I walked past this the other day when they were building it out in front of MIT. What was amazing to me was not that it can melt steel, but that the mirrors they used were built to such perfect concavity with insanely smooth surfaces. The article suggests a possible application of the technology is bringing heat and solar electricity to poorer countries, but I have a hard time believing those perfect mirrors are really that inexpensive.<p>To compare this thing to anything Archimedes could have made is laughable.
"When Marcellus withdrew them [his ships] a bow-shot, the old man [Archimedes] constructed a kind of hexagonal mirror, and at an interval proportionate to the size of the mirror he set similar small mirrors with four edges, moved by links and by a form of hinge, and made it the center of the sun's beams – its noon-tide beam, whether in summer or in mid-winter. Afterwards, when the beams were reflected in the mirror, a fearful kindling of fire was raised in the ships, and at the distance of a bow-shot he turned them into ashes. in this way did the old man prevail over Marcellus with his weapons."<p>"Archimedes and his Burning Mirrors, Reality or Fantasy?"
<a href="http://www.mlahanas.de/Greeks/Mirrors.htm" rel="nofollow">http://www.mlahanas.de/Greeks/Mirrors.htm</a>
Wonder what its efficiency is compared to a Fresnel lens:<p><a href="http://www.youtube.com/watch?v=DGtA8E5iw3k" rel="nofollow">http://www.youtube.com/watch?v=DGtA8E5iw3k</a><p><a href="http://images.google.com/imgres?imgurl=http://www.terrypepper.com/Lights/closeups/illumination/fresnel/fresnel-orders.gif&imgrefurl=http://www.terrypepper.com/Lights/closeups/illumination/fresnel/fresnel.htm&h=435&w=281&sz=8&hl=en&start=16&tbnid=l34jDm9V39EF9M:&tbnh=126&tbnw=81&prev=/images%3Fq%3Dfresnel%2Blens%26gbv%3D2%26hl%3Den%26sa%3DG" rel="nofollow">http://images.google.com/imgres?imgurl=http://www.terrypeppe...</a>