I have already explained the construction, working and wavelength of helium neon laser. Today I will explain the output, disadvantage and applications of helium neon laser.

Output: The helium neon laser output is continuous and it lies between 1mW and 50 mW for input of about 5-10 W.

Disadvantage: As internal mirrors are used in He-Ne laser to act as optical resonators, but these mirrors are usually eroded by the gas discharge and have to be replaced.

This problem is eliminated by placing two windows at the ends of the discharge tube at the Beflectrewster angle. For such windows, the light which is polarised in the plane of figure passes through without suffering any reflection loss while light with perpendicular polarisation suffers reflection. Due to use of these windows, the output laser beam is polarised.

Applications: He-Ne lasers are used in research, spectroscopy, holography, communications and weaponry.

Note: In case of any problem in this article or any other physics article, post in the comment section.

After reading this post, you will be able to answer following questions:

• What is the output of Helium Neon laser?
• Write the disadvantages of He-Ne lasers.
• Write the applications of He-Ne laser.
• Why and how light is polarised in He-Ne laser?

Reference: This article is referred from my authored book “optics and lasers” having ISBN 978-81-272-2948-2