Toward a complete metrologic solution for the mirrors for the Constellation-X Spectroscopy x-ray telescope

Lehan, John P.; Owens, Scott M.; Hadjimichael, Theo; Hong, M.; Chan, Kai-Wing; Saha, Timo T.; Reid, Paul B.; Zhang, W. W.

doi:10.1117/12.733080

Cited by 6 publications

(7 citation statements)

References 5 publications

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“…This can be separated into two primary causes fundamental to the problem: self weight deformation and vibration. In a previous publication, 5 we addressed both of these issues and concluded that the vibration is adequately being managed for most of the measurements. The self-weight distortion, although better managed than at that time, continues to limit the metrology accuracy and repeatability, especially in light of the stricter requirements.…”

Section: Instrumental Versus In-practice Performancementioning

confidence: 94%

“…The second mount is the so-called "CantorTree" mount. 5,10 This mount is also semi-kinematic and is akin to a 1-dimensional whiffle-tree with a mirror-image "upper branch" whiffle-tree that bears almost none of the mirror load but does suppress vibration. This mount is free of adhesives but suffers from frictional forces that limit its degree-of-repeatability with consecutive mountings of the same mirror.…”

Section: Refractive Null Lens and Strobe Fizeau Interferometermentioning

confidence: 99%

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Progress toward a complete metrology set for the International X-ray Observatory (IXO) soft x-ray mirrors

et al. 2009

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We present an overview update of the metrologic approach to be employed for the segmented mirror fabrication for the IXO soft x-ray telescope. We compare results achieved to date with mission requirements. This is discussed in terms of inherent capability versus in-practice capability of the metrology. We find that all the needed metrology equipment are in hand but that a number of the needed quantities remain too uncertain relative to mission requirements. This is driven by the mounting of the mirrors themselves. We then discuss some plans for addressing the mirror mounting issues. Finally, we also briefly discuss some promising mandrel metrology techniques.

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Section: Instrumental Versus In-practice Performancementioning

confidence: 94%

Section: Refractive Null Lens and Strobe Fizeau Interferometermentioning

confidence: 99%

Progress toward a complete metrology set for the International X-ray Observatory (IXO) soft x-ray mirrors

et al. 2009

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“…The measurement equipment is shown in Figure 6 (Lehan et al, 2007). For a mirror substrate to be measured with the equipment, it is sputtered with ~2 nm of Ir which is sufficiently reflective but is not thick enough to distort the figure of the substrate.…”

Section: Metrologymentioning

confidence: 99%

Manufacture of mirror glass substrates for the NuSTAR mission

Zhang

2009

SPIE Proceedings

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The NuSTAR (Nuclear Spectroscopy Telescope Array) observatory (Harrison et al. 2009), expected to be launched into an equatorial low earth orbit in 2011, will have two mirror assemblies capable of imaging X-rays in the hard X-ray band between 5 keV and 80 keV. It will be the first X-ray observatory using multilayer coatings to significantly expand the bandwidth of the typical X-ray telescope of 0.1 keV to 10 keV. The mirror assemblies use a segmented design to simplify the construction process, as such they require 4,680 mirror substrates coated with appropriately designed multilayers to enhance reflectivity for hard X-rays. These substrates are produced by slumping commercially available thin glass sheets. In this paper we report on our work of manufacturing these substrates at NASA Goddard Space Flight Center.The NuSTAR mirror assemblies have their heritage in the previously flown balloon payload HEFT (High Energy Focusing Telescope) (Koglin et al. 2005). They use the conical approximation to the traditional Wolter-I optical design. The conical approximation is implemented in two steps: (1) starting with cylindrically-shaped mirror segments whose radii of curvature are within 1 mm of their respective design values; (2) the alignment and integration process bends the cylindrical mirror segments into the required conical shapes and attaches them to the mirror assemblies under the monitoring of real-time metrology. As such the first step of making these mirror assemblies is the manufacture of cylindrically shaped glass substrates.The NuSTAR substrate production is based on a glass slumping technique developed for the International X-ray Observatory (IXO mission, formerly known as the Constellation-X (Zhang et al, 2006) mission. It uses commercially available thin borosilicate glass sheets and slump them on precisely polished and figured fused quartz mandrels. As a result, the finished curved glass is a replica of the mandrel. It takes up the overall shape of the mandrel while preserving the excellent microroughness of the glass sheets.

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“…It copies the figure of conventionally fabricated mandrels to cOlllIJlercially procured (Schott D263) thin (-0.4 mm) float glass sheets while preserving their excellent micro-roughness (-4A rms measured over a 300 /lm span). As shown in Figure 2 (right panel), it has been able to make mirror substrates consistently at -6.5 are-seconds (HPD); Each entry in the histogram represents a substrate pair which has been precisely measured with optical metrology [19,20,21,22,23,24] and whose x-ray imaging performance calculated with standard performance prediction techniques. The glass slumping process is capable of making substrates the meet the requirements of a sub-l0 arc-second mirror assembly: It has been used to making the more than 10,000 substrates for the NuST AR mission [7].…”

Section: Technical Approaches and Statusmentioning

confidence: 99%

Next generation astronomical x-ray optics: high angular resolution, light weight, and low production cost

et al. 2012

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X-ray astronomy depends on the availability of telescopes with high resolution and large photon collecting areas. Since x-ray observation can only be carried out above the atmosphere, these telescopes must be necessarily lightweight. Compounding the lightweight requirement is that an x-ray telescope consists of many nested concentric shells, which further require that x-ray mirrors must also be geometrically thin to achieve high packing efficiency. This double lightweight and geometrically thin requirement poses significant technical challenges in fabricating the mirrors and in integrating them into mirror assemblies. This paper reports on the approach, strategy and status of our x-ray optics development program whose objective is to meet these technical challenges at modest cost to enable future x -ray missions, including small Explorer missions in the near term, probe class missions in the medium term, and large flagship missions in the long term.

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Toward a complete metrologic solution for the mirrors for the Constellation-X Spectroscopy x-ray telescope

Cited by 6 publications

References 5 publications

Progress toward a complete metrology set for the International X-ray Observatory (IXO) soft x-ray mirrors

Progress toward a complete metrology set for the International X-ray Observatory (IXO) soft x-ray mirrors

Manufacture of mirror glass substrates for the NuSTAR mission

Next generation astronomical x-ray optics: high angular resolution, light weight, and low production cost

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