Optical Coatings for Deep Concave Surface

Current IR domes utilize hemispherical shapes because they introduce minimal optical distortion and are relatively easy to fabricate. Future missile systems will use domes with more aerodynamic shapes to reduce drag , increase range and decrease aerodynamic heating. Technologies to produce dome blanks of suitable materials, and subsequently fabricated them into aerodynamic shapes with appropriate optical tolerances are being developed. Once such domes are available, they will require anti-reflection (AR) coatings to achieve desired levels of transmission. The exterior surface missile domes are subject to extreme environmental loading during captive carry and high speed flight. For this reason, the preferred configuration is to leave the exterior surface of the dome bare, applying an AR coating only to the interior surface. However, the desired aerodynamic domes have geometries that are difficult to coat using conventional coating processes. Surmet has developed a proprietary coating process which is routinely used to conformally apply coatings to substrates with complicated geometries. This same process has been used to apply AR coatings to a variety of substrates which are similar to the polycrystalline alumina material of interest to this program. Surmet proposes to use this coating technology to apply AR coatings to aerodynamic shapes.