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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
Hi all. OK try not to laugh but... To get Gen >0 tubes is crazy expensive these days because everyone is using them for night fishing/rabbiting/etc...
so why not use a gen 0 tube, have a small B/W camera taking an image of the output window and then take the data and feed it back to the input window via an IR diode+LCD setup ?
the basic plan is that even if there is horrible feedback this can be dampened down to achieve a "super regeneration" effect that shows an image of particles etc for not much money.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
have a small B/W camera taking an image of the output window and then take the data and feed it back to the input window
Regenerating feeble images with the hope of achieving a critical point sensitivity may connect you with that purported to be detected by the third eye, which if we had it, would be in the center of our forehead.
I believe the transcommunication crowd used to use video feedback as you suggest.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Video feedback loops have been used as fractal generators.
Many PMTs can be configured to have gains of 10E6 - the order of magnitude needed for single photon counting.
The chief problem with small signal detection is not amplification at any scale, but ensuring that the SNR remains workable. The signal must be extracted from the noise floor, and resolved into useful data proportional to the magnitude of the detected particle's energy, which implies linear amplification.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
For amateur astronomy (another pastime of mine) there are many examples on the web of 'hacked' webcams, some of which have excellent sensors. e.g. Basically the exposure time is as long as required, and to reduce noise the voltage is reduced and the onboard amplifier is disabled whilst the light is being gathered. Then if multiple similar pictures are taken a program such as Registax can minimise noise, hot pixels etc.).
I haven't tried 'hacking' but judging from the photo's, the setup must be pretty light sensitive.
Then you need a good (f#) lens sytem.
For Gen0 why not just use IR LEDs, Regenerative amplification sounds unlikely to give stable results, Signal processing of consecutive video frames is probably a cheap option. You could do your regeneration in software too. (AtoD converters can be chosen that have a wider dynamic range than optical sensors)
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Proud Mary wrote ...
The chief problem with small signal detection is not amplification at any scale, but ensuring that the SNR remains workable.
Or, in layman's language, You can't polish a turd. (No matter how much DSP you throw at it.)
This is a lesson I learnt the hard way in my last job, developing DSP algorithms for laser spectroscopy. I spent weeks trying to filter out ripples in one signal, and eventually I gave up and started beating on the optics guys to get rid of them for me. They knocked them down by 20dB in an afternoon by swapping a regular piece of glass for a wedged piece, and the instrument finally performed to spec.
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Optical regenerator?
