[time-nuts] CCD lock detection (was: DIY Physics Article)

paul swed paulswedb at gmail.com
Wed Feb 22 18:33:33 UTC 2012


Hmm in interesting prospect. However its unclear to me as to the benefit of
trying this. I do know what gets lost. Its not just a dimming of the light
1-2% as stated its also the modulation on the light beam. I think 286 Hz
thats critical to locking the system.
So the ccd is very capable of recovering that signal, but a lot of stuff to
match the photo cell.
Regards
Paul.
WB8TSL

On Wed, Feb 22, 2012 at 1:19 PM, Attila Kinali <attila at kinali.ch> wrote:

> On Wed, 22 Feb 2012 09:14:34 -0700
> Tom Knox <actast at hotmail.com> wrote:
>
> > Rather then a simple lock LED I think what would be interesting if
> possible
> > to place a CCD next to a Rubidium or Cesium cell to  view the luminance
> at
> > the hyperfine transiton. I am sure someone has done this but I have not
> > seen it.
>
> I dont think this is easily possible. You have the CCD operating in a
> strong
> electromagnetic field which will disturb it quite a bit. Though i think
> one could try to use one of the modern CCD like the OVM7690 (a tiny little
> thing of just 2.5x2.5x2.9mm^3 and quite cheap too!) and mount it in some
> empty corner that has little to no field.
>
> The other problem would be to see the luminance trough the strong
> background. IIRC the "modulation" strength of the absortion is 1-2%
> of the singal. So the luminance would be quite weak behind some strong
> background light as well.
>
> But it would be nevertheless a cool project :-)
>
>                        Attila Kinali
>
> --
> Why does it take years to find the answers to
> the questions one should have asked long ago?
>
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