Transparent Aluminum
I remember seeing this from the Star Trek Movie - Do you suppose the idea came from there?
Article came from http://www.spiegel.de/wissenschaft/mensch/0,1518,183008,00.html
A 10 times 10 centimeters large disk (strength: ) only about 400 gram weigh, are however three times harder 1.0 cm as hardened steel. With firing tests under contract of the German Federal Armed Forces from the Bundeswehr in Koblenz "outstanding results" were obtained, report the researcher Andreas Krell.
Also in the US state Idaho were examined the tiles: The pentagon is fascinated of the transparency of the material, with which firingfixed of visors or large windows of armored reconnaissance vehicles can be built.