[filleokus]

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...

[andreareina]

Check 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.

[rootusrootus]

I 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]

This 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]

Now when you mention it, I realised that the guy in TFV have actually done something like that: https://www.youtube.com/watch?v=8JrqH2oOTK4

[BenoitEssiambre]

I wonder if you could use a spotlight like a bit like this: https://www.amazon.com/Primelux-8-inch-14400-Lumens-Driving/... to get the intensity and parallel rays.

[davidhyde]

There is also severe lens flare to deal with for fresnel lenses.