[time-nuts] Re: Creating a D.I.Y Rubidium Atomic Clock

[Leo Ahluwalia]

Hi Magnus, I'll definitely have to take a look at the resources Tom, zfe,
and Andy sent my way. To my theoretical knowledge, the attenuation of the
photo-detector is a possibility - to avoid having to dim out the room where
the apparatus is contained - and I was wondering if you or anyone else had
experience working with something of that nature. I appreciate the advice
on the setup, it definitely cleared up some things for me.

- Leo

On Wed, Jun 7, 2023 at 9:27 PM Magnus Danielson via time-nuts <
time-nuts at lists.febo.com> wrote:

> Hi Leo,
>
> So, the setup is very straight forward. You put the Rb-lamp, the filter,
> the Rb resonance cell all lined up in a straight path and at the far end
> of that you have a photo-detector. The resonance cell you want to keep
> magnetically shielded, which is typically done by one or more (I have
> clocks with 3) layers of mu-metal. You have a coil, called C-field coil,
> through which a DC current creates a magnetic field that separates the 5
> Rb resonances so that only the (1,0)->(2,0) absorption occurs, which is
> detected by a thad lower intensity of the pump light.
>
> Look at Tom's email and I strongly suggest you get "Rubidium Frequency
> Standard Primer" of William J. Riley which has a lot of info in it
> covering a lot of the things that goes into it. This includes a lot of
> photo of the actual inner parts of the rubidium clocks. There is more
> material to gather, but already that book will answer a lot of things
> for you and summarizes a lot of stuff in a very condensed and straight
> forward way.
>
> Cheers,
> Magnus
>
> On 2023-06-08 00:38, Leo Ahluwalia via time-nuts wrote:
> > I appreciate all of the help so far, and assuming the procurement of a
> > rubidium vapour cell and rubidium lamp (and of course all the other
> > components), I was wondering how exactly the optical pumping setup should
> > be achieved (to make sure all the components are "hooked up" so to
> speak),
> > and whether there was already a standard way of achieving it along with
> the
> > installation of the magnetic shielding?
> >
> > - Leo
> >
> > On Wed, Jun 7, 2023 at 6:27 PM Bruce Griffiths via time-nuts <
> > time-nuts at lists.febo.com> wrote:
> >
> >> That just leaves the Rubidium lamp.
> >> An ECDL (external cavity diode laser) locked to the appropriate Rubidium
> >> transition is much easier to build. There are several ECDL designs in
> the
> >> literature. Mostly these are Littrow designs. A Cateye resonator design
> is
> >> another option. All the components required are readily availble.
> >> VCSEL's should be avoided as those without polarisation mode
> stabilisation
> >> gratings on the output face randomly mode hop between a pair or
> >> orthogonally polarised modes.
> >> A well designed but relatively simple ECDL can have a much narrower line
> >> width than a typical DFB laser.
> >>
> >> Bruce
> >>> On 08/06/2023 06:37 NZST djl via time-nuts <time-nuts at lists.febo.com>
> >> wrote:
> >>>
> >>> The Rb capsules are available on ebay, eg:  124012486501
> >>> the classblowing part is done?
> >>>
> >>> On 2023-06-07 07:50, Richard (Rick) Karlquist via time-nuts wrote:
> >>>> On 6/7/2023 5:03 AM, Stephen C. Menasian via time-nuts wrote:
> >>>>
> >>>>> 1) some pure Rb87
> >>>>> 2) a glass blowing setup (and some skill)
> >>>>> 3) A selection of inert gasses (at least including Ar)
> >>>>> 4) Light source (Rb discharge was used then with a circular
> polarizer;
> >>>>
> >>>> At HP we had really skilled glass blowers, with specific experience in
> >>>> making Rb glassware.  We had to use an exotic grade of glass that was
> >>>> only one step removed from fused quartz.  It had a part number that I
> >>>> don't remember.  Very difficult to work with.
> >>>>
> >>>> The Rb lamp (one of three pieces of glassware) is very tricky to work
> >>>> with.  We used a resonant coil driven at 95 MHz at several watts.
> >>>> The trick is to "strike" the plasma and make the lamp light up;
> >>>> you can at least see visible light when that happens. I spent a
> >>>> lot of time fooling with it.  We never got it to work as
> >>>> well as the 5065 lamp.
> >>>>
> >>>> BTW, one of the Rb isotopes is slightly radioactive.  Might be
> >>>> hard to get as a hobbyist due to regulations.  The physicist I
> >>>> sat next to had a tank of it illegally stored in his cubicle.
> >>>>
> >>>> Rick
> >>>> N6RK
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