Diffractive/refractive optics for high energy astronomy

Skinner, G.

doi:10.1051/0004-6361:20010745

Cited by 53 publications

(55 citation statements)

References 46 publications

(35 reference statements)

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“…Fig. 4 The efficiency of a 500 keV PFL if the detector distance is adjusted to match the focal length for each energy (note -the corresponding curve in reference [1] is slightly incorrect).…”

Section: Chromatic Aberrationmentioning

confidence: 99%

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Gamma ray Fresnel lenses — why not?

Skinner¹

2006

Focusing Telescopes in Nuclear Astrophysics

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Fresnel lenses offer the possibility of concentrating the flux of X-rays or gamma-rays flux falling on a geometric area of many square metres onto a focal point which need only be a millimetre or so in diameter (and which may even be very much smaller). They can do so with an efficiency that can approach 100%, and yet they are easily fabricated and have no special alignment requirements. Fresnel lenses can offer diffraction-limited angular resolution, even in a domain where that limit corresponds to less than a micro second of arc.Given all these highly desirable attributes, it is natural to ask why Fresnel gamma ray lenses are not already being used, or at least why there is not yet any mission that plans to use the technology. Possible reasons (apart from the obvious one that nobody thought of doing so) include the narrow bandwidth of simple Fresnel lenses, their very long focal length, and the problems of target finding. It is argued that none of these is a 'show stopper' and that this technique should be seriously considered for nuclear astrophysics.

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Section: Chromatic Aberrationmentioning

confidence: 99%

“…For it to be constant we must havev 1 =v 2 . If the first spacecraft is in a free orbit then its accelerationv 1 is provided by the gravitational field at v 1 . In general the gravitational field at v 2 will be different and so cannot correspond to the accelerationv 2 .…”

Section: The Focal Lengthmentioning

confidence: 99%

Gamma ray Fresnel lenses — why not?

Skinner¹

2006

Focusing Telescopes in Nuclear Astrophysics

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“…Recently, G. Skinner proposed a Fresnel lens-based system for astronomical observations at hard X-ray and gamma-ray energies [9,10]. This system would have the highest diffraction-limited angular resolution of any wavelength band, resulting in a greater than 10 8 improvement over current gamma-ray imaging systems.…”

Section: Fresnel Lensesmentioning

confidence: 99%

“…More elaborate lens designs may help alleviate this problem [10], but the properties of a single lens must be investigated first. As stated earlier, the proposed PFL system should provide a 10 8 increase in angular resolution and a 10 3 increase in sensitivity over current instruments.…”

Section: The Proposed Fresnel Lens-based Telescopementioning

confidence: 99%

Development of a Deep Silicon Phase Fresnel Lens Using Gray-Scale Lithography and Deep Reactive Ion Etching

Morgan

Waits

Krizmanic

et al. 2004

J. Microelectromech. Syst.

125

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A phase Fresnel lens (PFL) could achieve higher sensitivity and angular resolution in astronomical observations than the current generation of gamma and hard x-ray instruments. For ground tests of a PFL system, silicon lenses must be fabricated on the micro-scale with controlled profiles to enable high lens efficiency. Thus, two MEMS-based technologies, gray-scale lithography and deep reactive ion etching (DRIE), are extended to create multiple controlled step heights in silicon on the necessary scale.A Gaussian approximation is introduced as a method of predicting a photoresist gray level height given the amount of transmitted light through a grayscale optical mask. Etch selectivity during DRIE is then accurately controlled by introducing an oxygen-only step to a standard Bosch cycle to produce the desired scaling factor between the photoresist and silicon profiles. Finally, a profile evaluation method is developed to calculate the expected efficiency of measured silicon profiles. Calculated efficiencies above 87% have been achieved.

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“…At very high photon energies (e.g. greater than 100 keV) filled aperture lenses of the required diameter may be just practical (Skinner 2001), but at lower energies much larger apertures would be needed. VLBI radio observations have been suggested as a possible way of achieving this objective (e.g.…”

mentioning

confidence: 99%

X-ray interferometry with transmissive beam combiners for ultra-high angular resolution astronomy

Skinner

Krizmanic

2009

Exp Astron

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Interferometry provides one of the possible routes to ultra-high angular resolution for X-ray and gamma-ray astronomy. Sub-micro-arc-second angular resolution, necessary to achieve objectives such as imaging the regions around the event horizon of a super-massive black hole at the center of an active galaxy, can be achieved if beams from parts of the incoming wavefront separated by 100s of meters can be stably and accurately brought together at small angles. One way of achieving this is by using grazing incidence mirrors. We here investigate an alternative approach in which the beams are recombined by optical elements working in transmission. It is shown that the use of diffractive elements is a particularly attractive option. We report experimental results from a simple 2-beam interferometer using a low-cost commercially available profiled film as the diffractive elements. A rotationally symmetric filled (or mostly filled) aperture variant of such an interferometer, equivalent to an X-ray axicon, is shown to offer a much wider bandpass than either a Phase Fresnel Lens (PFL) or a PFL with a refractive lens in an achromatic pair. Simulations of an example system are presented. Keywords

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Diffractive/refractive optics for high energy astronomy

Cited by 53 publications

References 46 publications

Gamma ray Fresnel lenses — why not?

Gamma ray Fresnel lenses — why not?

Development of a Deep Silicon Phase Fresnel Lens Using Gray-Scale Lithography and Deep Reactive Ion Etching

X-ray interferometry with transmissive beam combiners for ultra-high angular resolution astronomy

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