Helium neon laser is better than ruby laser or most of the four level lasers are better than three level lasers due to the following reasons:

• The laser output is continuous in the case of helium-neon laser. But it is in the form of pulse in the ruby laser.
• Ruby laser requires high power pumping source, whereas Helium-neon laser requires low power pumping source like electric discharge.
• Efficiency of helium-neon laser is more than ruby laser.
• The defects due to crystalline imperfections are also present in the ruby laser. But it is not so in the helium-neon laser.

Reference: This article is referred from my authored book “optics and lasers” having ISBN 81-272-2948-2. In case of any doubt, post in the comment section.

Kindly Read This Also :

Note from winnerscience: If you want the e-notes of all the laser  articles that will include the basics of lasers like stimulated absorption, difference between spontaneous and stimulated emission, Einstein  Coefficients, properties and applications of lasers, complete construction and working of lasers like Ruby laser, He-Ne laser, Carbon dioxide laser, Nd:YAG laser, dye laser, semiconductor laser, holography and additional articles of Q-switching and mode locking, then please contact winnerscience@gmail.com. You can post your queries also there.