Quote:
Originally Posted by alpal
There is always going to be noise -
it's a physical property of semiconductors.
|
but the little bit of noise that is left is now close to being vanishingly small compared to detected signal - some lucky imaging systems have sensors with such low noise that they can count the arrival of individual photons and that process has no electronic noise at all (all that is left is the shot noise in the signal). The new CMOS chips are not in that league, but they aren't far off.
Glen, I think that tip/tilt AO will still have a place for some time to come, but the low read noise chips and lucky imaging have the potential to bypass it in some applications - will be interesting to see how this all pans out.
edit: Re narrowband, just ran my system model, but replaced the read noise (5e for the 694) with a read noise of 1.5 and bumped up the dark current to 0.05. Sky-limited narrowband with that assumption cuts in at a bit longer than 2 minute subs for a 5 nm filter and average sky - even at 30 second subs, the stacked SNR is only down to ~0.8 of maximum possible. there definitely seems to be some resolution benefit with subs this short.