You are indeed right, both image intensifiers and EMCCDs have 20%-80% QE depending upon materials, build and wavelength.
There is an important point with regard to what the amplification does - it's analog. You can't meaningfully increase a digital signal - it is what it is - but if you're amplifying the analog signal you can potentially increase signal _before_ the digitisation takes place, and since this is a major source of noise you can potentially gain signal.
Of course image intensifiers are also useful even if they are noisy because they present a bright image when you need it to kill your enemies in the dark. The noise in this case is not terribly relevant.
Cheers,
Cam
Quote:
Originally Posted by RickS
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. |