What does this mean for telescopes?
Most professional telescopes don’t even have lenses, they use mirrors to concentrate the light instead. However, since this approach would make the lenses far lighter (eliminating lense sag) and apparently you can tune it to allow far shorter focal lengths then currently possible you could have some fantastic wide angle images available to people.
You could, maybe, get a cool inexpensive refractor equivalent to a dobsonian.
Right now with cheap image sensors and lenses there’s no shortage of cheap, compact, but incredibly shitty microscopes. But if these metalenses are as good as the hype implies, you might be able to get a cheap and compact microscope with resolving power approaching that of a good research grade compound microscope.
I’d imagine that it means that you’ll see some REALLY spiffy eyepieces based wholly or in part on this technology once it’s commercialized. Plus, for Schmidt/Maksutov-Cassegrain telescopes, you could make better front corrector plates, I’d think.
I wonder if it would be handy for big refractor objectives without crazy long focal lengths. How cool would it be to have a 200mm f6 refractor?
Well yes, but imagine if you could use this to concentrate the light instead. Have a honeycomb 10 metres in diameter focusing down - in a way you cannot achieve with glass - to a single detector. Would this not make telescopes much lighter?
Thanks for this. This is REALLY cool!
Maybe, but I think the improvement would be better applied to space telescopes.
There may be no theoretical limit, but there is a practical limit. They are using semiconductor fabrication techniques, and currently, the largest standard wafer size is 12 inches. Which is probably why he happened to mention that size. For anything larger, they’d need to build a new foundry with all new equipment to handle the larger wafer size.
It is possible to make a telescope out of multiple mirror segments, like the Keck telescope. But it’s very difficult, because the segments need to be aligned to a very high precision (order of several microns). Making a telescope out of metalens segments would be more difficult - they need to be aligned to the same accuracy, but because they are lenses, you can’t have a support structure behind it.
Also, the metalens may have perfect on-axis performance, but there may be a limit to how much off-axis aberration it can correct for. A perfect parabolic mirror has perfect on-axis performance (i.e. if you point it directly at a star, it will form an infinitely small spot, limited only by diffraction and external factors such as the atmosphere), but it has off-axis aberration (coma). I suspect a metalens will have the same limitation, and it will take at least 2 metalenses to make a telescope with a reasonable field of view.