This guy is melting a brick using a piece of plastic no thicker than 1/16″, scrounged from an old projection TV. It’s a Fresnel lens, and this particular one can focus about four square feet of sunlight onto a spot smaller than a square inch — pennies melt within seconds, pieces of wood instantly burn, and water flash-boils.
Also found on lighthouses and aircraft carriers, these lenses have some serious energy-production potential — they remind me of that huge array of mirrors out in the desert that superheats oil. The video’s a little dry, so you might want to skip around to get to the good stuff.
[YouTube]
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8 Responses to It's Just Cool: Giant Fresnel Lenses
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Toolmonger on Flickr
I’ve seen those lenses before, but never one that big. I must have one!
I see these in dumpsters all the time.
I’ve had a little fun with these before as well, and taken a few videos: http://www.brotherswhitney.com/2008/11/light-and-heat/
I can see some nut case putting them on his roof trying to generate electricity.
cool
Where can you just buy one?
OK, here: http://greenpowerscience.com/FRESNELSHOP/45INCHSPOT.html
Just looking at what’s available there, it seems that if you could get about a ten foot one you could weld or smelt with it!