Hydrophobic Anti-Reflection Nanotextures For Panoramic Photonic Mast Windows

A major advance in submarine sensing technology was enabled in the early 2000s with the Navys Integrated Submarine Imaging Systems (ISIS) program, which has incorporated visual and digital imaging into photonic mast assemblies, providing all-weather, high-resolution imagery for data analysts. Next generation ISIS systems will see a size reduction and more advanced sensing capabilities, including multispectral imaging. The photonic mast will incorporate multiple transparencies including hyper-hemispheric domes to allow for 360 panoramic viewing, and will greatly increase battlefield situational awareness. The photonic mast windows must be durable and hydrophobic for the extreme maritime environment; and transmit over broad visible and infrared wavelength ranges to provide transparency for the range of sensors to be incorporated. The Navy has identified that current antireflection coatings do not adequately meet mission specifications for bandwidth, durability, and hydrophobicity; and cannot be reliably deposited on next generation ISIS hyper-hemispherical domes. An innovative and rugged solution to the AR problem is based on Random AntiReflective (RAR) textures imparted directly into the domed windows. Durable AR surface textures have been shown to exhibit ultra-hydrophobic properties, and possess optical performance that is far superior to thin film coatings with respect to transmission, bandwidth, and off-axis performance