This PDF file contains the front matter associated with SPIE Proceedings Volume 8777, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

This manuscript presents an overview of recent work performed on x-ray optics development, metrology and calibration for the Soft X-ray Research (SXR) and the Coherent X-ray Imaging (CXI) instruments at the Linac Coherent Light Source (LCLS) free-electron laser. We also present results on the first LCLS exposures of boron carbide (B4C)-coated samples at photon energies near the carbon K edge and discuss relevant analysis and implications for future experiments.

Vacuum ultraviolet (VUV) –ultraviolet (UV) multiwavelength excitation process for high-quality ablation of fused silica, in which VUV laser beam with low laser fluence and UV laser beam with relatively high fluence are simultaneously irradiated, is reviewed. Ablation mechanism is explained as absorption of the UV laser by excited-states formed by the VUV laser irradiation (excited-state absorption: ESA). A coaxial irradiation system of F₂ (157 nm) and KrF excimer (248 nm) lasers has been developed for this process. This system performs well-defined micropatterning of not only fused silica but also other advanced materials including sapphire and GaN with little thermal influence and little damage. The discussion includes characterization of optimum experimental conditions and the detailed mechanism of multiwavelength excitation process.

We studied 1-on-1 and 10-on-1 damage threshold investigations on Mo/Si multilayers with EUV radiation of 13.5 nm wavelength, using a table-top laser produced plasma source based on solid gold as target material. The experiments were performed on different types of Mo/Si mirrors, showing no significant difference in single pulse damage thresholds. However, the damage threshold for ten pulses is ≈ 60 % lower than the single pulse threshold, implying a defect dominated damage process. Using Nomarski (DIC) and atomic force microscopy (AFM) we analysed the damage morphologies, indicating a primarily thermally induced damage mechanism. Furthermore, we studied the radiationinduced change of reflectivity upon damage of a multilayer mirror. Additionally, we characterised transmission and reflection properties of novel Mo/Si multilayer beam splitters performing wavefront measurements with a Hartmann sensor at 13.5 nm wavelength. Such wavefront measurements allow also actinic investigations of thermal lens effects on EUV optics.

We have investigated responses of polymers to EUV radiation from laser-produced plasmas beyond ablation thresholds and micromachining. We concentrated on fabricate precise 3D micro-structures of PDMS, PMMA, acrylic block copolymers (BCP), and silica. The micromachining technique can be applied to three-dimensional micro-fluidic and bio-medical devices. The EUV processing is a promising to realize a practical micromachining technique. In the present work, we used two EUV radiation sources; (a) Wide band EUV light in a range of 10{300 eV was generated by irradiation of Ta targets with Nd:YAG laser light at 500 mJ/pulse. (b) Narrow band EUV light at 11 and 13 nm was generated by irradiation of solid Xe and Sn targets, respectively, with pulsed TEA CO2 laser light. The generated EUV light was condensed onto the materials at high power density beyond the ablation thresholds, using ellipsoidal mirrors. We found that through-holes with a diameter of one micrometer an be fabricated in PMMA and PDMS sheets with thicknesses of 4-10 micrometers, at 250 and 230 nm/shot, respectively. The effective ablation of PMMA sheets can be applied to a LIGA-like process for fabricating micro-structures of metals for micro- and nano-molds. PDMS sheets are ablated if it is irradiated with EUV light beyond a distinct threshold power density, while PDMS surfaces were modified at lower power densities. Furthermore, BCP sheets were ablated to have 1-micrometer structures. Thus, we have developed a practical technique for micromachining of PMMA, PDMS and BCP sheets in a micrometer scale.

We report results of experiments connected with surface modification of materials with an intense extreme ultraviolet (EUV) laser beam. Irradiated by the laser beam from a discharge-plasma EUV source (with wavelength of 46.9 nm) based on a high-current capillary discharge driver, the samples have been investigated by atomic-force microscope (AFM). The laser beam is focused with a spherical Si/Sc multilayer-coated mirror on polymethylmethacrylate (PMMA), gold-covered- PMMA and gallium arsenide (GaAs) samples. It turned out that desorption and ablation regimes, which are observed in all these cases strongly depends on substrate materials.

Extreme ultraviolet (EUV) is an ionizing radiation strongly absorbed in any kind of mater. In case of polymers absorption depth is of the order of 100 nm. Interaction of EUV photons with polymer chains results in chain scission and formation of low weight fractions. In this work interaction of intense EUV pulses with poly(vinylidene fluoride) (PVDF) was investigated. Mass spectroscopy was employed to investigate the ablation products indicating emission of numerous molecular species of C-containing fragments of the polymer chain. Chemical surface changes after irradiation were investigated using X-ray photoelectron spectroscopy (XPS). The XPS spectra obtained for PVDF, samples irradiated with low and high EUV fluence, indicate significant differences between chemical structures in near-surface layers. It was shown that irradiation with low fluence results in defluorination and thus carbon enrichment in near-surface layer. In contrary, irradiation with high fluence leads to intense material ablation and hardly modifies the chemical structure of the remaining material. Additionally chemical modification of the PVDF surface by EUV irradiation in a presence of ionized nitrogen was investigated. The nitrogen gas, injected into an interaction region, was ionized and excited by the EUV radiation from a laser-plasma source. An ionization degree and excited states of nitrogen were investigated using an EUV spectrometry and the corresponding spectra are presented. Chemical modification of the polymer after combined EUV and ionized nitrogen treatment was investigated using an X-ray photoelectron spectroscopy. Significant contribution of the nitrogen atoms in the polymer near-surface layer after the treatment was demonstrated.

When a semiconductor or a dielectric is irradiated with ultrashort intense X-ray pulse, several processes occur: first the photoabsorption brings the electron subsystem out of equilibrium, bringing valence or deeper shells electrons into high energy states of the conduction band. Then, secondary electron cascading promotes further electrons of the valence to conduction band increasing their number there. These electrons also influence the atomic motion, modifying the interatomic forces. This process is known as a nonthermal melting. It can turn a material into a new phase state on ultrashort timescales. Recently developed hybrid model for treating all of these processes with different computational tools was reported in [N. Medvedev et al, New J. Phys. 15, 015016 (2013)]. Based on this model, we present here further investigations of nonthermal processes occurring in diamond under irradiation with a FLASH pulse of 10 fs FWHM and 92 eV photon energy. It is shown that the diamond turns into graphite under such irradiation, independently whether constant pressure or constant volume modeling is performed. However, for the latter case, the time of the nonthermal phase transition is longer (few tens of fs for P=const vs few hundreds of fs for V=const) and the damage threshold is slightly higher (0.69 eV/atom vs 0.74 eV/atom, correspondingly).

A numerical study of the interaction of short (15 fs), intense (10¹⁶ − 2 × 10¹⁷ W/cm²), soft X-ray pulses with vanadium targets has been performed by means of a 1D hydrodynamics code. The code which considers the non-equilibrium between electrons and ions, includes a proper treatment of the atomic processes involved in the absorption of x-ray photons and in the evolution of the subsequent heated material. By associating the ablation depth to the spatial profile of the shock wave into the material, numerical values of this ablation depth have been obtained.

Availability of numerical model providing reliable estimation of the parameters of ablation processes induced by extreme ultraviolet laser pulses in the range of nanosecond and sub-picosecond timescales is highly desirable for recent experimental research as well as for practical purposes. Performance of the one-dimensional thermodynamic code (XUV-ABLATOR) in predicting the relationship of ablation rate and laser fluence is investigated for three reference materials: (i) silicon, (ii) fused silica and (iii) polymethyl methacrylate. The effect of pulse duration and different material properties on the model predictions is studied in the frame of this contribution for the conditions typical for two compact laser systems operating at 46.9 nm. Software implementation of the XUV-ABLATOR code including graphical user's interface and the set of tools for sensitivity analysis was developed. Global sensitivity analysis using high dimensional model representation in combination with quasi-random sampling was applied in order to identify the most critical input data as well as to explore the uncertainty range of model results.

An overview is presented on various structural changes in non-metallic materials induced by electronic excitations from the viewpoints of energy transfer, relaxation, and symmetry breaking. Photonic irradiation to solids excites valence and/or core electrons, which creates imbalance in atomic forces. The key mechanism of extrinsic self-trapping is introduced to understand strong carrier localization and symmetry-breaking structural instability in connection with the Jahn-Teller effect. Structural changes induced by intense photonic irradiation are discussed including desorption, phase transition, laser annealing, and nonthermal melting.

Interaction of the X-ray Free Electron Laser (XFEL) femtosecond pulses with a crystal is investigated beyond the means of the conventional linear response theory. In order to analyze the time dependence of the X-ray scattering properties of a crystal we analyze the electron density evolution on the basis of rate equations.¹ In order to take into account the influence of the electron plasma that appears due to the ionization of the atoms of a crystal we couple the system of rate equations to the Boltzmann kinetic equation. As a result, the system of master equations involves such evolution channels as: photoionization, Auger recombination, electron impact ionization, electron-electron scattering and three body recombination. In order to consider these channels effectively expressions for the cross sections of these processes are calculated within the framework of the effective charge approximation.² The numerical algorithm and software are developed for calculation of the intensity of the diffraction reflection of the XFEL pulse taking into account the specific characteristics of the kinetic processes in a crystal. Numerical results are analyzed on the example of the Si crystal in the wide range of the pulse parameters variation.

The fourth generation of XUV-, soft x-ray- and x-ray-light sources, like the free electron lasers FLASH and FERMI@Elettra, leads to new seminal scientific findings and technical challenges. For the facilities the question of the beam transport is of utmost importance. To provide a good reflectivity over a large range of photon energies up to about 300 eV mostly carbon coated silicon mirrors illuminated under gracing incidence angle are mostly chosen. Thereby the coating for the mirrors must tolerate high light intensities at high photon energies and also high repetition rates. In the present experiment an amorphous carbon coated silicon substrate was illuminated at photon energies of 21 nm (58 eV) and an average pulse energy of ~27 μJ. The ellipsoidal spot size of 300 μm × 600 μm at FLASH leads to a fluence of 0.019 J/cm². The influence of multiple (100 - 20.000) light pulses to the coated surface is analyzed. Depending on the number of pulses a change in reflectivity is visible under a light microscope. Both an AFM profile and measurements with a profilometer yield no topological changes. The investigation of the illuminated spots with a microfocus Raman spectrometer shows a decrease of the carbon signal at higher pulse repetition rates.

With the development of hard X-ray free electron lasers, there is a pressing need to experimentally determine the single shot damage limits of presently used and potential future optical coating materials. To this end we present damage results, and analysis of fluence threshold limits, from grazing incidence geometry experiments conducted at the Spring-8 Angstrom Compact free electron LAser (SACLA) on Carbon coatings at 7 and 12 keV photon energies.

Here is presented the spectroscopic study of the evolution of the first buried interfaces of a B₄C capped Co/Mo₂C multilayer mirror induced by thermal treatment up to 600°C. This kind of study is typically performed to simulate the response of multilayer optics working in extreme conditions, as for instance when irradiated by new high brilliance sources as Free Electron Lasers. In fact, the efficiency of multilayers is related to the optical contrast between the alternating high and low density layers, and then to the degree of interdiffusion and the creation or evolution of interface compounds. The analysis has been performed at the Co L₂₃ edge with different soft x-ray spectroscopic techniques including diffuse and specular reflectivity, total electron and fluorescent yield at the BEAR beamline at Elettra (Trieste) (http://www.elettra.trieste.it/elettra-beamlines/bear.html). The presentation is focused on the spectroscopic results obtained by soft x-ray standing wave enhanced photoemission (XSW) from the Mo 3d, B 1s, C 1s, O 1s core levels by using a photon energy close to the Co L₂₃ edge and corresponding to the first Bragg peak of the multilayer. The experimental results have been compared with simulations to obtain information both on the chemical state (e.g. oxidation state) and interface morphology in terms of profiles of distribution of elements and interdiffusion of B, oxidized B and C in the interface region. In summary, it is possible to conclude in favour of a good stability of the multilayer in the investigated temperature range, as confirmed by the good performance in terms of reflectivity. These results confirm the usefulness of XSW for this kind analysis of multilayer optics.

Understanding the ultrafast dynamics of matter under extreme conditions is relevant for structural studies and plasma physics with X-ray lasers. We used the pulses from free-electron lasers (FLASH in Hamburg and LCLS in Stanford) to trigger X-ray induced explosions in atomic atoms (Xe) and molecular clusters (CH₄ and CD₄). The explosion dynamics depends on cluster size and the intensity of the X-ray pulse, and a transition from Coulomb explosion to hydrodynamic expansion is expected with increasing size and increasing pulse intensity. In methane clusters experiments at FLASH, the time-of-flight spectrometry shows the appearance of molecular adducts which are the result of molecular recombination between ions and molecules. The recombination depends on the cluster size and the expansion mechanism and becomes significant in larger clusters. In Xenon cluster experiments at the LCLS, measurements of the ion charge states in clusters suggest a formation of Xe nanoplasma which expands hydrodynamically. The dominance of low charge states of Xe is due to three-body recombination processes involving electron and Xe ions, and it depends on the X-ray intensity and nanoplasma formation.

The high intensity and high repetition rate of the XFEL, the European X-ray Free-Electron Laser presently under construction in Hamburg, results in X-ray doses of up to 1 GGy in silicon sensors for 3 years of operation. Within the AGIPD Collaboration the Hamburg group has systematically studied X-ray-radiation damage using test structures and segmented sensors fabricated on high-ohmic n-type silicon. MOS Capacitors and Gate- Controlled Diodes from 4 vendors with different crystal orientations and different technological parameters, as well as strip sensors have been irradiated in the dose range between 10 kGy and 1 GGy. Current-Voltage, Capacitance/Conductance-Voltage and Thermal Dielectric Relaxation Current measurements were used to extract oxide-charge densities, interface-trap densities and surface-current densities as function of dose and annealing conditions. The results have been implemented into TCAD simulations, and the radiation performance of strip sensors and guard-ring structures simulated and compared to experimental results. Finally, with the help of detailed TCAD simulations, the layout and technological parameters of the AGIPD pixel sensor have been optimized. It is found that the optimization for sensors exposed to high X-ray doses is significantly different than for non-irradiated sensors, and that the specifications of the AGIPD sensor can be met. In 2012 sensors have been ordered, the first batch has been delivered recently, and first results on a comparison between simulations and measurements will be presented.

Solid material damaging induced by an intense and short electromagnetic pulse is accompanied by structural modifications, such as solid/solid phase transition, solid/liquid phase transition or ablation. In such an interaction, the energy is mainly absorbed by electrons, and then transferred to the lattice over a 1 − 10 ps time scale. Such out-of-equilibrium physics is the subject of intense experimental and theoretical work, rising fundamental questions about the thermal or non-thermal nature of phase transitions, the softening or hardening of chemical bonds, and the competition between thermal ablation and coulomb explosion. Here, an experimental technique based on pump-probe interfero-polarimetry in reflection, is presented. It allows us to measure the reflectivity and phase shift of an optical probe reflecting on the sample, in both P and S polarization directions, with a sub-100 fs time resolution. The accuracies on phase shift and on reflectivity are 10 mrad and 1%, respectively. These quantities depend on both the sample optical properties (dielectric function) and the heated sample hydrodynamics. Careful comparison of signals in P and S polarizations allows us to distinguish between optical properties and hydrodynamics contributions. Optical properties give information about the dynamics of the electron properties which drive the damage formation, while the hydrodynamic contribution includes sample surface motion and modofication of the electron density profile, at the nanometer scale. This interfero-polarimetry technique was employed to study damage on aluminum induced by an infrared ultrashort laser pulse (800 nm, 30 fs, 1 J:cm^-2)

It is well known that at interaction of femtosecond Extreme Ultraviolet Radiation (XUV) with a surface it is possible – according to local fluency - to distinguish two main regions: the desorption region (when efficiency η of removing particles is <10%), and the ablation region (when efficiency η ~ 100%). In this case, the ablation threshold determination is very simple and relatively accurate. It was e.g. shown that with the help of mapping of morphology of the ablationdug- craters it is possible to determine the fluency distribution in/near the beam focus. However, recently we found that (1) the desorption efficiency η for nanosecond pulses is much higher than that for femtosecond ones and spans from zero at the periphery imprint to ~90% at the ablation threshold; this complicates the ablation threshold determination; (2) the direct nano-structuring of solid surfaces is possible only in the desorption region (e.g. the diffraction pattern generated in windows of in-proximity-standing-grid [K.Kolacek et.al., Laser and Particle Beams 30, 57-63, (2012)] is visible only in these parts of laser-beam-spot, which correspond to the desorption region). This prompted us to use this nano-patterning for determination of ablation threshold contour. The best possibility seems to be covering the laser beam spot by interference pattern. For that, it was necessary to develop a new type of interferometer, which (a) provides as dense interference pattern as possible, (b) uses practically all the energy of laser beam, (c) works with focused beams. Such interferometer has been designed and is described in this contribution.

In this study, we present the results from an analysis of the various aspects of the low pressure RF plasma cleaning process for the removal of graphitic carbon contamination layers deposited on different test objects. After determining the optimum parameters for a time-minimized cleaning process using an inductively coupled plasma source as well as oxygen/argon mixtures as feedstock gas, a special emphasis has been put on the characterization of the cleaned surface (Au, Ni, Rh) both in their pristine as well as in their cleaned state. This includes the physical as well as the chemical properties of the surfaces involved. Last but not least, an effort has been made to characterize/monitor the RF plasma during the cleaning procedure in order to allow for an improved process control.

This work presents the results of long-term observation of the silicon photodiodes spatial profile response and the silicon photodiodes dark current after their exposure to 10.2 eV quanta and in the spectral range of 150–300 eV. Exposure of the photodiodes to quanta of an energy of 10.2 eV was repeated. Several other photodiodes have been irradiated in the spectral range of 700-1800 eV with a dose of 8 J/cm². The spatial profile of the irradiated photodiodes was studied with 3.49 eV, 10.2 eV and 100 eV quanta. The effect of the recovery of the response spatial profile has been proved for the p⁺-n diode. An additional useful method of visualization of irradiated photodiode area is also presented.

We model numerically the interaction of an ultrashort VUV laser pulse (FWHM = 10 fs, photon energy of 100 eV) with liquid water. The incident laser photons interact with water by ionizing water molecules and creating free electrons. These excited electrons are elastically scattered by water molecules and are able to produce secondary electrons via ionization. To track each free electron and its collisions event by event, we use the Monte Carlo method similar to (N. Medvedev and B. Rethfeld, Transient dynamics of the electronic subsystem of semiconductors irradiated with an ultrashort vacuum ultraviolet laser pulse, New Journal of Physics, Vol. 12, p. 073037 (2010)). This approach allows us to describe the transient non-equilibrium behaviour of excited electrons on femtosecond time scales. We present transient electron energy distributions and a time resolved energy transfer, i.e.: the changing kinetic energy of excited electrons, the increase of the energy of holes, and excitation of water molecules via elastic collisions. We compare results obtained with different models for the energy levels in liquid water: either assuming dense water vapour or an amorphous semiconductor with a band gap.

A super-polished substrate with an off-axis parabola figure was coated with a Sc/B₄C/Cr multilayer. This optic was used to focus pulses of 4.3 nm photons from the Free-electron LASer in Hamburg (FLASH) at normal incidence. Beam imprints were made in poly(methyl methacrylate) to align the optic and to measure the beam profile at the focal plane. The intense interaction resulted in imprints with raised perimeters, surrounded by ablated material extending out several micrometres. These features interfere with the beam profile measurement. The effect of a post-exposure development step on the beam imprints was investigated.

The aim of this work is to design and build a source for a range of applications, with optimized multilayer structures in order to use the source output as efficiently as possible. The source is built around a Nd:YAG laser with fundamental wavelength 1064 nm, frequency doubled 532 nm (green) and tripled 355 nm, with a pulse length of about 800 ps and a repetition rate up to 50 Hz. The target material is Mylar (C₁₀H₈O₄) tape, which is cheap, readily available and has many benefits as explained in this article. A versatile cubic target chamber and a set of computer controlled stage motors are used to allow positioning of the X-ray emission point. A range of measures is used to protect delicate components and optics, including a glass slide between the focusing lens and the target to prevent the lens being coated with debris. A low pressure gas (typically 3–6 mbar) is used inside the chamber as collision of atomic size debris particles with gas molecules reduces their kinetic energy and consequently their adhesion to the surrounding surfaces. The gas used is typically helium or nitrogen, the latter also acting as a spectral filter. Finally, the chamber is continually pumped to ensure that more than 70% of the debris particles are pumped out of the chamber.

NASA's Marshall Space Flight Center (MSFC) has a successful history of fabricating optics for astronomical x-ray telescopes. In recent years optics have been created using electroforming replication for missions such as the balloon payload HERO (High energy replicated optics) and the rocket payload FOXSI (Focusing Optics x-ray Solar Imager). The same replication process is currently being used in the creation seven x-ray mirror modules (one module comprising of 28 nested shells) for the Russian ART-XC (Astronomical Rontgen Telescope) instrument aboard the Spectrum-Roentgen-Gamma mission and for large-diameter mirror shells for the Micro-X rocket payload.

In addition to MSFC's optics fabrication, there are also several areas of research and development to create the high resolution light weight optics which are required by future x-ray telescopes. Differential deposition is one technique which aims to improve the angular resolution of lightweight optics through depositing a filler material to smooth out fabrication imperfections. Following on from proof of concept studies, two new purpose built coating chambers are being assembled to apply this deposition technique to astronomical x-ray optics. Furthermore, MSFC aims to broaden its optics fabrication through the recent acquisition of a Zeeko IRP 600 robotic polishing machine. This paper will provide a summary of the current missions and research and development being undertaken at NASA's MSFC.

In this work, we investigate a novel design of optical system for astrophysics. In addition, a new testing method in the X-ray laboratory was verified. The proposed optical system is composed of modules with Kirkpatrick-Baez configuration allowing usage of multi-foil mirrors arranged to parabolic profile. This system effectively uses a circular aperture, which is divided into petals. Individual petals consist of diagonally oriented KB cells with common focus. The hybrid optical system includes a set of rotationally symmetrical parabolic mirrors to achieve higher reflection efficiency of harder X-rays. New results are presented.

We perform ray-tracing simulations aimed at investigating the impact on the overall sensitivity of eROSITA of possible small errors in the mechanical shaping and positioning of the baffle rings above the mirror modules, to estimate to what extent they may contribute to degrade the efficiency of the baffle in eliminating the stray-light at the focal plane as well as to increase at the same time the vignetting, then reducing the effective area of the mirrors. Through the simulations we identify the ranges of acceptable tolerances.

Space X-ray imaging telescopes have delivered unique observations that have been significantly contributing to many important discoveries of current astrophysics. For future telescopes with a larger collecting area and a better angular resolution, the limiting factor is their X-ray reflecting mirror array. Therefore, for a successful construction of future lightweight and highly reflecting X-ray mirrors, new cost-effective technologies and progressive materials are needed. Currently, the very promising materials are silicon foils which are commercially produced on a large scale. We focused on the plastic deformation of thin monocrystalline silicon foils, which was necessary for the precise thermal forming of the foils to 3D shapes. To achieve the plastic deformation, we applied forced slumping at temperatures from 1200 to 1400°C. The final shapes and the surface quality of the foils were measured using a Taylor Hobson contact profilometer and examined with an Atomic Forced Microscopy. We studied the effects of temperature, applied slumping force, heattreatment time, crystal orientation, and furnace atmosphere on the shape and surface quality of the formed foils.

A method simplifying the common ray-tracing procedure is presented. In some specific cases, to perform numerical simulations of reflective optical system, not traces of all rays are necessary to simulate but only of few ones. Therefore, the presented method is extremely effective. Moreover, to simplify the equations, the specific mathematical formalism is used. Because only few simple equations are used only, the program code can be simple as well.

We present the idea of a low-cost satellite providing permanent monitoring of X-ray binaries. These systems contain a compact object (a neutron star or a black hole) accreting matter from a donor companion. They concentrate in the vicinity of the Galactic plane and toward the center of the Galaxy. It therefore appears very advantageous to point the telescope toward the Galactic center. The strong activity of X-ray binaries with non-predictable episodes of brightening suggests that we can obtain meaningful and physically important information even by a study using a small, inexpensive satellite. The proposed spacecraft can be of the nano-satellite class. We propose Schmidt lobster optics for this satellite. The results of experimental tests of the specimen of such optics show that the mission is feasible.

The Clessidra prism array lens appears like an hourglass with two perfectly triangular opposing areas. Each of these halves is then formed of a multitude of smaller abutting triangular prisms. These devices focus an incident plane X-ray wave into a focus by refraction. Due to the wavelength dependence of the refractive index the focusing is suffering from chromatic aberrations. This can be used in order to operate the structure as a monochromator in combination with an exit slit. Photon energy tuning in a fixed exit slit is possible, when the structure is rotated around an axis, which is perpendicular with respect to the incident beam and perpendicular to the bases of the prisms. Such a rotation can be performed with rather high speed. In this study the advantages of this concept for the energy tuning are discussed as are the limitations.

Dedicated diffractive VUV- and X-ray optical elements are essential for future developments in synchrotron instrumentation and methods like e.g. time-resolved spectroscopy. The quality of optical components like gratings or diffractive focusing elements matters directly to the results achievable. On the other hand the availability of such optical components is very limited at present. In this contribution we report on the development of new methods of time-resolved x-ray spectroscopy based on novel 3D diffractive optical elements (DOE) with a unique combination of properties. Such optical elements are of highest interest for application in modern synchrotron facilities like Free Electron Lasers (FELs) as well as for laboratory facilities with high harmonic generators (HHG). The project includes theoretical work as well as the development of a dedicated technology, including metrology, to manufacture such type of optics for applications in atomic, molecular and condensed matter physics. The here discussed type of optics was successfully implemented for soft-X-ray-application at the femto-second-slicing beamline at BESSY II storage ring of the Helmholtz Zentrum Berlin. DOE are expected to be important components in beamlines at upcoming new high brilliance X-ray sources such as FELs. The application of DOE`s allows to reduce the number of optical elements in a beamline. Thus allow to provide the highest possible transmission and flux as well as preserving the unique properties of FEL´s, like wave-front and coherence.

Refractive optics is proposed as a Fourier transformer for high resolution X-ray crystal diffraction. Employing refractive lenses the wave transmitted through the object transforms into spatial intensity distribution at its back focal plane according to the Fourier relations. A theoretical consideration of the Fourier transform technique is presented. Two types of samples were studied in Bragg reflection geometry: a grating made of strips of a thin SiO₂ film on Si substrate and a grating made by profiling a Si crystal. Rocking curves of Si(111) Bragg reflection and corresponding Fourier patterns were analyzed.

Grazing-incidence optics for X-ray applications require extremely smooth surfaces with precise mirror figures to provide well focused beams and small image spot sizes for astronomical telescopes and laboratory test facilities. The required precision has traditionally been achieved by time-consuming grinding and polishing of thick substrates with frequent pauses for precise metrology to check the mirror figure. More recently, substrates with high quality surface finish and figures have become available at reasonable cost, and techniques have been developed to mechanically adjust the figure of these traditionally polished substrates for ground-based applications. The beam-bending techniques currently in use are mechanically complex, however, with little control over mid-spatial frequency errors. AOA-Xinetics has been developing been developing techniques for shaping grazing incidence optics with surface-normal and surface-parallel electrostrictive Lead magnesium niobate (PMN) actuators bonded to mirror substrates for several years. These actuators are highly reliable; exhibit little to no hysteresis, aging or creep; and can be closely spaced to correct low and mid-spatial frequency errors in a compact package. In this paper we discuss recent development of adaptive x-ray optics at AOA-Xinetics.

The future of X-ray astronomy requires heavily nested large area X-ray mirrors with arcsecond angular resolution in future X-ray astrophysics experiments. Despite of promising results of several exploited technologies during the past decade, it is not demonstrated yet that these technologies will provide the angular resolutions better than few arcsec. The alternative approach is the method of active X-ray optics. In addition, active approaches based on computer control may be applied directly during manufacturing of advanced X-ray optics elements, such as substrate slumping. In this report, we present and discuss preliminary results of X-ray tests of various modules in active X-ray optics arrangements.

Photon-based (bosonic-type) imaging at short wavelength vs. electron, or recently neutron, imaging has additional advantages due to different interaction of photons with matter and thus high resolution photon-based imaging is still of high interest to the scientific community. In this work we try to combine the advantages of employing compact, laboratory type laser-plasma short wavelength source, based on Ar/He gas puff target, emitting incoherent radiation, with the “water-window” spectral range. This unique combination is highly suitable for biological imaging, and allows developing a small size microscopy setup, which might be used in various fields of science and technology. Thus, in this paper we report on recent advances in “water-window” desk-top microscopy setup employing a laser-plasma SXR source based on a double stream gas puff target and Wolter type-I objective. The system allows capturing magnified images of the objects with ~1 μm spatial resolution up to ~40 μm thickness and single SXR pulse exposure time as low as 3 ns. For the SXR microscope Ar plasma was produced by focusing of the pumping laser pulses, from Nd:YAG laser (Eksma), by a lens onto a gas puff target. EUV radiation from the plasma was collected and focused by an ellipsoidal, axi-symmetrical nickel coated condenser mirror, developed by Rigaku, Inc. The condenser is a broad-band optic, capable of efficiently reflecting radiation from the EUV range down to SXR region with energy cut-off of ~800 eV. To spectrally narrow the emission from argon plasma a free-standing titanium filter (Lebow) was used. Spectrally filtered radiation illuminates the sample. Then the sample was imaged onto a SXR sensitive back-illuminated, CCD camera (Andor) by a Wolter type-I reflective objective. A characterization and optimization of both the source and the microscope setups are presented and discussed.

A new channel of an X-ray broadband spectrometer has been developed for the 2 – 4 keV spectral range. It uses a spectral filtering by using a non-periodic multilayer mirror. This channel is composed by a filter, an aperiodic multilayer mirror and a detector. The design and realization of the optical coating mirror has been defined such as the reflectivity is above 8% in almost the entire bandwidth range 2 – 4 keV and lower than 2% outside. The mirror is optimized for working at 1.9° grazing incidence. The mirror is coated with a stack of 115 chromium / scandium (Cr / Sc) non-periodic layers, between 0.6 nm and 7.3 nm and a 3 nm thick top SiO₂ layer to protect the stack from oxidization. To control thin thicknesses, we produced specific multilayer mirrors which consist on a superposition of two periodic Cr / Sc multilayers with the layer to calibrate in between. The mirror and subnanometric layers characterizations were made at the “Laboratoire Charles Fabry” (LCF) with a grazing incidence reflectometer working at 8.048 keV (Cu Kα radiation) and at the synchrotron radiation facility SOLEIL on the hard X-ray branch of the “Metrology” beamline. The reflectivity of the mirrors as a function of the photon energy was obtained in the Physikalisch Technische Bundesanstalt (PTB) laboratory at the synchrotron radiation facility Bessy II.

We report on further development of reflective multilayer coatings containing aluminum as low absorbing material for the extreme ultra-violet (EUV) applications, in particular for solar physics. Optimizations of the multilayer design and deposition process have allowed us to produce Al-based multilayers having relatively low interface roughness and record EUV reflectances in the range from 17 to 40 nm. The peak reflectance values of 56 % at 17.5 nm, 50 % at around 21 nm, and 42 % at 32 nm were achieved with new three-material multilayers Al/Mo/SiC and Al/Mo/B₄C at near-normal incidence. We observe a good temporal stability of optical parameters of the multilayers over the period of 4 years. Moreover, the multilayer structure remains stable upon annealing at 100 °C in air during several weeks. We will discuss the optical properties of more complex Al-based systems with regard to the design of multilayer coatings that reflect more than one wavelength and reject some others within the spectral range from 17 to 40 nm. Such multichannel systems with enhanced reflectance and selectivity would provide a further advance in optical performance and compactness of EUV solar imaging instruments. We will discuss general aspects of design, optimization and fabrication of single- and multi-channel multilayer mirrors made with the use of aluminum. We will present recent results on the EUV reflectivity of multilayer coatings based on the Al/Mo/SiC and Al/Mo/B₄C material combinations. Al-based multilayer systems are proposed as optical coatings in EUV telescopes of future space missions and in other EUV applications.

Polarimetry in the far ultraviolet (FUV) is a powerful tool for the interpretation of the role of the coronal plasma in the energy transfer processes from the inner parts of the Sun to the outer space. FUV polarimetry from space provides more accurate observations on the kinetics of the features and on local magnetic fields through the Doppler and Hanle resonant electron scattering effects. Particularly interesting lines for FUV polarimetry are H Lyman α (121.6 nm) and β (102.6 nm), along with OVI lines at 103.2 and 103.8 nm. One key element to perform polarimetry measurements at these wavelengths is the need of efficient polarizers. A limitation of the available polarizers, such as crystal plates of MgF₂ and LiF working at Brewster angle, is their moderate reflectance at the non-extinguished component of the electric field, which results in a modest polarizer efficiency.

Observations in the far ultraviolet (FUV) at wavelengths in the ~100-105 nm range, which include 102.6 nm (H Lyman β), 103.2 and 103.8 nm (O VI lines), are expected to unveil fundamental information for solar physics and astrophysics. Often the intensity of those lines is weak, and they may be masked by more intense lines, such as H Lyman α at 121.6 nm for observations of the solar corona. Narrowband multilayers peaked in the ~100-105 nm have not been available because of the absorption of materials at these wavelengths along with a strong influence of contamination in this range. When efficient narrowband coatings are not possible, an option is the use of coatings with high reflectance at the target wavelength and simultaneously low reflectance at the undesired wavelength, such as 121.6 nm. High-reflective-narrowband coatings peaked at 100-105 nm have been developed. We have designed a four-layer system (Al/LiF/SiC/LiF) that results in a high H Lyman β-to-Lyman α reflectance ratio. Three samples with slightly different film thicknesses were prepared and measured in the 50-190 nm spectral range. All samples showed a promising reflectance ratio when fresh; however, some sample ageing was observed after months of storage in a desiccator, probably due to the effect of reaction with water vapor among other contaminants at the outermost layer (LiF). All samples retained a narrowband performance over time. The reflectance at 121.6 nm, which was very low on fresh samples, typically increased over time, although keeping a high 102.6-to-121.6-nm reflectance ratio. The same system results in an efficient narrowband coating peaked in the target spectral range. We measured a reflectance as high as 63% at the peak wavelength of 100.3 nm, at near-normal incidence, the highest experimental reflectance reported in this range for a narrowband coating.

We report on further development of the optical, structural performances and temporal stability of Al(1%wtSi)/Zr multilayers. The multilayers with variable periods (from 10 to 80) are fitted by four-layer model. Below 40 periods, the surface and interfacial roughnesses are increased with the period numbers, but not decrease the reflectivity of Al(1%wtSi)/Zr multilayers. Above 40 periods, such as 80 periods, the reflectivity is down to 34.7% due to larger roughness and worse interfacial boundary. To improve the reflectivity, we modify some parameters during deposition process. The results in the EUV reflectivity show that the reflectivity of the sample with 40 periods is increased from 41.2% to 48.2%. The temporal stability of Al(1%wtSi)/Zr samples with different annealing temperatures has been observed over 35 days.

In this work photoionized plasmas were created by irradiation of He, Ne and Ar gases with a focused EUV beam from one of two laser-plasma sources employing Nd:YAG laser systems of different parameters. First of them was a 10-Hz laser-plasma EUV source, based on a double-stream gas-puff target, irradiated with the 3-ns/0.8J laser pulse. EUV radiation in this case was focused using a gold-plated grazing incidence ellipsoidal collector in the wavelength range λ = 9÷70 nm. The most intense emission was in the relatively narrow spectral region centred at λ = 11 ± 1 nm. The second source was based on a 10 ns/10 J/10 Hz laser system. In this case EUV radiation was focused using a gold-plated grazing incidence multifoil collector or a Mo-coated ellipsoidal collector. The most intense emission in this case was in the 5 ÷ 15 nm spectral region. Radiation fluence ranged from 60 mJ/cm² to 400 mJ/cm². Different gases were injected into the interaction region, perpendicularly to an optical axis of the irradiation system, using an auxiliary gas puff valve. Irradiation of the gases resulted in ionization and excitation of atoms and ions. Spectra in EUV range were measured using a grazing incidence, flat-field spectrometer (McPherson Model 251), equipped with a 450 lines/mm toroidal grating. In all cases the most intense emission lines were assigned to singly charged ions. The other emission lines belong to atoms or doubly charged ions. The spectra were excited in low density gases of the order of 1 ÷ 10% atmospheric density.

Reflection zone plates (RZP), which consist of elliptical zone plates fabricated on a total external reflection mirror surface, can be effectively used to produce a monochromatic x-ray beam and to focus it at photon energies below 1400 eV. However, as RZPs are highly chromatic, they can be designed only for one specific photon energy. We alleviate this problem by using a novel approach: a Reflection Zone Plate Array (RZPA). Here, we report about successful implementation of novel monochromator based on RZPAs for experiments with 100 fs time resolution at the upgraded Femtoslicing facility at BESSY-II. Aiming at minimum losses in x-ray flux up to 2000 resolution, we fabricated and used an RZPA as a single optical element for diffraction and focusing. Nine Fresnel lenses, designed for the energies of 410 eV, 543 eV, 644 eV, 715 eV, 786 eV, 861 eV, 1221 eV and 1333 eV which correspond to the absorption edges of NK, O-K, Mn-L, Fe-L, Co-L, Ni-L, Gd-M and Dy-M, were fabricated on the same substrate with a diameter of 100 mm. At resolution E/ΔE up to 2000 all edges of other elements in that range (400-1400 eV) are covered, too.

Work reports on results in development of 4H-SiC and semi-insulating (SI) GaAs large area surface barrier detectors. 4H-SiC detectors are based on high purity liquid phase epitaxy layer with the Schottky barrier contact formed by semitransparent Ni. SI GaAs detectors are based on bulk undoped material using novel electrode metallization with improved sensitivity in UV and soft X-ray ranges. The novel detector use semitransparent low work function Mg metal contact giving a new electronic characteristic of the junction. Electrical characteristics of the diodes, photocurrent measurements and pulse height spectra of gamma and low energy X-rays using the ²⁴¹Am source, are presented. Improvement of 4H-SiC detector resistance to gamma radiation and neutron fluency is demonstrated. Problems with design and application of related ultra-low noise electronics are introduced and discussed.