A document discusses a proposal to use axially stretched metal nanolaminate membranes as lightweight parabolic cylindrical reflectors in the Dual Anamorphic Reflector Telescope (DART) — a planned spaceborne telescope in which the cylindrical reflectors would be arranged to obtain a point focus. The discussion brings together a combination of concepts reported separately in several prior NASA Tech Briefs articles, the most relevant being “Nanolaminate Mirrors With Integral Figure-Control Actuators” NPO-30221, Vol. 26, No. 5 (May 2002), page 90; and “Reflectors Made From Membranes Stretched Between Beams” NPO-30571, Vol. 33, No. 10 (October 2009), page 11a. The engineering issues receiving the greatest emphasis in the instant document are (1) the change in curvature associated with the Poisson contraction of a stretched nanolaminate reflector membrane and (2) the feasibility of using patches of poly(vinylidene fluoride) on the rear membrane surface as piezoelectric actuators to correct the surface figure for the effect of Poisson contraction and other shape errors.
This work was done by Jennifer Dooley, Mark Dragovan, Gregory Hickey, and Shyh-Shiu Lih of Caltech for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Physical Sciences category. NPO-40797
This Brief includes a Technical Support Package (TSP).
Nanolaminate Membranes as Cylindrical Telescope Reflectors
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Overview
The document titled "Nanolaminate Membranes as Cylindrical Telescope Reflectors" from NASA's Jet Propulsion Laboratory discusses advancements in optical systems for space science, particularly focusing on the use of nanolaminate materials in telescope design. The primary goal is to develop ultra-lightweight, large aperture optical systems capable of producing high-resolution images in visible and infrared/submillimeter wavelengths, which are essential for future astrophysics missions.
The core innovation presented is the Cu/CuZr multilayer nanolaminate, which consists of 1540 layers of copper and zirconium, resulting in a crystalline Cu and amorphous CuZr alloy nanolaminate. This structure is deposited onto polished Zerodur substrates, achieving a surface roughness of less than 5 Angstroms. The document highlights that these nanolaminates can be produced with an areal density of 0.5 kg/m² and can be deposited in approximately 96 hours for a ~100 micron thickness.
The application of these nanolaminates in cylindrical optics represents a significant shift from traditional methods, which have focused on minimizing bending stiffness using materials like metallized polyimide films. The new approach allows for tensioning the membrane at the boundary, which helps maintain the optical figure without the complications of bonding to a backing structure. This tensioning method is expected to alleviate issues related to Poisson contraction, which can distort the optical figure when the membrane is under tension.
Additionally, the document discusses the integration of PVDF (Polyvinylidene fluoride) actuators to enhance the performance of the nanolaminate membranes. These actuators can be mounted at the boundary of the membrane to correct deformations caused by tension, thereby improving the optical performance of the telescope.
The relevance of this research is underscored by the growing need for advanced optical systems in space science, particularly for missions aimed at exploring the origins and structure of the universe. The combination of DART and nanolaminate technologies aligns with the objectives of NASA's Space Science Enterprise, offering a promising pathway for the development of future far-infrared and submillimeter optical systems.
In summary, the document outlines a transformative approach to telescope design using nanolaminate materials, emphasizing their lightweight properties, ease of handling, and potential for high-resolution imaging in space exploration.
