[time-nuts] Can anyone spare an LPRO lamp?

J. Forster jfor at quik.com
Tue Sep 29 17:51:59 UTC 2009

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)



> In message <602BE75E324D4D31B5A2D7AB3EC79B9E at vectron.com>, "Bob Camp"
> writes:
>>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
> phk at FreeBSD.ORG         | 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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