Hi,
back in the 80s I used a few different brands of HeNe laser.
Some had their windows cemented to the tube and the He could leak out.
The cure was to put the tube in a paper bag, point it at a power
meter, and
release the contents of a He party balloon into the bag. After 5 or
10 minutes
the power would be rising and when it looked right the bag was
whipped off.
The tube was then good for another year or two.
The mass of He in the fill must have been very small.
The mass of rubidium in a lamp must be very small.
cheers, Neville Michie
On 30/09/2009, at 3:51 AM, J. Forster wrote:
You can find out pretty easily with an optical spectrometer if you
can get
a view of an operating lamp, either directly or via an optical fiber.
There are only about 5 possible fill gases and even a crude
spectrometer
will identify which ones are there. Something capable of resolving
lines
spaced roughly 2 to 5 nM appart should do it.
If you can measure the strength of the lines, you can compute the
relative
percentage of the fill gases.
With better equipment, you should be able to measure the pressure
in the
bulb by broadening of the spectral lines, but that will require more
sophisticated gear. I've not tried that.
I check gases routinely with surplus HeNe and HeCd lasers. Neither
work if
the gas mix is off. Often a non-lasing unit can be brought back to
useful
output with some care. (BTW, I do NOT do it from 'first principles'. I
compare the spectra of good and bad tubes)
-John
==============
In message <[email protected]>, "Bob Camp"
writes:
Hi
The exact "fill" in the lamp is one of those things the Efratom
does not
like to talk about. Best guess is that there is more than just Rb in
there.
It is no secret that buffer-gasses are used, but which they are is
not
disclosed. Argon is a good guess.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
[email protected] | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
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