[time-nuts] Re: Testing replacement lamps for HP5065A

[Stephen C. Menasian]

As a bit of background - When I was an undergraduate, I worked with a
group using optically pumped 87Rb to orient hydrogen via spin exchange to
measure the hydrogen hyperfine frequency. At that time, our Rb lamps were
RF excited 1 cm dia spherical bulbs. There was a bit of black magic in
the choice and type of noble gas used to maintain the discharge. Rb vapor
pressure was controlled by bulb temperature. I don't believe there was
any teflon coating in the lamps; teflon coating was used, however, in the
optical pumping cell to reduce collisional disorientation and consequent
broadening. At that time we used circular polarizers to achieve the
pumping effect. I note that the SRS Rb standard uses intensity pumping,
which I consider cruder.

I note that Laser diodes in the correct wavelength range are available
for under $20.00 (Rohm RLD78NZM5 and similar) from Digikey and Mouser.
These have 10 mW optical single mode output. Most laser diodes are easily
tuned over a small range; the well defined beam and its polarization
characteristics could provide a significant advantage over a gas
discharge lamp. Intensity stabilization would probably be necessary to
achieve the low noise level necessary for optical pumping. These laser
diodes include an integrated photodetector to facilitate stabilization.

Anyway, it might be worth looking into them as lamp replacements.

Stephen Menasian

On Fri, 16 Sep 2022 22:59:22 +0200
Ke-Fong Lin via time-nuts <time-nuts at lists.febo.com> wrote:

> Hi Corby,
> 
> It seems that all the lamps tested are from used rubidium standards.
> Is it possible to buy "off the shelf" rubidium lamps somewhere?
> Or is it so "specialized" that's only way to obtain them?
> Thank  you.
> 
> Best regards
> 
> On Thu, Sep 15, 2022 at 10:53 PM Corby Dawson via time-nuts
> <time-nuts at lists.febo.com> wrote:
> >
> > Here are details on some tests I ran on replacement lamps for the
> > HP5065A.
> >
> > Cheers!
> >
> > Corby_______________________________________________
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> 
> 
> -- 
> /* Lin Ke-Fong
>  * anotherlin at gmail.com
>  * I always do what I say, especially if it's something stupid.
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