A Fresnel Lens (array) "Super Telescope"?

[Macavity]

When I wuz a lad, there was a *science shop* (in Manchester), that sold
all kinds of exciting "experimental" stuff! Among my purchases was a
plastic FRESNEL lens. Even at a tender age, I was really impressed! 😅

Sadly, I left it on a *sunny* window ledge, and it "warped a bit". lol!
But, I often wondered about the possibilites? These days, folks are
looking for a JWST successor... Fresnel lenses that deliver "quality"
images are being developed? An Array(?) looks rather interesting! 😎

https://en.wikipedia.org/wiki/Fresnel_imager  (+More specific links)

(Give it a rest, you Refractor Guys? lol) 🤣

Edited July 17, 2023 by Macavity

[DaveL59]

interesting, tho I'd have thought a fresnel would create constructive & destructive interference given the rings? Been a long while since I looked closely at one tho but I do recall they could be had to put in front of smaller screens to give a bigger screen "feel" at little cost. Not good for off-axis viewing tho.

[Macavity]

I hadn't made the connection between Frenel lenses and Diffraction Patterns? 😏
It seems it is the "Lens" is etched into a thin substrate? Maybe I should watch:
https://www.youtube.com/watch?v=NWrQmsa3Kkg (Not sure of its relevance,
But if a commentator is correct, it might explain "Near and Far" Field stuff?!?)  😛

 

Edited July 17, 2023 by Macavity

[Macavity]

Or, better still, the Actual Article (with prototype pictures)! 😅

[DaveL59]

7 hours ago, Macavity said:

Or, better still, the Actual Article (with prototype pictures)! 😅

ahh so the technique has moved on significantly since I last messed about with one then, sounds very interesting. Wonder if we'll be able to get a nice, light 36-inch frac made with one of those... 😉 

probably not so good for the solar observers here tho depending on what its made from unless you want one of those wobbly fairground mirror effects as it melts under the heat.

Edited July 18, 2023 by DaveL59

[andrew s]

Diffractive optics is already alive and well in commercial photographic lenes https://www.canon.co.uk/pro/infobank/lenses-multi-layer-diffractive-optical-element/

Regards Andrew