[time-nuts] Sapphire oscillators
alex at pcscons.com
Wed Nov 9 20:20:49 EST 2016
there was another sapphire oscillator company:
<http://www.microwavejournal.com/topics/3369-industry-news>/ Test and
A Mobile Ultra-low Phase Noise Sapphire Oscillator
Introduction to a low noise fixed-frequency X-band sapphire
Poseidon Scientific Instruments Pty Ltd.
Fremantle WA near Perth
January 1, 2002
They were acquired, the produced shoe-box size oscillators ready for
industrial/military application ...A self-confessed alternative guy from
Fremantle has sold the world-leading high technology firm he founded 24
years ago to global defense giant Raytheon.....
On 11/9/2016 4:48 PM, Attila Kinali wrote:
> On Thu, 10 Nov 2016 11:20:37 +1100
> Jim Palfreyman <jim77742 at gmail.com> wrote:
>> Anyone got any comments on this?
> Cryogenic sapphire or whispering gallery mode oscillators have been around
> for quite some time. You basically have a piece of sapphire (aluminium oxide
> in crystaline form) in a cavity[2,3], cool everything down to liquid
> helium temperatures and use this as an oscillator. There are two popular
> configurations, one is to use the sapphire as resonant element like in
> an LC or crystal oscillator, or more commonly, to use the sapphire as a
> filter element in Pound locking scheme.
> The short term stability of these oscillators is AFAIK unsurpassed
> and flat up to 1000-10'000s, but exhibits drift at longer taus.
> Their biggest problem is that they need a liquid helium cryo-cooler
> which causes vibrations that need to be carefully filtered out.
> This also makes them relatively large (fill between one and two 19" racks)
> Attila Kinali
>  http://www.uliss-st.com/uploads/pics/tech2.jpg
>  http://inspirehep.net/record/1244235/files/cavity.png
>  http://www.uliss-st.com/uploads/media/imgmedias.jpg
>  That's the (original) microwave variant of the Pound-Drever-Hall
> locking scheme, see https://en.wikipedia.org/wiki/Pound%E2%80%93Drever%E2%80%93Hall_technique
>  http://inspirehep.net/record/1409150/plots
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