Ignoring manufacturing and installation costs and assuming far future technology will be able to cost-effectively position every atom of either a telescope mirror or a telescope lens with extreme precision and within an arbitrarily tiny fraction of a width of an atom and in exactly the correct position, for a given aperture diameter of a telescope, would the 'best' design of a telescope (only for astronomy) ONLY in terms of quality of images it obtains, necessarily be of a 'all-mirror' design, by which I mean it uses only curved mirrors and no lenses?
I know such lensless 'pure mirror' telescopes have already been made (example; http://www.astrofox.nl/contents/en-uk/d33.html )
and I know of various types of optical distortions that lenses can give which mirrors don't but don't know of any of the reverse. So, ignoring costs and assuming maximum possible accuracy of fabrication, and for a given diameter of mirror/lens, are there any types of optical distortions that mirrors have but lenses don't or are there any disadvantages mirrors have over lenses?
I am trying to work out whether the ultimate far future telescope design only for astronomy would necessarily be a lensless all-mirror one or whether there would still some niche for lenses for far future optical telescopes for astronomy.
@humy saidLensless scopes have one problem: They don't focus all the light, they are not as efficient in terms of the number of photons gathered vs scattered. Maybe 70% of the photons get focused. Which means actual mirrors are more efficient in that regard. That said, the large scopes of today are built with multiple mirror segments which is a lot cheaper than one huge scope.
Ignoring manufacturing and installation costs and assuming far future technology will be able to cost-effectively position every atom of either a telescope mirror or a telescope lens with extreme precision and within an arbitrarily tiny fraction of a width of an atom and in exactly the correct position, for a given aperture diameter of a telescope, would the 'best' design of a t ...[text shortened]... or whether there would still some niche for lenses for far future optical telescopes for astronomy.
One thing about resolution: mirrors separated by some distance simulate for resolution purposes, the size of a dish that would be as if one dish the size of the separation so say you have a 10 meter dish, and another 10 meter dish, both would have the photon gathering power of a 10 meter dish but separated by 100 meters, they would simulate a 100 meter diameter dish.
There is another way, I think you probably remember my post of the idea of a gravitational lens scope, where you go to the 1000AU + region of space away from the sun and have a dish that gathers light from a distant source focused by the sun.
The interesting thing about that technology is EVERYTHING is focused, that includes gravitational waves, neutrinos and so forth besides the usual EM bands.
To me, that would be the ultimate scope.
For resolution, you get a lens over a million km in diameter, the sun.
Also the further you go from the sun the more resolution your system gets because the light is focused by a larger and larger disc.
That is only one way that effect can be used however.
So as for nano tech, it is like the manufacture of flat screen tv's, you need to have a machine capable of handling large areas. But if you have say roll to roll tech, and saran wrap thick sheets and sent into space, say you could make such a device one km wide, then the structure to stretch it out like a large drum would have to make sure the sheet didn't have wrinkles and such which would screw up the resolution introducing distortions into the incoming light.
But if you could do that, there would be no reason why you couldn't make a thousand of those assemblies spread out over the entire width of the solar system, say 10 billion km apart. Then you get large light gathering power and the effect of a telescope 10 billion km in diameter which of course can be done with mirrors also but I think it would be a lot cheaper to make nano tech sheets. Of course you would still have the delivery problem and after all those sheets were in place, coordinating all those scopes to aim at one point which is another kind of problem altogether.
So in terms of resolution, if such a system was built, comparing to Hubble, which is basically a 2 meter dish getting one part in 25 million resolution which means at 25 million km away that object would have a 1 km resolution.
So a 2000 meter dish, 1 km res at 25 billion km away, a 2 million km dish, 1 km res at 25 tillion km away, so 2 billion km dish, 1 km res at around 1000 light year range so you can see the effect that would have on astronomy. At the distance of Alpha Centauri, about 4 ly, the res would be more like 2 METERS. and 40 ly, 20 meters. Game changing res for sure.