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

Neville Michie namichie at gmail.com
Tue Sep 29 22:03:32 UTC 2009

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 <602BE75E324D4D31B5A2D7AB3EC79B9E at vectron.com>, "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
>> 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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