This PDF file contains the front matter associated with SPIE Proceedings Volume 8147, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

ASTRO-H is an astrophysics satellite dedicated for X-ray spectroscopic study non-dispersively and to carry out survey complementally, which will be borne out of US-Japanese collaborative effort. Among the onboard instruments there are four conically approximated Wolter-I X-ray mirrors, among which two of them are soft X-ray mirrors1, of which the energy range is from a few hundred eV to 15 keV, currently being fabricated in the X-ray Optics Lab at Goddard Space Flight Center. The focal point instruments will be a calorimeter (SXS) and a CCD camera (SXI), respectively. The reflectors of the mirror are made of heat-formed aluminum substrate of the thickness gauged of 152 μm, 229 μm, and 305 μm of the alloy 5052 H-19, followed by epoxy replication on gold-sputtered smooth Pyrex cylindrical mandrels to acquire the X-ray reflective surface. The epoxy layer is 10 μm nominal and surface gold layer of 0.2 μm. Improvements on angular response over the Astro-E1/Suzaku mirrors come from error reduction on the figure, the roundness, and the grazing angle/radius mismatching of the reflecting surface, and tighter specs and mechanical strength on supporting structure to reduce the reflector positioning and the assembly errors. In this paper, we report the results of calibration of the engineering model of SXT (EM), and project the quality of the flight mirrors.

Japan's sixth X-ray satellite mission ASTRO-H is planned to be launched in 2014. Hard X-ray Telescope (HXT) to cover hard X-rays up to 80 keV is thin-foil, multi-nested conical optics with depth-graded Pt/C multilayer. The mass production of the reflectors for the flight model has been going on since August 2010. We have introduced a new screening method for replication mandrels with optical imagers. In addition, we have adopted a new replication mandrel which consists of glass tube coated with thin glass sheet for large size mandrels. The selected 212 pairs (95 pairs (segment 1), 59 pairs (segment 2), 58 pairs (segment 3)) of multilayer mirror have been characterized at a large synchrotron radiation facility, Spring-8 beamline BL20B2. We present the current status of reflector production and hard X-ray characterization for HXT.

ASTRO-H is a general purpose X-ray observatory scheduled for launch in 2014. Two soft X-ray telescopes (SXT) and two hard X-ray telescopes (HXT) will be onboard covering energy range of 0.2 -80 keV. Thermal control of the telescope is similar to that of Suzaku, using a thermal shield (TS) placed in front of the telescope and a electric heater attached on the telescope housing. Thus it is required for a TS to have high soft X-ray transmission, low solar absorptance and a low infrared emissivity. To meet these requirement, TS should be made of thin plastic film coated by metal such as aluminum. Then most important property of TS is mechanical strength to survive various environments at the launch and in orbit. This paper describes designing of TS, method of TS production, various environmental conditions and tests, risk management of treatment of ultra-thin film of TS in the process of production, testing and assembling.

The Focusing Optics x-ray Solar Imager (FOXSI) is a sounding rocket payload funded under the NASA Low Cost Access to Space program to test hard x-ray (HXR) focusing optics and position-sensitive solid state detectors for solar observations. Today's leading solar HXR instrument, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) provides excellent spatial (2 arcseconds) and spectral (1 keV) resolution. Yet, due to its use of an indirect imaging system, the derived images have a low dynamic range (typically <10) and sensitivity. These limitations make it difficult to study faint x-ray sources in the solar corona which are crucial for understanding the particle acceleration processes which occur there. Grazing-incidence x-ray focusing optics combined with position-sensitive solid state detectors can overcome both of these limitations enabling the next breakthrough in understanding impulsive energy release on the Sun. The FOXSI project is led by the Space Sciences Laboratory at the University of California, Berkeley. The NASA Marshall Space Flight Center is responsible for the grazingincidence optics, while the Astro-H team at JAXA/ISAS has provided double-sided silicon strip detectors. FOXSI is a pathfinder for the next generation of solar hard x-ray spectroscopic imagers. Such observatories will be able to image the non-thermal electrons within the solar flare acceleration region, trace their paths through the corona, and provide essential quantitative measurements such as energy spectra, density, and energy content in accelerated electrons.

Spectrum Roentgen Gamma (SRG) is an X-ray astrophysical observatory, developed by Russia in collaboration with Germany. The mission will be launched in 2013 from Baikonur, by a Zenit rocket with a Fregat booster and placed in a 6-month-period halo orbit around L2. The scientific payload consists of two independent telescopes - a soft-x-ray survey instrument, eROSITA, being provided by Germany and a medium-x-ray-energy survey instrument ART-XC being developed by Russia. ART-XC will consist of seven independent, but co-aligned, telescope modules with seven corresponding cadmiumtelluride focal plane detectors. Each will operate over the approximate energy range of 6-30 keV, with an angular resolution of 1 arcmin, a field of view of ~30 arcmin and an energy resolution about 10% at 14 keV. The NASA Marshall Space Flight Center (MSFC) will fabricate some of the mirror modules, to complement others fabricated by VNIIEF in Russia.

Focusing mirrors manufactured via a galvanic replication process from negative shape mandrels is the chosen solution for the eROSITA X-ray mission. Media Lario Technologies (MLT) is the industrial enabler for manufacturing (in collaboration with the Max Planck Institute (MPE) and the German Space Agency (DLR)) of the Optical Payload for eROSITA - including the flight quality mandrels. Mandrels manufacturing holds a crucial role in the process of fabrication of the optics. In fact, the shape accuracy and the roughness of the replicated mirrors are strongly affected by the starting quality of the mandrel. For the e-ROSITA mandrel production an evolution of the approach used for the manufacturing of past mission mandrels (JET-X, XMM) have been developed. The low energy angular resolution of the eROSITA mirror payload needs to be 15 arcsec HEW or better; and at 8.05keV the angular resolution needs to be 20 arcsec HEW or better. Replicated mirrors with performance in this range for the low energy radiation have been obtained in the past by using mandrels that have superior geometrical shape accuracy. A proprietary multistep surface finishing process has now been developed for reaching the aggressive performance requirements demanded by the mission. The status and the metrology of the eROSITA series mandrels manufactured so far, by using the advanced polishing process, are presented. In the paper, the x-ray performance of mirror shells (as measured at MPE PANTER facility) replicated from a flight quality eROSITA mandrel, are reported.

MPE will provide the X-ray Survey Telescope eROSITA for the Russian Spektrum-Roentgen-Gamma Mission to be launched in 2013. It consists of a compact bundle of 7 co-aligned mirror modules with a focal length of 1600 mm and 54 nested mirror shells each. Therefore, its sensitivity in terms of effective area, field-of-view (61'), and angular resolution (15" HEW on-axis) will yield a high grasp of about 1000 cm² deg² around 1 keV with an average angular resolution of ~26" HEW over the field-of-view (30" including optical and spacecraft error contributions). After an extended test program on single mirror shells, assembled test modules (6 shells) and a qualification model we have now started integration of flight mirror modules. We give a résumé on the development and test program including key improvements to the shell integration method. Moreover, we report on the integration progress and present first results on the X-ray performance of partially integrated mirror modules.

The New Hard X-ray Mission (NHXM) is a space X-ray telescope project focused on the 0.2 to 80 keV energy band, coupled to good imaging, spectroscopic and polarimetry detectors. The mission is currently undergoing the Phase B study and it has been proposed to ESA as a small-size mission to be further studied in the context of the M3 call; even if the mission was not downselected for this call, its study is being continued by ASI. The required performance is reached with a focal length of 10 m and with four mirror modules, each of them composed of 70 NiCo electroformed mirror shells. The reflecting coating is a broadband graded multilayer film, and the focal plane is mounted onto an extensible bench. Three of the four modules are equipped with a camera made of two detectors positioned in series, a Silicon low energy detector covering the range 0.2 to 15 keV and a high energy detector based on CdTe sensitive from 10 keV up to 120 keV. The fourth module is dedicated to the polarimetry to be performed with enhanced imaging capabilities. In this paper the latest development in the design and manufacturing of the optics is presented. The design has been optimized in order to increase as much as possible the effective area in the high-energy band. The manufacturing of the mirror shells benefits from the latest development in the mandrel production (figuring and polishing), in the multilayer deposition and in the integration improvements.

The realization of X-ray telescopes with imaging capabilities in the hard (> 10 keV) X-ray band requires the adoption of optics with shallow (< 0.25 deg) grazing angles to enhance the reflectivity of reflective coatings. On the other hand, to obtain large collecting area, large mirror diameters (< 350 mm) are necessary. This implies that mirrors with focal lengths ≥10 m shall be produced and tested. Full-illumination tests of such mirrors are usually performed with onground X-ray facilities, aimed at measuring their effective area and the angular resolution; however, they in general suffer from effects of the finite distance of the X-ray source, e.g. a loss of effective area for double reflection. These effects increase with the focal length of the mirror under test; hence a "partial" full-illumination measurement might not be fully representative of the in-flight performances. Indeed, a pencil beam test can be adopted to overcome this shortcoming, because a sector at a time is exposed to the X-ray flux, and the compensation of the beam divergence is achieved by tilting the optic. In this work we present the result of a hard X-ray test campaign performed at the BL20B2 beamline of the SPring-8 synchrotron radiation facility, aimed at characterizing the Point Spread Function (PSF) of a multilayer-coated Wolter-I mirror shell manufactured by Nickel electroforming. The mirror shell is a demonstrator for the NHXM hard X-ray imaging telescope (0.3 - 80 keV), with a predicted HEW (Half Energy Width) close to 20 arcsec. We show some reconstructed PSFs at monochromatic X-ray energies of 15 to 63 keV, and compare them with the PSFs computed from post-campaign metrology data, self-consistently treating profile and roughness data by means of a method based on the Fresnel diffraction theory. The modeling matches the measured PSFs accurately.

In the case of neutrons the refractive index is slightly less than unity for most elements and their isotopes [1]. Consequently, thermal and cold neutrons can be reflected from smooth surfaces at grazing-incidence angles. Hence, the optical technologies developed for x-ray astronomy can be applied for neutron focusing. The focusing capabilities of grazing incidence neutron imaging optics have been successfully demonstrated using nickel mirrors. The mirrors were fabricated using an electroformed nickel replication process at Marshall Space Flight Center. Results of the neutron optics experiments and current status of the multilayer coating replication technique development are presented.

The International X-ray Observatory (IXO) is a candidate mission in the ESA Space Science Programme Cosmic Vision 1525, and was studied as a joint mission with NASA and JAXA. Considering the programmatic evolution of the international context, the mission is being reformulated as an ESA-led mission, under the name of ATHENA (Advanced Telescope for High Energy Astrophysics), with possible participation of NASA and JAXA. The mission is building on the novel Silicon Pore Optics (SPO) technology to achieve the required performance for this demanding astrophysics observatory. This technology is being developed by an industrial consortium, and involves also several research institutes [1-12]. A second optics technology, slumped glass optics (SGO), which is being developed in Europe and the USA, was the backup technology for IXO, and additionally work is progressing on improved reflective coatings and X-ray test facilities [13-17].

Silicon pore optics is a technology developed to enable future large area X-ray telescopes, such as the International X-ray Observatory (IXO) or the Advanced Telescope for High ENergy Astrophysics (ATHENA), an L-class candidate mission in the ESA Space Science Programme 'Cosmic Visions 2015-2025'. ATHENA/IXO use nested mirrors in Wolter-I configuration to focus grazing incidence X-ray photons on a detector plane. The x-ray optics will have to meet stringent performance requirements including an effective area of a few m² at 1.25 keV and angular resolution between 5(IXO) and 9(ATHENA) arc seconds. To achieve the collecting area requires a total polished mirror surface area close to 1000 m² with a surface roughness better than 0.5 nm rms. By using commercial high-quality 12" silicon wafers which are diced, structured, wedged, coated, bent and stacked, the stringent performance requirements can be met without any costly polishing steps. Two of such stacks are then assembled into a co-aligned mirror module, which is a complete X-ray imaging system. Included in the mirror module are the isostatic mounting points, providing a reliable interface to the telescope. Hundreds of such mirror modules are finally integrated into petals, and mounted onto the spacecraft to form an X-ray optic. In this paper we will present the silicon pore optics mass manufacturing process and latest X-ray test results.

Silicon Pore Optics (SPO) provide high angular resolution with low area density as required for the International X-ray Observatory (IXO) or the Advanced Telescope for High Energy Astrophysics (ATHENA). The baseline for both telescopes consists of populating the mirror assembly with hundreds of SPO mirror modules. During the development of the process steps of the SPO technology, specific requirements of a future mass production have been considered right from the beginning. The manufacturing methods heavily utilise off-the-shelf equipment from the semiconductor industry, robotic automation and parallel processing. This allows to upscale the present production flow in a cost effective way, to produce hundreds of mirror modules per year. Considering manufacturing predictions based on the current technology status, we present an analysis of the time and resources required for a future flight programme. This includes the full production process starting with Si wafers up to the integration of the mirror modules. We present the times required for the individual process steps and identify the equipment required to produce several mirror modules per day. A preliminary timeline for building and commissioning the required infrastructure, and for flight model production of about 500 (ATHENA) and 2000 (IXO) mirror modules, is presented.

The establishment of Silicon Pore Optics (SPO) as the technology of choice for the implementation of future large X-ray space optics has opened up the road to its use in all classes of X-ray missions with varying scientific goals. This interest has given us the possibility to broaden the design parameter space which is normally considered for SPO optics. In doing so a number of classical space X-ray optics design issues (e.g., field of view, stray light, baffling, aberrations) have been tackled. In this paper we report on recent results achieved in this effort. Particular attention will be given to the issues of stray light and baffling, a topic upon which a combination of analytical, simulation, and data analysis means can be effectively brought to bear. Missions considering the use of SPO optics have requirements spanning more than two orders of magnitude in energy, and a factor 20 in focal length. The possibilities that can be considered and the trade offs that must be made when applying SPO to such a wide range of optical designs will be illustrated, and some of the possible solutions discussed.

We describe the fabrication of the two NuSTAR flight optics modules. The NuSTAR optics modules are glass-graphiteepoxy composite structures to be employed for the first time in space-based X-ray optics by NuSTAR, a NASA Small Explorer schedule for launch in February 2012. We discuss the optics manufacturing process, the qualification and environmental testing performed, and briefly discuss the results of X-ray performance testing of the two modules. The integration and alignment of the completed flight optics modules into the NuSTAR instrument is described as are the optics module thermal shields.

The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing hard X-ray (5-80 keV ) telescope to orbit. The ground calibration of the three flight optics was carried out at the Rainwater Memorial Calibration Facility (RaMCaF) built for this purpose. In this article we present the facility and its use for the ground calibration of the three optics.

NuSTAR is a hard X-ray satellite experiment to be launched in 2012. Two optics with 10.15 m focal length focus Xrays with energies between 5 and 80 keV onto CdZnTe detectors located at the end of a deployable mast. The FM1 and FM2 flight optics were built at the same time based on the same design and with very similar components, and thus the performance of both is expected to be very similar. We provide an overview of calibration data that is being used to build an optics response model for each optic and describe initial results for energies above 10 keV from the ground calibration of the flight optics. From a preliminary analysis of the data, our current best determination of the overall HPD of both the FM1 and FM2 flight optics is 52", and nearly independent of energy. The statistical error is negligible, and a preliminary estimate of the systematic error is of order 4". The as-measured effective area and HPD meet the toplevel NuSTAR mission sensitivity requirements.

X-ray optics of both high angular resolution and light weight are essential for advancing x-ray astrophysics. High angular resolution is important for avoiding source confusion and reducing background, thus allowing observation of the most distant objects in the early Universe. It is also important in enabling gratings to achieve high spectral resolution, to study the myriad plasmas in planetary, stellar, and galactic environments, as well as inter-planetary, inter-stellar, and inter-galactic media. Light weight is essential for further increasing photon collection area: X-ray observations must be performed from space, where mass available for a telescope has always been and is expected to continue to be quite limited. This paper reports on a program to develop x-ray optics satisfying these two requirements. The objective of this technology program is to enable Explorer-class missions in the near term and facility-class missions in the long term.

The mirrors of the International X-ray Observatory (IXO) were based on of a large number of high quality segments, aiming at achieving a global spatial resolution better than 5 arcsec (HEW). A study concerning the slumping of thin glass foils for the IXO mirrors is under development in Europe, funded by ESA and led by the Brera Observatory and is continuing even after that the programhas been descoped, in the perspective of using the technology under development for other future missions. After a preliminary trade-off study, we have focused our the effort on the "Direct" slumping approach, based on the use of convex moulds. In this case during the thermal cycle the optical surface of the glass is in direct contact with the mould surface. The thin plates are made of thin glass sheets (0.4 mm thick), with a reflecting area of 200 mm × 200 mm. The adopted integration process foresees the use of reinforcing ribs for bonding together the plates and forming in that way a rigid and stiff stack of segmented mirror shells; the stack is supported by a thick backplane. During the bonding process the plates are constrained to stay in close contact with the surface of the master (i.e. the same mould used for the hot slumping process) by the application of vacuum pump suction. In this way the spring-back deformations and low frequency errors still present on the foil profile after slumping can be corrected. In this paper we will give an overview and a status report of the project.

The large dimensions of the future X-ray telescopes, with diameters ranging from 3.5 m and up to several meters, will require the adoption of segmented optics and hence the development of new technologies for their manufacturing. These technologies are based on lightweight materials and structures to comply with the mass constrains imposed by the launcher. The Astronomical Observatory of Brera (INAF-OAB) is involved in the development of a glass shaping technology for the production of grazing incidence segmented optics to be employed onboard the next generation of Xray Observatories. This technique, named "Hot slumping technology with pressure", is based on the viscosity change of the glass with the temperature: by applying a suitable thermal cycle the viscosity of the glass is decreased enough to allow its slumping on a mould so to replicate its shape without significantly degrade its surface finishing. Following this replication approach, it is possible to obtain, with the same mould, a number of equal mirror segments that will be integrated and aligned in the telescope aperture so to create a mirror shell in configuration Wolter I. The entire study has been financed by ESA in the context of the International X-ray Observatory (IXO) mission with the aim of developing a back-up technology for the IXO mirror manufacturing. The study started in 2009 and it is scheduled to finish in 2012 with the production of representative module prototypes, named POC and XOU_BB. After a brief review of past results, this paper reports the latest advancement in the slumping of Schott glass D263 foils on Fused Silica and Zerodur moulds and its status as for summer 2011.

A method of thermally shaping individual sheets of glass for the International X-Ray Observatory using porous mandrels as air bearings has been developed, which eliminates the problems of sticking and dust particleinduced distortion which plague traditional slumping methods. A detailed mathematical model of the process has been developed, allowing prediction of final glass shape based on process parameters that include air supply pressure, imperfections on the mandrel surface, glass total thickness variations and gravity vector orientation. Experiments to verify model findings are conducted under closed-loop control of pressure and apparatus tilt. Little improvement in repeatability is seen, suggesting that the error is due to unmodeled forces such as contact forces from the glass holding technique. Finally, the design process and fabrication of a third generation slumping tool is presented. In addition to scaling the design to accomodate larger flats, slumps are done horizontally to float the glass and minimize contact during the process. New capabilities of the tool include active gap measurement and control, as well as plenum air temperature monitoring.

Advancements in X-ray astronomy demand thin, light, and closely packed thin optics which lend themselves to segmentation of the annular mirrors and, in turn, a modular approach to the mirror design. The functionality requirements of such a mirror module are well understood. A baseline modular concept for the proposed International X-Ray Observatory (IXO) Flight Mirror Assembly (FMA) consisting of 14,000 glass mirror segments divided into 60 modules was developed and extensively analyzed. Through this development, our understanding of module loads, mirror stress, thermal performance, and gravity distortion have greatly progressed. The latest progress in each of these areas is discussed herein. Gravity distortion during horizontal X-ray testing and on-orbit thermal performance have proved especially difficult design challenges. In light of these challenges, fundamental trades in modular X-ray mirror design have been performed. Future directions in module X-ray mirror design are explored including the development of a 1.8 m diameter FMA utilizing smaller mirror modules. The effect of module size on mirror stress, module selfweight distortion, thermal control, and range of segment sizes required is explored with advantages demonstrated from smaller module size in most cases.

The optics for the International X-Ray Observatory (IXO) require alignment and integration of about fourteen thousand thin mirror segments to achieve the mission goal of 3.0 square meters of effective area at 1.25 keV with an angular resolution of five arc-seconds. These mirror segments are 0.4 mm thick, and 200 to 400 mm in size, which makes it difficult not to impart distortion at the sub-arc-second level. This paper outlines the precise alignment, permanent bonding, and verification testing techniques developed at NASA's Goddard Space Flight Center (GSFC). Improvements in alignment include new hardware and automation software. Improvements in bonding include two module new simulators to bond mirrors into, a glass housing for proving single pair bonding, and a Kovar module for bonding multiple pairs of mirrors. Three separate bonding trials were x-ray tested producing results meeting the requirement of sub ten arc-second alignment . This paper will highlight these recent advances in alignment, testing, and bonding techniques and the exciting developments in thin x-ray optic technology development.

Effective area requirements for the large X-ray mirror of the International X-ray Observatory (IXO) are about 3 m² at 1keV, 0.65 m² at 6 keV and 150 cm² at 30 keV. Because of its large dimension, the telescope cannot be realized as a monolithic structure but rather it requires the integration and assembly in the telescope optical bench of a number of basic module units, called X-ray Optical Unit (XOU). We are currently studying a method for the production of these basic units that is based on the slumping technology for the production of thin glass segmented mirrors. It foresees the implementation of a stacking integration concept based on the use of reinforcing ribs connecting the glass segments in order to create very stiff structures. This paper reports on the last design of the single optical module and describe the results of FEM analyses that show how it is possible to use an innovative approach to the integration of the slumped glass foils.

The International X-ray Observatory (IXO) is a joint mission concept studied by the ESA, NASA, and JAXA space agencies. The main goal of the mission design is to achieve a large effective area (>2.5m² at 1 keV) and a good angular resolution (5 arcsec HEW at 1 keV) at the same time. The Brera Astronomical Observatory - INAF (Italy), under the support of ESA, is developing a method for the realization of the X-Ray Optical Units, based on the use of slumped thin glass segments to form densely packed modules in a Wolter type I optical configuration. In order to reach the very challenging integration requirements, it has been developed an innovative assembly approach for aligning and mounting the IXO mirror segments. The method is based on the use of an integration mould for each foil. In particular the glass segment is forced to adhere to the integration mould in order to maintain the optimal figure without deformations until the integration of the foil in the stack is completed. In this way an active correction for major existing figure errors after slumping is also achieved. Moreover reinforcing ribs are used in order to connect the facets to each-other and to realize a robust monolithic stack of plates. In this paper we present the design, the development and the validation status of a special Integration Machine (IMA) that has been specifically developed to allow the integration of the Plate Pairs into prototypal X-Ray Optical Unit stacks.

We present initial novel coating design for ATHENA. We make use of both simple bilayer coatings of Ir and B₄C and more complex constant period multilayer coatings to enhance the effective area and cover the energy range from 0.1 to 10 keV. We also present the coating technology used for these designs and present test results from coatings.

The NuSTAR mission will be the first mission to carry a hard X-ray(5-80 keV) focusing telescope to orbit. The optics are based on the use of multilayer coated thin slumped glass. Two different material combinations were used for the flight optics, namely W/Si and Pt/C. In this paper we describe the entire coating effort including the final coating design that was used for the two flight optics. We also present data on the performance verification of the coatings both on Si witness samples as well as on individual flight mirrors.

Japan's sixth X-ray satellite missions, ASTRO-H, features two hard X-ray telescopes with depth-graded, multilayer reflectors. Our laboratory has advanced the technology for multilayer reflectors through development of a balloon-borne experiment, InFOCuS. While its base model for the multilayer design (with the minimum incident angle of 0.11 degrees and 8m focal length) is adequate for the ASTRO-H mission, we opt to improve it further so that better performance can be derived with the minimum incident angle of 0.07 degrees and 12m focal length. The improved design has resulted in the reduction of layers from 28 to 10-21 layers per reflector while gaining higher reflectivity by 3-5% at 40-70 keV. A multilayer optics will be used in ATHENA. ATHENA's principal design requires its energy bandpass of 0.1-20 keV with the minimum incident angle of 0.31 degrees and 12m focal length. With the narrower bandpass and the larger incident angles, it necessitates following changes in the multilayer design: adjustment of top Pt layer thickness and a total number of top layers to boost reflectivity (especially in the lower energy band), and refinement of Pt/C-layer spacing and depth-graded period below the third layer to bunch up the Bragg peaks tightly in the required hard X-ray band. In this presentation, we discuss the key parameters for ATHENA's multilayers to achieve a larger effective area at 10-20 keV.

X-ray astronomy grazing incidence telescopes use the principle of nested shells to maximize the collecting area. Some of the more recent missions, such as XMM-Newton [1], have used an electroformed nickel replication (ENR) process [2] to fabricate the mirror shells. Upcoming missions, such as Spectrum-Röntgen-Gamma [3] and Focusing Optics X-ray Solar Imager ^[4], also use the electroforming process to fabricate nested shell grazing incidence X-ray telescopes. We present recent results on fabrication of replicas with multilayer coatings from Wolter-1 mandrels using a new hardcoat release material to simplify and improve this electroforming process.

A coating technique is being developed to correct the surface figure deviations in grazing-incidence X-ray optics. These optics are typically designed to have precise conic profiles, and any deviation in this profile, as a result of fabrication, results in a degradation of the imaging performance. To correct the mirror profiles, physical vapor deposition has been utilized to selectively deposit a filler material inside the mirror shell. The technique, termed differential deposition, has been implemented as a proof of concept on miniature X-ray optics developed at MSFC for medical-imaging applications. The technique is now being transferred to larger grazing-incidence optics suitable for astronomy.

The prediction of the properties of X-ray telescopes is important for the planning of observations and the interpretation of data. The mirror quality in terms of micro-roughness scattering and deformations relative to the idealized shape plays a crucial role for the sensitivity of the telescope for detecting celestial X-ray sources. Monte-Carlo raytracing systems have been used in all X-ray telescope missions. MT RAYOR is a system that can be used to analyze any Wolter-1 optics including simulation of extended sources, celestial or in the laboratory, with position dependent spectral properties. Examples that explore the MT RAYOR capabilities have been chosen from the future missions NuSTAR and Astrosat.

The Point Spread Function (PSF) of an imaging X-ray telescope is mostly determined by the defects of its grazing reflection optics. In terms of Fourier components of the mirrors' profile, figure errors comprise long spatial wavelengths, whilst short spatial wavelengths are identified as microroughness. The former contribution is in general treated by means of geometrical optics, while the contribution of the latter - strongly dependent on the X-ray energy - is usually derived from the first order scattering theory. This approach, however, requires setting a sudden transition between these two treatments, whereas in the general case the change is expectedly more gradual. In order to compute the PSF expected from a mirror profile, we need a general method that does not need to classify surface defects as roughness or profile errors. In this work we show how to compute the PSF of real X-ray mirror shells in a typical Wolter-I configuration, at any X-ray energy. The suggested method is an application of the Huygens-Fresnel principle to grazing incidence Wolter-I profiles, and is an extension of the single-reflection formalism we presented in a previous paper. A few integral equations, applied from UV to hard X-rays, return the expected PSFs from measured or simulated profiles, accounting for the surface roughness along with its PSD (Power Spectral Density). The results are consistent with the ray-tracing results whenever geometric optic can be applied, and they merge with the results of the first order X-ray scattering theory when the roughness is within the smooth-surface limit. Finally, the PSF computed from the profile and the roughness of a real mirror is in very good agreement with the one experimentally measured in hard X-rays.

Several hard X-ray imaging telescopes of the next future will be characterized by a high angular resolution. To this end, it is necessary to produce optics with a very low surface microroughness, as this is responsible of X-ray scattering, which results in image quality degradation especially at the higher energies. To the smooth surface approximation, it is possible to compute the X-Ray Scattering (XRS) from the Power Spectral Density (PSD) of the surface roughness. Indeed, multilayers coatings will be used to reflect X-rays beyond 10 keV; in this case the scattering pattern is more complicated but it can still be computed from the PSDs of each interface and the cross-correlation functions of the rough profiles. A growth model able to describe the roughness evolution of the surfaces enables us to compute the XRS of the multilayer, which can be directly compared to the experimental data. With this approach we aim to validate the roughening model assumed and to accurately predict the scattering pattern we expect on the focal plane. In this work we show the application of this formalism: direct measurements of the PSDs for the substrate and the outermost layer of a multilayer sample are used as input for the code to model the PSD growth. XRS measurements of that sample, performed at the energy of 8.05 keV, are presented to validate the modeling achieved.

Flight Mirror Assemblies (FMAs) for X-ray telescopes similar to that of the International X-ray Observatory (IXO) concept consist of several thousands of individual mirror segments. The size, shape, and location of these mirrors affect many characteristics of the telescope design. Mission requirements among other factors in turn restrict mirror segment parameters such as thickness, axial length, azimuthal span, and mass density. This paper provides an overview of the critical relationships relating to mirror segment size and configuration throughout the design and analysis of an X-ray mirror assembly. A computational analysis is presented in the form of ray tracing pairs of thin X-ray mirror segments of varying sizes aligned in gravity and supported using kinematic constraints with corresponding self weight distortions calculated using finite element analysis (FEA). The work in this paper may be used as a starting point for determining mirror segment sizes for X-ray missions like that of IXO and beyond.

We describe a mathematical formalism for determining the mirror shell nodal positions and detector tilts that optimize the spatial resolution averaged over a field-of-view for a nested x-ray telescope, assuming known mirror segment surface prescriptions and known detector focal surface. The results are expressed in terms of ensemble averages over variable combinations of the ray positions and wavevectors in the flat focal plane intersecting the optical axis at the nominal on-axis focus, which can be determined by Monte-Carlo ray traces of the individual mirror shells. This work is part of our continuing efforts to provide analytical tools to aid in the design process for wide-field survey x-ray astronomy missions.

Future x-ray astronomical missions, similar to the proposed International X-ray Observatory (IXO), will utilize replicated mirrors to reduce both mass and production costs. Accurately figured and measured molds (called mandrels) - on which the mirror substrates are thermally formed, replicating the surface of the mandrels - are essential to enable these missions. The Optics Branches of the Goddard Space Flight Center (GSFC) and Marshall Space Flight Center (MSFC) have developed fabrication processes along with metrologies that yield high-precision mandrels; and through the SBIR program, they encourage small businesses to attack parts of the remaining problems. The Goddard full-aperture mandrel polisher (the MPM-500) has been developed to a level where mandrel surfaces match the 1.5 arcsec HPD level allocation in a 5 arcsec telescope program. This paper reviews this current technology and describes a pilot program to design a suite of machine tools and process parameters capable of producing many hundreds of these precision objects. A major challenge is to keep mid-spatial frequency errors below 2 nm rms - a severe specification; but we must also note the factors which work to our advantage: e.g., how the figure departs from a pure cone by only one micron, and how the demanding figure specifications which apply in the axial direction are relaxed by an order of magnitude in the azimuthal. Careful study of other large optical fabrication programs in the light of these challenges and advantages has yielded a realistic plan for the economical production of mandrels that meet program requirements in both surface and quantity.

The next generation wide-field X-ray telescope (WFXT) will require an angular resolution of ~5-10 arcsec almost constant across a wide field of view (~1 deg² diameter). To achieve this goal, the design of the optical system has to be based on mirrors characterized by short length and polynomial profiles, as well as focal plane curvature and plate scale corrections. These concepts guarantee an improved angular resolution at large off-axis angle with respect to the normally used Wolter-I configuration. These telescopes are therefore optimal for survey purposes. A significant increase of effective area and grasp with respect to previous missions must also be achieved. This is possible with high precision but at the same time thin (2-3 mm thickness for mirror diameters of 30-110 cm) glass mirror shells. To achieve the goal of 5 arcsec and improve further the technology, we are considering different materials. Fused silica, a well-known material with good thermo-mechanical and polishability characteristics provide the best choice. To bring the mirror shells to the needed accuracy, we are adopting a deterministic direct polishing method (already used for past missions as Einstein, Rosat, Chandra). The technological challenge now is to apply it for almost ten times thinner shells.

Microelectromechanical systems (MEMS) micropore X-ray optics were proposed as an ultralightweight, high- resolution, and low cost X-ray focusing optic alternative to the large, heavy and expensive optic systems in use today. The optic's monolithic design which includes high-aspect-ratio curvilinear micropores with minimal sidewall roughness is challenging to fabricate. When made by either deep reactive ion etching or X-ray LIGA, the micropore sidewalls (re ecting surfaces) exhibit unacceptably high surface roughness. A magnetic eld-assisted nishing (MAF) process was proposed to reduce the micropore sidewall roughness of MEMS micropore optics and improvements in roughness have been reported. At this point, the best surface roughness achieved is 3 nm Rq on nickel optics and 0.2 nm Rq on silicon optics. These improvements bring MEMS micropore optics closer to their realization as functional X-ray optics. This paper details the manufacturing and post-processing of MEMS micropore X-ray optics including results of recent polishing experiments with MAF.

For future x-ray astrophysics mission that demands optics with large throughput and excellent angular resolution, many telescope concepts build around assembling thin mirror segments in a Wolter I geometry, such as that originally proposed for the International X-ray Observatory. The arc-second resolution requirement posts unique challenges not just for fabrication, mounting but also for metrology of these mirror segments. In this paper, we shall discuss the metrology of these segments using normal incidence metrological method with interferometers and null lenses. We present results of the calibration of the metrology systems we are currently using, discuss their accuracy and address the precision in measuring near-cylindrical mirror segments and the stability of the measurements.

Evaluation of interferometric mirror metrology data and characterization of a telescope wavefront can be powerful tools in understanding image characteristics of an x-ray optical system. In the development of soft x-ray telescope for the International X-Ray Observatory (IXO), we have developed new approaches to support the telescope development process. Interferometrically measuring the optical components over all relevant spatial frequencies can be used to evaluate and predict the performance of an x-ray telescope. Typically, the mirrors are measured using a mount that minimizes the mount and gravity induced errors. In the assembly and mounting process the shape of the mirror segments can dramatically change. We have developed wavefront sensing techniques suitable for the x-ray optical components to aid us in the characterization and evaluation of these changes. Hartmann sensing of a telescope and its components is a simple method that can be used to evaluate low order mirror surface errors and alignment errors. Phase retrieval techniques can also be used to assess and estimate the low order axial errors of the primary and secondary mirror segments. In this paper we describe the mathematical foundation of our Hartmann and phase retrieval sensing techniques. We show how these techniques can be used in the evaluation and performance prediction process of x-ray telescopes.

This paper presents the huge advance in metrology represented by a new free-form profilometer, the Profilometer/Rotondimeter (MPR-700). The MPR-700 is a 3D metrological machine capable to measure quasicylindrical and free-form normal incidence optics maintaining the 2D measuring error below 40 nm at 2σ up to a length of 700 mm. The key to success of MPR is its innovative detection system design that boasts remarkable advantages in the positioning error reduction and to the instantaneous subtraction of the dynamical error. These characteristics make the MPR extremely precise and accurate, insomuch that measurements can be acquired in flight at high speed maintaining the measuring performances. The main advantage of the MPR design is the capability to couple the measuring quality offered by one-dimensional profilometer to the opportunity to the three-dimensional motion of a 3D machines. Here we present the MPR design and the results obtained on single profiles measurements and 3D shape reconstruction for optics of different geometry.

In order to fulfill the angular resolution requirements and make the performance goals for future NASA missions feasible, it is crucial to develop instruments capable of fast and precise figure metrology of x-ray optical elements for further correction of the surface errors. The Long Trace Profilometer (LTP) is an instrument widely used for measuring the surface figure of grazing incidence X-ray mirrors. In the case of replicated optics designed for x-ray astronomy applications, such as mirrors and the corresponding mandrels have a cylindrical shape and their tangential profile is parabolic or hyperbolic. Modern LTPs have sub-micro radian accuracy, but the measuring speed is very low, because the profilometer measures surface figure point by point using a single laser beam. The measurement rate can be significantly improved by replacing the single optical beam with multiple beams. The goal of this study is to demonstrate the viability of multi-beam metrology as a way of significantly improving the quality and affordability of replicated x-ray optics. The multi-beam LTP would allow one- and two-dimensional scanning with sub-micro radian resolution and a measurement rate of about ten times faster compared to the current LTP. The design details of the instrument's optical layout and the status of optical tests will be presented.

This paper will describe a new Extreme Ultraviolet (EUV) test facility that is being developed at the Marshall Space Flight Center (MSFC) to test EUV telescopes. Two flight programs, Hi-C, the high resolution coronal imager (a sounding rocket program), and SUVI, the Solar Ultraviolet Imager (GOES-R), set the requirements for this new facility. This paper will discuss those requirements, the EUV source characteristics, the wavelength resolution that is expected and the vacuum chambers (Stray Light Facility, Xray Calibration Facility and the NSSTC EUV test chamber) where this facility will be used.

We present the results obtained with the new Laue lens prototype built in the LARIX facility in the Physics Department of University of Ferrara. Following the results of the first prototype presented at the SPIE conference in Marseille, and also thanks to the methods adopted for improving the prototype (SPIE conference in San Diego, Ferrari et al. 2009) here we present the results of the new prototype with improved performances in terms of point spread function (PSF) and spectral response.

We present the LAUE project devoted to develop an advanced technology for building a high focal length Laue lens for soft gamma-ray astronomy (80-600 keV). The final goal is to develop a focusing optics that can improve the current sensitivity in the above energy band by 2 orders of magnitude.

Laue lenses are an emerging technology that will enhance gamma-ray telescope sensitivity by one to two orders of magnitude in selected energy bands of the ~100 keV to ~1.5 MeV range. This optic would be particularly well adapted to the observation of faint gamma ray lines, as required for the study of Supernovae and Galactic positron annihilation. It could also prove very useful for the study of hard X-ray tails from a variety of compact objects, especially making a difference by providing sufficient sensitivity for polarization to be measured by the focal plane detector. Our group has been addressing the two key issues relevant to improve performance with respect to the first generation of Laue lens prototypes: obtaining large numbers of efficient crystals and developing a method to fix them with accurate orientation and dense packing factor onto a substrate. We present preliminary results of an on-going study aiming to enable a large number of crystals suitable for diffraction at energies above 500 keV. In addition, we show the first results of the Laue lens prototype assembled using our beamline at SSL/UC Berkeley, which demonstrates our ability to orient and glue crystals with accuracy of a few arcsec, as required for an efficient Laue lens telescope.

We present an experimental study on the method of surface grooving for bending crystals for the realization of a hard x-ray Laue lens. Bent Si and Ge crystalline plates were analyzed by x-ray diffraction of their (111) planes at the European Synchrotron Radiation Facility. Crystals diffracted photons from 150 to 700 keV with efficiency peaking 95% at 150 keV for Si. Measured rocking curves of the samples showed flat-topped profiles with their FWHM equal to the crystal bending, i.e., the method of surface grooving proved to evenly bend the crystals, their energy passband being very well controlled. Surface grooving technique has been found to offer both high reproducibility and easy control of diffraction properties of the crystals. Besides, this method is cheap, simple and compatible with mass production, making it a reliable technique for fabrication of a Laue lens, where serial production of crystals should be envisaged. A Laue lens made of crystals bent by surface grooves can lead to significant detection improvement in astrophysical applications.

We have analyzed GaAs, Cu, CdTe, and CdZnTe crystals as possible optical elements for hard x-ray lenses for x-ray astronomy. We used high resolution x-ray diffraction at 8keV in Bragg geometry and Laue transmission diffraction at synchrotron at energies up to 500 keV. A good agreement was found between the mosaicity evaluated in Bragg diffraction geometry with x-ray penetration of the order of few tens micrometers and in Laue transmission geometry at synchrotron. All the analyzed crystals showed mosaicity values in a range between a few to 150 arcseconds and suitable for the application. Nevertheless -CdTe and CdZnTe crystals exhibit non-uniformity due to the presence of low angle grain boundaries; -Cu crystals exhibit mosaicity of the order of several arcminutes; they indeed suffer by a severe cutting damage that had to be removed with a very deep etching. The FWHM was also rapidly decreasing with the x-ray energy showing that the mosaic spread is not the only origin of peak broadening; -GaAs crystals grown by Czochralski method show mosaicity up to 30 arcseconds and good diffraction efficiency up to energies of 500 keV. The use of thermal treatments as a possible method to increase the mosaic spread is also evaluated.

Quasi-mosaicity is an effect of secondary bending within a crystal driven by crystalline anisotropy. This effect can be used to fabricate a series of curved crystals for the realization of a Laue lens. We highlight that crystals bent by quasi-mosaic effect envisage very high resolution focusing with respect to mosaic crystals. Under same conditions for energy passband and flux of incident photons, a Laue lens based on quasi-mosaic crystals would increase the signal-to-noise ratio by more than one order of magnitude as for the same lens with mosaic crystals. A proposal for the realization of a self-standing quasi-mosaic crystal is given. Here permanent bending of a crystal is achieved as a result of superficial indentations.

Curved crystals can be used as optical elements of a x-ray lens for hard x-ray astronomy in order to increase the diffraction efficiency. In this work we propose to obtain bent crystals by a controlled surface damaging, which introduces defects in a superficial layer of few tens nanometers in thickness undergoing a highly compressive strain. Several (100) oriented silicon and gallium arsenide wafer crystals have been treated. By using high resolution x-ray diffraction measurements in Bragg condition at low energy x-rays the local and mean curvature radius of each sample have been determined. Curvature radii between 3 and 70 m were easily obtained in wafers of different thicknesses. In particular, spherical curvatures have been determined in silicon samples whereas GaAs treated samples showed an elliptical curvature with the major axes corresponding to the <011> crystallographic directions. The characterization of GaAs samples performed in the Laue geometry at gamma-ray energy of 120 keV confirmed the increase of the diffraction efficiency in the bent crystals.

The x-ray astronomy community has never flown a celestial source spectrograph that can resolve natural line widths in absorption the way the ultraviolet community did with OAO-3 Copernicus back in 1972. Yet there is important science to be mined there, and right now, the large flagship missions like the International X-ray Observatory are not progressing toward launch. WHIMEx is an Explorer concept proposed earlier this year to open up that science regime in the next few years. The concept features a modified off-plane grating spectrograph design that will support high resolution (λ/δλ ~ 4000) in the soft x-ray band with a high packing density that will enable a modest cost space mission. We discuss the design and capabilities for the WHIMEx mission. Its prime science goal is detecting high temperature oxygen in the Intergalactic Medium, but it has a broad range of science potential cutting across all of x-ray astronomy and should give us a new window on the Universe.

Future X-ray astronomical missions will need to address a number of important goals such as studying the dynamics of clusters of galaxies, determining how elements are created in the explosions of massive stars, and revealing most of the "normal" matter in the universe which is currently thought to be hidden in hot filaments of gas stretching between galaxies. In order to achieve these goals, spectrometers capable of high resolution and high throughput are necessary for the lowest X-ray energies, 0.3-1.0 keV. We present recent progress in the development of off-plane reflection grating technology for use on upcoming missions. Off-plane grating spectrometers consist of an array of gratings capable of reaching resolutions above 3000 (λ/Δλ). Concept designs have been made for the International X-ray Observatory X-ray Grating Spectrometer. More recently however, we have designed an Optics Module Assembly for WHIMex, an Explorer mission concept that incorporates a Wolter telescope, steering flats, and an array of gratings. This paper will discuss these designs and the application of off-plane arrays for the future.

Diffraction grating-based, wavelength dispersive high-resolution soft x-ray spectroscopy of celestial sources promises to reveal crucial data for the study of the Warm-Hot Intergalactic Medium, the Interstellar Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, and other areas of interest to the astrophysics community. Our recently developed critical-angle transmission (CAT) gratings combine the advantages of the Chandra high and medium energy transmission gratings (low mass, high tolerance of misalignments and figure errors, polarization insensitivity) with those of blazed reflection gratings (high broad band diffraction efficiency, high resolution through use of higher diffraction orders) such as the ones on XMM-Newton. Extensive instrument and system configuration studies have shown that a CAT grating-based spectrometer is an outstanding instrument capable of delivering resolving power on the order of 5,000 and high effective area, even with a telescope point-spread function on the order of many arc-seconds. We have fabricated freestanding, ultra-high aspect-ratio CAT grating bars from silicon-on-insulator wafers using both wet and dry etch processes. The 200 nm-period grating bars are supported by an integrated Level 1 support mesh, and a coarser external Level 2 support mesh. The resulting grating membrane is mounted to a frame, resulting in a grating facet. Many such facets comprise a grating array that provides light-weight coverage of large-area telescope apertures. Here we present fabrication results on the integration of CAT gratings and the different high-throughput support mesh levels and on membrane-frame bonding. We also summarize recent x-ray data analysis of 3 and 6 micron deep wet-etched CAT grating prototypes.

The Marshall Grazing Incidence X-ray Spectrograph (MaGIXS) is a proposed sounding rocket experiment designed to observe spatially resolved soft X-ray spectra of the solar corona for the first time. The instrument is a purely grazing-incidence design, consisting of aWolter Type-1 sector telescope and a slit spectrograph. The telescope mirror is a monolithic Zerodur mirror with both the parabolic and hyperbolic surfaces. The spectrograph comprises a pair of paraboloid mirrors acting as a collimator and reimaging mirror, and a planar varied-line-space grating, with reflective surfaces operate at a graze angle of 2 degrees. This produces a flat spectrum on a detector covering a wavelength range of 6-24Å (0.5-1.2 keV). The design achieves 20 mÅ spectral resolution (10 mÅ /pixel) and 5 arcsec spatial resolution (2.5 arcsec / pixel) over an 8-arcminute long slit. The spectrograph is currently being fabricated as a laboratory prototype. A flight candidate telescope mirror is also under development.

The Extreme Physics Explorer (EPE) is a concept timing/spectroscopy mission that would use micro-channel plate optics (MCPO) to provide 4m² effective area focused to ~1 arc-min onto an X-ray calorimeter. We describe science drivers for such a mission, possible designs for the large area MCPO needed for EPE, and the challenges of the large area MCPO design.

The soft X-ray band hosts a larger, more diverse range of variable sources than any other region of the electromagnetic spectrum. They are stars, compact binaries, SMBH's, the X-ray components of Gamma-Ray Bursts, their X-ray afterglows, and soft X-ray flares from supernova. We describe a concept for a very wide field (~ 4 ster) modular hybrid X-ray telescope system that can measure positions of bursts and fast transients with as good as arc second accuracy, the precision required to identify fainter and increasingly more distant events. The dimensions and materials of all telescope modules are identical. All but two are part of a cylindrical lobster-eye telescope with flat double sided mirrors that focus in one dimension and utilize a coded mask for resolution in the other. Their positioning accuracy is about an arc minute. The two remaining modules are made from the same materials but configured as a Kirkpatrick-Baez telescope with longer focal length that focuses in two dimensions. When pointed it refines the hybrid telescope's arc minute positions to an arc second and provides larger effective area for spectral and temporal measurements. Above 10 keV the mirrors act as an imaging collimator with positioning capability. For short duration events this hybrid focusing/coded mask system is more sensitive and versatile than either a 2D coded mask or a 2D lobster-eye telescope. Very wide field X-ray telescopes have become feasible as the ability to fabricate large area arrays of CCD and CMOS detectors has improved. This instrument's function in the soft X-ray band is similar to that of Swift in hard X-ray band and there is a larger variety of fast transients in the soft X-ray band. An instrument with considerably more sensitivity than current wide field X-ray detectors would be compatible with a modest NASA Explorer mission.

We report a study of a new X-ray interferometer with a beam splitter for future observation of celestial objects. A possible configuration of an interferometer is proposed. By using a beam splitter, the length of the interferometer becomes short and without a formation flight of satellites a reasonable X-ray interferometric observation can be possible. An observation of early type stars is discussed. A laboratory experiment for performance verification is also discussed.

Future x-ray observatories will require high-resolution (< 1") optics with very-large-aperture (> 25 m²) areas. Even with the next generation of heavy-lift launch vehicles, launch-mass constraints and aperture-area requirements will limit the areal density of the grazing-incidence mirrors to about 1 kg/m² or less. Achieving sub-arcsecond x-ray imaging with such lightweight mirrors will require excellent mirror surfaces, precise and stable alignment, and exceptional stiffness or deformation compensation. Attaining and maintaining alignment and figure control will likely involve active (in-space adjustable) x-ray optics. In contrast with infrared and visible astronomy, active optics for x-ray astronomy is in its infancy. In the middle of the past decade, two efforts began to advance technologies for adaptive x-ray telescopes: The Smart X-ray Optics (SXO) Basic Technology project in the United Kingdom (UK) and the Generation-X (Gen-X) concept studies in the United States (US). This paper discusses relevant technological issues and summarizes progress toward active x-ray telescopes.

The present generation of X-ray telescopes emphasizes either high image quality (e.g. Chandra with sub-arc second resolution) or large effective area (e.g. XMM-Newton), while future observatories under consideration (e.g. Athena, AXSIO) aim to greatly enhance the effective area, while maintaining moderate (~10 arc-seconds) image quality. To go beyond the limits of present and planned missions, the use of thin adjustable optics for the control of low-order figure error is needed to obtain the high image quality of precisely figured mirrors along with the large effective area of thin mirrors. The adjustable mirror prototypes under study at Smithsonian Astrophysical Observatory are based on two different principles and designs: 1) thin film lead-zirconate-titanate (PZT) piezoelectric actuators directly deposited on the mirror back surface, with the strain direction parallel to the glass surface (for sub-arc-second angular resolution and large effective area), and 2) conventional leadmagnesium- niobate (PMN) electrostrictive actuators with their strain direction perpendicular to the mirror surface (for 3-5 arc second resolution and moderate effective area). We have built and operated flat test mirrors of these adjustable optics. We present the comparison between theoretical influence functions as obtained by finite element analysis and the measured influence functions obtained from the two test configurations.

To extend the effective collecting area for future X-ray astronomy observatories, it is necessary to use highly nested, very thin glass shells. The capability to adjust the figure of these shells on-orbit is essential in order to achieve the present X-ray imaging capability, of order 1/2 arcsec resolution, which is provided to astronomers world-wide by the Chandra X-ray Observatory. We are pursuing concepts to carry out this adjustment using piezoelectric crystals deposited directly on the back sides of the reflectors, and divided into a pattern of discrete actuators by individually controlled electrodes. In this paper we carry out a simulation of how well gravity induced errors might be corrected by this process. We consider a conical glass piece 205 mm axially by 410 mm azimuthally, and with 1 m radius of curvature. We do a finite element analysis to calculate the influence function of each of a set of 20 × 20 piezo pixels. Then we apply a 1g force axially, using various constraint conditions, and calculate the coefficients of the set of influence functions such that the adjusted shape minimizes the slope errors.