Random Anti-Reflective Hydrophobic Textures on Semi-Hemispheric Domes

A major advance in submarine sensing technology was enabled in the early 2000s with the advent of the Navy’s Integrated Submarine Imaging Systems (ISIS) program, which has incorporated visual and digital imaging into photonic mast assemblies, providing all-weather, high-resolution imagery. The Navy has identified that current antireflection (AR) coatings do not adequately meet photonic mast specifications for bandwidth, durability, and hydrophobicity. An innovative and rugged solution to the AR problem is based on Random AntiReflective (RAR) nanotextures imparted directly into the mast windows. The optical performance of nano-textures has been demonstrated to be far superior to thin film coatings with respect to transmission, bandwidth, off-axis performance, and laser power handling; as well as exhibiting ultra-hydrophobic properties in sea water. In Phase I, extreme optical performance and hydrophobicity was maintained in nanotextured fused silica after 8-days submerged in flowing sea water. The Phase II and Options effort will demonstrate extreme AR bandwidth in sapphire windows, extending from the visible out to the mid-wave infrared. Full-scale fused silica and sapphire photonic mast transparencies for various mast programs will be nanotextured and undergo extensive environmental durability testing in sea water, along with development of an automated cleaning system for shipboard use.