Quote:
Originally Posted by rally
Rick,
You can make a sensor with more than 100% Qe
Its called a PhotoMultiplier.
They just havent done it commercially in large Silicon semiconductor arrays yet with a large Dynamic range.
The High Gain Avalanche Photodiodes only have single or small array of detectors.
SiOnyx's Black Silicon has looked extremely promising for years but seems to be taking an aeon to get to market but In-Q-Tel's investment in the co. last year would indicate that the prospects are still looking good
However given that In-Q-Tel is a US not for profit military investment vehicle - we'll probably not be seeing the technology in our amateur hands for a long while !
They used to have a detailed Technology section on their website but I see anything about how it works, how it performs etc is gone completely.
I suspect that since superior dark imaging/night vision is a huge strategic advantage - so it always seems to get snaffled up by the military - depriving us poor amateurs !!!
Rally
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Rally,
My knowledge of photomultipliers is pretty rusty (last time I remember reading about them they still used vacuum tubes!) but I don't see how they would get around the fundamental problem of shot noise. The limitation is that you only receive a small number of photons from a dim object. A photomultiplier can't create any information that isn't available in that original signal. It can only apply gain to that signal. You might as well take the digital output of your 100% QE sensor and just multiply it by 5
I would think that a QE greater than 100% implies the ability to detect photons that don't exist. That would certainly be a clever trick.
Cheers,
Rick.