[time-nuts] hm H Maser

Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed Jan 11 19:05:13 EST 2017

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.

    On Thursday, 12 January 2017 12:19 PM, Angus <not.again at btinternet.com> 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. 


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


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