Durable 3-5 μm transmitting infrared window materials

Properties of 3-5 mu m infrared-transmitting window materials are reviewed, with an emphasis on durable materials for applications in environments involving moisture, impact by solid and liquid particles, high temperatures and rapid heating rates. Infrared, visible and ultraviolet transmission windows are compared for MgF2, aluminum oxynitride, sapphire, spinel, MgO, Y2O3, calcium aluminate, SiO2, CaF2, LiF, ZnS, ZnSe, GaAs, GaP, Si and Ge. Emission at elevated temperature, reflection and optical scatter are also discussed. A comparison of mechanical and thermal properties is given, as is a brief discussion of rain and particle erosion resistance. (C) 1998 Elsevier Science B.V. All rights reserved.