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That's my problem - the small ones are $5 at most, but you cross a certain radius and bam - $10k. I wanted to build a "fake sun" in my apartment, but lenses of
by Tade0 4y ago
That's my problem - the small ones are $5 at most, but you cross a certain radius and bam - $10k.
I wanted to build a "fake sun" in my apartment, but lenses of proper size were either unavailable or had to be custom made, ballooning the price heavily.
Plan B is to use a parabolic dish to collimate the light, but such a setup is pretty awkward.
- dzhiurgis 4y agoI still want to make giant parabolic mirror from mylar space blanket
- marcus_holmes 4y agoIs there any way of building an array of small lenses that can output the same power? Optics is not my thing, but I'm fascinated at the possibility of a solar-powered forge
- Gravityloss 4y agoI think there is. Furthermore, the machining should be very simple, as the triangles can be all the same shape as the focus doesn't need to be so sharp. The lenses can be angled so that they focus the sun in the same spot.
- marcus_holmes 4y agothanks, that's interesting. I'm moving back to Australia next year, might give this a try there (where the sun is a little more reliable than here in Berlin)
- bradyd 4y agoYou should look for old rear projection TVs. The screen in these have a fresnal lens the size of the viewable area.
- cwkoss 4y agoAll the fresnel lenses i've seen have the focus in the center of the panel, because they only expect you to use one at a time. I would imagine it wouldn't be too hard to make an array of n^2 (9?) fresnel lenses where they each have the appropriate pattern for their position in the array. I think you might be able to get away with three molds for a 9-array (middle, side, corner). The resulting lenses would be much cheaper to manufacture and ship because shipping a stack of 9 6-ft squares is much easier logistically than shipping an 18ft square.