This mirror was made here in Tucson at the UofA Mirror Lab, which is located under the stands of the football stadium. It is cast in a honeycombed mold (to reduce its mass) out of a glass similar to Pyrex, which also reduces the time needed to anneal it. The glass is placed into the mold and heated until it begins to soften and fill the spaces at the bottom. When it becomes smooth at the surface, the kiln, containing the mold and glass, begins to spin at a rate that forces the glass outward to the edges and allows it to take on the hyperbolic curved shape needed to focus light (otherwise the surface would be flat). Then it is allowed to cool, still while spinning, until it will no longer move, The spinning stops and it is allowed to cool slowly over a month or more (the annealing cycle) which prevents stress cracking. The power required to heat the glass in preparation for spinning is over one million watts and about six very large additional mobile generators are needed to provide the extra electricity.
Posted on: Sat, 27 Jul 2013 20:58:10 +0000
Trending Topics
Recently Viewed Topics
© 2015