Reply #9: I have a fresnel lense, about 1 square meter, which came from [View All]

[phantom power]

a big-screen TV. It is one of my prized posessions, and it will pass on to my descendents, if I believe they are worthy. With this lense, I can take a square meter of incoming sunlight, and focus it down to about 1/2 a square inch. I'm estimating, since any ruler I placed on the focal point would either burst into flame or melt. And I could't look at it anyway, since I'd damage my retinas.

With this lense, I have melted (among other things) glass, concrete, aluminum, copper and steel.

So, it ought to be possible to get temperatures even higher than 550C, although I don't know if it's practical on an industrial scale.

It's damnably fun, though. I recommend it.