Typically, the cost of a spaceborne imaging system is driven by the size and mass of the primary aperture. Innovative solutions for imagers that are less complex and are lightweight are very desirable. Currently, telescopes such as JWST and ATLAST are very expensive and very complex.

The solution described here uses a method to construct an imaging system in space in which the nonlinear optical properties of a cloud of micron-sized particles, shaped into a specific surface by light pressure, allow one to form a very large and lightweight aperture of an optical system, reducing overall mass and cost. Specifically, the method is based on a cloud of reflective particles, shaped into a reflector via electromagnetic and/or optical forces.

The primary aperture of the imaging system is a cloud instead of a monolithic aperture, hence the name “cloud imager.” A cloud imager may be well suited to X-ray applications that do not require coherent imaging, but rather rely on X-ray diffraction to collect photons in a given X-ray energy range. The large aperture of the cloud imager will enable much improved spatial and spectral resolution over current X-ray telescopes and may allow for imaging of SuperMassive Black Hole event horizons. Preliminary system design considerations indicate that the Sun-Earth halo L2 orbit is more promising than others due to reduced geomagnetic disturbances on a cloud. The optical figure of the collecting surface may be made uniform with a wavefront sensing and control system.

Recent work has investigated the feasibility of a granular imaging system, concluding that such a system could be built and controlled in orbit. The most innovative aspect of this concept is the use of light to position granular media to synthesize and shape a cloud in space. This new solution is based on a cloud of reflective particles shaped into a reflector via electromagnetic and/or optical trapping forces. If a sunshade would be provided, no UV-induced photoelectric charging would be induced on the grains, thus improving the stability of the system.

The cloud imager would open the way to revolutionizing large-scale optics. The cloud imager would feature emerging formation flying control technology, which supports very-large-aperture space telescope systems because formation control of separated optical telescope modules would allow for very high ground imaging resolution in visible and infrared surface targets. Ultra-lightweight telescope technology, provided by elimination of heavy metering structures, would lead to simple and low-cost designs. Scalable apertures for high-resolution, large focal length (f#>10), on-axis and off-axis telescope options would be available. Autonomous on-orbit operations would be enabled for long periods of time. The cloud imager would have the potential to enable autonomous reflective, refractive, or diffractive imaging architectures. The cloud aperture could distribute itself to large scales, from meters to tens of meters, using sparse aperture technology. It would be simple to package, transport, and deploy; would be reconfigurable; and could be retargeted and repointed with non-mechanical means.

This work was done by Marco B. Quadrelli, David M. Palacios, and Harold W. Yorke of Caltech for NASA’s Jet Propulsion Laboratory. NASA is actively seeking licensees to commercialize this technology. Please contact Dan Broderick at This email address is being protected from spambots. You need JavaScript enabled to view it. to initiate licensing discussions. NPO-49934

NASA Tech Briefs Magazine

This article first appeared in the April, 2017 issue of NASA Tech Briefs Magazine.

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