Acronym predecessor coherence divergence pump energy cavity stimulated emission

1. The ________of this device was much slower and not as efficient.

2. Such beams exhibit the minimum ________for a given diameter.

3. Then, after the _________ stored in the laser medium has approached the maximum possible level, the introduced loss mechanism is rapidly removed.

4. In 1957 Gordon Gould used the LASER _________

and described the technologic elements for constructing the device.

5. The mechanism of producing radiation in a laser relies on _________, where energy is extracted from a transition in an atom or molecule.

6. When an optical amplifier is placed inside a resonant optical _________, one obtains a laser.

7. This unique property of laser light, spatial

_________, cannot be replicated using standard light sources.

Now go back to ex. 3 – 8 and mark the studied words and word combinations in Text A. Reproduce the contexts found (1). Then reuse these words and word combinations in the contexts of your own (2).

Example: Acronym – 1) The term "laser"originated as an acronym for Light Amplification by Stimulated Emission of Radiation. – 2) Acronyms are abbreviations formed from the initial components in a phrase or name.

Electronic Engineering 45

DETAILED COMPREHENSION

13. Read the text again and choose the best option (a, b, c or d) to complete the following statements:

1. A laser is a device, emitting light through a process of…

a) emitted amplification of stimulated photons;

b) amplification of photons;

c) optical amplification based on the stimulated emission of photons;

d) emitted amplification.

2. Devices which were laser predecessors are called "masers", because…

a) they were developed first;

b) they don’t exist any more;

c) they have more opportunities than lasers;

d) they operate at microwave and radio frequencies.

3. The name “laser amplifiers” is illogical, because…

a) it’s redundant;

b) it doesn’t explain all the functions of lasers;

c) it is used rarely;

d) these two words are never used together.

4. Spatial coherence gives the opportunity to…

a) achieve high radiance;

b) operate at a single frequency;

c) focus laser beams to very small spots;

d) not to use semiconductors.

5. Stimulated emission…

a) Is the difference between types of lasers;

b) Is the common method of producing light for all types of lasers;

c) Is typical only for lasers with broad spectrum of light;

d) Is typical only for lasers with different wavelength of light.

6. The gain medium…

a)	is a material which doesn’t allow to amplify light by stimulated emission;

b)	is a material of any purity, size, concentration, and shape;

c)	irradiates pump energy;

d)	can be of any state: gas, liquid, solid or plasma.