Question

reason for narrow tube in helium neon laser​

Answer 1

Answer:

In the helium–neon laser, the gain is an inverse function of the diameter of the gas tube, because the lower level of the laser transition is depopulated by collisions of the neon atoms with the walls of the tube. In order that the collision rate of neon atoms with the wall be high, the tube diameter must be small.

Answer 2

Answer:

• The laser gain is inversely proportional to the tube radius because the number of impacts with the tube walls increases as the tube becomes narrower.
• As a result, a He-Ne laser's tube diameter must be as narrow as feasible.

• A He-Ne laser's output power is limited by the low gain of the active medium.
• As a result, in a helium neon laser, a narrow tube is used.