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For X-ray astronomy, 0.1 arc-second imaging resolution will result in a significant advance in our understanding of the Universe. Similarly, the advent of low cost high performance X-ray mirrors will also increase the likelihood of more X-ray telescopes being funded and built. We discuss the development plans of two different types of adjustable grazing incidence optics: one being a tenth arc-second resolution bimorph mirror approach also suitable for extremely large collecting areas, and the second being a few arc-second radially adjustable mirror approach more suitable for modest sized telescopes. Bimorph mirrors will be developed using thin (0.1 - 0.4 mm) thermally formed glass or electroplated metal mirror segments with thin film piezo-electric actuators deposited directly on the mirror back surface. Mirror figure will be adjusted on-orbit. Radially adjustable mirrors will employ discreet radially electrostrictive actuators for mirror alignment and low spatial error frequency figure correction during assembly and alignment. In this paper we report on. In this paper we describe mirror design and our development plans for both mirror concepts.

We present an overview update of the metrologic approach to be employed for the segmented mirror fabrication for Constellation-X spectroscopy x-ray telescope. We compare results achieved to date with mission requirements. This is discussed in terms of inherent capability versus in-practice capability. We find that all the needed metrics for the mirrors are in hand but that they are currently limited by the mounting of the mirrors themselves.

著者人数：29名, Accepted: 2007-03-08, 資料番号: SA1000202000

X-rays provide one of the few bands through which we can study the epoch of reionization, when the first galaxies, black holes and stars were born. To reach the sensitivity required to image these first discrete objects in the universe needs a major advance in X-ray optics. Generation-X (Gen-X) is currently the only X-ray astronomy mission concept that addresses this goal. Gen-X aims to improve substantially on the Chandra angular resolution and to do so with substantially larger effective area. These two goals can only be met if a mirror technology can be developed that yields high angular resolution at much lower mass/unit area than the Chandra optics, matching that of Constellation-X (Con-X). We describe an approach to this goal based on active X-ray optics that correct the mid-frequency departures from an ideal Wolter optic on-orbit. We concentrate on the problems of sensing figure errors, calculating the corrections required, and applying those corrections. The time needed to make this in-flight calibration is reasonable. A laboratory version of these optics has already been developed by others and is successfully operating at synchrotron light sources. With only a moderate investment in these optics the goals of Gen-X resolution can be realized., Enhanced version of SPIE presentation. 11 pages, 5 figures

One of the key instruments on the Reconnection and Microscale (RAM) Solar-Terrestrial Probe mission is a normal incidence multilayer x-ray telescope designed to provide 10 milli-arc-sec imaging of the solar corona. To achieve this level of imaging it will be necessary to fabricate meter-class reflective optics with diffraction limited performance at 193 Angstroms. Because of the use of multilayer optics, surface micro-roughness must also be maintained at very low levels (a few Angstroms rms) to maintain good reflectance. To ease fabrication constraints and the sometimes competing requirements of micro-roughness and figure, we have explored a number of potential designs and fabrication approaches for RAM. Figure error budgets and optical designs are shown, demonstrating that RAM can be built with existing mirror fabrication technology.

Recent studies and planning for a variety of x-ray astronomy missions (Constellation-X, XEUS, Generation-X) have driven astronomers to explore grazing incidence telescopes with focal lengths of 50 m or greater. One approach to implementing such long focal lengths is to employ formation flying: separate optic and detector spacecraft travel in formation. Formation flying removes the "telescope tube" which was an integral part of shielding the telescope from straylight. We consider the implications of formation flying with respect to straylight, and discuss some design guidelines for baffling the straylight. The Constellation-X mission is used as an example.

Large collecting area x-ray telescopes are designed to study the early Universe, trace the evolution of black holes, starsand galaxies, study the chemical evolution of the Universe, and study matter in extreme environments. TheConstellation-X mission (Con-X), planned for launch in 2016, will provide ~ 10 4 cm 2 collecting area with 15 arc-secresolution, with a goal of 5 arc-sec. Future missions require larger coll ecting area and finer resolution. Generation-X(Gen-X), a NASA Visions Missio n, will achieve 100 m 2 effective area at 1 keV and angular resolution of 0.1 arc-sec, half power diameter. We briefly describe the Con-X flowdown of imaging requ irements to reflector figure error. Tomeet requirements beyond Con-X, Gen-X optics will be thinner and more accurately shaped than has ever beenaccomplished. To meet these challenging goals, we incorporate for the first time active figure control with grazing incidence optics. Piezoelectric material will be deposited in discrete cells directly on the back surface of the optical segments, with the strain directions oriented parallel to the surface. Differential strain between the two layers of the mirror causes localized bending in two directions, enablin g local figure control. Adjusting figure on-orbit eases fabrication and metrology. The ability to make changes to mirro r figure adds margin by mitigating risk due to launch-induced deformations and/or on-orbit degradation. We flow down the Gen-X requirements to mirror figure and fourtelescope designs, and discuss various trades between the designs.Keywords: x-ray optics, active optics, adjustable optics, Con-X, Gen-X

We present the metrology requirements and metrology implementation necessary to optically characterize the reflector technology for the Constellation-X (C-X) spectroscopy x-ray telescope (SXT). This segmented, 1.6m diameter highly nested telescope presents many metrology and alignment challenges. In particular, these mirrors have a stringent imaging error budget as compared to their intrinsic stiffness. The low stiffness is seen to be implied by the required effective area and the required weight. The low mirror stiffness has implications for the metrology that can be used. A variety of contact and non-contact optical profiling and interferometric methods are combined to test the formed glass substrates before replication and the replicated reflector segments. The reflectors are tested both stand-alone and in-situ in an alignment tower. Some of these methods have not been used on prior x-ray telescopes and some are feasible only because of the segmented approach used on the SXT. Methods to be discussed include high precision coordinate measurement machines using very low force or optical probes, axial interferometric profiling, azimuthal circularity profiling, and use of advanced null optics such as conical computer generated hologram (CGHs).

The new frontier in astrophysics is the study of the very first stars, galaxies and black holes in the early Universe. These objects are beyond the grasp of the current generation of X-ray telescopes such as Chandra, and so the Generation-X Vision Mission has been proposed as an X-ray observatory which will be capable of detecting these earliest objects. Xray imaging and spectroscopy of such distant objects will require an X-ray telescope with large collecting area and high angular resolution. The Generation-X concept has 100 m2 collecting area at 1 keV (1000 times larger than Chandra) and 0.1 arcsecond angular resolution (several times better than Chandra and 50 times better than the resolution goal for Constellation-X). The baseline mission involves four 8 m diameter telescopes operating at Sun-Earth L2. Such large telescopes will require either robotic or human-assisted in-flight assembly. To achieve the required effective area with launchable mass, very lightweight grazing incidence X-ray optics must be developed, having an areal density 100 times lower than in Chandra, with perhaps 0.1 mm thick mirrors requiring on-orbit figure control. The suite of available detectors for Generation-X should include a large-area high resolution imager, a cryogenic imaging spectrometer and a grating spectrometer.

The Constellation-X Spectroscopy X-ray telescope (SXT) is designed to be built from X-ray optic segments. The X-ray segments will be fabricated from the segmented mandrels using a replication process. The purpose of the incoming metrology is to map the surface of the mandrels, so the performance of the X-ray optics produced can be predicted. Three Constellation-X segmented mandrels have been delivered to MSFC for incoming metrology. The segmented mandrels are 30-degree sections of a cylindrical surface and have diameters of 1.0 m, 1.2 m and 1.6 m. The maximum dimensions of the optical surface are 1.0 m axial length and 0.5 m azimuthal segment length. The metrology of the mandrels consists of the measurement of their slope differences, roundness, absolute radius, axial profile and microroughness. Accuracy goals for each type of measurement and the accuracy of the instruments used for the measurements will be discussed. The results of the mandrel metrology together with the performance predictions will be presented.

This paper describes the system performance for Micrascan VII and reports on some of the photo-resist testing results. The challenges of tool design range from the optical form to new resists. The Micrascan VII architecture has the traditional look of the prior Micrascan family of tools. The evolution of design for operation at 157 nm wavelength has been implemented and is presented. The use of calcium fluoride exclusively in the projection optics design presented many challenges. Performance of the projection optics is shown as well as lithographic results. Initial lithographic results indicate that pattern features well below 100 nm can be printed even with first generation 157 nm resists. 60 nm resist lines with 0.3 μm depth of focus are reported.

We have measured the x-ray imaging performance of a grazing incidence telescope mirror, the HT #17, employing a hyperboloid-hyperboloid design. This design provides improved wide-field imaging compared to an optimally defocused Wolter Type I mirror. This improvement will be advantageous for future Geostationary Operational Environmental Satellite (GOES) missions that will provide full disk images of the sun with the Solar X-ray Imager (SXI). The x-ray measurements were made in the X-Ray Calibration Facility (XRCF) at Marshall Space Flight Center and the results are presented here.

This paper describes a mathematical model, called the Bridging model, for predicting the smoothing of high spatial frequency surface errors in optical surfaces during polishing processes, which use large flexible polishing laps. The mathematical model is developed in two stages. First, the Kirchoff flat plate equation, which is modified to include the effect of shear flexibility of the lap and compressive stiffness of the pitch, is solved for lap pressure distribution over a surface error feature represented by a sinusoidal spectrum. This pressure distribution is used as an input to the Preston's equation for material removal rate. The resulting equation is then solved for material removal and surface error smoothing predictions. Available data from a laboratory test and a real optics fabrication program are compared with analytical predictions of the mathematical model. Good correlation is obtained between the two.

The solar x-ray imager (SXI) is a grazing incidence Wolter Type I X-ray Telescope to be fabricated and flown on the National Oceanic and Atmospheric Administration's (NOAA) Geo-Stationary Operational Environmental Satellite. The SXI will image the full sun at wavelengths between approximately 6 and 60 angstroms with a detector having 5 arc sec pixels. The goal for SXI is to forecast 'space weather', i.e., effects of charged particles that are produced at the Sun as they interact at the earth. Major contributors to space weather include: variations in the Sun's solar wind, solar flares, and solar mass ejections. Effects of space weather include: radiation damage and particle events in high- inclination orbit spacecraft, disruption of various kinds of communications equipment, degradation of navigational tools such as GPS, potential health hazard during space walks, and power blackouts the SXI and the resulting optical design for the grazing incidence telescope. Parametric performance predictions of image quality as degraded by diffraction, geometrical aberrations, and surface scattering effects due to residual optical fabrication errors are presented that establish realistic optical fabrication tolerances necessary to satisfy top-level image quality requirements.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Advanced X-ray Astrophysics Facility (AXAF) mirrors represent the largest, most precise, grazing incidence optics every built. The eight cylindrical mirrors, 0.84 meters long, and ranging in diameter from 0.6 to 1.2 meters, have all been successfully fabricated. The optical surfaces were fabricated using a deterministic, computer controlled, approach. Modeling of the computer controlled process was employed to achieve desired figure levels in a minimum of polish/metrology cycles. Figure error corrections of 80 to over 90 percent per cycle were routinely achieved. Final full-bandwidth figure levels ranged from about 180 angstroms rms to about 40 angstroms rms. Surface roughness values range from about 3.5 to less than 2 angstroms, rms, over a bandwidth of 1 to 1000 mm-1. Numerous metrology cross-checks give good confidence in the data. The fabrication, modeling, and metrology are described. Results of figure correction are presented. We also present an estimate for the predicted performance of the eight mirror ensemble and compare that with program requirements and goals.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Properly planned and executed metrology crosschecks at low to mid system test levels can provide up to the same degree of end item performance insurance protection that a top-level end-to-end test can, at a small fraction of the cost, and in a much more timely manner in terms of identifying and correcting problems. This philosophy has been put into rigorous practice on the optics fabrication activity being performed by Hughes Danbury Optical Systems, under contract to TRW, on the Advanced X-ray Astrophysics Facility (AXAF) program being managed by NASA's Marshall Space Flight Center. The process to date, while for the most part having provided confidence that the primary calibrations and tests are correct, has also identified several significant but subtle errors that were corrected. The focus of the paper is on the process itself as an optical quality insurance tool, with examples from AXAF described.

The first two mirrors for the Advanced X-Ray Astrophysics Facility (AXAF) have been successfully fabricated and tested. The methodology developed has demonstrated figure convergence rates previously unseen on large area, precision optics. These results were based on developing a unified systems approach to fabrication and testing aided by the extensive use of analytical models. This paper presents a summary of the optic requirements, an overview of the fabrication process, the metrology used, and a summary of the results.

Orthonormal polynomials have long been used as a convenient tool to describe optic surface errors. Previously, the products of Fourier and Legendre polynomials have been employed to describe the surface errors for grazing incidence optics. We have applied an alternate set of polynomials, Fourier-Fourier polynomials, to describe the surface errors. This new set differs functionally from the Fourier Legendre set in that each term has a finite bandwidth frequency spectrum. The advantages of this difference with respect to predictions of grazing incidence telescope performance based on measured surface figure errors are discussed.

Multiwire proportional counters with 1 ?m polypropylene windows, of dimensions 75 mm × 75 mm and 100 mm × 100 mm, have been built to map soft cosmic X-rays. The counters are constructed with a large drift region which allows us to use the center-of-gravity technique to improve the counter's efficiency and position resolution. Using 330 Torr of propane as the gas fill and an anode plane composed of 20 ?m diameter, gold-plated tungsten wire spaced 1 mm apart, we have achieved a position resolution of better than 280 ?m (FWHM) in two orthogonal directions at an X-ray energy of 0.94 keV.

The fabrication of the Technology Mirror Assembly (TMA) is complete, and performance predictions were made based upon mechanical and visible light measurements of the surface properties. An X-ray calibration program has been executed, and a preliminary analysis of a portion of the data is presented. The X-ray image distribution results are in reasonable agreement with the performance predictions which were calculated prior the start of the X-ray tests. The measured X-ray imaging performance approaches that expected for the Advanced X-ray Astrophysics Facility (AXAF).

We have developed a math model relating the measured parameters of the Technology Mirror Assembly (TMA) to its final performance. This scalar scattering model is valid for large and small amplitude features. It allows the user to specify power spectral densities and/or autocovariance functions within any spatial bandwidth, including microroughness. We present new TMA data in the bandwidth of ~0.1-1000 mm(-1), predicting performance and comparing them with x-ray test data. We also account for assembly, alignment. and particulate contamination. Finally, we comment on improved performance expected after repolishing.