Final Testing and Evaluation of a Meter-Class Actively Controlled Membrane Mirror (Preprint)
Journal article (preprint)
SRS TECHNOLOGIES HUNTSVILLE AL
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Testing has been completed of a O.7O meter diameter mirror using thin-film polymer membranes. Advances in polymer film science have resulted in polymer membranes less than 24 microns in thickness with excellent surface roughness and sub wavelength thickness variation. The cause of such high quality material production, this has allowed the concept of a lenticular mirror design to be reconsidered. This involves the use of a clear canopy integrated with a reflectively coated membrane and pressurization is used to establish a desired focal length Boundary errors as well as significant spherical aberration are typical aberrations associated with such a mirror system. The membrane mirror described here accounts for these errors by utilizing an active boundary control system to help alleviate any errors near the boundary due to possible uneven stresses and any mounting errors. A varied stress coating is also deposited onto the reflective-polymer membrane to alter the mechanical properties of the film, that when pressurized it pushes more towards a parabola instead of a severely aberrated aspheric mirror. The final test data obtained on this system is presented in this paper.