Lasers in Communication

Fiber optic cables are a major mode of communication partly because multiple signals can be sent with high quality and low loss by light propagating along the fibers. The light signals can be modulated with the information to be sent by either light emitting diodes or lasers. The lasers have significant advantages because they are more nearly monochromatic and this allows the pulse shape to be maintained better over long distances. If a better pulse shape can be maintained, then the communication can be sent at higher rates without overlap of the pulses. Telephone fiber drivers may be solid state lasers consuming power of only half a milliwatt. Yet they can sent 50 million pulses per second into an attached telephone fiber and encode over 600 telephone conversations.

1. What is the text about?

2. Why are fiber optic cables becoming a major mode of communication?

3. What lasers may be telephone fiber drives?

4. How many telephone conversations can be encoded per second?

TASK 7

Translate the text and entitle it.

Laser cutters are credited with keeping the U.S. garment industry competitive in the world market. The programmed cutter can cut dozens to hundreds of thicknesses of cloth, and can cut every piece of the garment in a single run. The usefulness of the laser for such operations comes from the fact that the beam is highly collimated and can be further focused to a microscopic dot of extremely high energy density for cutting.

TASK 8

Read the text given below and answer in what abstract your can you find the information about:

1. holography;

2. b)using of laser beams in building construction;

3. computing the distance to the Moon;

4. medical uses of lasers.