Date: Sat, 14 Aug 2010 10:37:35

Author: Thomas J. Bauer

Subject: Re: Use for dead HeNe Lasers?

Post:

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Hi Adam,

I am not certain how impressive this would be, but if the seal is intact
then
shining a HeNe into a dead one won't produce fluorescence since the laser
line
in not a normally permitted transition from the ground state. This makes
the state long lived so that it has time to undergo stimulated emission.
This might be more impressive
if you used a green HeNe tubes and an evacuated cell filled with iodine.
The iodine cell
fluoresces, but the HeNe cell will not. I have never tried it with a red
laser and iodine cell,
but I know that iodine fluoresces from a red HeNe, but the wavelength is
shifted towards the
red so I don't know how bright it would be. The florescence from the green
HeNe beam looks very yellow and is
quite visible in room light with a 10mW laser. (I got 350mW laser at the
AAPT meeting and am interested in trying it out when I get back to the
lab.) I had a glass blower make my cells and then I filled them from glass
ampules of iodine i obtained from a chemical supply house.

Tom Bauer
Wellesley College

tap-l@lists.ncsu.edu writes:
>Tappers,
>Is there anything useful one can do with a "dead" HeNe laser? I have
>one just so folks can see the insides, but I recall reading once that if
>the tube is still intact and has a good seal, then somehow one can shine
>a working HeNe laser into the "dead" one to show something. Does this
>ring a bell to anyone? Thanks.
>Adam Beehler



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Hi Adam,

I am not certain how impressive this woul=
d be, but if the seal is intact then
shining a HeNe into a dead one won't prod=
uce fluorescence since the laser line
in not a normally permitted transition fr=
om the ground state. This makes the state long lived so that it has time to=
undergo stimulated emission. This might be more impressive
if you used a green HeNe tubes and an eva=
cuated cell filled with iodine. The iodine cell
fluoresces, but the HeNe cell will not. I=
have never tried it with a red laser and iodine cell,
but I know that iodine fluoresces from a =
red HeNe, but the wavelength is shifted towards the
red so I don't know how bright it would b=
e. The florescence from the green HeNe beam looks very yellow and is=

quite visible in room light with a 10mW l=
aser. (I got 350mW laser at the AAPT meeting and am interested in try=
ing it out when I get back to the lab.) I had a glass blower make my cells =
and then I filled them from glass ampules of iodine i obtained from a chemi=
cal supply house.

Tom Bauer
Wellesley College

tap-l=40lists.ncsu.edu writes:
Tappers,
Is there anything useful one can do with a "dead" HeNe l=
aser? I have
one just so folks can see the insides, but I recall reading once t=
hat if
the tube is still intact and has a good seal, then somehow one can=
shine
a working HeNe laser into the "dead" one to show somethi=
ng. Does this
ring a bell to anyone? Thanks.
Adam Beehler





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