pure helium or neon lasers

[kristien]

hey,

I'm a student commercial engineering and because of the engineering part, we have to take some course that I wouldn't be taking if I didn't have to.
One of the possible questions on the examination will be :'Why can't pure neon or helium lasers work?'
Is there someone who could explain this to me?

thank you!

[Dr. Burne]

Hi,

the helium give the power from elektic stimulation on the neon atoms, so the neon atoms get pumped by the helium.


Greetings Stefan

[kristien]

thanks,
getting there...

danke sehr,
ich begin es mehr zu verstehen.
(mein Deutsch is nicht sehr gut, entschuldigung)

[yves]

Auf http://www.hotpixel.de/laser findest du die Funktion eines HENE-Lasers erklärt.

[thorsten]

Hi!

None of the above answers are real answers to the question.

- If He atoms get electrically pumped to 20 eV, why don't He-Atoms emit light when the electrons fall back to the lower level? Helium also has population inversion and it also got the right energy level to emit at red.

- Why can't pure Neon be used? Why is it not possible to get Neon atoms electrically stimulated? If a high voltage electrical arc is established in pure Neon, what does happen (or not happen) there?

I don't know the answers, but i could imagine that both, pure He and pure Ne would be able to lase. But probably neither of the gases would lase as effective as the mixed gases.

Remember, even a 30 cm HeNe cavity only gets around 10 mW power.

Thorsten

[Dr. Burne]

hi,

if you use pure Neon a laser with 10mW where perhaps not buildable in lengh.
The He doesn´t lase, because the line is not coated on the optics and the He atoms give the energy to the Ne atoms.

I can´t explain it better in English, perhaps you schould use a special book over lasers.


Greetings Stefan

[jimbeam]

Hi!

Take a look at Sam's Laser FAQ, in the Chapter "HeNe Laser: Theory of Operation" there is very much Information, for example:

"It turns out that the upper level of the transition [of Neon] that produces the 632.8 nm line has an energy level that almost exactly matches the energy level of helium's lowest excited state. The vibrational coupling between these two states is highly efficient."

But a Laser without Helium is also possible:

"A neon laser with no helium can be constructed but it is much more difficult without this means of energy coupling."

HTH
Kristof