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

[Magnus Danielson]

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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