Advanced Processing of the Optical Surface on Large Lightweight Mirrors

The primary goal of the Phase I work is to explore two processing routes to produce mirror systems based on the replication technique using master mandrel. One processing route is based on the deposition of nano-laminates of ceramics to provide optical aswell as mechanical integrity of the mirror. The other processing involves the construction of mirror system (both mirror and substructure) based on a unique ceramic composite uni-body fabrication technique. These two processing routes involve thereplication technique, which is capable of providing fast and low-cost production of the high optical surface finish of the large mirrors. The ceramic nano-laminate mirror deposition will be followed various deposition techniques (Large Area Filtered ArcDeposition/Magnetron Sputtering/EB-PVD ). The composite bonding (between mirror and substructure) materials will be developed utilizing negative CTE nano-powder and geopolymer. The negative CTE nano-powder will be utilized to process ceramic compositeuni-body using chemically driven densification (CDD) processing. Successful completion of Phase II will provide a solid technical foundation for fabricating a primary mirror at least one-meter in diameter. It will also provide a list of limitations anddifficulties in scaling up to a 3 to 4 meter mirror segment with desired quality/performance. However, the Phase II research will demonstrate the optimum design/methodology for the rapid manufacturing of lightweight, low cost primary imaging and beamconverging mirrors, which have a variety of DoD and commercial applications. A successful manufacturing technology for producing large quantities of negative CTE single-phase, nano-sized powder will allow for its use in a variety of applications fromstructural and electronic, to space materials. Using the composite concept of negative CTE powder with conventional materials will give tremendous opportunities for thermal management of these materials for various applications. The processes to bedeveloped further under this program, geopolymerization and CDD, have much potential to be explored in the field of structural ceramics.