Lightweight cylindrical reflectors of a proposed type would be made from reflective membranes stretched between pairs of identically curved and identically oriented end rails. In each such reflector, the curvature of the two beams would define the reflector shape required for the intended application. For example, the beams could be curved to define a reflector of parabolic cross section, so that light incident along the axis of symmetry perpendicular to the cylindrical axis would be focused to a line. In addition, by applying suitable forces to the ends of the beams, one could bend the beams to adjust the reflector surface figure to within a precision of the order of the wavelength of the radiation to be reflected.
The figure depicts an example of beams shaped so that in the absence of applied forces, each would be flat on one side and would have a radius of curvature R on the opposite side. Alternatively, the curvature of the reflector-membrane side could be other than circular. In general, the initial curvature would be chosen to optimize the final reflector shape. Then by applying forces F between the beam ends in the positions and orientations shown in the figure, one could bend beams to adjust their shape to a closer approximation of the desired precise circular or noncircular curvature.
This work was done by Jennifer Dooley and Mark Dragovan of Caltech and Jason Tolomeo of Lockheed-Martin for NASA’s Jet Propulsion Laboratory. NPO-30571
This Brief includes a Technical Support Package (TSP).
Reflectors Made From Membranes Stretched Between Beams
(reference NPO-30571) is currently available for download from the TSP library.
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Overview
The document discusses a novel method for constructing reflectors using membranes stretched between beams, as detailed in NASA Tech Brief NPO-30571. The primary focus is on the design and shaping of optical membrane surfaces, which are essential for applications requiring precise reflectors, such as in telescopes or satellite communications.
The problem addressed is the need for a boundary that can accurately define the shape of the membrane reflector. This boundary must be adjustable and precise, particularly on the scale of the operating wavelength of the intended application. The solution proposed involves using beams that can be bent into a desired shape by applying specific forces and moments at their ends. This bending process allows the flat side of the beam to take on a conic section shape, which is particularly useful for creating parabolic reflectors that can focus light to a point.
The construction method involves two parallel beams across which a membrane is tensioned. Initially, the beams have one flat side and an opposite side that is circular, with a defined radius. By applying forces, the beams can be bent into a curved shape, allowing for the creation of a scalable and low-mass reflector. The document also notes that the curvature of the beam can be adjusted by choosing a different curve instead of a circular one, optimizing the final shape of the reflector.
The novelty of this approach lies in its ability to create a membrane reflector with a boundary that is both lightweight and precise, making it suitable for large-scale applications. The technology is scalable, meaning it can be adapted for various sizes depending on the specific requirements of the project.
For further inquiries or detailed information, the document provides contact details for the Innovative Technology Assets Management at NASA's Jet Propulsion Laboratory. Overall, this technical support package highlights significant advancements in reflector technology, emphasizing the potential for broader applications in scientific and commercial fields.
