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Proceedings Paper

Fresnel lenses for x-ray and gamma-ray astronomy
Author(s): Gerald K. Skinner; Peter von Ballmoos; Neil Gehrels; John Krizmanic
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Paper Abstract

Phase Fresnel lenses have the same imaging properties as zone plates, but with the possibility of concentrating all of the incident power into the primary focus, increasing the maximum theoretical efficiency from 11% to close to 100%. For X-rays, and in particular for gamma-rays, large, diffraction-limited phase Fresnel lenses can be made relatively easily. The focal length is very long - for example up to a million kms. However, the correspondingly high 'plate-scale' of the image means that the ultra-high (sub-micro-arc-second) angular resolution possible with a diffraction limited gamma-ray lens a few meters in diameter can be exploited with detectors having mm spatial resolution. The potential of such systems for ultra-high angular resolution astronomy, and for attaining the sensitivity improvements desperately needed for certain other studies, are reviewed and the advantages and disadvantages vis-a-vis alternative approaches are discussed. We report on reduced-scale 'proof-of-principle tests' which are planned and on mission studies of the implementation of a Fresnel telescope on a space mission with lens and detector on two spacecraft separated by one million km. Such a telescope would be capable of resolving emission from super-massive black holes on the scale of their event horizons and would have the sensitivity necessary to detect gamma-ray lines from distant supernovae. We show how diffractive/refractive optics leads to a continuum of possible system designs between filled aperture lenses and wideband interferometric arrays.

Paper Details

Date Published: 29 January 2004
PDF: 12 pages
Proc. SPIE 5168, Optics for EUV, X-Ray, and Gamma-Ray Astronomy, (29 January 2004); doi: 10.1117/12.508316
Show Author Affiliations
Gerald K. Skinner, Ctr. d'Etude Spatiale des Rayonnements (France)
Peter von Ballmoos, Ctr. d'Etude Spatiale des Rayonnements (France)
Neil Gehrels, NASA Goddard Space Flight Ctr. (United States)
John Krizmanic, NASA Goddard Space Flight Ctr. (United States)


Published in SPIE Proceedings Vol. 5168:
Optics for EUV, X-Ray, and Gamma-Ray Astronomy
Oberto Citterio; Stephen L. O'Dell, Editor(s)

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