This PDF file contains the front matter associated with SPIE Proceedings Volume 9207 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Hard X-ray free electron lasers provide almost fully transverse coherent X-rays. Though the natural divergence of these X-rays is a few micro-radians, they still need to be collimated or focused while traveling up to 1km towards the sample. This can be done with beryllium compound refractive lenses (CRLs). Due to the coherence of the beam, it is important that the impurities or granular boundaries in these CRLs do not distort the wavefront of the X-ray beam to a measurable extend. We measured the SAXS signal of various beryllium grades and of 2D parabolic lenses made of IF-1 beryllium. Then, we imaged these samples using X-ray computed laminography at a resolution of around 1 micrometer. Computed laminography is a 3D imaging technique similar to computed tomography, but particularly adapted for at extended objects. These measurements are used to characterize the voids and granular boundaries in the beryllium samples. Boundaries between the former powder particles are easily seen for beryllium grades produced via powder metallurgy methods. This is not the case for cast ingots. Common to all samples are voids with diameters in the 10 micrometer range as well as smaller sized, denser impurities. Finally, we use wavefront propagation simulations in order to analyze the effect of voids in the CRLs on the wavefront of the XFEL beam. If the distance "lens to focus and sample" is large enough, the diffraction patterns emerging from the voids smoothen out.

We report a multilens X-ray interferometer consisting of six parallel arrays of planar compound refractive lenses. The main concept of new interferometer is based on the same principle such a bilens interferometer. The interference fringe pattern produced by the multilens interferometer was described by Talbot imaging formalism. A theoretical analysis of the interference pattern formation was carried out and corresponding computer simulations were performed. The proposed multilens interferometer was experimentally tested at ID06 ESRF beamline in the X-ray energy range from 10 to 30 keV. Experimentally recorded fractional Talbot images are in a good agreement with computer calculations.

High-energy x-rays from a synchrotron source are well suited for numerous applications, such as studies of materials structure and stress in bulk or extreme environments. Some of these methods require high spatial resolution. Planar kinoforms are shown to focus monochromatized undulator radiation in the 50–100 keV range down to 0.2–1.5 μm beam sizes at 0.25–2 m focal distances. These lenses were fabricated by reactive ion etching of silicon. At such high x-ray energies, these optics can offer substantial transmission and lens aperture.

A Variable Line Spacing (VLS) diffraction grating has been fabricated using an optical direct write technique. This grating is now in use at the Advanced Light Source, in beamline 12.0.1, delivering light for EUV lithography. Direct Write Lithography (DWL) with focused light at λ = 442 nm was used for the first time to record a VLS grating pattern on a substrate coated with a photoresist. The pattern was transferred to the Si substrate surface using reactive plasma etch. Precision of groove placement was verified by wavefront measurements of a witness grating recorded simultaneously with the VLS pattern. Atomic force microscope measurements confirmed near ideal groove shape and high smoothness of the grating grooves. The grating coated with a Ru coating demonstrated diffraction efficiency of 39.5% in the negative first diffraction order which corresponds to theoretical efficiency at the wavelength of 13.5 nm. This work validates the DWL approach as a promising technique for advanced grating fabrication.

Most of the currently used reflective coatings for EUV and X-ray mirrors are periodic nanometer multilayers. Depending on the number of periods and the absorption in the multilayer stack a certain band width of the incoming radiation can be reflected. In order to increase the integral reflectance or to accept larger ranges of incidence angles, non-periodic multilayers are needed. With the transition from periodic to non-periodic multilayers new challenges arise for the deposition process. Since the reflectance spectra are sensitive to every single layer thickness a precise coating control and an exact knowledge of the interface reactions are required. Furthermore substrate roughness influences the reflectance spectra. With an advanced coating process using additional ion bombardment during thin film growth the integrated reflectance of broadband mirrors can be conserved even for an initial substrate roughness of about 0.7 nm rms.

Stress in multilayer Laue lenses can be reduced by choosing unequal thicknesses for the two layers comprising a bilayer in the zone plate structure. We demonstrate this with the wafer curvature measured in-operando for sputter deposition of WSi2/Si bilayers. The curvature measurements showed that the compressive stress built in the multilayers during the deposition process bent the substrate wafers where these multilayers were coated onto it. Within equal thickness WSi2/Si bilayers, the Si layers contribute more compressive stress than the WSi₂ layers at a 4 mTorr Argon environment. Reducing the ratio of Si’s thickness in the WSi₂/Si bilayer decreased the total stress.

Under synchrotron radiation white beam exposure, strong mechanical stress can build up in multilayer optics, caused by the thermal mismatch between layer material and substrate material. To study the stability and performance of multilayer optics under heat load, Pd, Cr, and B₄C single layers of thicknesses in the nanometer range and [Pd/B₄C] multilayers were prepared in the sputter-depositing facility of the ESRF Multilayer Laboratory. Curvature changes versus temperature were measured using a Shack-Hartmann wave front sensor. Films coated on 200 μm thin Si wafers induced significant curvature changes over a temperature range from 60°C to 200°C. A combined parameter K including Young’s modulus and thermal expansion coefficient (CTE) was defined to describe the thermal deformation properties of the thin-film layer. The investigation shows that all three materials in thin film cause less thermal expansion than expected from material properties for bulk material in the literature. In particular, the thermal expansion of B₄C films appears to be close to that of the Si substrate.

In order to focus light in two dimensions a lens needs to be curved in two orthogonal directions. When the lens is symmetrically oriented around the optical axis this is usually achieved in an object with at least one rotationally symmetric surface. X-rays are refracted very little in such configuration as the refractive index differs very little from unity. However, the deflection angle can be increased at rather grazing angle of incidence. And in this condition X-rays can be refracted significantly and focused upon refraction at concave interfaces. It will be shown here that on passage through a slightly curved rectangular prism at very grazing angle of incidence an X-ray beam can be subject to two consecutive refraction processes at two orthogonal concave interfaces, which will lead to focusing. Such object thus functions like a lens, even though it has little similarity with a classical lens. A proof of principle experiment will be described, in which the focusing is observed. The optical properties of optimised lenses of this type will be very similar to those, which were discussed already for more classical stacks of concave lenses. This refers essentially to the absorption limited aperture and to the achievable spatial resolution. The latter could be smaller than 100 nm.

An electrical response of a diffracting diamond (111) crystal was studied in a single electrode configuration where the electrode was deposited on a small portion of the crystal entrance surface. The experiment was performed in ambient air using an x-ray beam after a Si (111) double-crystal monochromator with the diamond crystal set in the Bragg diffraction condition. It was found that the electric current as a function of the Bragg angle exhibits behavior characteristic of secondary yield curves (e.g.,¹). It is proposed to utilize this effect to monitor the intensity of the Bragg reflected x-ray beam. Such non-invasive monitoring does not rely on the use of stand-alone radiation monitors (e.g., ionization chambers) and is expected to facilitate x-ray optics alignment procedures. As an attempt to improve signal-to-noise ratio by containing the electric field in the optical element an electric response of a high-resistivity silicon crystal was studied in a two-electrode configuration. Preliminary results are reported.

The 2-Dimensional and 3-Dimensional variable line spacing (VLS) gratings based on total external reflection give the unique possibility for spectroscopy and focusing in application to 4^th and 5^th generation synchrotron sources. We focus on the elaboration of novel approaches for design and fabrication of 3D VLS working in the entire energy range, from THz to hard X-rays. These optical elements have unique combination of properties and can operate at all XUV sources including Free Electron Lasers (FELs), Energy Recovery Linacs (ERLs) and High Harmonic Generators (HHGs). Such 3D DOEs are able to cover the energy range of up to 20 keV with energy resolution λ/Δλ ≥ 1000 for soft x-ray and λ/Δλ ≥ 10000 for hard x-ray. We fabricate 3D VLS for time-resolved spectroscopy (energy range 100 – 2000 eV, 7500-9500 eV), FELs and ERLs (energy range up to 3 keV), and HHGs (energy range 10 – 200 eV).

The future beamline Magneto Dynamics (MagneDyn) will be devoted to study the electronic states and the local magnetic properties of excited and transient states of complex systems by means of the time-resolved X-ray absorption spectroscopy (TR-XAS) technique. The beamline will use the high energy source at FERMI covering the wavelength range from 60 nm down to 1.3 nm. An on-line photon energy spectrometer will allow to measure the spectrum with high resolution while delivering most of the beam to the end-stations. Downstream the beam will be possibly split and delayed, by means of a delay line, and then focused with a set of active KB mirrors. These mirrors will be able to focus the radiation in one of the two MagneDyn experimental chambers: the electro-magnet end-station and the Resonant Inelastic X-ray Scattering (RIXS) end-station. After an introduction of MagneDyn scientific case, we will discuss the layout showing the expected performances of the beamline.

In this paper, we present recent progress on polarization optics using the 1-BM beamline at the Advanced Photon Source, Argonne National Laboratory. Beamline 1-BM was recently repurposed for optics and detector testing. SHADOW software, a ray-tracing program for the simulation of optical systems of synchrotron radiation beamlines, is used to model the beamline. In this paper, we present optical ray-tracing studies for test set-ups that take advantage of the polarization variation of the bending magnet radiation above and below the horizontal plane of the beamline.

This paper reports a simplified and compact mechanical scheme designed for providing alternatively high flux or high spectral resolution from a monochromator for the 2 - 14 keV X-ray range in a stationary spot at a sample. The example case treats a bending magnet source at the Elettra storage ring. The properties of the continuously tunable monochromatic beam are adapted for a variety of experimental techniques, which include also the need to operate the sample in the total reflection regime, i.e. at angles of grazing incidence smaller than the critical angle of the sample material. The positional stability of the monochromatised beam during tuning was the major concern in the design of the monochromator.

Advanced research light sources, such as free-electron lasers, require ultra-precise and long x-ray mirrors that provide high reflectivity, high flux and a wide wavelength range. An X-ray mirror is a combination of a substrate and a coating. The demand for large mirrors has increased during the last few years, since surface finishing technology is able to process longer substrate lengths on the rms-level of a few nanometers. A state-of-the-art X-ray mirror could be coated with more than one single layer to allow a selection of thin-film materials suitable for the large wavelength range of a free-electron laser. Presented here is an X-ray mirror fabrication method to achieve low variation in thickness of less than 1 nm (peak-to-valley) over the whole mirror length of about 1 m. Low figure errors and low roughness are essential for a wave front preserving transport of photons and a high reflectance of a mirror surface. At FLASH II, the new extension of the Free-electron LASer in Hamburg (FLASH) at DESY, Germany, the wavelength range will be 4-80 nm. It is further expected that the photon beam will possess average single pulse energy of 1-500 μJ, pulse duration of 10-300 fs (FWHM), and peak power of 1-5 GW. At the Helmholtz-Zentrum Geesthacht, an in-house designed magnetronsputtering facility enabled us to deposit single layers and multilayers on up to 1.5 m long substrates. Earlier results confirmed the excellent uniformity of X-ray optical coating properties in the tangential and sagittal direction of the mirrors. Moreover, the deposition facility provided the simultaneous fabrication of two mirrors to achieve identical properties. Thin films of amorphous carbon (a-C), boron carbide (B4C) and nickel (Ni) are deposited by means of magnetron sputtering. The thin-film properties were investigated and analyzed by means of X-ray reflectometry (XRR), atomic force (AFM), and interference microscopy. The experimental results were analysed using simulations for the determination of layer thickness, density and roughness.

The Advanced Photon Source (APS) has recently invested resources to upgrade or replace aging deposition systems with modern equipment. Of the three existing deposition systems, one will receive an upgrade, while two are being replaced. A design which adds a three-substrate planetary for the APS rotary deposition system is almost complete. The replacement for the APS large deposition system, dubbed the “Modular Deposition System”, has been conceptually designed and is in the procurement process. Eight cathodes will sputter horizontally on mirrors up to 1.5 meters in length. This new instrument is designed to interface with ion-milling instruments and various metrology equipment for ion-beam figuring. A third linear machine, called the APS Profile Coating System, has two cathodes and is designed to accept substrates up to 200mm in length. While this machine is primarily intended for fabrication of figured KB mirrors using the profile-coating technique, it has also been used to produce multilayer monochromators for beamline use.

On the upgraded ESRF soft x-ray beamline ID32 a new spectrometer for Resonant X-ray Inelastic Scattering (RIXS) will be installed. To operate in fully polarized mode, a polarimeter will be inserted in the instrument to measure simultaneously the energy spectra and the linear polarization. The new spectrometer works between 500 eV and 1000 eV and requires graded multilayers to optimize the energy tunability and the polarization sensitivity. The present work covers the design, the fabrication, and the characterization of the multilayers. Performance evaluations during test and commissioning experiments with soft x-rays complement the paper.

Phase controlled multilayer mirrors provide an efficient solution to transport, focus and/or compress attosecond pulses in the extreme ultraviolet (EUV) domain (30 – 100 eV). In this spectral range, one can access the spectral phase of the multilayer stack by measuring the photocurrent generated at the mirror surface as a function of the incoming photon energy. It has been already demonstrated that one can extract the spectral phase from such measurements under specific hypotheses. In this paper, we present the experimental protocol for such measurements and discuss the validity of this technique in the EUV and in the soft x-ray domains. In the EUV spectral range, our experimental results are in good agreement with simulations. However, the previous hypotheses are no longer valid at shorter wavelengths, in the soft xrays domain. This is mainly due to the fact that the electron mean free path becomes comparable to the individual layer thickness in the multilayer mirror. Here we propose a new method that enables one to extend the validity of phase characterization using photocurrent measurements in the soft x-ray domain (100 – 1000 eV). We present the first experimental results concerning the phase characterization of Cr/Sc multilayer mirrors in the water window and compare these results with simulation.

Recent advances in the development of attosecond soft X-ray sources ranging into the ‘water window’ spectral range, between the carbon 1s and oxygen 1s states (284 eV - 543 eV), are also driving the development of suited broadband multilayer optics for attosecond beam steering and dispersion management. The relatively low intensity of current High Harmonic Generation (HHG) soft X-ray sources calls for an efficient use of photons, thus the development of low-loss multilayer optics is of uttermost importance. Here, we report about the realization of atomically smooth interfaces in broadband CrSc multilayer mirrors by an optimized ion beam deposition and assisted interface polishing process.

The phase delay induced by multilayer (ML) mirrors is an important feature in many fields such as attosecond pulses compression, photolithography or in pump and probe experiments performed with Free Electron Laser (FEL) pulses. The experimental characterization of the ML phase delay can be obtained by the standing wave distribution measurement (by using Total Electron Yield (TEY) signal) combined to reflectance measurement. In this work, a ML structure with aperiodic capping-layers was designed and deposited for FEL applications and their reflectance and phase delay was characterized. The method adopted allows to retrieve the ML phase delay by using the TEY signals taken at different working configurations and it doesn’t require the comparison with a bulk reference sample. The results obtained are presented and discussed.

X-ray transmission properties of a thin HPHT IIa diamond crystal were characterized around Bragg diffraction, using a pseudo plane-wave setup at the 1-km beamline of SPring-8. Monochromatic x-rays of 19.75 keV were used for diamond 400 reflection from 120-μm-thick (001) diamond crystals, and 9.44-keV x-rays were used for diamond 111 reflection from 180-μm-thick (111) crystals. These thin crystals were mounted on the aluminum plate using an ultraviolet-cured resin. Several thin crystals showed rocking curve broadening due to bend. However, by limiting a small area of the crystal, transmittance curves agreed well with those of calculation. We can select a practically usable region for various applications: phase retarder, beam splitter, and also self-seeding of x-ray free electron laser.

Fast miniature plasma focus (FMPF-3), a low energy (235 J) device, is an attractive option for being a potential source for soft X-ray (SXR) (0.9 – 1.6 keV) lithography due to its smaller X-ray generation spot size and the capability of being a high repetition source. As a continuation of our work on the enhancement of SXR emission from this device, in present investigation the insulator sleeve length is optimized for efficient SXR emission. It plays a major role in the current sheath formation, which is determinant of the efficient compression and the consequent radiation emission. The influence of the presence or absence of cathode rods on the SXR emission is also investigated. It is one least explored parameter although it plays a major role in the determination of plasma sheath curvature which in turn influences the dynamic plasma inductance and the magnetic flux associated with moving current sheath. Another major highlight of this study is the time resolved laser shadowgraphy of the plasma sheath dynamics to understand the influence of the variation of these parameters on it. Through optimization of the insulator sleeve length, the highest ever obtained SXR yield of 1.8 J/shot was achieved for this device.

An achromatic and high-resolution hard X-ray microscope was developed, in which advanced Kirkpatrick-Baez mirror optics with four total-reflection mirrors was employed as an objective. A fine test pattern with a 100 nm feature size could successfully be resolved. Full-field imaging, in combination with X-ray absorption near edge structure (XANES) spectroscopy, was used to characterize tungsten particles. XANES spectra were obtained over the entire observation area, showing good agreement with the XANES spectrum of pure tungsten.

The Wolter mirror has been a promising imaging device in X-ray microscopy owing to its excellent characteristics such as no achromatic aberration, a large aperture and a long work distance. Despite its long history, a Wolter mirror has not been practically used for high resolution microscopy because extremely high figure accuracy is required on the surface. In this paper, we will show the result of optical simulations targeted at the design of a soft X-ray imaging system with sub-10nm spatial resolution.

The ESA mission Solar Orbiter (SOLO) is dedicated to the study of Solar Atmosphere and Heliosphere. As a part of the payload, the instrument METIS (Multi Element Telescope for Imaging and Spectroscopy) will provide images of the corona, both in the visible range and at the hydrogen Lyman-α emission line (121.6 nm). The realization of optical coatings, based on Al and MgF2, able to reflect/transmit such spectral component is therefore necessary. Since optical characteristics of materials in the VUV range are not well studied and greatly varying with realization process, we implemented a study of their properties in different deposition conditions. This is aimed to the realization of a custom designed filter, able to transmit the 121.6 nm while reflecting the visible light, and thus separate visible from UV light paths in the METIS instrument.

This work addresses the issue of X-ray monitoring for astrophysical applications. The proposed wide-field optical system has not been used in space yet. The proposed novel approach is based on the use of 1D "Lobster eye" optics in combination with Timepix X-ray detector in the energy range 3 - 40 keV. The proposed project includes theoretical study and a functional sample of the Timepix X-ray detector with multifoil wide-field X-ray "Lobster eye" optics. Using optics to focus X-rays on a detector is the only solution in cases the intensity of impinging X-ray radiation is below the sensitivity of the detector, e.g. while monitoring astrophysical objects in space, or phenomena in the Earth's atmosphere. The optical system could be used in a student rocket experiment at University of Colorado. Ideal opportunity is to extend the CubeSat of Pennsylvania State University with the hard X-ray telescope demonstrator consisting of an optical module and Timepix detector.

Phase contrast x-ray imaging, a new technique to increase the imaging contrast for the tissues with close attenuation coefficients, has been studied since mid 1990s. This technique reveals the possibility to show the clear details of the soft tissues and tumors in small scale resolution. A compact and low cost phase contrast imaging system using a conventional x-ray source is described in this paper. Using the conventional x-ray source is of great importance, because it provides the possibility to use the method in hospitals and clinical offices. Simple materials and components are used in the setup to keep the cost in a reasonable and affordable range.Tungsten Kα1 line with the photon energy 59.3 keV was used for imaging. Some of the system design details are discussed. The method that was used to stabilize the system is introduced. A chicken thigh bone tissue sample was used for imaging followed by the image quality, image acquisition time and the potential clinical application discussion. High energy x-ray beam can be used in phase contrast imaging. Therefore the radiation dose to the patients can be greatly decreased compared to the traditional x-ray radiography.

The main advantage of Bragg reflection from a multilayer mirror as a monochromator for hard X-rays, is the higher photon flux density because of the larger spectral bandpass compared with crystal lattice reflection. The main disadvantage lies in the strong modulations of the reflected beam profile. This is a major issue for micro-imaging applications, where multilayer-based monochromators are frequently employed to deliver high photon flux density. A subject of particular interest is the origin of the beam profile modifications, namely the irregular stripe patterns, induced by the reflection on a multilayer. For multilayer coatings in general it is known that the substrate and its surface quality significantly influence the performance of mirrors, as the coating reproduces to a certain degree the roughness and shape of the substrate. This proceedings article reviews recent experiments that indicate potential options for producing wave front-preserving multilayer mirrors, as well as new details on the particular mirrors our group has extensively studied in the past.

Contrast in conventional imaging of soft tissues is often limited due to the very similar attenuation of tissues to be distinguished. Phase contrast techniques can enable discrimination of tissues with similar attenuation. A major limitation to the widespread adoption of phase-contrast techniques is that for tabletop sources the required degree of coherence generally requires a small (10 to 50 μm) source. In this work, a polycapillary optic was employed to create a small virtual source from a large spot rotating anode. Phase contrast images obtained with two optics and several pinholes have been analyzed and preliminary results obtained for quantitative phase measurements.

Advanced X-ray imaging techniques of weakly absorbing structures require an increase of the sensitivity to small refractive angles considering that they are based more on coherent X-ray phase contrast than on X-ray absorption one. Simulations of diffraction properties of germanium (Ge) X-ray crystal monochromators and of analyzer based imaging (ABI) method were performed for various asymmetry factors and several lattice plane orientations using an X-ray energy range from 8 keV to 20 keV. Using an appropriate phase/amplitude retrieval method one can recover the phase information from the ABI image, which is directly proportional to the projected electron density. We are using germanium based optics for X-ray imaging or image magnification. The use of Ge crystals offers several advantages over silicon crystals. The integrated reflectivity of Ge crystals is two to three times larger than that of Si crystals. The spatial resolution of Ge magnifiers is typically two times better than the spatial resolution of Si magnifiers. We used high asymmetry diffractions to increase effectively the propagation distance and decrease the effective pixel size of the detector, to achieve a sufficient magnification of the sample and to improve coherence and increase output intensity. The most important parameter of a highly asymmetric monochromators as image magnifiers is the crystal surface quality. We have applied several crystal surface finishing methods including conventional mechanical lapping, chemical polishing, chemo-mechanical polishing and advanced nano-machining using single point diamond turning (SPDT), and we have evaluated these methods by means of AFM, diffractometry, reciprocal space mapping and others.

Saw-tooth refractive lens (SRL) provides a comparatively attractive option for X-ray focusing. An SRL assembly consists of two parts, each with an array of triangular structures (prisms), set tilted symmetrically with respect to the incoming beam. Its main advantage is a simple, continuous tunability in energy and focal length. SRLs can be used for both long and short focal length focusing. Long focal distance focusing of an SRL can accurately be predicted using simple analytical relations. However, the focus size at short focal distances focusing may deviate appreciably from the expected demagnified source size when: (1) the length of the SRL is comparable with the focusing distance, (2) the incident beam is not monochromatic, and (3) and the distance between adjacent prism tips, the tip step, is large . The first factor was considered in a previous work while the other two are addressed is this paper. This preliminary work is aimed at a better understanding of the SRL lenses for focusing an undulator beamline at the Advanced Photon Source (APS).

X-ray refractive lenses were successfully applied to harmonics rejection by using the fact that focal distance of the lens is energy-dependent. Spatial separation of energy spectrum by focusing the fundamental harmonic at the focal point and suppressing the unfocused high-energy radiation with a screen absorber or slit was achieved by usage of an off-axis illumination of refractive lenses at the ESRF ID06 beam-line. The presence of the 3^rd harmonic has been reduced down to 10^-3 using this technique and down to 10^-5 by additionally using of monochromator detuning. The method is well suited to third-generation synchrotron radiation sources and very promising at the future ultimate storage rings.

X-ray laser facilities are being constructed all over the world: Linac Coherent Light Source (LCLS) in California, RIKEN X-Ray Free-Electron Laser at SPring-8 in Japan, European XFEL in Germany etc. XFEL is the next-generation (4th) light source. However, the number of such experimental facilities (SRS and FEL) is quite limited. At the same time, relatively small vacuum ultraviolet laboratories with impulse sources [High Harmonic Generators (HHG)] allow one conduct in-house research. This makes the research community directly involved in experiments with time resolution much wider. The latest radiation sources and modern physical experiments require application of the newest diffractive elements. Such diffractive elements are required for implementation of experiments with time resolution using synchrotron radiation sources or high harmonics generators. For example, valence state evolution or molecules dissociation in time-resolved investigation. Modern experiments like this might require implementation of time resolution in femto - (10^-15) and even atto- (10^-18) seconds.

In the present work the X-ray optical anisotropy of 5CB type liquid crystals has been investigated based on the method of X-ray interferometry. In this way Moire fringes have been obtained both in the absence and presence of specimens with different orientations of optical axes. The relative displacement of Moire fringes enabled us to observe and immediately ascertain the presence of X-ray optical anisotropy, to measure the values of refractive indices n_o and n_e for this specimen (n_o is the refractive index for radiation with polarization normal to the principal plain, n_e is that for radiation with polarization in the principal plain parallel to the optical axis). X-ray optical anisotropy of 5CB type liquid crystal was observed using the proposed method and values of refractive indices n_o and n_e for this specimen were measured. It was found out that 5CB type nematic liquid crystal was X-ray anisotropic optically positive medium.

Future solar missions will investigate the Sun from very close distances and optical components are constantly exposed to low energy ions irradiation. Single layer thin films as well as extreme ultraviolet multilayer coatings have been exposed to low energy alpha particles (4keV). In order to change the total dose accumulated, for each ion fluency the time of exposure was varied. The experiment was carried out considering typical doses accumulated during the ESA Solar Orbiter mission. Results show that ion implantation affects the performances of both single and multilayer coatings.

A novel space communication method is presented in this paper based on X-ray photons. As a result of its short wavelength and great penetrability, X-ray has no attenuation for transmission in space when its photon energy is more than 10keV (λ<0.1nm). Thus a communication technology of long distance signal transmission in space can be achieved with smaller volume, lower weight and lower power. Therefore, X-ray communication (XCOM) is especially valuable to the deep space missions, which will be able to realize higher data rates, smaller SWAP than with RF and laser communications. Using X-ray photons as information carrier will not only be a good complement to laser and RF communications, but will also have unique applications when RF and laser signals are not available like the spacecraft’s re-entering to the earth. High-speed modulation and high-sensitivity detection of X-rays are two major technical issues which should be addressed in order for the X-ray communication to take place. A Grid-controlled Modulated X-ray tube (GMXT) is proposed and developed as X-ray transmitter. One or more specially designed grid electrodes are added to the traditional X-ray tube to modulate the electrons. The communication signal is coded and applied to the modulated grid electrode, and then the corresponding X-ray signals are generated and sent out. X-ray detector based on micro-channel plate(MCP) is used as communication receiver because of its high temporal resolution. An audio communication experiment system based on XCOM is setup in laboratory including the X-ray transmitter and the receiver. X-ray communication is successfully demonstrated and the communication speed reaches 64 kilobits per second in a vacuum tube of 6 meters long. As a new concept of space communication, X-ray communication will have more important scientific significance and application prospects when technologies for X-ray modulation and detection are further developed.