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To improve over today's CCD's, future chips will need to have
1)Higher QE
2)Lower noise
3)Higher resolution
4)Higher dynamic range
Unfortunately in general terms, point 3 usually means smaller pixels, and point 4 larger pixels.
Similarly High QE devices are great at picking up all signals, including noise with higher efficiency. These are very tricky problems that at best are seeing incremental improvements.
Two interesting points of investigation are *orthogonal transfer CCD's* and *clipper chips* (suggest you Google them). These promise adaptive optics on a chip and sub electron read noise.
Chip size is very much a double edged sword
as there are very few telescopes available with well corrected & flat photographic fields in the 50mm round region, let alone the 65mm square required (read 3" fittings) by soon-to be released large format self-guided systems.
Sure there are a few 4" focusers out there, but I suspect it will be quite a while...indeed...maybe never, due lack of demand...before we commonly see 90mm back ends on affordable telescopes.
While CMOS continues to improve leaps and bounds, I find it interesting to see that the APS format DSLR has not been swamped by 35mm chips...and suspect the cost of well corrected DSLR optics is the sticking point.
Going back through the literature, just a handful of amateur astrophotographers used anything larger than 35mm film. 2 1/4" was a rarity. Sure there were some notable professionals using up to 14" plates
but they also had instruments optimized for these plates, and hey..the AAT Focal length is pretty long.
Just my 2 cents worth....
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