29 January 2004 Development of a prototype nickel optic for the Constellation-X hard x-ray telescope
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Abstract
The Constellation-X mission, planned for launch in 2013, will feature an array of hard-x-ray telescopes (HXT) with a total collecting area of greater than 1500 cm2 at 40 keV. Two technologies are currently being investigated for the optics of these telescopes including multilayer-coated Eletroformed-Nickel-Replicated (ENR) shells. The attraction of the ENR process is that the resulting full-shell optics are inherently stable and offer the prospect of better angular resolution which results in lower background and higher instrument sensitivity. The challenge for this process is to meet a relatively tight weight budget with a relatively dense material (ρnickel = 9 g/cm3.) To demonstrate the viability of the ENR process we are fabricating a prototype HXT mirror module to be tested against a competing segmented-glass-shell optic. The ENR prototype will consist of 5 shells of diameters from 150 mm to 280 mm with a length of 426 mm. To meet the stringent weight budget for Con-X, the shells will range in thickness from 100 microns to 150 microns. The innermost of these will be coated with Iridium, while the remainder will be coated with graded-dspaced W/Si multilayers. Mandrels for these shells are in the fabrication stage, the first test shells have been produced and are currently undergoing tests for figure and microroughness. A tentative date of June '04 has been set for the prototype X-ray testing at MSFC. Issues currently being addressed are the control of stresses in the multiplayer coating and ways of mitigating their effects on the figure of the necessarily thin shells. The fabrication, handling and mounting of these shells must be accomplished without inducing permanent figure distortions. A full status report on the prototype optic will be presented along with test results as available.
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Suzanne E. Romaine, Stefano Basso, Ricardo J. Bruni, Oberto Citterio, Darell Engelhaupt, Mauro Ghigo, Paul Gorenstein, Mikhail V. Gubarev, Francesco Mazzoleni, Stephen L. O'Dell, Giovanni Pareschi, Giancarlo Parodi, Brian D. Ramsey, Chet O. Speegle, "Development of a prototype nickel optic for the Constellation-X hard x-ray telescope", Proc. SPIE 5168, Optics for EUV, X-Ray, and Gamma-Ray Astronomy, (29 January 2004); doi: 10.1117/12.508096; http://dx.doi.org/10.1117/12.508096
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KEYWORDS
Coating

Prototyping

Multilayers

Optical fabrication

Mirrors

X-ray optics

Nickel

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