Kevin Moore and Grant Reynolds from the Science Channel looked at one of their favourite childhood pastimes – burning things with the rays from a magnifying glass – and wanted to magnify it. They wanted to magnify the ray so much so that it could melt metal.
So how do you get that much heat? Pretty simple really. They used an old fresnel lens from a rear-projection TV in place of the magnifying glass, thus increasing the intensity of the light.
The effect, as you can see in the video, is pretty incredible.