynamic characteristics of the Earth-Moon system offer precision several factors higher and enable more delicate geodynamic phenomena to be explored and geodetic constructions to be performed with a high degree of precision. It will give us a better understanding of the laws governing the movements of the Earth and the Moon.

III. Say where new types of lasers find wide applications.

IV. Find the information about laser-controlled thermonuclear fusion.

V. Unite paragraphs 2 and 3 and choose the most suitable title for this part out of the following ones:

1. New Types of Lasers.

2. Lasers in Optoelectronics.

3. New Applications of Lasers.

6. Which paragraph contains the information directly connected with the title of the text? Render this information to your group-mate.

7. Imagine that you are to make a report on the theme "Lasers today and tomorrow". Use the information of texts А, В and С and the following plan:

1. The definition of a laser.

2. The principle of laser operation.

3. The application of lasers in industry, electronics, engineering, holography, computer technology, communications, medicine, science.

The key to text B: "New Applications of Lasers".