[time-nuts] Optical Cesium or maybe Cesium "light"!

Magnus Danielson magnus at rubidium.dyndns.org
Sat Mar 18 06:13:17 EDT 2017


The NIST-7 was a optically pumped cesium beam, and a pre-cursor to the 
fountain clocks. There should be a bunch of papers on it.

If you look on the picture from wikipedia:

https://en.wikipedia.org/wiki/NIST-7

You can see the optical bench on top of the electronics rack.

The modern books go into length about the issues of laser pumping and 
detection, so there is plenty of material to work from.

The A magnet being replaced by the A laser will for the same flow from 
the cesium oven produce twice as much atoms and thus improve signal to 
noise. I also expect that the optical detection does not experience the 
same wear mechanisms as the traditional setup. Laser wear is however a 
concern, but easier to handle.

I am however somewhat wondering about if we will see this coming out of 
Oscilloquartz. We will see.

Cheers,
Magnus

On 03/18/2017 09:05 AM, Bruce Griffiths wrote:
> An Early (~1980?) NS/FEI paper on optically pumped cesium beam tubes:
>
> http://tf.nist.gov/general/pdf/732.pdf
>
> Bruce
>
>>
>>     On 18 March 2017 at 17:28 "Richard (Rick) Karlquist" <richard at karlquist.com> wrote:
>>
>>     Len Cutler was all set to build an optically
>>     pumped Cs beam 20 years ago. Even then, he could get the lasers.
>>     He was only missing one thing: money. HP management never
>>     agreed to fund it. The paper conspicuously omits any spec
>>     on absolute accuracy. The optical pumping does nothing to
>>     improve that AFAIK. It still depends on phase error in the CBT.
>>     The 5071 has a guaranteed accuracy of 10^-12, and is typically
>>     several times better than that.
>>
>>     It is surprising that none of the various makers of the 5071A
>>     ever made an optical version. I wonder what they are thinking
>>     now that someone else has done it.
>>
>>     Rick
>>
>>     On 3/17/2017 7:48 PM, cdelect at juno.com wrote:
>>
>>         > >
>>>         Looks like Oscilloquartz is getting ready to sell this commercially!
>>>         Will give the 5071A a run for the money!
>>>         Reliability should go way up as:
>>>         -No electron multiplier
>>>         -No ionizer filament
>>>         -No state selection magnets
>>>         Also all the fiddley bits (laser diodes and photodetectors) are external
>>>         to the tube and can be easily updated as needed.
>>>
>>>         https://www.slideshare.net/ADVAOpticalNetworking/performance-results-of-a
>>>         n-optically-pumped-cesium-beam-clock
>>>
>>>         Cheers,
>>>
>>>         Corby
>>>
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