Angus
Read the paper I posted on the current state of the art.
ADEV ~ 2E-13/SQRT(Tau) is feasible with large cells and using a laser instead
of rubidium lamp.In principle, one can use the same cell to lock the laser to
the rubidium absorption line and lock the microwave signal.Suitable laser
diodes are readily available.
Increasing the contrast of the signal used for locking reduces the noise
significantly.One approach is to use an integrating sphere cell and use an
optical fibre to bring the laser signal into the cell.Since random scattering
in an integrating sphere depolarises the light and virtually eliminates any
effect of spatial coherence a multimode fibre should suffice.Laser speckle can
be reduced significantly by using a colloidal suspension of titanium dioxide if
the colloidal suspension fills another integrating sphere or equivalent.I've
tried the latter using plastic optical fibres to transport the laser light into
and out of the colloid. Its extremely effective in eliminating speckle in an
optical interferometer.
Bruce
On Thursday, 12 January 2017 12:19 PM, Angus <[email protected]>
wrote:
On Tue, 10 Jan 2017 21:43:07 -0500, you wrote:
>
>This does get back to state of the art Rb and what that means. In my suggested
>case thats measured in terms of ADEV for Tau = 1 to 1,000,000
>seconds. If you wanted an Rb with (only) state of the art phase noise at 1 MHz
>offset … thats a different thing. State of the art for
>power consumption and size is also not what Im suggesting in this case. Why
>the choice of spec? … this is TimeNuts.
Hi,
Some discussions on the performance that might be practically achieved
with different designs may be a useful start - as long as it's done in
the context of a practical unit that could actually get built, rather
than just a theoretical wish list.
It would also be good to have some idea of the cost of any special
parts like cells too. Without that info, it's hard to know how
practical particular designs would be.
Looking at export/technology controls might be useful early on too,
since we're going for high performance.
I've often wondered how a 21st century version of a 5065 would
perform, so it's great to see that I'm not completely alone in my
insanity!
Angus.
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