>"Aluminium oxynitride (marketed under the name ALON by Surmet Corporation[3]) is a transparent ceramic composed of aluminium, oxygen and nitrogen. ALON is opt

>"Aluminium oxynitride (marketed under the name ALON by Surmet Corporation[3]) is a transparent ceramic composed of aluminium, oxygen and nitrogen. ALON is optically transparent (≥ 80%) in the near-ultraviolet, visible and midwave-infrared regions of the electromagnetic spectrum. (PDS: I'm thinking waveguide -- for that EM frequency range...) >"It is four times as hard as fused silica glass, 85% as hard as sapphire, and nearly 115% as hard as magnesium aluminate spinel. Since it has a cubic spinel structure, it can be fabricated to transparent windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques. ALON is the hardest polycrystalline transparent ceramic available commercially.[2]" [...] >"ALON also appears to be radiation-resistant and resistant to damage from various acids, bases, and water.[8]" [...] >"It can withstand temperatures of about 2100 °C in inert atmospheres." [...] >"'Transparent aluminum' became a popular term after its use in the 1986 film Star Trek IV: The Voyage Home. [15] [16]" PDS: I found this while searching for the most recent research in Optical ALU's... Would it make a good Optical ALU? Well, we don't (as of yet!) know, but according to Wikipedia: >"In addition to being used as a transparent armor material, ALON is used as infrared-optical windows. As such it has applications as a sensor component, speciality IR domes, windows for laser communications, and in some semiconductor-related applications.[9][10]" PDS: Also, it might make a good material for some parts or components of future spaceships -- as alluded to in the Star Trek IV reference, above...