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I wonder if you could make a better fresnel version, with less chromatic aberration by using a more expensive lens? The parabolic version is cool, but extremely
by filleokus 6y ago
I wonder if you could make a better fresnel version, with less chromatic aberration by using a more expensive lens? The parabolic version is cool, but extremely unwieldily...
Also, are there fresnel lenses with a much shorter focal length? The dream would be to have something like this in a ≈ 10 cm (4 in) thick picture frame hung on the wall...
- rootusrootus 6y agoI thought there was some people building things similar to this (not as bright) and they were using lenses from the front of LCD TVs. But I may be remembering the details wrong.
- erentz 6y agoThis same guy has a video doing just that somewhere in his history. It's not nearly as bright though which is the big difference.
- filleokus 6y agoNow when you mention it, I realised that the guy in TFV have actually done something like that: https://www.youtube.com/watch?v=8JrqH2oOTK4 https://www.youtube.com/watch?v=8JrqH2oOTK4
- davidhyde 6y agoThere is also severe lens flare to deal with for fresnel lenses.
- BenoitEssiambre 6y agoI wonder if you could use a spotlight like a bit like this: https://www.amazon.com/Primelux-8-inch-14400-Lumens-Driving/dp/B01GZST326/ https://www.amazon.com/Primelux-8-inch-14400-Lumens-Driving/... to get the intensity and parallel rays.
- andreareina 6y agoCheck out Edmund Optics. They do have precision fresnels but they're tiny. The lenses I've seen at EO have focal lengths that aren't much shorter than the side length---20cm for 25cm sheets. I'm pretty sure this is a limitation on the refractive index plus maybe the precision required for steep incidence angles.