The UK Smart X-Ray Optics programme is developing the techniques required to both enhance the performance of existing X-ray systems, such as X-ray telescopes, while also extending the utility of X-ray optics to a broader class of scientific investigation. The approach requires the control of the inherent aberrations of X-ray systems using an active/adaptive method. One of the technologies proposed to achieve this is micro-structured optical arrays, which use grazing incidence reflection through consecutive aligned arrays of channels. Although such arrays are similar in concept to polycapillary and microchannel plate optics, they are more flexible. Bending the arrays allows variable focal length, while flexing parts of them provides adaptive or active systems. Custom configurations can be designed, using ray tracing and finite element analysis, for applications from sub-keV to several-keV X-rays. The channels may be made using deep silicon etching, which can provide appropriate aspect ratios, and flexed using piezo actuators. An exemplar application will be in the micro-probing of biological cells and tissue samples using Ti K_α radiation (4.5 keV) in studies related to radiation induced cancers.

Recently, the ESRF Optics Group installed a new multilayer deposition facility. This upgrade was motivated by increasingly demanding requirements for multilayer based x-ray optics on modern 3rd generation synchrotron beamlines. Improved accuracy, stability, and reproducibility are key issues. The deposition process is based on non-reactive magnetron sputtering. The machine is equipped with four cathodes and one ion source for surface treatment. Conducting, insulating, and ferromagnetic materials can be deposited. A linear substrate motion will enable coatings up to 100 cm long and 15 cm wide. The talk will describe the basic concept of the machine and will give an overview of the operating conditions. Initial coating results will complement the presentation.

We report our progress in the growth of periodic and depth-graded multilayers in the APS rotary deposition system, a machine designed for fabrication of films tens of microns thick with thousands of layers. A computational method was employed to design depth-graded multilayers for use as wide-angular bandpass reflective optics. We present experimental results for a 154-layer WSi₂/Si multilayer system with bilayer thickness ranging from 2.2 nm to 5.5 nm that closely match theoretical flat-top reflectivity predictions of 9.8% from 15.6 mrad to 23.3 mrad at 8 keV.

Optimizing the lens design and improving the technological process, we manufactured X-ray planar compound refractive lenses with vertical sidewalls up to 70 microns deep. The lens surface roughness in the order of 20 nm was attained. The minimal thickness of the material between two individual lenses of 2 µm was realized. Driven by the requirements of new 100 m-long beamlines at the ESRF, the first prototype chip of Si planar nanofocusing lenses was designed and manufactured. The technological breakthrough allows to reach the nanometer focusing. The optical tests of the new planar lenses were performed at the ESRF beamlines BM5 and ID15. The resolution below 200 nm was measured in the energy region of 15-80 keV. The best resolution of 150 nm was demonstrated at 50 keV energy. As a next step dedicated chip design for two-dimensional focusing with nanopositioning stages will be realized.

The Diamond Optics & Metrology Group and the collaborators at the STFC Central Microstructure Facility have initiated a program for the design and fabrication of in-line micro- and nano-focusing optics for synchrotron radiation beamlines. The first type of optics fabricated is a kinoform lens in silicon on the same model proposed by K. Evans- Lutterodt et al [Opt. Expr. 11 (2003) 919.]. The fabrication utilised ultra high resolution electron beam lithographic patterning of an electron sensitive SU8 polymer and deep reactive ion etching of silicon. The first test of the focusing properties was performed at the ESRF BM5 optics beamline. In this paper we present details on the design and fabrication, and discuss the test results.

Nanopositioners have been integrated into a system to perform 2D focusing of the X-ray beam by using silicon planar lenses in cross geometry. Those positioners have been tested in the ESRF metrology laboratory to measure their resolutions. The whole system was found to have a good tunability; it is compact and led to an easy alignment of the two lenses along the common beam axis. Experiments were made with this system at the BM05 ESRF beamline using the Micro-optics test bench.

New projection- type X-ray microscope with a compound refractive lens as the optical element is presented. The microscope consists of an X-ray source that is 1-2 mm in diameter, compound X-ray lens and X-ray camera that are placed in-line to satisfy the lens formula. The lens forms an image of the X-ray source at camera sensitive plate. An object is placed between the X-ray source and the lens as close as possible to the source, and the camera shows a shadow image of the object. Spatial resolution of the microscope depends on the lens focal length, lens aperture and the distance from the source to the object. One to two micron resolution may be achieved by placing the object at a distance of 1-5mm from the source. The X-ray source may be designed with the target deposited on a 200-μm thick Be window, which permits the object to be placed very close to the emitting surface. The tube focal spot is equal to 1-2 mm. Results of imaging experiments with an ordinary copper anode X-ray tube and a 10-cm focal length spherical compound refractive X-ray lens are discussed.

A method for the determination of the deposited layer thickness distribution through the stack has been presented in a previous article [1]. We illustrate the validity of this model by considering the deposition of a Mo/B₄C design. This method is further improved to allow for the additional determination of roughness/diffusion through the multilayer stack. We show results of the analysis for a deposited small d-spacing W/B₄C design (d_avg=1.5nm) which give compelling evidence for the existence and determination of a minimum value of thickness that can be allowed in the design of the structure. From this analysis the multilayer was redesigned with a constraint on the minimum thickness allowed in the stack. We show successful results of the deposited redesigned structure. Finally, we show the influence of random layer thickness error on the resultant reflectivity.

Among X-ray and extreme ultraviolet light sources able to produce shorter and shorter, coherent and intense pulses, High order harmonics generated in rare gases are currently the unique way to generate attosecond pulses. However, the manipulation and transport of attosecond pulses require the development of dedicated optics for reaching specific characteristics in terms of amplitude but also in terms of spectral phase control. We present here a multilayer design for chirp compensation of attosecond pulses. We also present an application of these multilayers mirrors for attosecond train pulse holography experiment with high harmonics. This experience took benefit of both temporal and spatial phase properties of high harmonics. A resolution of 750 nm has been achieved by using a 350 as train pulse for the reference wave constituted of four consecutive harmonics (λ=28 nm to λ=41 nm). This new method will allow making ultra fast movies with attosecond resolution of transient phenomena with quasi-3D resolution.

Replicated multilayers inside the rotationally symmetric x-ray mirrors with diameter 0.5-4 mm are being investigated. While the replicated Micromirror technology as well as replicated multilayers on the planar surface were already studied, we present here the combination of both technologies. Initial simulations and development of metrology of multilayers inside small cavities are described, as well as very first results of experiments.

Resonant Inelastic X-ray Scattering (RIXS) is the one of the most powerful methods for investigation of the electronic structure of materials, specifically of excitations in correlated electron systems. However the potential of the RIXS technique has not been fully exploited because conventional grating spectrometers have not been capable of achieving the extreme resolving powers that RIXS can utilize. State of the art spectrometers in the soft x-ray energy range achieve ~0.25 eV resolution, compared to the energy scales of soft excitations and superconducting gap openings down to a few meV. Development of diffraction gratings with super high resolving power is necessary to solve this problem. In this paper we study the possibilities of fabrication of gratings of resolving power of up to 10⁶ for the 0.5 - 1.5 KeV energy range. This energy range corresponds to all or most of the useful dipole transitions for elements of interest in most correlated electronic systems, i.e. oxygen K-edge of relevance to all oxides, the transition metal L_2,3 edges, and the M_4,5 edges of the rare earths. Various approaches based on different kinds of diffraction gratings such as deep-etched multilayer gratings, and multilayer coated echelettes are discussed. We also present simulations of diffraction efficiency for such gratings, and investigate the necessary fabrication tolerances.

We demonstrate a compact instrument for rapid and accurate measurements of the absolute and local efficiency of soft x-ray zone plates in the water window [M. Bertilson, et al, Rev. Sci. Instrum 78, 026103 (2007)]. The arrangement is based on a new single-line λ = 2.88 nm liquid-nitrogen-jet laser-plasma source. The versatility of the instrument enables micro and condenser zone plates with focal lengths in the range from ~200 μm to ~100 mm to be measured. We demonstrate an accurate local efficiency map of a in-house fabricated micro zone plate. Furthermore, we show how this compact instrument allows rapid feedback to the fabrication process which is important for future improvements.

Stacking technique was developed in order to increase focusing efficiency of Fresnel zone plates at high energies. Two identical Si chips each of which containing Fresnel zone plates were used for stacking. Alignment of the chips was achieved by on-line observation of the moiré pattern from the two zone plates. The formation of moiré patterns was studied theoretically and experimentally at different experimental conditions. To provide the desired stability Si-chips with zone plates were bonded together with slow solidification speed epoxy glue. Technique of angular alignment in order to compensate a linear displacement in the process of gluing was proposed. Two sets of stacked FZPs were produced and experimentally tested to focus 15 and 50 keV X-rays. Gain in the efficiency by factor 2.5 was demonstrated at 15 keV. Focal spot of 1.8 μm vertically and 14 μm horizontally with 35% efficiency was measured at 50 keV. Forecast for the stacking of nanofocusing Fresnel zone plates was discussed.

We characterized beryllium foils and CVD diamond films/plates for synchrotron radiation beamline windows and x-ray beam monitor especially in coherent x-ray applications. Sub-micron-resolution imaging with a zooming tube was performed using spatially coherent x-rays at 1-km beamline 29XU of SPring-8. We found that the speckles observed in the conventional powder and ingot beryllium foils were due to voids with diameter of several to ten-several microns. The physical vapor deposition (PVD) eliminated the voids and the PVD beryllium showed the best performance with no speckles. We characterized a commercially available polycrystalline CVD diamond window and CVD films as well as beryllium foils. Polished thin diamond film showed rather uniform transmission image. We found dark spots at in-line image due to Bragg diffraction from grains for thicker CVD diamond window.

We present the theory and implementation of a numerical model capable of simulating two-dimensional images for an x-ray microscope using partially coherent illumination considerations. Partially coherent illumination is found in all x-ray microscopes and particularly in the latest generation of our in-house compact soft x-ray microscope. This is due to an introduced mismatch in numerical aperture of the condenser and objective zone plate, and will yield diffraction-like artifacts in phase-shifting objects. The numerical model approximates the condenser zone plate as a secondary incoherent source represented by individually coherent but mutually incoherent source emitters, each giving rise to a separate image. A final image is obtained by adding up the image intensities of the individual contributions. The simulation has been a useful tool for investigating the influence of coherence on images in both the mirror and zone plate condenser arrangement of the in-house compact soft x-ray microscope. The latest development included in the program is the effect of astigmatism and partial coherence, where the calculated results show good qualitative agreement with respect to the microscope images.

X-ray diffraction by perfect crystal is discussed from the viewpoint of mutual coherence of an x-ray beam. From the time-dependent Takagi-Taupin equations that x-ray wavefields obey in crystal, the reflected wavefield is formulated as an integral transform of a general incident wavefield with temporal and spatial inhomogeneity. A reformulation of rocking-curve profile from the field solution of the time-dependent Takagi-Taupin equations allows experimental evaluation of the mutual coherence function of an x-ray beam. The rigorous relationship of the coherence functions before and after reflection clarifies how the coherence is transferred by a crystal.

There is currently interest in low strain HPHT diamond due to its expected application as various types of X-ray optical elements at Synchrotrons, where the X-ray intensity is becoming progressively too severe for the existing materials. The diamond crystals need to be synthesised with unprecedented lattice quality. In recent measurements at the ID19 beamline of European Synchrotron Radiation Facility (ESRF), the strain sensitivity of the (quantitative) X-ray plane wave monochromatic topography was increased to the level of 10^-8 using the double crystal technique with successively higher order reflections and correspondingly higher energy X-rays. At this level the strain fields of certain defects have a clearly visible macroscopic extent. In particular, both compressive and tensile strain fields of sparse single dislocations are well observed, as are long range strain fields due to isolated surface scratches. The surface processing of diamond for low roughness and good near surface crystal quality is a priority. A study of the progress towards this goal using the X-ray techniques of reflectivity, Grazing Incidence small angle X-ray Scattering (GISAXS) and Grazing Incidence X-ray Diffraction (GID) has been undertaken. The ability of diamond X-ray optical elements to process X-ray beams while preserving the coherence properties of the beam is essential to establish, and measurements of this via the Talbot effect have been carried out. This contribution will detail some of the latest results and comment on future prospects.

Nanofocused X-rays are indispensable because they can provide high spatial resolution and high sensitivity for X-ray nanoscopy/spectroscopy. A focusing system with reflective optics is one of the most promising methods for producing nanofocused X-rays due to its high efficiency and beams size. So, far we realize efficient hard X-ray focusing with a beam size of 25nm. Our next project is realization of sub-10nm hard X-ray focusing. Here, we describe the design of the graded multilayer mirror and evaluation method for hard X-ray focused beam.

This paper describes the progress made in a proof of concept study and recent results of a research program into large active x-ray mirrors that is part of the UK Smart X-ray Optics project. The ultimate aim is to apply the techniques of active/adaptive optics to the next generation of nested shell astronomical X-ray space telescopes. A variety of deformable mirror technologies are currently available, the most promising of which for active X-ray mirrors are probably unimorph and bimorph piezoelectric mirrors. In this type of mirror one or more sheets of piezoelectric material are bonded to or coated with a passive reflective layer. On the back or between the piezoceramic layer/layers are series of electrodes. Application of an electric field causes the piezoelectric material to undergo local deformation thus changing the mirror shape. Starting in 2005 a proof of concept active mirror research program has been undertaken. This work included modelling and development of actively controlled thin shell mirrors. Finite element models of piezo-electric actuated mirrors have been developed and verified against experimental test systems. This has included the modelling and test of piezo-electric hexagonal unimorph segments. Various actuator types and low shrinkage conductive bonding methods have been investigated and laboratory tests of the use of piezo-electric actuators to adjust the form of an XMM-Newton space telescope engineering model mirror shell have been conducted and show that movement of the optics at the required level is achievable. Promising technological approaches have been identified including moulded piezo-ceramics and piezo-electrics fibre bundles.

We have evaluated the applicability of vertically-focusing kinoform lenses for tailoring the vertical coherence length of storage-ring undulator x-ray beams so that the entirety of the coherent flux can be used for small angle multi-speckle x-ray photon correlation spectroscopy (XPCS) experiments. We find that the focused beam produced by a kinoform lens preserves the coherence of the incident unfocused beam and that at an appropriate distance downstream of the focus, the diverging beam produces speckles nearly identical to those produced by an equivalently-sized unfocused beam. We have also investigated the effect of imperfect beamline optics on the observed coherence properties of the beam. Via phase contrast imaging and beam-divergence measurements, we find that a horizontally-deflecting mirror in our beamline precludes us from seeing the true radiation source point but instead acts as an apparent source of fixed size at the center of our insertion device straight section. Finally, we discuss how expected near-future optimization of these optics will greatly benefit XPCS measurements performed at beamline 8-ID-I at the Advanced Photon Source.

The Linac Coherent Light Source (LCLS) is a 0.15-1.5 nm wavelength free-electron laser (FEL) being constructed at the Stanford Linear Accelerator Center (SLAC) by a multi-institution consortium, including Lawrence Livermore National Laboratory (LLNL). One of LLNL's responsibilities involves the design and construction of two grazing-incidence mirror systems whose primary intent is to reduce radiation levels in the experimental halls by separating the FEL beam from unwanted high-energy photons. This paper discusses one of these systems, the Soft X-ray Offset Mirror System (SOMS) that will operate in the wavelength range 0.62-1.5 nm (0.827-2.00 keV). The unusual properties of the FEL beam translate to stringent specifications in terms of stability, material choice and mirror properties. It also precludes using approaches previously developed for synchrotron light sources. This situation has led us to a unique mirror design, consisting of a reflective boron carbide layer deposited on a silicon substrate. In the first part of this paper, we discuss the basic system requirements for the SOMS and motivate the need for these novel reflective elements. In the second part of this paper, we discuss the development work we have performed, including simulation and experimental verification of the boron carbide coating properties, and the expected performance of the final system.

We describe a set of two cooled mirrors used in tandem on a high-heat-load undulator beamline at the Advanced Photon Source (APS) to spatially split an incoming X-ray beam into two parts, allowing simultaneous operation on two beamlines. Such arrangements have the potential to increase beamline throughput by as much as a factor of two at a modest cost. Conceptual design, engineering analyses, and fabrication steps are outlined.

The directly water-cooled first crystal of the SPring-8 standard monochromator for bending magnet beamlines has been developed. Thanks to the bonding technique, the performance of the new crystal has been improved without decreasing the cooling efficiency. The finite element analyses show the deformation of the crystal by the hydraulic pressure and by the crystal clamping is negligible small, which were dominated for the previous crystal. Both Si(111) and Si(311) crystal were evaluated in SPring-8 beamlines, the deformation induced while the bonding process is comparable to the thermal deformation. and long-term endurance test shows the lifetime of the O-ring becomes long because they are not on the direct path of the SR beam. Although the overall performance is insufficient, much improvement was shown.

Direct cooling is adopted for most high heat load components in SPring-8 beamlines. On the other hand, contact cooling is employed for some components such as a graphite filter, aluminum filter, mirror, and cryogenic monochromator silicon crystal. For the thermal design of the contact cooling components, it is important to obtain reliable thermal contact conductance value. The conductance depends on many parameters such as the surface materials, surface roughness, flatness of the surface, interstitial materials, temperature of the contact surface, and contact pressure. An experimental setup is fablicated to measure the conductance at liquid nitrogen temperature and room temperature. The thermal contact conductance of a Si-Cu interface and that of a Si-In-Cu interface are measured at cryogenic temperature at contact pressures ranging from 0.1-1.1 MPa. The conductance of an Al-Cu interface and that of a graphite-Cu interface are measured using gold and silver foils as interstitial materials. The measurements are performed at room temperature and at pressures ranging from 0.5-4 MPa. The experimental setup and the results obtained are presented.

A multilayer coating mirror of Mo/Si is usually used for space science in the spectral range of extreme ultraviolet (EUV), especially for He-II (30.4 nm) radiation, because it is highly stable under vacuum and atmosphere. It has the fairly high reflectivity of 15-20%. However, the space science community needs the coating of higher reflectivity at 30.4 nm radiation for the future satellite missions, especially for the small satellite (to reduce the size of optics). In this work, for developing a new multilayer mirror for He-II radiation, we report the performance of a multilayer consisting of Mg/SiC and the aging in reflectivity under atmosphere and vacuum.

High-reflective multilayer coatings were designed at the wavelength of 106 nm and deposited by different deposition technologies (magnetron sputtering, thermal and e-beam evaporations). Various capping layers were suggested to protect Al/LiF coatings against the surface degradation. The microstructure and the surface morphology of all coatings were studied by Small Angle X-ray Reflectometry (SAXR) and Atomic Force Microscopy (AFM) methods. The optical properties were characterized in the Vacuum Ultraviolet (VUV) spectral range by VUV-reflectometry. Finally, the aging stability of coatings was studied.

A versatile instrument capable of high resolution X-ray optics characterization has been implemented at the ESRF. The Micro-Optics Test Bench (MOTB) is installed in EH2 of BM5 and is located 55 meters from the tangent point of a dipole magnet. Substantial gain has been demonstrated in the characterization of microfocusing and imaging optical elements, including diffractive, refractive and reflective optics.

We have developed a high-resolution monochromator (HRM) for the measurement of nuclear resonant scattering (NRS) of synchrotron radiation by Te-125 at 35.49 keV using the backscattering of sapphire (9 1 -10 68). HRMs for nuclei with excitation energies less than 30 keV have been successfully developed using high angle diffractions by silicon crystals. Nearly perfect silicon crystal, however, is not suitable for high efficient HRMs at higher energy regions because the symmetry of the crystal structure is high and the Debye-temperature is low. Therefore, we used high quality synthetic sapphire crystal, which has low symmetry of crystal structure and high Debye-temperature. The temperature of the crystal was precisely controlled around 218 K to diffract synchrotron radiation with a Bragg angle of π/2 - 0.52 mrad. Energy was tuned by changing the crystal temperature under the condition of constant diffraction angle. Energy resolution was measured by detecting nuclear forward scattering by Te-125 in enriched TeO₂. The relative energy resolution of 2.1×10^-7 is achieved, that is 7.5 meV in energy bandwidth. This HRM opens studies on element-specific dynamics and electronic state of substances containing Te-125.