Internal Antireflection Coatings for Aerodynamic Missile Domes

The use of an antireflection coating can potentially increase the 85% MWIR transparency of polycrystalline alumina ogive missile domes to further transmit IR radiation while protecting the sensor from heat. However, the unique structure of the dome creates a coating challenge for traditionally line of sight physical vapor deposition processes. Additionally, the usage profile dictates high durability in temperatures up to 1000C dictating a careful choice of materials. SOC proposes a program that combines our off-axis development coating capabilities of three dimensional parts in our large area (3m) deposition chamber, our infrared region measurement capabilities, and our optical thin film design expertise to create a functional 4 micron coating with less than 1 percent reflectance at near normal angles of incidence without severely diminishing performance at angles up to 60 degrees. SOC will accomplish this by performing a materials study, designing an antireflection coating with the characterized materials, developing a coating that passes the antireflection coating requirements, and demonstrating this capability on flat polycrystalline alumina substrate with associated measurements. SOC will explore the feasibility of coating ogive structure by performing a thickness distribution study using differing positions of an off-axis source on a mock structure during the option phase.