Reported is a summary of the development of EUV Mo/Si multilayer coating technology. Though the results are developed for application in Extreme Ultraviolet Lithography, they are of a broader relevance including optics for astronomy. The coating process used consists of electron beam evaporation in combination with low energy ion beam smoothening. The radiation hardness of these coatings is discussed and methods to reduce the multilayer induced substrate stress. The reflectance of the coatings, which are covered with a special protective capping layer, is typically around 65%, while the non correctable figure error added by the full multilayer stack is controlled to better than 15 picometer.

The Multi-order Solar EUV Spectrograph (MOSES) is a slitless spectrograph designed to study solar He II emission at 303.8 Å (1 Å = 0.1 nm), to be launched on a sounding rocket payload. One difference between MOSES and other slitless spectrographs is that the images are recorded simultaneously at three spectral orders, m = -1, 0, +1. Another is the addition of a narrow-band multilayer coating on both the grating and the fold flat, which will reject out-of-band lines that normally contaminate the image of a slitless instrument. The primary metrics for the coating were high peak reflectivity and suppression of Fe XV and XVI emission lines at 284 Å and 335 Å, respectively. We chose B₄C/Mg₂Si for our material combination since it provides excellent peak reflectivity and rejection of out-of-band wavelengths. Measurements of witness flats at NIST indicate the peak reflectivity at 303.8 is 39.0% for a 15 bilayer stack, while suppression ranges from 7.5x to 12.9x at 284 Å and from 3.4x to 15.1x at 335 Å for the individual reflections in the optical path. We present the results of coating the MOSES flight gratings and fold flat, including the spectral response of the fold flat and grating as measured at NIST's SURF III and Brookhaven's X24C beamline, respectively.

We have systematically investigated the thermal and particle stability of several state-of-the-art EUV multilayer coatings suitable for use in high-performance solar instrumentation. Our research has been motivated principally by the performance requirements for extreme solar missions such as Solar Orbiter, an approved ESA mission with an expected launch date of 2013. The goal of this particular mission is to explore the solar atmosphere with both in situ and remote sensing instrumentation at a close encounter. At perihelion the mission will reach 0.2 A.U. providing a unique viewpoint where the instruments can both 'see' and 'feel' the dynamic atmosphere. But the orbit is technically challenging- no remote sensing instrument has been put in such close proximity to the Sun before. Furthermore, the thermal and particle environment will not only be severe but will suffer huge fluctuations as the elliptical orbit changes from 0.2 A.U. to 1.1 A.U. Several of the remote sensing packages on the strawman payload of the mission contain multilayer coatings, thus the stability of these coatings to the expected thermal and particle environment must be established. In this paper, we investigate the impact on the integrity of several candidate EUV multilayer coatings after long-term thermal annealing, and upon exposure to energetic protons and neutrons. In summary, we find no significant degradation in any of the multilayer samples tested. These results suggest that the multilayers we have studied can be safely used for Solar Orbiter or other extreme solar missions.

We have been developing X-ray mirrors for X-ray telescope using a ion-beam sputtering system. X-rays can be reflected by two processes, one is total reflection, and another is Bragg reflection. Total reflection is used for previous telescope below 10 keV. Its reflectivity determined by the optical constant. We suggests composite-layer mirror for soft X-ray optics, which has consists some different materials and optical constant has structure to the depth direction. The penetration depth of X-ray depends on the X-ray energy, so effective optical constant changes with X-ray energy. The depth graded multilayer, called "supermirror" was applied to the soft X-ray region. We designed nickelcarbon supermirror to obtain high reflectivity below 10 keV.

Future missions that may be deployed in the European Space Agency's Cosmic Visions 2025 scientific programme may include high energy astrophysics observatories that require focusing optics with unprecedented collection area. We describe scientific drivers for such missions, and discuss various implementations of optics designs that could satisfy the requirements. Options for lightweight reflectors and a possible implementation scenario are described and trade-offs for various coatings are presented.

This paper will discuss the coatings for the Nuclear Spectroscopic Telescope Array (NuSTAR) and describe the updates of the coating facility at the Danish National Space Center, necessary to make all the coatings in the required time frame. The inner part of the three NuSTAR telescopes will be coated with Pt/SiC and the outer part with W/SiC. To understand the roughness of the flight coatings, we will present results from 10 bilayer constant d-spacing coatings for both types of flight coatings. Also, data showing the homogeneity over the octant mirror segments as well as X-ray data from realistic depth graded coatings will be presented. The long time stability and stress in the coatings will be discussed.

The Ni electroforming replication process has been used successfully by Beppo-SAX, JET-X/SWIFT, and XMM-Newton, to produce their gold-coated X-ray mirrors. The important feature of the technique is that, also with thin substrates, it is possible to achieve a good angular resolution, which is important for obtaining high signal-to-noise ratios in deep observations and imaging extended sources, while the assembly and integration of the monolithic shells is a relatively easy task. Two approaches can be used for the up grade of this technique also to the case of mirrors with multilayer coating, to be used in future hard X-ray missions: i) the direct replication of the mirror shell, after the deposition of the multilayer film on the master (mandrel) surface followed by the electroforming of the Ni walls, ii) the application of the multilayer film to the internal surface of Ni mirror shells, previously realized by replication. In this paper the last results achieved in Italy in the context of an activity aiming at the development of the former of the two methods will be presented and discussed.

Reflection gratings offer high dispersion and thus the potential for high spectral resolution in the soft x-ray band. The requirements of high efficiency and maximum collecting area at minimum mass lead to the desire for densely stacked and exquisitely flat thin-foil grating substrates. In the past we have successfully addressed the problems of thin substrate figure metrology and blazed grating profile fabrication. Our recently developed low-stress thin-foil metrology truss with 50 nm figure repeatability removed a metrology bottleneck and allows us to make progress in the shaping of thin-foil substrates. We present results on the figuring of 100 mm-diameter silicon wafers via magnetorheological finishing to a flatness below 100 nm peak-to-valley, allowing for sub-arcsecond reflection optics.

XEUS is a single focus X-ray telescope which will provide a collecting area of 10-20 m² at 1 keV with angular resolution 2-5 arc seconds. Such a large area can be achieved with low mass using pore optics manufactured from silicon. A high resolution X-ray spectrometer which can exploit this enormous collecting area to the full is difficult to construct. Non-dispersive devices are limited by solid state device technology and objective grating spectrometers require a very large number of massive high quality gratings. We describe an alternative focal plane grating spectrometer which employs relatively few plane reflection gratings and focusing MCP square pore optics to utilize a large fraction of the full aperture from the primary mirror.

Efficiency measurements of a grazing-incidence diffraction grating, planned for the Constellation-X Reflection Grating Spectrometer (RGS), were performed using polarized synchrotron radiation at the NRL Brookhaven beamline X24C. The off-plane TM and TE efficiencies of the 5000 groove/mm MIT test grating, patterned on a silicon wafer, were measured and compared to the efficiencies calculated using the PCGRATE-SX code. The calculated and measured efficiencies are in agreement when using groove profiles derived from AFM measurements. The TM and TE efficiencies differ, offering the possibility of performing unique astrophysical science studies by exploiting the polarization sensitivity of the off-plane gratings. The grating calibrations demonstrate the importance of using polarized synchrotron radiation and code calculations for the understanding of the Constellation-X grating performance, in particular the effects of the groove profile and microroughness on the efficiency. The optimization of grazing incidence gratings, for both the off-plane and in-plane mounts, planned for the RGS and x-ray spectrometers on other missions will require detailed synchrotron measurements and code calculations.

The validity of approximating the efficiency of a multilayer grating operating at close to normal incidence in the soft-X-ray-EUV range with a product of the relative grating efficiency by the reflectance of its multilayer coating has been studied by the rigorous integral method. The widely used approximated approach has until recently been considered accurate enough for analysis of short-wavelength normal-incidence multilayer-coated gratings. Real gratings employed in the soft-X-ray-EUV range are used to demonstrate the inapplicability of this approximation to an analysis of precise positions of efficiency maxima for the external (n > 0) and internal (n < 0) diffraction orders, despite the small ratios of wavelength and groove depth to period. The present authors have performed an analysis of the accuracy inherent in a derived simple expression for spectral separation of the same plus and minus orders with respect to the wavelength, order's number, incident angle, period, and groove depth. The reason for the observed substantial (a few Angstrom or even nm) wavelength separation between the maxima of positive and negative orders is related to oblique, close-tonormal incidence of radiation on a grating operating in the short-wavelength spectral region and different angles of deviation of respective orders. The modeling carried out with the commercial code PCGrate-S(X) v.6.1 permitted not only prediction of the separation between positive and negative orders for a multilayer Mo/Si 4200-gr/mm grating with FM-measured trapezoidal groove profile, which is designed for operation in the EIS spectrometer on the Solar-B spacecraft, but obtaining a good agreement with synchrotron radiation measurements, including high orders as well. A conclusion is drawn that high-precision calculations of the efficiency of multilayer normal-incidence soft-X-ray-EUV range gratings have in some cases to be performed, although this may require increasing the computation time by several times compared to the commonly used approximate approach.

The brightness distribution of specularly reflected and diffusely scattered rays off an X-ray mirror illuminated under grazing incidence is determined by the mirror surface topography. An attempt is made to cover the full range of random surface roughness which runs from microscopic to macroscopic imperfections, for which currently available scattering theories cannot be used. In a new attempt the size of geometric slope errors and diffraction angles of a 1-D profile are compared, spatial frequency component by spatial frequency component of the Fourier decomposed profile. By this approach the well known expression of the Rayleigh scattering factor could be derived though, for each component separately. Because of the different dependence of the relevant angles on spatial frequency a critical spatial frequency is found at which geometric optics and the diffraction regime separate. Furthermore, for frequencies greater than the intersection frequency the total microroughness is shown to be as low as to allow the application of the existing scattering theories in the smooth surface limit. At lower spatial frequencies geometric slope errors dominate.

The Solar-B X-ray telescope (XRT) is a grazing-incidence modified Wolter I X-ray telescope, of 35 cm inner diameter and 2.7 m focal length. XRT, designed for full sun imaging over the wavelength 6-60 Angstroms, will be the highest resolution solar X-Ray telescope ever flown. Images will be recorded by a 2048 X 2048 back-illuminated CCD with 13.5 μm pixels (1 arc-sec/pixel ) with full sun field of view. XRT will have a wide temperature sensitivity in order to observe and discriminate both the high (5-10 MK) and low temperature (1-5 MK) phenomena in the coronal plasma. This paper presents preliminary results of the XRT mirror calibration performed at the X-ray Calibration Facility, NASA-MSFC, Huntsville, Alabama during January and February 2005. We discuss the methods and the most significant results of the XRT mirror performance, namely: characteristics of the point response function (PSF), the encircled energy and the effective area. The mirror FWHM is 0.8" when corrected for 1-g, finite source distance, and CCD pixelization. With the above corrections the encircled energy at 27 μm and 1keV is 52%. The effective area is greater than 2cm² at 0.5keV and greater than 1.7cm² at 1.0keV.

This paper presents characterization of hard X-ray telescope using synchrotron facility, mainly on experimental setup, benefits of such experiment, and measurement results only available by means of bright synchrotron light. We have developed hard X-ray telescope consisting of Wolter-I grazing incidence optics with platinum-carbon multilayer supermirror surfaces. Telescopes have been fabricated for InFOCuS balloon experiment, and we achieved first scientific flight in 2004. The hard X-ray telescope on board InFOCuS has been characterized at synchrotron facility SPring-8/BL20B2, Japan. Measurement at BL20B2 has great advantages such as extremely high flux, large sized and less divergent beam, and monochromatic beam covering entire hard X-ray region from 8 to over 100keV. A 16m-long experiment hutch is another feature suitable for measurements of hard X-ray telescopes. The telescope was illuminated by monochromatic hard X-rays, and focused image was measured by high resolution hard X-ray imager. Whole telescope aperture was mapped by small beam, and effective area and point spread function are obtained as well as local optical properties for further diagnostics of telescope characteristics.

Since 1993, research in the fabrication of extreme ultraviolet (EUV) optical imaging systems, conducted at Lawrence Berkeley National Laboratory (LBNL) and Lawrence Livermore National Laboratory (LLNL), has produced the highest resolution optical systems ever made. We have pioneered the development of ultra-high-accuracy optical testing and alignment methods, working at extreme ultraviolet wavelengths, and pushing wavefront-measuring interferometry into the 2-20-nm wavelength range (60-600 eV). These coherent measurement techniques, including lateral shearing interferometry and phase-shifting point-diffraction interferometry (PS/PDI) have achieved RMS wavefront measurement accuracies of 0.5-1-Å and better for primary aberration terms, enabling the creation of diffraction-limited EUV optics. The measurement accuracy is established using careful null-testing procedures, and has been verified repeatedly through high-resolution imaging. We believe these methods are broadly applicable to the advancement of short-wavelength optical systems including space telescopes, microscope objectives, projection lenses, synchrotron beamline optics, diffractive and holographic optics, and more. Measurements have been performed on a tunable undulator beamline at LBNL's Advanced Light Source (ALS), optimized for high coherent flux; although many of these techniques should be adaptable to alternative ultraviolet, EUV, and soft x-ray light sources. To date, we have measured nine prototype all-reflective EUV optical systems with NA values between 0.08 and 0.30 (f/6.25 to f/1.67). These projection-imaging lenses were created for the semiconductor industry's advanced research in EUV photolithography, a technology slated for introduction in 2009-13. This paper reviews the methods used and our program's accomplishments to date.

XEUS is a single focus X-ray telescope which will provide a collecting area of 10-20 m² at 1 keV with angular resolution 2-5 arc seconds. Such a large area can be achieved with low mass using pore optics manufactured from silicon. The aperture utilisation of the pore optics is ~ 0:5 and with an aperture diameter of 7 m and gold reflecting surfaces the effective area can be 14 m² at 1 keV and 1.5 m² at 8 keV, providing it is possible to launch the required mass. Diffraction imposes a limit on the angular resolution that can be obtained with pore optics. If the focal length is 30 m then the angular resolution limit would be ~ 1 arc second but the pore size must be 0.2 mm. If the pore size is limited by manufacturing to 0.6 mm then the goal of 2 arc seconds half energy width will require a focal length ≥ 40 m. The hard X-ray response can be extended using multilayer coatings on the innermost shells giving ~ 1270 cm² effective area at 40 keV for an increase in Si mass of ~ 96 kg.

The DIOS, Diffuse Intergalactic Oxygen Surveyor mission, is planned to observe diffuse soft X-rays, which might originate from warm-hot intergalactic medium as a target of missing baryon and as a probe of dark matter. To observe very weak diffuse soft X-rays, the FXT, four-stage X- ray telescope, is specially designed to have wide field of view and large effective area for the small satellite DIOS. It is confirmed that FXT meets basic requirements of the DIOS mission based on the ray tracing analysis. Al-foil based epoxy replication method is applied to the fabrication of element mirror of the FXT. Several tens of foil mirrors were fabricated and measured their performance. Mirror material combination was also reviewed from the view point of line observation other than oxygen.

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.

The 10-100 keV region of the electromagnetic spectrum contains the potential for a dramatic improvement in our understanding of a number of key problems in high energy astrophysics. A deep inspection of the universe in this band is on the other hand still lacking because of the demanding sensitivity (fraction of μCrab in the 20-40 keV for 1 Ms integration time) and imaging (≈ 15" angular resolution) requirements. The mission ideas currently being proposed are based on long focal length, grazing incidence, multi-layer optics, coupled with focal plane detectors with few hundreds μm spatial resolution capability. The required large focal lengths, ranging between 8 and 50 m, can be realized by means of extendable optical benches (as foreseen e.g. for the HEXITSAT, NEXT and NuSTAR missions) or formation flight scenarios (e.g. Simbol-X and XEUS). While the final telescope design will require a detailed trade-off analysis between all the relevant parameters (focal length, plate scale value, angular resolution, field of view, detector size, and sensitivity degradation due to detector dead area and telescope vignetting), extreme attention must be dedicated to the background minimization. In this respect, key issues are represented by the passive baffling system, which in case of large focal lengths requires particular design assessments, and by the active/passive shielding geometries and materials. In this work, the result of a study of the expected background for a hard X-ray telescope is presented, and its implication on the required sensitivity, together with the possible implementation design concepts for active and passive shielding in the framework of future satellite missions, are discussed.

While investigating the feasibility of the accommodation of X-ray instrumentations on the International Space Station (ISS) a major question remained still open, i.e. the unknown extent of degradation of X-ray mirror surfaces and X-ray detector material caused by contamination in the ISS environment. Therefore, a sample expose experiment has been started in 2001 to investigate these effects in detail using the Russian expose facility provided by the Russian space industry company RKK Energia. While Kayser-Threde GmbH was responsible to organize and coordinate the experiment, gold-coated Zerodur and silicon samples have been provided by the Max-Planck-Institute (MPE). In total 5 samples were flown with the expose facility and have been exposed to the ISS environment for a total duration of 756 days. The analyses of 4 of them are presented in this paper. X-ray reflection measurements before and after the experiment at MPE's PANTER X-ray test facility and microscopy inspections revealed a thin structured surface layer which reduced the X-ray reflection of the exposed mirror samples dramatically. In addition, the samples have been analyzed with a scanning electron microscope, an energy dispersive X-ray spectrometer, and electron spectroscopy for chemical analysis. The results of all these measurements revealing the degradation of the X-ray mirrors and polished silicon detector surfaces are presented.

We propose an all-sky-survey at hard X-ray region (up to 80 keV) by using a formation flight of two satellites. They consist of a telescope satellite, carrying a super mirror focusing at hard X-ray region, and a detector satellite, carrying scintillator deposited CCDs (SDCCDs) for hard X-ray region. These two satellites are in the same orbit (altitude is about 500 km) in formation flight. Since the super mirror will be a thin-foil mirror with poor imaging capability. Therefore, they control the separation of 20m±10 cm. Both satellites are in Keplerian orbit, then the viewing direction (from the detector satellite to the telescope satellite) scans along a large circle. Due to the precession of the orbit, the large circle gradually moves in the sky so that we can cover a large fraction of the sky. We can cover a large fraction of the sky without consuming a lot of fuel. However, the unseen regions are left near the ecliptic poles. This project, Formation Flight All Sky Telescope (FFAST), will be the first all sky survey at hard X-ray region.

SIMBOL-X is a hard X-ray mission, operating in the ~ 0.5-70 keV range, which is proposed by a consortium of European laboratories in response to the 2004 call for ideas of CNES for a scientific mission to be flown on a formation flying demonstrator. Relying on two spacecrafts in a formation flying configuration, SIMBOL-X uses for the first time a ~ 30 m focal length X-ray mirror to focus X-rays with energy above 10 keV, resulting in a two orders of magnitude improvement in angular resolution and sensitivity in the hard X-ray range with respect to non focusing techniques. The SIMBOL-X revolutionary instrumental capabilities will allow to elucidate outstanding questions in high energy astrophysics, related in particular to the physics of accretion onto compact objects, to the acceleration of particles to the highest energies, and to the nature of the Cosmic X-Ray background. The mission, which has gone through a thorough assessment study performed by CNES, is expected to start a competitive phase A in autumn 2005, leading to a flight decision at the end of 2006, for a launch in 2012. The mission science objectives, the current status of the instrumentation and mission design, as well as potential trade-offs are presented in this paper.

The development of hard X-ray focusing optics for astrophysical observation is widely recognized as one of key technologies for future X-ray satellite missions. Utilizing InFOCμS balloon-borne experiment, we have developed thin-foil-nested hard X-ray telescope employing depth-graded Pt/C multilayer. Pre-flight calibration of the hard X-ray telescope for the 2004 flight was performed at X-ray beamline facilities in ISAS/JAXA and SPring-8. The effective area and image quality were estimated to be 51 cm² and 2.4 arcmin (half power diameter) at 30 keV, respectively. Limiting factors of its performance also investigated. And we revealed that the main factor was image degradation of an individual reflector. Based on such an investigation we are now continuously developing advanced hard X-ray telescope for future balloon experiments. From evaluation of upgraded test telescope, we get a response toward high resolution telescope in future years.

As technological and scientific path-finder towards future observatory missions, a balloon-born hard X-ray imaging observation experiment InFOCμS has been developed. The payload has flown four times since 2000. In its 2004 Fall flight campaign InFOCμS successfully achieved first scientific observations of multiple astronomical objects from galactic compacts to cluster of galaxies. Significant signal has been detected from bright galactic objects while analysis of extragalactic objects is underway. InFOCμS plans additional and upgraded telescope-detector system as early as 2006. High energy telescope for nuclear gamma-ray line observations is under planning.

The Constellation-X (Con-X) mission planned for launch in 2015, will feature an array of Hard X-ray telescopes (HXT) with a total collecting area greater than 1500 cm² at 40 keV. Two technologies are being investigated for the optics of these telescopes, including multilayer coated Electroformed-Nickel-Replicated (ENR) shells. The attraction of the ENR process is that the resulting full-shell optics are inherently stable and offer the prospect of better angular resolution which results in lower background and higher instrument sensitivity. We are building a prototype HXT mirror module using an ENR process to fabricate the individual shells. This prototype consists of 5 shells with diameters ranging from 150 mm to 280 mm with a length of 426 mm. The innermost of these will be coated with iridium, while the remainder will be coated with graded d-spaced W/Si multilayers. Parts I and II of this work were presented at the SPIE meetings in 2003 and 2004. This paper presents a progress update and focuses on accomplishments during this past year. In particular, we will present results from full illumination X-ray tests of multilayer coated shells, taken at the MPE-Panter X-ray facility.

We are developing grazing incidence x-ray imaging optics for a balloon-borne hard x-ray telescope (HERO). The HERO payload, scheduled for launch in May 2006, consists of 8 mirror modules with 12 mirror shells each fabricated using electroform-nickel replication off super polished cylindrical mandrels. An optical system for alignment and assembly of the shells into their modules will be described together with an assessment of the systematic errors associated with this process. Full details of the assembly procedures and results of the on-ground x-ray testing of the HERO modules will be provided.

The Constellation-X Spectroscopy X-ray Telescope (SXT) is a large diameter, high throughput, grazing incidence imaging mirror system, designed to perform high sensitivity spectroscopy of cosmic X-ray sources in the 0.2-10.0 keV band. The baseline effective area requirement is ~3 m² at 1 keV. The system-level angular-resolution requirement is a 15-arcseconds half-power diameter, with a 5-arcsecond goal. The effective area is attained through a modular design, involving the nesting of many confocal, thin-walled Wolter I mirror segments. Considerable progress has been made in developing thin, thermally formed, glass mirror substrates that meet or better the angular-resolution requirement. Several approaches to mounting and aligning reflector segments into a mirror system are under investigation. We report here on the progress of the SXT technology development program toward reaching the performance goals.

The Constellation-X mission's Spectroscopic X-Ray Telescopes (SXT) require an angular resolution of 15" half-power diameter (HPD) with extremely lightweight grazing incidence mirrors. The areal density of the mirror must be about 1 kg/m² or less. In comparison with the state of the art X-ray mirrors represented by the XMM/Newton telescopes, this is approximately an order of magnitude less in mass areal density while maintaining the same angular resolution. We use a precision glass forming technique to fabricate mirrors that are 0.4mm thick and optical metrology to demonstrate that these mirrors can meet the stringent figure and micro-roughness requirements of the Constellation-X mission. We expect in the next few years to significantly improve the production yield and mirror quality to meet the goal of the mission, which is 5" HPD for two reflections at the same mass.

Future X-ray missions are aiming at large mirror collecting areas of the order of several square meters. This is obtained with mirror assemblies composed of a large number of segments. The angular resolution of each one must be measured separately down to 1 arcsec. The mass limits imposed by the launchers require low weight and high stiffness materials. In this context we have focused our recent studies on the manufacturing of thin glass mirror segments. These mirrors are made from sheet glass which can be shaped in a high-precision slumping process to e.g. a Wolter-I figure. The excellent surface roughness of the sheet glass chosen is conserved during the slumping process and the final figure corrections with non-contacting tools. The influence of several parameters of the process, such as glass and mould material, heating and cooling, has been measured and controlled with adequate metrology. In this paper we describe our current efforts which are aiming at the production of a Wolter-I scaled demonstration model - preferentially with parabola and hyperbola in one piece - made of thin sheet glass.

The Nuclear Spectroscopic Telescope Array (NuSTAR) is a small explorer (SMEX) mission currently under an extended Phase A study by NASA. NuSTAR will be the first satellite mission to employ focusing optics in the hard X-ray band (8-80 keV). Its design eliminates high detector backgrounds, allows true imaging, and permits the use of compact high performance detectors. The result: a combination of clarity, sensitivity, and spectral resolution surpassing the largest observatories that have operated in this band by orders of magnitude. We present an overview of the NuSTAR optics design and production process. We also describe the progress of several components of our independent optics development program that are beginning to reach maturity and could possibly be incorporated into the NuSTAR production scheme. We then present environmental test results that are being conducted in preparation of full space qualification of the NuSTAR optics.

The future large space X-ray telescopes in study (such as the ESAs XEUS) require novel approaches and innovative lightweight technologies. Although there are several alternative possibilities, in general the shaped thin glass foils and shaped Si wafers are considered to belong to the most promising ones. We present and discuss the recent progress in these technologies, as well as properties of test mirrors produced and tested. For both technologies, both flat and curved samples have been produced and tested. The achieved profile accuracy is of order of 1 micrometer or better, while the bending technologies maintain the intrinsic fine surface microroughness of substrates (better than 0.5 nm).

The X-ray telescope forms the core of the high energy astrophysics observatory XEUS, currently under study at ESA as a well positioned candidate for its Cosmic Visions 1525 Science Programme, which is presently under formulation. The science requirements of XEUS are particularly demanding, combining a large effective area (10m² at 1 keV), moderate angular resolution (5" requirement, with a goal of 2"), and a low mass for the optics system. The preferred operational orbit for XEUS is a halo orbit around the Lagrangian Point 2 (L2). Background and costing considerations led to the requirement of a single focal plane location, which in combination with the required broad energy response function, in turn requires a focal length of 50m. The mission design is based on formation flying, with the Mirror Spacecraft (MSC) flying inertially, and the Detector Spacecraft (DSC) actively following the focal point. The ambitious XEUS telescope relies on the novel X-ray technology currently under development in Europe. The X-ray optics technology development activities and status as well as the telescope design in general are addressed.

The next generation astronomical X-ray telescopes (such as the X-ray Evolving Universe Spectroscopy mission XEUS) require extremely large collecting areas (effective area of ~10 m² at 1 keV) in combination with good angular resolution of ~5" or better. The existing technologies such as polished glass and nickel electroforming would lead to excessively heavy and expensive optics, and/or are not able to produce the required large area. We have developed an entirely novel technology for producing X-ray optics which results in very light, stiff and modular optics. These can be assembled into almost arbitrarily large apertures and are perfectly suited for future astrophysics missions such as XEUS. Indeed this crucial technology ensures that the ambitious mission profile is actually feasible. The technology makes use of commercially available silicon wafers from the semiconductor industry. The latest generation of 12 inch silicon wafers have a surface roughness that is sufficiently low (~0.3 nm) for X-ray reflection, almost perfect mechanical properties and are considerably cheaper than other high-quality optical materials. The wafers are bent into an accurate cone and assembled to form a stiff pore structure. The resulting light and stiff modules, which we term a High-performance Pore Optics (HPO), form a small segment of a Wolter-I optic, and are easily assembled into a modular optic with large collecting area. We have implemented an automated production process of HPOs on laboratory scale and describe facilities developed with ESA at the Cosine Research Centre. We present the status of the production and the results obtained with this highly innovative technology.

With Photonis and cosine Research BV, ESA has been developing and testing micro pore optics for x-ray imaging. Applications of the technology are foreseen to reduce mass and volume in, for example, a planetary x-ray imager, x-ray timing observatory or high-energy astrophysics. Photonis, a world leader in the design and development of micro pore optics, have developed a technique for manufacturing square channel pores formed from extruded glass fibres. Single square fibres, formed with soluble glass cores, are stacked into a former and redrawn to form multifibres of the required dimension. Radial sectors of an optic are then cut from a block formed by stacking multifibres and fusing them to form a monolithic glass structure. Sectors can be sliced, polished, etched and slumped to form the segment of an optic with specific radius. Two of these sectors will be mounted to form, for example, a Wolter I optic configuration. To improve reflectivity of the channel surfaces coating techniques have also been considered. The results of x-ray tests performed by ESA and cosine Research, using the BESSY-II synchrotron facility four-crystal monochromator beamline of the Physikalisch-Technische Bundesanstalt (PTB), on multi-fibres, sectors and slumped sectors will be discussed in this paper. Test measurements determine the x-ray transmission and focussing characteristics as they relate to the overall transmission, x-ray reflectivity of the channel walls, radial alignment of the fibres, slumping radius and fibre position in a fused block. The multifibres and sectors have also been inspected under microscope and Scanning electron Microscope (SEM) to inspect the channel walls and determine the improvements made in fibre stacking.

Square pore optics offer a very low mass solution for X-ray mirrors in the X-ray spectrometer on Bepi-Columbo. We describe several square pore packing schemes which could be used and determine the optimum configuration.

Development of a new light-weight and low-cost micro pore optics is reported. Utilizing anisotropic chemical wet etching of MEMS (Micro Electro Mechanical System) technology, a number of smooth sidewalls are obtained at once. These sidewalls are potential X-ray mirrors. As a first step of R&D, basic characters of sidewalls such as surface roughness and X-ray reflectivity are experimentally studied. Rms-roughness of 10 ~ 20Å is confirmed in a KOH-etched wafer. Furthermore, the X-ray reflection is for the first time detected at Mg Kα 1.25 keV. Based on the obtained results, numerical simulations of four-stage MEMS X-ray optics are performed for future satellite mission.

EXIST is being studied as the Black Hole Finder Probe, one of the 3 Einstein Probe missions under NASA's Beyond Einstein program. The major science goals for EXIST include highly sensitive full-sky hard X-ray survey in a very wide energy band of 5 - 600 keV. The scientific requirements of wide energy band (10-600 keV for the High Energy Telescope considered for EXIST) and large field of view (approximately 130° × 60° in the current design, incorporating an array of 18 contiguous very large area coded aperture telescopes) presents significant imaging challenges. The requirement of achieving high imaging sensitivity puts stringent limits on the uniformity and knowledge of systematics for the detector plane. In order to accomplish the ambitious scientific requirements of EXIST, it is necessary to implement many novel techniques. Here we present the initial results of our extensive Monte-Carlo simulations of coded mask imaging for EXIST to estimate the performance degradation due to various factors affecting the imaging such as the non-ideal detector plane and bright partially coded sources.

A Laue lens for focusing X-ray photons with energies above 60 keV for astrophysical applications is being developed. The lens is based on mosaic crystals of Cu (111) produced at the Institute Laue-Langevin. A feasibility study has allowed to establish lens geometry and crystal properties required. The test of the crystals has provided very satisfactory results. We are now developing a Demonstration Model (DM) of the lens in order to establish the best assembling technique of the crystals. We will discuss the status of the project and its prospects.

A focusing gamma-ray telescope based upon perfect crystals was originally proposed for astrophysical observations in 1990s. However, the high angular resolution/low integral reflectivity of the perfect crystals employed made these types of optics less attractive for astrophysics than grazing incidence multilayer mirrors. Unlike astrophysical applications, the long-range detection of nuclear materials requires modest angular resolution and narrow energy bandwidth (or several narrow bands) at specific gamma-lines emitted from nuclear materials. A development of large high gamma-reflective Ge and Si mosaic crystals makes the use of a diffraction mosaic gamma-telescope for long-distance detection of nuclear materials, as well as for astrophysics, a distinct possibility. This paper describes gammareflectivity results for Ge mosaic crystals in the range of 100-300 keV and a gamma-ray focusing telescope design based on the Ge and Si mosaic crystals with mosaicity in range of 1-15 arc minutes both for long-range detection of nuclear materials and astrophysics.

The 0.5 arcsec angular resolution of the Chandra X-Ray Observatory is likely to be the best that a grazing incidence telescope with substantial collecting area will ever attain. We describe a concept for a telescope composed of diffractive and refractive components that transmit rather than reflect X-rays. Therefore, its angular resolution would be relatively insensitive to figure errors and surface roughness. With appropriately selected values for the two focal lengths the chromatic aberration that is inherent in both the diffractive and refractive components individually would compensate each other within a limited but not insignificant energy band. The system has a focal length of about 10⁴ km because the refractive component is rather weak. The long focal length requires a very demanding type of formation flying between an optics spacecraft and a detector spacecraft. We simulate the simplest diffractive/refractive imaging system where chromatic aberration is corrected to first order at 6 keV. The angular resolution is expected to be better than a miliarcsec within a 10 % bandwidth. The energy band could be broadened either by employing an array of smaller systems with the same total area or by modifying the diffractive component in situ. The components are lightweight, not difficult to fabricate and can probably be made in a machine shop. We also consider possible sites for the system.

We are developing a soft x-ray telescope with an adaptive optics system for future astronomical observation with very fine angular resolution of an order of milli-arc-second. From a technical point of view, we are trying to develop a normal incident telescope with multi layers. Thus the wave length is limited to be around 13.5 nm with a band pass of roughly 1nm. Since the x-ray telescope must be installed on a satellite, a stable conditions of temperature, gravity etc, can not be expected. Therefore, we investigate to use an adaptive optics system using an optical light source attached in the telescope. In this paper, we report our present status of the development. The primary mirror is an off-axis paraboloid with 80 mm effective diameter and 2 m focal length. This mirror has been coated with Mo/Si multi-layers. The reflectivity of the 13.5 nm x rays is ranging from 35% to 55%. We use a deformable mirror for the secondary mirror, which has also been coated with Mo/Si multi-layers. This mirror consists of 31 element-bimorph-piezo electrodes. The surface roughness of the mirror is ~6 nm rms. The reflectivity of the 13.5 nm x rays is roughly 65%. The adaptive optics system using an optical laser and a wave front sensor has been performed. We are using a shack-hartmann sensor (HASO 32) with a micro-lens array and a CCD. A pin hole with one micron diameter is used for the optical light source. The precision of the measurement of the wave front shape is a few nm. X-ray exposure test is now conducting, although the optical adaptive optics system is not yet installed. The x-ray detector is a back illumination CCD. The quantum efficiency for 13.5 nm x ray is ~50%. The pixel size is 24 micron square. X-ray source is an electron impact source with an Al/Si alloy target. We confirmed that the x-ray intensity around 13.55 nm is bright enough for our experiment. The imaging performance is now trying to improve and the adaptive optics system will be installed in this year.

A multilayer coating mirror of Mo/Si is usually integrated into an EUV optics for space science, especially for He-II (30.4 nm) radiation, because it is highly stable under vacuum and atmosphere and achieves the fairly high reflectance of 15-20%. But space science community needs the coating of higher reflectance at 30.4 nm radiation for the future satellite missions. In this work, to develop a new multilayer mirror of He-II radiation, we report the design of a multilayer consisting of a pair of Mg and SiC, and its production, and aging change of the reflectance under the atmosphere and vacuum circumstance.

We present progress in the development of a new sounding rocket payload that will perform high resolution (R~100) x-ray spectroscopy of diffuse celestial x-ray sources. The instrument features a new geometry that allows for high resolution along with high throughput. A wire-grid collimator constrains light from diffuse sources into a converging beam that feeds an array of diffraction gratings in the extreme off-plane mount. Starting with launch in 2006 we can obtain physical diagnostics of supernova remnants such as the Cygnus Loop and ultimately the hot phase of the interstellar medium.

This paper presents an error budget for the imaging performance of the Generation X telescope. This budget is used to inform the selection of the intrinsic imaging performance of the mirror modules. This calculation is done by forming a budget of top level claims to imaging performance and calculating the intrinsic optic performance, α, needed to meet the top level goal with some margin and contingency. This intrinsic optical performance is quantified by the image half-power diameter of a point source. Different values of telescope misalignment and necessary top level imaging performance is used in a Monte Carlo calculation to determine the imaging half power and the resultant optic performance.

We designed a refractive null lens for (visible) optical testing of the segmented mirrors for the Constellation-X spectroscopy x-ray telescope. We explored two solution families and identified the trade-offs. We also present some initial results of the realization of one solution family.

We are studying on a press forming of a 0.3-mm-thick foil in order to make advanced thin-foil substrates with a two-stage reflector for large X-ray telescopes. Aluminum alloy has been used as a material for thin-foil substrates. We propose a use of Mg foil as lightweight substrates, since more lightweight material is necessary for building the large telescopes. Furthermore, we are making a two-stage reflector with a stage 200 mm long, since a long substrate has an advantage for fabrication of large X-ray telescopes. After various experiments, we formed a Mg foil with a figure error of +/-20 μm. This large figure error can be removed by a replication method. We also made an evaluation system of an image quality by using a Newtonian telescope. The evaluation system can generate a collimated optical light with a diameter of 450 mm and with a parallelism of about 4". Using this system, we found that an image quality of our Mg foil was similar to that of the ASCA foils.

Generation-X is a Vision Mission for a future x-ray observatory. It is to have an effective area of 150 m² at 1 keV, a resolution of ~0.1 arc seconds and the goal of probing the universe from redshifts of 5 to 10. Fabrication of the telescope is quite challenging and the best approach is unclear. We report our study of the use of Kirkpatrick-Baez telescopes applied to Gen-X. Such systems can be manufactured relatively inexpensively using simple flat mirrors. Huge effective areas can be obtained without the need for complicated deployable optics. In this study we found that Kirkpatrick-Baez optics provide an attractive and feasible approach to fabrication. The trade off is a 5km focal length.

An X-ray interferometer can be realised using a simple geometric arrangement of flat grazing incidence mirrors and a slatted grazing incidence mirror. This optical design has the advantage that large baseline separations ~ 1m can be accomodated within an envelope 2m by 20m. Operating at 1 keV such a device could provide angular resolutions of 100 micro arc seconds with a collecting area large enough to allow imaging of many potential astronomical targets. We describe the construction of an Optical Demonstration Model, working in the visible band, used as a proof of concept for the proposed scheme.