High Structural Efficiency Silicon Lightweight Mirrors (SLMS) for Optical/RF Communications Antennas

The Air Force Electro-Optical Combat Identification Technology Branch (AFRL/SNJM) has interest in developing multi-function EO/IR components such as Laser Radar Communications Antennas. A lightweight antenna for operation in the Ku-band, Ka-band and the1.55 micron laser wavelength would provide a technology breakthrough for aircraft communications. The Global Hawk unmanned reconnaissance aircraft currently houses a 48-inch Ku-band satellite communications antenna. Schafer's Phase II objective is todemonstrate the feasibility of high structural efficiency Silicon Lightweight Mirrors (SLMS), a novel, athermal, all-silicon, foam-core, lightweight mirror technology, for Optical/RF Communications Antennas for the Global Hawk system. We will performdesign and analysis of a 48-inch antenna for operation in Ku-band, Ka-band and at 1.55 microns. We will produce a flight-worthy 50 cm aperture pathfinder antenna suitable for verification testing at AFRL. The surface figure error specification andsurface roughness for the antenna are driven by the 1.55 micron laser wavelength. Unlike silicon carbide mirrors, silicon-based SLMS are quickly and inexpensively polished to low surface error and roughness. SLMS also have lower weight and cost thanUltralow Expansion (ULE) glass mirrors. The athermal nature of SLMS make them ideal for operation in the high-altitude aerospace environment.SLMS technology will significantly impact and benefit a very broad set of future DoD (Communications, Directed Energy, Imaging) and DoC/NOAA (Remote Imaging) Missions. SLMS will provide a national benefit beyond DoD for the NASA Space Science Enterprise(e.g., Explorer Program) and Earth Science Enterprise (e.g., GOES-R) and commercial system houses (L3 Communications, Northrop Grumman, Raytheon, ITT, Boeing, Lockheed Martin, et.al.).