Deployable near-net-shaped membrane optics

摘要

The Air Force Research Laboratory is developing a large space-based optical membrane telescope. When this research began a little more than three years ago, the conceptual design was based upon a totally inflatable structure. An inflatable structure has been used for space solar power collection and radio-frequency antennas. To place the development of the membrane optical telescope in perspective, a short history of past inflatables will be presented. The totally inflatable lenticular design used in a variety of space-based applications in radio and radar antennae, solar power for propulsion applications and solar shields is of particular interest. Recently, a new version of a membrane telescope has emerged. Thin membranes on the order of 10 to 100 $mu@m thick will be packaged and deployed without using inflation to maintain the surface figure. The move away from a pure inflatable is driven by several factors, including wavelength-level tolerances required of optical telescopes, even when real-time holography is invoked as the adaptive optics correction technique. Issues that led us to de-emphasize an inflatable, lenticular design and concentrate on a near-net shape film using stress coatings and dual boundary edge control are discussed.