[time-nuts] CCD lock detection

[Tom Knox]

Thanks for your insights Bruce, I think I worded my thoughts badly. The fiber would be in addition to, not replacing the photocell. It would feed a CCD for display purposes only, although perhaps in the future if the concerns you brought up were addressed the CCD could also act as photocel. The question was would this display provide useful information beyond the traditional alpha numeric info.
Thomas Knox



> Date: Thu, 23 Feb 2012 23:29:48 +1300
> From: bruce.griffiths at xtra.co.nz
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] CCD lock detection
> 
> If and only if you want to reduce the SNR substantially.
> A typical glass fibre will capture insufficient light to be useful 
> compared to the standard arrangement using a photocell.
> Plastic fibres are not usable as the temperature in the vicinity of the 
> absorption cell is too high.
> 
> Bruce
> 
> Tom Knox wrote:
> > I was thinking you could view it through fiber
> >
> > Thomas Knox
> >
> >
> >
> >    
> >> Date: Wed, 22 Feb 2012 19:19:57 +0100
> >> From: attila at kinali.ch
> >> To: time-nuts at febo.com
> >> Subject: [time-nuts] CCD lock detection (was: DIY Physics Article)
> >>
> >> 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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> 
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