Superior and Affordable Infrared Windows for High-Speed Missiles

During this Phase II STTR, Foster-Miller will develop Yttria-Alumina-Garnet (YAG) IR windows made by our innovative process and establish a property database to confirm the potential for cost-effectiveness and superior optical and mechanical properties compared to current materials. This YAG is made from a single crystal YAG preform and hot pressed to >99 percent density. Windows made during Phase I were visibly transparent and transmitted to 6 µm, beyond spinel, sapphire, and ALON. High-temperature emission should be quite low to present a much stronger signal-to-noise ratio than the other materials. YAG does not exhibit birefringence. Mechanical properties measured in Phase I include Knoop hardness 13 percent higher than single crystal YAG. This, along with its fine-grained microcomposite structure, is encouraging for thermal shock resistance, key to survivability of a missile window. Phase II will focus on producibility and repeatability, and thorough optical property and thermal shock assessment. The Phase II team includes Boston University for processing, Johns Hopkins (APL) for testing, and an MDA systems integrator to define requirements. (P-040345)