Fabrication of single crystal silicon mirror substrates for X-ray astronomical missions
25 Jul 2014-Proceedings of SPIE (International Society for Optics and Photonics)-Vol. 9144, pp 914445
TL;DR: In this article, the authors describe the early pursuit of suitable fabrication technologies for the mass production of sub-arcsecond angular resolution single-crystal silicon mirror substrates for X-ray telescopes.
Abstract: The advancement of X-ray astronomy largely depends on technological advances in the manufacturing of X-ray optics. Future X-ray astronomy missions will require thousands of nearly perfect mirror segments to produce an X-ray optical assembly with < 5 arcsecond resolving capability. Present-day optical manufacturing technologies are not capable of producing thousands of such mirrors within typical mission time and budget allotments. Therefore, efforts towards the establishment of a process capable of producing sufficiently precise X-ray mirrors in a time-efficient and cost-effective manner are needed. Single-crystal silicon is preferred as a mirror substrate material over glass since it is stronger and free of internal stress, allowing it to retain its precision when cut into very thin mirror substrates. This paper details our early pursuits of suitable fabrication technologies for the mass production of sub-arcsecond angular resolution single-crystal silicon mirror substrates for X-ray telescopes.
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TL;DR: The X-ray Surveyor (X-S) as discussed by the authors is a large-scale mission with a high-resolution mirror assembly and an instrument set, which may include an x-ray microcalorimeter, a highdefinition imager, and a dispersive grating spectrometer and its readout.
Abstract: NASA's Chandra X-ray Observatory continues to provide an unparalleled means for exploring the high-energy universe. With its half-arcsecond angular resolution, Chandra studies have deepened our understanding of galaxy clusters, active galactic nuclei, galaxies, supernova remnants, neutron stars, black holes, and solar system objects. As we look beyond Chandra, it is clear that comparable or even better angular resolution with greatly increased photon throughput is essential to address ever more demanding science questions—such as the formation and growth of black hole seeds at very high redshifts; the emergence of the first galaxy groups; and details of feedback over a large range of scales from galaxies to galaxy clusters. Recently, we initiated a concept study for such a mission, dubbed X-ray Surveyor. The X-ray Surveyor strawman payload is comprised of a high-resolution mirror assembly and an instrument set, which may include an X-ray microcalorimeter, a high-definition imager, and a dispersive grating spectrometer and its readout. The mirror assembly will consist of highly nested, thin, grazing-incidence mirrors, for which a number of technical approaches are currently under development—including adjustable X-ray optics, differential deposition, and new polishing techniques applied to a variety of substrates. This study benefits from previous studies of large missions carried out over the past two decades and, in most areas, points to mission requirements no more stringent than those of Chandra.
76 citations
TL;DR: An approach to build an x-ray mirror assembly that can meet Lynx’s requirements of high-angular resolution, large effective area, light weight, short production schedule, and low-production cost is described.
Abstract: We describe an approach to build an x-ray mirror assembly that can meet Lynx’s requirements of high-angular resolution, large effective area, light weight, short production schedule, and low-production cost. Adopting a modular hierarchy, the assembly is composed of 37,492 mirror segments, each of which measures ∼100 mm × 100 mm × 0.5 mm. These segments are integrated into 611 modules, which are individually tested and qualified to meet both science performance and spaceflight environment requirements before they in turn are integrated into 12 metashells. The 12 metashells are then integrated to form the mirror assembly. This approach combines the latest precision polishing technology and the monocrystalline silicon material to fabricate the thin and lightweight mirror segments. Because of the use of commercially available equipment and material and because of its highly modular and hierarchical building-up process, this approach is highly amenable to automation and mass production to maximize production throughput and to minimize production schedule and cost. As of fall 2018, the basic elements of this approach, including substrate fabrication, coating, alignment, and bonding, have been validated by the successful building and testing of single-pair mirror modules. In the next few years, the many steps of the approach will be refined and perfected by repeatedly building and testing mirror modules containing progressively more mirror segments to fully meet science performance, spaceflight environments, as well as programmatic requirements of the Lynx mission and other proposed missions, such as AXIS.
34 citations
TL;DR: In this paper, the authors report on progress of an x-ray optics development program that has been designed to address all of these requirements, including fabrication of mirror substrates, coating, alignment, bonding, and testing.
Abstract: Future x-ray astronomical missions require x-ray mirror assemblies that provide both high angular resolution and large photon collecting area. In addition, as x-ray astronomy undertakes more sensitive sky surveys, a large field of view is becoming increasingly important as well. Since implementation of these requirements must be carried out in broad political and economical contexts, any technology that meets these performance requirements must also be financially affordable and can be implemented on a reasonable schedule. In this paper we report on progress of an x-ray optics development program that has been designed to address all of these requirements. The program adopts the segmented optical design, thereby is capable of making both small and large mirror assemblies for missions of any size. This program has five technical elements: (1) fabrication of mirror substrates, (2) coating, (3) alignment, (4) bonding, and (5) mirror module systems engineering and testing. In the past year we have made progress in each of these five areas, advancing the angular resolution of mirror modules from 10.8 arc-seconds half-power diameter reported (HPD) a year ago to 8.3 arc-seconds now. These mirror modules have been subjected to and passed all environmental tests, including vibration, acoustic, and thermal vacuum. As such this technology is ready for implementing a mission that requires a 10-arc-second mirror assembly. Further development in the next two years would make it ready for a mission requiring a 5-arc-second mirror assembly. We expect that, by the end of this decade, this technology would enable the x-ray astrophysical community to compete effectively for a major x-ray mission in the 2020s that would require one or more 1-arc-second mirror assemblies for imaging, spectroscopic, timing, and survey studies.
24 citations
Cites background or methods from "Fabrication of single crystal silic..."
...Our experimental effort in the past year has enabled us to develop a polishing and light-weighting process that is based on existing equipment and technology and that takes advantage of the near cylindrical geometry of x-ray mirrors and that achieves high efficiency and low cost [25]....
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...Concurrently, we are developing a process of fabricating mirror substrates out of single crystal silicon [25]....
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TL;DR: In this paper, a thin film piezoelectric actuator is used to correct mirror figure errors due to fabrication, mounting and alignment, using calibration and a one-time figure adjustment on the ground.
Abstract: We describe progress in the development of adjustable grazing incidence X-ray optics for 0.5 arcsec resolution cosmic X-ray imaging. To date, no optics technology is available to blend high resolution imaging like the Chandra X-ray Observatory, with square meter collecting area. Our approach to achieve these goals simultaneously is to directly deposit thin film piezoelectric actuators on the back surface of thin, lightweight Wolter-I or Wolter- Schwarschild mirror segments. The actuators are used to correct mirror figure errors due to fabrication, mounting and alignment, using calibration and a one-time figure adjustment on the ground. If necessary, it will also be possible to correct for residual gravity release and thermal effects on-orbit. In this paper we discuss our most recent results measuring influence functions of the piezoelectric actuators using a Shack-Hartmann wavefront sensor. We describe accelerated and real-time lifetime testing of the piezoelectric material, and we also discuss changes to, and recent results of, our simulations of mirror correction.
22 citations
05 Dec 2011
TL;DR: In this article, the authors describe a comprehensive program to advance the technology for x-ray telescopes well beyond the state of the art represented by the three currently operating missions: Chandra, XMM-Newton, and Suzaku.
Abstract: X-ray telescopes are essential to the future of x-ray astronomy. This paper describes a comprehensive program to advance the technology for x-ray telescopes well beyond the state of the art represented by the three currently operating missions: Chandra, XMM-Newton , and Suzaku . This program will address the three key issues in making an x-ray telescope: (I) angular resolution, (2) effective area per unit mass, and (3) cost per unit effective area. The objectives of this technology program are (1) in the near term, to enable Explorer-class x-ray missions and an IXO type mission, and (2) in the long term, to enable a flagship x-ray mission with sub-arcsecond angular resolution and multi-square-meter effective area, at an affordable cost. We pursue two approaches concurrently, emphasizing the first approach in the near term (2-5 years) and the second in the long term (4-10 years). The first approach is precision slumping of borosilicate glass sheets. By design and choice at the outset, this technique makes lightweight and low-cost mirrors. The development program will continue to improve angular resolution, to enable the production of 5-arcsecond x-ray telescopes, to support Explorer-class missions and one or more missions to supersede the original IXO mission. The second approach is precision polishing and light-weighting of single-crystal silicon mirrors. This approach benefits from two recent commercial developments: (1) the inexpensive and abundant availability of large blocks of mono crystalline silicon, and (2) revolutionary advances in deterministic, precision polishing of mirrors. By design and choice at the outset, this technique is capable of producing lightweight mirrors with sub-arcsecond angular resolution. The development program will increase the efficiency and reduce the cost of the polishing and the lightweighting processes, to enable the production of lightweight sub-arcsecond x-ray telescopes. Concurrent with the fabrication of lightweight mirror segments is the continued development and perfection of alignment and integration techniques, for incorporating individual mirror segments into a precision mirror assembly. Recently, we have been developing a technique called edge-bonding, which has achieved an accuracy to enable 10- arcsecond x-ray telescopes. Currently, we are investigating and improving the long-term alignment stability of so-bonded mirrors. Next, we shall refine this process to enable 5-arsecond x-ray telescopes. This technology development program includes all elements to demonstrate progress toward TRL-6: metrology; x-ray performance tests; coupled structural, thermal, and optical performance analysis, and environmental testing.
20 citations
References
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TL;DR: In this article, the design parameters, production process, and in-flight performance of the X-ray telescopes (XRTs) onboard Suzaku were presented. And the optical axes were found to be distributed within a radius of 1. 0 8 −2.
Abstract: We present the design parameters, production process, and in-flight performance of the X-ray telescopes (XRTs) onboard Suzaku. The imaging capability is significantly improved over the ASCA XRT, which had half-power diameters of 3. 0 6, to 1. 0 8–2. 0 3 for all four XRT-I modules. The optical axes are found to be distributed within a radius of 1. 3, which makes the observation efficiency of all the XRTs more than 97% at the XIS-default observing position. The vignetting over the XIS field of view predicted via ray-tracing coincides with that measured for observations of the Crab Nebula to within »10%. Contemporaneous fits of a power law to all the XIS spectra of the Crab Nebula taken at the two standard observing positions (XIS/HXDdefault positions) gives a flux consistent with that obtained by Toor & Seward (1974) to within »2%. The pre-collimator on the top of each XRT module successfully re
615 citations
"Fabrication of single crystal silic..." refers background in this paper
...The Suzaku X-ray observatory features extremely cost-efficient and lightweight segmented mirrors, though its angular resolution (120 arcsec) is relatively poor.(10) XMM-Newtons mirrors achieved a good angular resolution of 5 arcsec and a relatively large 0....
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TL;DR: In this paper, the in-orbit imaging performance of the three X-ray telescopes on board of the Xray astronomy observatory XMM-Newton is compared with the performance measured on ground at the MPE PANTER test facility.
Abstract: The in-orbit imaging performance of the three X-ray telescopes on board of the X-ray astronomy observatory XMM- Newton is presented and compared with the performance measured on ground at the MPE PANTER test facility. The comparison shows an excellent agreement the on ground and in-orbit performance.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
82 citations
TL;DR: SMART-X as discussed by the authors is a mission concept for a 2.3 m 2 effective area, with 5' FOV, 1" pixel size microcalorimeter, 22' fOV imager, and high-throughput capabilities.
Abstract: SMART-X is a mission concept for a 2.3 m 2 effective area,
0.5" angular resolution X-ray telescope, with 5' FOV, 1" pixel
size microcalorimeter, 22' FOV imager, and high-throughput
gratings.
58 citations
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TL;DR: The Chandra X-ray Observatory as mentioned in this paper is an observatory designed to study the x-ray emission from all categories of astronomical objects-from comets, planets, and normal stars to quasars, galaxies, and clusters of galaxies.
Abstract: Significant advances in science always occur when the state of the art in instrumentation improves dramatically. NASA's Chandra X-ray Observatory represents such an advance. Launched in July of 1999, Chandra is an observatory designed to study the x-ray emission from all categories of astronomical objects-from comets, planets, and normal stars to quasars, galaxies, and clusters of galaxies. At the heart of this observatory is the precision x-ray optic that has been vital for Chandra's outstanding success and that features an angular resolution improved by an order of magnitude compared to its forerunners. The Chandra mission is now entering its thirteenth year of operation, which, given that the observatory was designed for a minimum of three years of operation, testifies to its robust and carefully thought-out design. We review the design and construction of the remarkable telescope, present examples of its usage for astronomy and astrophysics, and speculate on its future.
33 citations
"Fabrication of single crystal silic..." refers background in this paper
...5 arcsec).(9) The Suzaku X-ray observatory features extremely cost-efficient and lightweight segmented mirrors, though its angular resolution (120 arcsec) is relatively poor....
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TL;DR: The International X-ray Observatory (IXO) as discussed by the authors is a joint ESA-JAXA-NASA effort to address fundamental and timely questions in astrophysics: What happens close to a black hole? How did supermassive black holes grow? What is the connection between these processes?
Abstract: The International X-ray Observatory (IXO) is a joint ESA-JAXA-NASA effort to address fundamental and timely questions in astrophysics: What happens close to a black hole? How did supermassive black holes grow? How does large scale structure form? What is the connection between these processes? To address these questions IXO will employ optics with 3 sq m collecting area and 5 arc sec angular resolution - 20 times more collecting area at 1 keV than any previous X-ray observatory. Focal plane instruments will deliver a 100-fold increase in effective area for high-resolution spectroscopy, deep spectral imaging over a wide field of view, unprecedented polarimetric sensitivity, microsecond spectroscopic timing, and high count rate capability. The mission is being planned for launch in 2021 to an L2 orbit, with a five-year lifetime and consumables for 10 years.
29 citations