[time-nuts] LED instead of discharge lamp for Rb vapor cell standards

[paul swed]

Attila I haven't tried that and I suspect the lines are important because
that establishes the reference.
Now I would also suggest that an experiment like you suggest be tried on a
FRS-XXX cheapy Rb.
Easily dis-assembled and can be re-assembled back with the lamp. No harm.
Paul
WB8TSL

On Wed, Feb 21, 2018 at 12:49 PM, Attila Kinali <attila at kinali.ch> wrote:

> Moin,
>
> Has anyone ever tried using a LED instead of a discharge lamp for Rb
> standards?
> There are quite a few and very cheap 780nm IR LEDs available. They usually
> have a line width in the order of 20nm to 50nm (FWHM). This means that they
> still need the Rb85 filter, but they would not produce all those spectral
> lines
> that the discharge lamp has, thus one could get rid of the (not so cheap)
> optical filter that Corby uses for the super-5065.
>
> The one thing I am not sure about is the filter efficiency of Rb85.
> Because now the light isn't two discrete lines from the Rb87 lamb
> of which one needs to be masked, but a continuous and wide spectrum.
> So the Rb85 "notch" filter might not get rid of all the unwanted light
> and some of this might depopulate the excited state of the Rb87
> that are in the RF cavity.
>
> As a side-effect, you also get easier regulation of the light intensity
> of the LED, thus potentially less instability due to light-shift variation.
> Beside the LED operation being much simpler than that of a discharge lamp
> and overall less heat dissipation.
>
>                         Attila Kinali
>
> --
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> the prosperity and technological sophistication in the world is of no
> use without that foundation.
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