The idea of focusing the sun's rays into a concentrated beam of heat using a magnifying glass is so well known that all you have to do is say "ants under a magnifying glass" to conjure the image of a torturing bully.
Backyard tinkerer Grant Thompson isn't a bully, but he does have a giant magnifying glass. More specifically, he has a Fresnel lens -- that is, a giant lens made of corrugated concentric circles adapted from an old rear-projection TV.
What we hadn't seen was someone use one to blow up a beer bottle, incinerate a piece of wood, or melt a stack of coins. Probably because these are actually pretty dangerous things to be doing in your backyard, especially without protective goggles and with kids hanging around, but now that Thompson has done it anyway, it's fascinating to watch.Now, Fresnel lenses are pretty powerful. We've already seen industrial designer Marcus Kayser use one to create a solar-powered 3D printer for sand.
The resulting heat beam -- which reaches around 2,000 degrees Fahrenheit -- takes just seconds to boil water and melt metal.
Got a taste for Fresnel lenses? Here's how you can get one of your very own from an old television, and here's a video about how they work.
This story originally appeared on Crave Australia.
Posts
