NASA's Chandra X-ray Observatory includes a Flight Contamination Monitor (FCM), a system of 16 radioactive calibration sources mounted on the inside of the Observatory's forward contamination cover. The purpose of the FCM is to verify the ground-to-orbit transfer of the Chandra flux scale, through comparison of data acquired during the ground calibration with those obtained in orbit, immediately prior to opening the Observatory's sun-shade door. Here we report results of these measurements, which limit the absolute value of the change in mirror-detector system response to less than 2% at Ag Lα (3 keV) and Mn Kα (6 keV). This limit is consistent with the prelaunch estimate of less than 10 Å accumulation of molecular contamination between ground calibration and initial on-orbit operations.

Estimates of background in CZT detectorsi indicate that even with the beneficial concentration of a focussing telescope measurements in the 20 to 100 keV band of the Constellation X-ray Mission's HXT will become background limited after several thousand seconds of observing. This time is less than the expected exposure of most measurements. Consequently the sensitivity of most if not all observations of the HXT will be background limited. Therefore, the angular resolution should be as good as possible as long as the effective area remains high. We are pursuing a method for fabricating telescopes for thetwelve units of HXT that consists of electroforming integral shell substrates, a process that has been highly developed for XMM. We are attempting to adapt this method to higher energy X-rays by employing multilayer coatings, and smaller graze angles, and also reduce the mass of the telescopes from the XMM prescription by employing stronger, lighter alloys. The resolution that XMM has achieved, 15" HPW is an indication of the resolution we can expect.

We present an overview of our recent progress toward the development of segmented X-ray mirrors for the Constellation-X mission. Our reference design incorporates thin glass reflector substrates, with axially curved X-ray reflecting surfaces applied via epoxy replication. Alignment is accomplished via a precision structure incorporating ultraprecise etched Si alignment microstructures (as described in associated papers). Recent efforts have been devoted to demonstrating that the figure of prototype small segments and the alignment process will allow us to meet the 15" half-power diameter angular resolution requirement. We discuss the status of this, of our efforts to fabricate meter-class segments, and of the developments of supporting metrological techniques. We summarize our plans for a laboratory demonstration of a prototype mirror meeting the Constellation-X angular resolution and weight requirements.

The Constellation-X, grazing incidence, x-ray telescope may be fabricated from replicated segments. A series of mandrels will serve as the 'masters' in the replication processes. Diamond turning (milling) followed by abrasive figuring followed by a super polishing are the steps currently envisioned in making just one (of many) mandrel. The abrasive figuring of a mandrel is accomplished by moving a grinding tool along a helical path on this almost cylindrical surface. The measurement of the surface is, however, performed along 'axial' scan lines which intercept this helical path. This approach to figuring and measuring permits a relatively simple scheme to be implemented for the determination of the optimal dwell times of the figuring tool. These optimal dwell times are determined by a deconvolution which approaches the problem in a linear programming context and uses the Simplex Method. The approach maximizes the amount of material removed at any point subject to inequality constraints. The effects of using these 'optimum' dwell times is to significantly improve the tools effectiveness at removing the higher spatial frequencies while staying (strictly) within the bounds and constraints imposed by the hardware. In addition, the ringing at the edges of the optic, frequently present in deconvolution problems, is completely eliminated.

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.

For the next generation X-ray astronomy missions two main technological goals have to be achieved: (1) the possibility of making soft X-ray (0.1 - 10 keV) optics with much larger effective areas compared to the missions Chandra and XMM- Newton but still maintaining good angular resolution (better than 15 arcsec); (2) the extension of the use of focusing optics to the hard X-ray energy band (E equals 10 - 100 keV) by means of multilayer coating optics. The Brera Astronomical Observatory (Italy) is currently involved in technological development activities for the achievement of both these objectives. Concerning the realization of large diameter soft X-ray optics with low weight and good imaging capabilities, our efforts are devoted to the development of carriers made of ceramic materials like SiC and Alumina (Al₂O₃). The low density and the good mechanical parameters of these materials are very promising for this purpose. The technology for manufacturing hard X-ray optics based on multilayer mirrors, will be instead directly derived, with opportune modifications, from the replication process based on Nickel electroforming. This approach was already successfully used for the fabrication of the soft X-ray optics with Au coating of the Beppo-SAX, JET-X, SWIFT and XMM-Newton space experiments. In this case the use of Nickel instead of ceramics for the realization of the mirror carriers remains appropriate, due to the fact that, also for long focal length, hard X-ray telescopes are characterized by small diameters. In this paper we will present the more recent progresses achieved in pursuing these studies.

X-Ray Multi Mirror (XMM) satellite has been successfully launched on the 10th of December 1999. It is carrying 3 CCD detectors (2 MOS and 1 PN) optimized for X-Rays (EPIC instrument). These detectors have been calibrated using 2 synchrotron beam lines developed on purpose within the Institut d'Astrophysique Spatiale (IAS) and Laboratoire pour l'Utilisation du Rayonnement Electromagnetique (LURE) facilities in Orsay (France). The absolute calibration is performed by comparing the camera data with those obtained using a Gaz Proportional Counter for the 0.2 to 0.8 keV range and a Silicium-Lithium diode for the 0.6 to 12.0 keV range. These results are then to be compared to XMM in-flight calibration data.

The X-ray optics for the X-ray Evolving Universe Spectroscopy Mission (XEUS) have to satisfy the demanding requirements of this ambitious mission. XEUS is under study at the European Space Agency in the frame of the Horizon 2000+ program, utilizing the International Space Station (ISS) to take X-ray astrophysics into a new era. In a single launch XEUS1 is brought into orbit and deployed, providing a 4.5 m diameter X- ray optics with an angular resolution of 5 arcseconds. After a pre-cursor phase of astrophysical observation the XEUS mirror spacecraft docks to the ISS and is there significantly expanded, whereby the effective area of the optics is increased by a factor of 5, reaching 30 m². This servicing at the ISS is based on the currently foreseen capabilities of the ISS and strongly relies on robotics and the presence of astronauts. The progress in developing the X-ray optics for XEUS is reported. Based on electro-formed mirror plates, which are mounted into mirror petals, the optics is modular and elegantly breaks the size limitation dictated by current designs. The necessary high level of control of the Nickel electroforming process is based on the legacy of the XMM project, launched by ESA in December 1999, but substantially improves the angular resolution and the collecting area. New materials are being explored for the fabrication of the high precision Wolter I shaped mandrels, scaled model petals are being made to study the X-ray imaging properties, and full- scale structural models are built to confirm the numerical evaluation of the optics and engineering designs. Appreciable progress has been achieved on the X-ray optics, supporting the system level and feasibility studies of the mission, which are aimed at proving the feasibility of the novel concept of XEUS.

In the last years several coherent phenomena associated with the propagation of soft x-ray synchrotron radiation through capillary optical elements (polycapillary lenses and systems of capillaries) have been observed and investigated. Interference effects produced by soft x radiation travelling inside assembled capillary systems may be explained in the framework of the wave propagation theory. In this report a theoretical analysis of the dependence of the transmission characteristics by the internal structure of the capillary channel is presented and discussed.

The study of transmitting and focusing properties of capillary optical systems shows that a number of unexpected effects takes place during the experiments. One of those effects is a decrease of the beam divergence behind capillary structures. In this report we have considered an alignment procedure for capillary optics samples and presented the result on scattering of x rays at grazing angles. Decrease in beam divergence behind capillary systems is explained by use of the wave scattering theory for description of x-ray propagation.

The Lobster-eye optics represents a promising way of very wide field X-ray imaging with numerous applications especially in future X-ray astronomy projects and in fast yet sensitive monitoring of X-ray sky. We report on recent developments in design and construction of wide-field optical elements of Schmidt and Angel geometry. New compact Lobster-eye modules with both geometrical arrangements have been developed and tested. They feature improved parameters such as surface quality and angular resolution. Computer ray-tracing and first experimental results obtained in visible and X-ray regions are presented.

This paper discusses the development of a high resolution, hard x-ray telescope for imaging hard x-rays generated by energetic electrons accelerated in solar flares. We discuss the particular requirements of a hard x-ray telescope intended for solar observations, our approach to meeting these requirements, and progress made to date.

We have been developing high throughput X-ray telescope for hard X-ray region (20 - 40 keV) using Pt/C multilayer supermirrors for balloon borne experiment launched in 2001 June. The Walter type I telescope consists of about 2,000 supermirrors coated on very thin (150 micrometer) aluminum foils. We started mass production of the supermirror reflectors. Two different method is used for fabrication process. One is multilayer deposition on the platinum replica foil, and the other is direct replication of supermirror. The performance of the supermirrors are measured in X-ray beam line in Nagoya University and synchrotron radiation facility SPring-8. We obtained 30% reflectivity at 30 keV, corresponding to 0.35 nm interfacial roughness by Debye-Waller factor. The performance of multilayer supermirrors indicate that we can achieve about 100 cm² effective area for a telescope.

We are engaged in a program to develop focusing hard X-ray optics for future X-ray astronomy missions (such as the Hard X-ray Telescope of Constellation-X) and have built a DC magnetron sputtering system to deposit multilayers on candidate substrates for future telescopes. Although our emphasis is on the multilayer coating of integral cylindrical optics which will provide the highest spatial resolution, other types of substrates can easily be coated in this system. We present specular reflectivity data (using CuK_α X- rays) of W/Si constant d and depth graded-d multilayer depositions on substrates such as thermally formed DESAG glass and Duran glass cylinders. We will present data to show both azimuthal and linear uniformity of these coatings.

Historically, segmented optics similar to those used in BBXRT and ASTRO have achieved resolutions of a few arc minutes. Achieving substantially better performance requires significant improvement in both the optics themselves and how the optics are assembled and mounted to flight structure. While techniques for improving the optics themselves are underway at Goddard Space Flight Center (GSFC), Columbia University, and Smithsonian Astrophysical Observatory (SAO), here we address how the optics are assembled and mounted to flight structure. We have developed a concept for mounting large numbers of nested, segmented optics which require sub micron accuracy. This methodology uses lithographically defined and etched silicon alignment microstructure. A precision assembly station, incorporating the silicon micro structures is used to position the optics which are then bonded to a flight structure. The advantages of this procedure are that the flight structure has relaxed tolerance requirements and the precision assembly tooling can be reused. We show the positional requirements of the precision tooling as well as the mechanical requirements of the tooling itself.

We are developing high-energy grazing-incidence optics for a balloon-borne hard-x-ray telescope. When completed the instrument, termed HERO for High Energy Replicated Optics, will have 200 cm² effective collecting area at 40 keV and <EQ 30 arcsec angular resolution. The payload will offer unprecedented sensitivity in the hard-x-ray region, with milliCrab level sensitivity on a one-day balloon flight and 100 microCrab on an ultra-long-duration flight. While the full science payload is scheduled for flight in 2002, an engineering/proving flight is currently awaiting launch. This flight, consisting of just two mirror modules, each containing three nested shells above a pair of gas scintillation proportional counter focal plane detectors, is intended to test a newly designed gondola pointing and aspect system and to examine the stability of optical bench designs. This paper provides an overview of the HERO program.

The process of electroforming nickel x-ray mirror shells from superpolished mandrels has been widely used. The recently launched XMM mission by the European Space Agency (ESA) is an excellent example, containing 174 such mirror shells of diameters ranging from 0.3 - 0.7 meters and with a thickness range of 0.47 - 1.07 mm. To continue to utilize this technique for the next generation of x-ray observatories, where larger collecting areas will be required within the constraints of tight weight budgets, demands that new alloys be developed that can withstand the large stresses imposed on very thin shells by the replication, handling and launch processes. Towards this end, we began a development program in late 1997 to produce a high-strength alloy suitable for electroforming very thin high-resolution x-ray optics for the proposed Constellation-X project. Requirements for this task are quite severe; not only must the electroformed deposit be very strong, it must also have very low residual stresses to prevent serious figure distortions in large thin-walled shells. Further, the processing must be done reasonably near room temperature, as large temperature changes will modify the figure of the mandrel. Also the environment must not be corrosive or otherwise damaging to the mandrel during the processing. The results of the development program are presented, showing the evolution of our plating processes and materials through to the present 'glassy' nickel alloy that satisfies the above requirements.

Achieving arcsecond angular resolution in a grazing-incidence foil optic X-ray telescope, such as the segmented mirror approach being considered for the Constellation-X Spectroscopy X-Ray Telescope (SXT), requires accurate placement of individual foils. We have developed a method for mounting large numbers of nested, segmented foil optics with sub- micrometer accuracy using lithographically defined and etched silicon alignment micro-structures. A system of assembly tooling, incorporating the silicon micro-structures, is used to position the foils which are then bonded to a flight structure. The advantage of this procedure is that the flight structure has relaxed tolerance requirements while the high accuracy assembly tooling can be reused. A companion paper by Bergner et al. discusses how our process could be used for the SXT. We have built an assembly truss with a simplified rectilinear geometry designed to experimentally test this alignment and mounting technique. We report results of tests with this system that demonstrate its ability to provide sub- micrometer alignment of rigid test optics.

The design of the multilayer coatings and multilayer grating for the EIS spectrometer is presented. The grating substrate has a rectangular laminar groove profile with 4200 grooves/mm and a 58 angstrom groove depth. The grating and mirror have two multilayer coatings, each covering half of the areas of the grating and mirror, and with high reflectance in the two wavelength regions 170 - 210 angstrom and 250 - 290 angstrom. The reflectance of the multilayer coating and the efficiency of the multilayer grating were calculated using computer codes that were validated by comparison to reflectance and efficiency measurements performed using synchrotron radiation. The sensitivities of the calculated reflectance and grating efficiency to surface microroughness, layer interdiffusion, layer nonuniformity, illumination angle, grating groove variations, hydrocarbon contamination, and oxide buildup were analyzed.

The optical design for stigmatic grazing-incidence flat-field spectrometers with spatial resolution capability is presented. The spectral focal curve is almost a straight line by use of the flat-field focusing properties of spherical variable line- spaced gratings. The astigmatism in the plane perpendicular to the dispersion plane is corrected by a spherical mirror mounted with its sagittal plane coincident with the equatorial plane of the grating. The spectral and spatial focusing properties result almost fully uncoupled, so the ultimate spectral resolution depends only on the grating characteristics and on the detector pixel size and the spatial resolution depends only on the properties of the mirror. The image on the focal plane is stigmatic in the spectral direction both for on-plane and off-plane sources: no spectral broadening is observed for off-plane sources, maintaining therefore a constant spectral resolution also for extended sources. The resolution in the plane perpendicular to the plane of dispersion decreases for off-plane sources, depending on the incidence angle on the mirror and on the acceptance angle. Comparisons with optical performances of conventional stigmatic grazing-incidence spectrometers are presented.

A compact 90 degree-Compton scatter polarimeter has been developed to be used for energy resolved linear polarization analysis of Parametric X-radiation (PXR) in the energy range below 10 keV. The polarimeter employs 4 thermoelectrically cooled silicon drift detectors of excellent noise performance directed at a conical beryllium scatterer under azimuths spaced by 45 degrees to measure the azimuthal modulation of Compton scatter yields. One further drift detector is used to align the narrow PXR radiation cone with respect to the polarimeter axis. The polarization sensitivity and instrumental asymmetries of the polarimeter have been studied with monochromatized synchrotron radiation at energies from 6 to 11 keV. The analyzing power is close to unity in agreement with expectations and Monte Carlo simulation results. Instrumental asymmetries of a few percent have been measured and corrected for with residual statistical uncertainties of (Omicron) (10^-3). The orientation of the polarization plane is determined to within less than 4 milliradians.

A wide variety of x-ray and extreme ultraviolet (EUV) diagnostics are being developed to study z-pinch plasmas at the Nevada Terawatt Facility (NTF) at the University of Nevada, Reno. Time-resolved x-ray/EUV imaging and spectroscopy, polarization spectroscopy, and backlighting will be employed to measure profiles of plasma temperature, density, flow, and charge state and to investigate electron distribution functions and magnetic fields. These diagnostics are used to study the NTF pinch as an x-ray/EUV source for plasma spectroscopy research and to examine the early-time evolution of a current-driven wire, the formation of a plasma sheet from the explosion and merging of wires, etc. The instruments are state-of-the-art applications of glass capillary converters (GCC), multilayer mirrors (MLM), and crystals. Devices include: a novel glass-capillary-based two- dimensional imaging spectrometer, a time-resolved x-ray spectrometer, a 5-channel crystal/MLM spectrometer ('Polychromator') with a transmission grating spectrometer, and two-channel x-ray/EUV polarimeters-spectrometers (to study simultaneously polarization of K- and L-shell radiation). An x-pinch backlighter, yielding point-projection microscopy with ns resolution is under development. X-ray convex-crystal survey spectrometers, and fast filtered x-ray diodes have observed single Ti-, Fe and W-wire z-pinches, and Ti and Fe x- pinches. The NTF x-ray yield and x-ray pulse duration depend sensitively on the wire load. There is evidence of a strong energetic electron beam with a complex spatial structure in x- pinch plasmas. This work is supported by DOE, DOD, SNL, and UNR.

The three most important quantities used to assess the performance of astronomical x-ray telescope optics are the on- axis collecting area, the field of view, and the half-power diameter. The first two quantities depend on the mirror packing arrangement and the multilayer coating design. In order to optimize the coating design, we have developed a figure-of-merit (FOM) that accounts for the coating response over a specified range of energies and off-axis angles. We present an example where we have used this FOM to optimize a specific coating design for the High Energy Focusing Telescope (HEFT) and to understand tradeoffs between performance and coating thickness.