Ray-tracing critical-angle transmission gratings for the X-ray Surveyor and Explorer-size missions

Günther, H. M.; Bautz, Marshall W.; Heilmann, Ralf K.; Huenemoerder, David P.; Marshall, Herman L.; Nowak, Michael A.; Schulz, Norbert S.

doi:10.1117/12.2232157

Cited by 4 publications

(5 citation statements)

References 13 publications

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“…For future XGS instruments high collecting area (> 1000 cm 2 ) and high resolving power (R = λ/∆λ > 3000) need to go hand in hand -one is of limited use without the other. An XGS based on CAT gratings 2 can provide R > 10,000 for even better resolution of kinematically broadened lines, which has now been shown through ray-tracing of Arcus and X-ray Surveyor-type mission concepts, 10 and through experimental demonstrations described below.…”

Section: Introductionmentioning

confidence: 93%

“…Using SPO-like performance with modules that populate a 30 degree azimuthal wedge we find efficiency-weighted resolving power above 10,000, with relaxed alignment tolerances. 10 Further studies will investigate more detailed layouts and potential trade-offs between effective area and resolving power to maximize the figures of merit for the Arcus science case.…”

Section: Cat Gratings and Arcusmentioning

confidence: 99%

“…4 Further subaperturing will boost R well above 10,000. 10 Due to the high transparency of transmission gratings at higher energies a CATXGS will work in perfect synergy with a microcalorimeter at the focus, allowing for simultaneous high spectral resolution observations over the 0.2 -10 keV range with maximum collecting area. X-ray transmission gratings offer low mass and relaxed, easily achievable alignment requirements 10 compared to reflection gratings.…”

Section: Introductionmentioning

confidence: 99%

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Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

Heilmann

Bruccoleri²,

Kolodziejczak

et al. 2016

SPIE Proceedings

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A number of high priority subjects in astrophysics can be addressed by a state-of-the-art soft x-ray grating spectrometer, such as the role of Active Galactic Nuclei in galaxy and star formation, characterization of the Warm-Hot Intergalactic Medium and the missing baryon problem, characterization of halos around the Milky Way and nearby galaxies, as well as stellar coronae and surrounding winds and disks. An Explorer-scale, largearea (> 1,000 cm 2 ), high resolving power (R = λ/∆λ > 3,000) soft x-ray grating spectrometer is highly feasible based on Critical-Angle Transmission (CAT) grating technology, even for telescopes with angular resolution of 5-10 arcsec. Still, significantly higher performance can be provided by a CAT grating spectrometer on an X-raySurveyor-type mission. CAT gratings combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of conventional transmission gratings (low mass, relaxed alignment tolerances and temperature requirements, transparent at higher energies) with minimal mission resource requirements. They are high-efficiency blazed transmission gratings that consist of freestanding, ultra-high aspect-ratio grating bars fabricated from silicon-on-insulator (SOI) wafers using advanced anisotropic dry and wet etch techniques. Blazing is achieved through grazing-incidence reflection off the smooth grating bar sidewalls. The reflection properties of silicon are well matched to the soft x-ray band, and existing silicon CAT gratings can exceed 30% absolute diffraction efficiency, with clear paths for further improvement. Nevertheless, CAT gratings with sidewalls made of higher atomic number elements allow extension of the CAT grating principle to higher energies and larger dispersion angles, thus enabling higher resolving power at shorter wavelengths. We show x-ray data from CAT gratings coated with a thin layer of platinum using atomic layer deposition, and demonstrate efficient blazing to higher energies and much larger blaze angles than possible with silicon alone. We also report on measurements of the resolving power of a breadboard CAT grating spectrometer consisting of a Wolter-I slumped-glass focusing mirror pair from Goddard Space Flight Center and CAT gratings, performed at the Marshall Space Flight Center Stray Light Facility. Measurement of the Al K α doublet in 18 th diffraction order shows resolving power > 10,000, based on conservative preliminary analysis. This demonstrates that currently fabricated CAT gratings are compatible with the most advanced grating spectrometer instrument designs for future soft x-ray spectroscopy missions.

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Section: Introductionmentioning

confidence: 93%

Section: Cat Gratings and Arcusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

Heilmann

Bruccoleri²,

Kolodziejczak

et al. 2016

SPIE Proceedings

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“…However, XGS optical designs are neither free from aberrations, nor will a real XGS follow its design perfectly. We have undertaken numerous ray-trace studies of transmission XGS designs to understand the limits of performance, alignment tolerances, and other imperfections [18,19,[27][28][29][30], and came to the conclusion that instruments with R XGS ∼ 10000 and effective area > 1000 cm 2 should be feasible in the very near future.…”

Section: Introductionmentioning

confidence: 99%

Demonstration of resolving power λ/Δλ > 10,000 for a space-based x-ray transmission grating spectrometer

Heilmann

Kolodziejczak

Bruccoleri³

et al. 2019

Appl. Opt.

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We present measurements of the resolving power of a soft x-ray spectrometer consisting of 200 nm-period lightweight, alignment-insensitive critical-angle transmission (CAT) gratings and a lightweight slumpedglass Wolter-I focusing mirror pair. We measure and model contributions from source, mirrors, detector pixel size, and grating period variation to the natural line width spectrum of the Al and Mg K α 1 α 2 doublets. Measuring up to 18 th diffraction order at characteristic Al-K wavelengths we consistently obtain small broadening due to gratings corresponding to a minimum effective grating resolving power R g > 10, 000 with 90% confidence. Upper limits are often compatible with R g = ∞. Independent fitting of different diffraction orders, as well as ensemble fitting of multiple orders at multiple wavelengths, gives compatible results. Our data leads to uncertainties for the Al-K α doublet line width and line separation parameters 2-3 times smaller than values found in the literature. Data from three different gratings are mutually compatible. This demonstrates that CAT gratings perform in excess of the requirements for the Arcus Explorer mission and are suitable for next-generation space-based x-ray spectrometer designs with resolving power 5-10 times higher than the transmission grating spectrometer on the Chandra X-ray Observatory.

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“…The alignment sensitivities were derived using the methods described in [24]. The tightest tolerances are the 12.5 micron relative lateral translations of the SPO modules.…”

Section: Mounting and Aligning The Spo And Cat Petalsmentioning

confidence: 99%

Arcus: exploring the formation and evolution of clusters, galaxies, and stars

Abraham

Allured

Bautz

et al. 2017

UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX

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Ray-tracing critical-angle transmission gratings for the X-ray Surveyor and Explorer-size missions

Cited by 4 publications

References 13 publications

Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

Demonstration of resolving power λ/Δλ > 10,000 for a space-based x-ray transmission grating spectrometer

Arcus: exploring the formation and evolution of clusters, galaxies, and stars

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