[time-nuts] CCD lock detection

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Feb 23 10:29:48 UTC 2012


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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