Low-Cost Manufacturing Processes for Large Aperture Membrane Mirrors

Membrane mirrors constructed from materials that can withstand the space environment, have low thermal expansion, small mass, and compact stowage volume offer enabling technology for large space-based telescope systems. United Applied Technologies has demonstrated the feasibility and scaleability of the basic manufacturing processes for producing preformed deployable thin polyimide film mirrors using low-cost tooling for process refinement. Spherical polyimide film mirrors, 0.5- meter diameter with thicknesses ranging to less than 20 ¿m, have been produced that are self-supporting in one-G. These membrane mirrors passively maintain their preformed shape after deployment. The manufacture of large aperture preformed membrane mirrors with shape and smoothness control to within nanometers using the above approach requires both high-precision tooling with highly polished surfaces, and precise preforming process parameter control. The innovation to be evaluated in this effort is development and refinement of new membrane mirror preforming processes that produce highly accurate mirrors with tooling that is much lower in cost and is scaleable to large diameters. Alternate polyimide materials that produce membranes with higher surface smoothness and lower coefficients of thermal expansion will be evaluated using these new processes.