Check your understanding

Exercise 1. Answer the following questions.

1. Why do gases offer interesting possibilities as laser materials?

2. What is the most high powered type of gas laser?

3. Describe how helium-neon laser works. Why is the helium-neon type of laser of great value?

4. How do molecular lasers operate?

5. What are the advantages of carbon dioxide laser over neutral atom laser?

Exercise 2. Rearrange the sentences in a logical order to make a summary of the text.

1. If we want to obtain large amounts of power, the length of the carbon dioxide laser must be as long as possible.

2. The neon lasers were the first to be discovered and studied.

3. The vibrational energy of the nitrogen molecules transferred to the carbon dioxide molecules by collision.

4. Molecular lasers work by the transfer of vibrational energy from one type of molecules to another.

5. The energy from the internal discharge excites the helium atoms to a very high level. From which they normally would radiate energy.

6. The beam in the neon laser is reflected back and forth through the length of gas-filled tube by semi-reflecting end plates.

7. Later carbon dioxide atoms return to the ground state.

Exercise 3. Is it false or true?

1. Gas lasers, namely helium-neon lasers, have a very low level of monochromaticity.

2. The efficiency of the carbon dioxide laser is greater than that of the neutral atom lasers.

3. The first gas laser was built in 1960 at Bell Telephone Laboratories.

4. The vibrational energy of the nitrogen molecules is transferred to the carbon dioxide molecules by radiation.