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The most efficient diffraction at a periodic grating structure is expected to take place when the incident radiation can be considered to have been specularly reflected off the inclined part of grooves that are positioned parallel to the trajectory of the incident beam. Very encouraging results for this configuration, in which the diffraction takes place off-plane, have been reported recently for a grating to be used in a spectrometer for space science investigations. This grating provided high efficiency for a relatively large groove density and a large blaze angle. High efficiency was observed even in higher diffraction orders up to the fourth order. Here the performance parameters, especially for the combination of diffraction efficiency and achievable spectral resolution, will be discussed for a grating used in a grazing-incidence plane-grating monochromator for monochromatization of synchrotron radiation in the extreme ultraviolet (EUV) and soft X-ray range with photon energies between 30 eV and 2000 eV. It is found that the instrument can provide competitive spectral resolution in comparison with the use of in-plane diffraction. In the case of comparable spectral resolution, the off-plane diffraction is found to provide superior efficiency.

The first attempts to calculate the diffraction efficiencies of gratings in the soft X-ray range were made on a scalar model. The results were simple analytical equations, that always severely overestimated the performance of real objects. In this respect, computer programs were found to be more successful, which rigorously consider all diffracted and refracted waves. Consequently soft X-ray gratings are presently optimized using these tools, which requires rather extensive calculations for any instrument optimization as general trends are not immediately obvious. Here it will be shown that the results of the rigorous calculations for gratings with blaze or sawtooth profile can be approximated rather well with a simple analytical equation. This equation contains three multiplicative factors, which deal independently with the effect of the reflectivity, the blaze angle and the groove density. This opens the possibility to initially ignore the effects of the blaze angle and thus to start an optimization in a very general way. Such optimization can be based on isoreflectivity curves and it can then provide `blaze maximum efficiency maps', i.e. simple images. In these latter images, one can identify directly the optimum parameters for a grating, i.e. the groove density providing best efficiency for a requested spectral resolving power. Only successively will the blaze angle have to be fixed. Its choice is then not the result of an extensive optimization process but of a simple calculation applied for the photon energy at which maximum efficiency performance is requested. The maps presented here are used for the optimization of a medium-resolving-power soft X-ray monochromator, which can scan the photon energy range 300–2000 eV.

When the trajectory of an incident beam is oriented parallel to the grooves of a periodic grating structure the radiation beam is diffracted off-plane orthogonal to the plane of incidence. The diffraction efficiency in this condition is very high and in a grating with a sawtooth profile it can approach the reflection coefficient for a simple mirror, when the diffraction order of interest follows the direction for specular reflection at the flat part of the steps. When this concept is used in a plane grating in a monochromator for synchrotron radiation sources, the incident beam is almost always collimated in order to minimize any deterioration of the beam properties due to aberrations, which will be introduced in the diffraction process when an uncollimated beam is used. These aberrations are very severe when the groove density is constant. It will be shown that the effect of these aberrations can be corrected after the diffraction by the use of astigmatic focusing. The latter can be provided by a crossed mirror pair with different focal lengths in the corresponding orthogonal directions. Then a monochromator based on this concept can provide source size limited spectral resolution in an uncollimated incident beam. This is identical to the spectral resolution that can be provided by the same grating when operated at the same position in a collimated incident beam. The source size limited spectral resolution in this case corresponds to a high spectral resolving power of better than ΔE/E = 10 000 for photon energies around 300 eV in the soft X-ray range.

The confocal μ XRF spectrometer of Atominstitut (ATI) was transported and set up at the X-ray Fluorescence beamline at Elettra - Sincrotrone Trieste. It was successfully adjusted to the incoming beam (9.2 keV). Test measurements on a free-standing Cu wire were performed to determine the size of the focused micro-beam (non-confocal mode, 56 × 35 μ m 2 ) and the size of the confocal volume (confocal mode, 41 × 24 × 34 μ m 2 ) for the Cu–K α emission. In order to test the setup’s capabilities, two areas on different human bone samples were measured in confocal scanning mode. For one of the samples the comparison with a previous μ XRF measurement, obtained with a low power X-ray tube in the lab, is presented.

Neutron reflectivity is a powerful technique for characterizing interfaces in many areas of science. The traditional method of time of flight for measuring the wavelength of neutrons in a white beam is extremely wasteful, as the vast majority of neutrons must be absorbed in the choppers in order to produce a pulsed beam. A prism operates continuously, with a transmission up to two orders of magnitude higher than choppers. The wavelength-dependent deflection of the beam by the prism, coupled with a high spatial resolution detector, results in excellent wavelength resolution. The theory of how the resolution is considerably enhanced by curving the surface of the prism is described in detail for a real experimental arrangement. It is demonstrated how this can be used for faster neutron reflectometry, including the merging of different angles and subtraction of background. The technique shows considerable promise for neutron reflectivity, opening up new areas of science particularly in the realms of kinetics and small samples.

Soft X-ray monochromator designers know very well the program, which M. Neviere developed in order to predict the diffraction efficiencies of reflection gratings by use of the rigorous differential method. Infact it is used frequently for the grating parameter optimisation. Here a simple analytical equation is presented, which predicts for perfect grating profiles diffraction efficiencies, which correspond within 10% to the results with the more rigorous Neviere approach. This empirical equation, which is based on plausible assumptions, facilitates very much systematic studies, which can then easily be presented in the form of isoefficiency maps, which are valid rather generally and which can be further evaluated in simple image analysis programs. Infact such maps will allow one to identify the optimum grating parameters for a given application in a glimpse.

The fact that a diffraction grating can provide twofold-smaller bandwidth when operated in second-order diffraction is long known and applied routinely in the laboratory for spectroscopy in the visible and ultraviolet spectral range. A similar routine operation in monochromators for the soft X-ray range is not reported yet. This study will thus address the feasibility of efficient diffraction of soft X-rays in the second order at reflection gratings when operated at grazing angles of incidence. The related systematic study could make profitable use of a recently introduced simple analytical equation for the prediction of the diffraction efficiency of blazed gratings with an ideal sawtooth profile. The predictions are then verified by use of rigorous calculations. The principle finding is that, by operation of gratings with lower groove densities, and thus with higher efficiencies, in higher order diffraction, one can extend the tuning in existing instruments with mechanical/optical limitations to larger photon energies. The performance in terms of transmission and spectral resolving power can be very similar to the performance of a grating with a larger groove density, which would otherwise have to be used for accessing the same energy range. This would allow operation of a single highly efficient grating over a larger photon energy interval at a modern synchrotron radiation source, e.g. from 0.3 to 2.2 keV. Without any requirement for a sophisticated grating exchange scheme, a related instrument promises to be sufficiently stable for the needs imposed by the improvements in source point stability at diffraction-limited storage rings.

When reflection gratings are operated at grazing incidence in the extreme off-plane configuration and the incident beam trajectory is parallel to the grooves, the diffraction into the first order can be more efficient than in the classical orientation. This situation is referred to as the conical diffraction case. In the classical configuration the grooves are perpendicular to the incident beam and thus an efficiency-reducing shadowing effect will be observed at very grazing angles. It was recently shown that a laminar grating could provide symmetric and relatively high efficiencies in conical diffraction for diffraction even of photons with large energies of the order of 4 and 6 keV. For photon energies in the tender X-ray range, accurate computing tools for the calculation of diffraction efficiencies from gratings with simple coatings have not been available. Promising results for this spectral range now require the development of tools for modelling the diffraction efficiency expected in optical instrumentation, in which the provision of high efficiency in the indicated spectral range is mandatory. This is the case when weak sources are to be investigated, like in space science. In this study it will be shown that scalar calculations are not appropriate for this purpose, while newly introduced rigorous calculations based on the boundary integral equation method, implemented in the PCGrate ® code, can provide predictions that are in agreement with observed diffraction efficiencies. The agreement is achieved by modelling the exact surface profile. This applies for both the conical diffraction configuration and for the classical in-plane configuration, in which a significantly lower efficiency was obtained. Even though the profile of the presented grating was not perfect, but significantly distorted, the calculations show that efficiency-wise the structure provided already more than 75% of the ideally expected efficiency for conical diffraction. This is a very promising result for further optimization of diffraction gratings for use in the tender X-ray range.

Conical diffraction is obtained when a radiation beam impinges onto a periodically ruled surface structure parallel or almost parallel to the ruling. In this condition the incident intensity is diffracted through an arc, away from the plane of incidence. The diffracted intensity thus lies on a cone, which leads to the name `conical diffraction'. In this configuration almost no part of the ruled structure will produce any shadowing effect for the incident or the diffracted beam. Then, compared with a grating in the classical orientation, relatively higher diffraction efficiencies will be observed for fewer diffraction orders. When the incident beam is perfectly parallel to the grooves of a rectangular grating profile, the symmetry of the setup causes diffraction of the intensity symmetrically around the plane of incidence. This situation was previously tested experimentally in the VUV spectral range for the amplitude beam splitting of a radiation beam with a photon energy of 25 eV. In this case the ideally expected beam splitting efficiency of about 80% for the diffraction into the two first orders was confirmed for the optimum combination of groove depth and angle of grazing incidence. The feasibility of the amplitude beam splitting for hard X-rays with 12 keV photon energy by use of the same concept was theoretically confirmed. However, no related experimental data are presented yet, not even for lower energy soft X-rays. The present study reports the first experimental data for the conical diffraction from a rectangular grating profile in the tender X-ray range for photon energies of 4 keV and 6 keV. The expected symmetries are observed. The maximum absolute efficiency for beam splitting was measured to be only about 30%. As the reflectivity of the grating coating at the corresponding angle of grazing incidence was found to be only of the order of 50%, the relative beam splitting efficiency was thus 60%. This is to be compared also here with an ideally expected relative efficiency of 80%. It is predicted that a beam splitting efficiency exceeding 50% should be possible by use of more appropriate materials.

Recently it was verified that the diffraction efficiency of reflection gratings with rectangular profile, when illuminated at grazing angles of incidence with the beam trajectory along the grooves and not perpendicular to them, remains very high for tender X-rays of several keV photon energy. This very efficient operation of a reflection grating in the extreme off-plane orientation,i.e.in conical diffraction, offers the possibility of designing a conical diffraction monochromator scheme that provides efficient continuous photon energy tuning over rather large tuning ranges. For example, the tuning could cover photon energies from below 1000 eV up to 8 keV. The expected transmission of the entire instrument is high as all components are always operated below the critical angle for total reflection. In the simplest version of the instrument a plane grating is preceded by a plane mirror rotating simultaneously with it. The photon energy selection will then be made using the combination of a focusing mirror and exit slit. As is common for grating monochromators for soft X-ray radiation, the minimum spectral bandwidth is source-size-limited, while the bandwidth can be adjusted freely to any larger value. As far as tender X-rays (2–8 keV) are concerned, the minimum bandwidth is at least one and up to two orders of magnitude larger than the bandwidth provided by Si(111) double-crystal monochromators in a collimated beam. Therefore the instrument will provide more flux, which can even be increased at the expense of a bandwidth increase. On the other hand, for softer X-rays with photon energies below 1 keV, competitive relative spectral resolving powers of the order of 10000 are possible.

Prism arrays arranged to form a slightly open alligator mouth were found to focus incident X-rays, as with increasing distance from the object symmetry axis these rays hit an increasing number of refracting prism tips. Such an object is then formally a refractive lens. Due to the strong energy dependence of the refractive index of material for X-rays a refractive X-ray lens is chromatically focusing. The attractive feature of the alligator lens is the inherent zoomability possible as the mouth can easily be opened or closed. However, the required tolerances for the jaw rotations and the jaw positioning are so stringent, that the routine use of such systems has not been reported yet. This study will show that the related technical problems can be overcome by proper object fabrication. In fact the here presented objects can already be aligned in the production stage. Then the assembly can be made with simple tools. And the zooming is achieved by just a simple rotation. The transmission through the devices was found to be as expected, and thus performance-wise these objects can directly compete with other refractive X-ray focusing systems.

Recently the wavelength dispersion of cold neutrons in the refraction process at inclined interfaces was identified as an efficient tool for neutron spectrographs, in which a larger wavelength band can be registered simultaneously. This registration mode reduces the data acquisition time significantly as no need to monochromatise the incident neutron beam by use of inefficient choppers exists. In the related studies the spectrograph performance is treated with rather complex equations. This study instead provides a theoretical treatment of the dispersion properties with simpler analytical equations, which were previously used in connection with X-rays. It can be shown, that the spectral resolution in the original spectrographs is mostly limited by the finite size of the refracted beam, which is inconveniently increasing upon refraction at grazing internal incidence onto an inclined refracting interface. The blurring of the beam size of a monochromatic beam at the detector due to the angular spread of the incident beam is mostly negligible. It is thus proposed that a significant improvement in the spectral resolution of such a spectrograph can be achieved, when the beam size at the detector is reduced by introducing focusing in the refraction process. It is shown, that the spectral resolution can then ultimately be limited by the smaller size of the blurred image caused by the angular spread of the beam. Then the improvement in this beam divergence limit can be by an order of magnitude and it is achieved by refraction upon internal incidence onto a concave interface. It is found that such a configuration will focus appropriately in a larger wavelength interval. By this means for wavelengths between 5 A and 12 A spectral resolutions of below 1% are feasible, which are not yet reported for such prism spectrographs.

Simultaneous photon beam position and intensity monitoring is becoming of increasing importance for new generation synchrotron radiation sources and free electron lasers (FEL). Thus, novel concepts of beam diagnostics are required in order to keep such beams under control. From this perspective diamond is a promising material for the production of semitransparent in situ photon beam monitors, which can withstand the high dose rates occurring in such radiation facilities. Here, we report on the development of freestanding, single-crystal chemical-vapor-deposited diamond detectors with segmented electrodes. Due to their direct, low-energy band gap, InGaAs quantum well devices operated at room temperature may also be used as fast detectors for photons ranging from visible to X-ray. These features are valuable in low-energy and time-resolved FEL applications. In particular, a novel segmented InGaAs/InAlAs device has been developed and will be discussed. Dedicated measurements carried out on both these devices at the Elettra Synchrotron show their capability to monitor the position and the intensity of the photon beam with bunch-by-bunch temporal performances. Furthermore, preliminary tests have been performed on diamond detectors at the Fermi EEL, extracting quantitative intensity and position information for 100-fs-wide FEL pulses with a photon energy of 28.8 eV. (C) 2013 Elsevier B.V. All rights reserved

Recently it was found that reflection gratings of standard quality, which can be used at lower energy soft X-rays with photon energies of the order of 300 eV, diffract also efficiently X-rays with photon energies of the order of 5 keV, when these gratings are operated at grazing angle of incidence in the extreme off-plane configuration [1]. Consequently a grating employed in the extreme off-plane configuration has the capability to provide monochromatic radiation in the photon energy range from below 1 keV to far above 2 keV, where one usually switches for the same purpose between the diffraction at surface structures and the diffraction in bulk structures. Such an operation scheme requires rather complex mechanical structures. The present study will show that the tuning of diffraction gratings in the conical diffraction configuration can cover the indicated and even more extended tuning ranges employing a rather simple mechanical structure. Infact such a grating can be mounted together with a plane mirror in a pseudo channel-cut crystal monochromator configuration, i.e. with almost parallel surfaces and with fixed gap between them. The photon energy is then tuned simply by varying the angle of grazing incidence onto the pair of optics. Like in a double crystal monochromator scheme the monochromatic beam will exit from the configuration parallel to the incident beam with in most cases negligibly varying displacement in the plane of incidence. The optical performance data will be discussed depending on the properties of some state-of-the-art synchrotron radiation sources. [1] W. Jark and D. Eichert, Opt. Express 23, 22753 (2015).

This contribution will discuss the perspectives for the use of reflection gratings as amplitude beam splitters in the X-ray range including the tender X-rays after that very promising diffraction efficiencies were measured when such gratings are used in the conical diffraction scheme.

Recently it was shown experimentally that regular arrays of tiny prisms can be used as X-ray monochromators providing a spectral bandwidth of below 2%. Successively the measured spectral transmission functions of monochromators operated under different conditions were found to be in agreement with expectations within an analytical model. This type of monochromator focuses chromatically and thus necessitates the use of an exit slit for the monochromatization. This contribution will show that the lower limit for the achievable bandpass can be predicted under practically feasible experimental conditions. Refractive monochromators based on prism arrays are found to be feasible solutions for monochromatization with high transmission to a spectral bandwidth of the order of 0.5%. The bandwidth can easily be increased by adjusting the exit slit setting accordingly. Consequently, the presented refractive devices would make for tunable monochromators with tunable bandwidth, which provides more flexibility for an intermediate bandwidth of

Refractive lenses focus X-rays chromatically owing to a significant variation of the refractive index of the lens material with photon energy. Then, in combination with an exit slit in the focal plane, such lenses can be used as monochromators. The spectral resolution obtainable with refractive lenses based on prism arrays was recently systematically investigated experimentally. This contribution will show that a wide-bandpass performance can be predicted with a rather simple analytical approach. Based on the good agreement with the experimental data, one can then more rapidly and systematically optimize the lens structure for a given application. This contribution will then discuss more flexible solutions for the monochromator operation. It will be shown that a new monochromator scheme could easily provide tuning in a fixed-exit slit.

When small triangular prisms are arranged in arrays which have an overall appearance like an hourglass (in Italian: clessidra) they can focus X-rays owing to a combined action of diffraction and refraction. From the optical point of view these objects can be regarded as a Fresnel variant of concave transmission lenses. Consequently they can provide larger apertures than purely refractive lenses. However, one has to recognize that clessidra lenses will strongly diffract as the lens structure is periodic in the direction perpendicular to the incident beam. In experiments the diffraction is reduced because it is difficult to illuminate the large apertures with a full spatially coherent wavefront. So the illumination is at best partially coherent. In order to interpret available experimental data for this condition, diffraction theory has been applied appropriately to the clessidra structure, taking into account the limited spatial coherence. The agreement between the theoretical simulations and experimental data is very good, keeping the lens properties at their projected values and allowing for only two free model parameters. The first is the lateral spatial coherence; the second is a lens defect, a rounding of all edges and tips in the structure. Both values obtained from the simulations have been found to be in agreement with expectations.

X-ray Waveguides (WG) are optical elements able to provide nanometer size coherent X-ray beams. Both Resonant beam Coupling (RBC) and Front Coupling (FC) can be implemented to couple the incident radiation with the WG. In this paper we implemented a computer code based on finite difference scheme solutions of parabolic wave equations to simulate the coupling and the propagation of electromagnetic waves into air-gap waveguides in Front Coupling mode. Both a synchrotron source and a table-top laboratory sources have been considered. In this last case the degree of coherence of the incoming beam has been explicitly taken into consideration. Air-gap WGs have been fabricated following simple procedures, and tested at the Elettra synchrotron source. The results are in good agreement with theoretical expectations.

This report describes the fabrication process by deep X-ray lithography of a new type of hard X-ray lens made of stacks of identical prisms with dimensions in the 10-20 @mm range. The size deviations of the structural dimensions are evaluated for lenses fabricated in PMMA and SU-8 polymer materials. Radiographs taken on a synchrotron allows the measurement of the prism etched depth showing that the focusing quality is directly correlated with the quality of the etching. Finally the technological process parameters are optimized to achieve aspect ratio of 25:1.

Thin-film slab waveguides can confine incident X-ray beams in one direction in guiding layers as thin as 10 nm. Consequently they can provide attractive beam dimensions for microscopy purposes. This report presents a simple model and analytical equations for the transmission calculation, which provide results consistent with the rigorous calculations based on recursion techniques. By using these results the waveguide transmission can be compared directly with other microscopy objectives. Ideally X-ray waveguides can filter the spatially coherent content out of an incident radiation beam with an efficiency of 1. The transmissions measured for state-of-the-art one- and two-dimensional waveguides are found to correspond to experimental efficiencies of 0.5 for each confinement direction. Waveguides with thinner guiding layers cannot be used efficiently in highly collimated beams; instead the beam divergence in unfocused beamlines at state-of-the-art synchrotron radiation sources may eventually have to be increased to the larger angular acceptance of these waveguides by use of other focusing optics.

This report discusses the optimization strategy, the theoretical background and first experimental data of a new refractive lens for focusing X-rays. In order to reduce the absorption of X-rays in this transmission lens, optically passive material was removed from the necessarily concave lens shape in a highly regular pattern. The feature dimensions require lens production and replication by deep X-ray lithography, which allows shaping in only one dimension. Consequently such a lens can focus in one direction only, so a crossed lens pair is needed for two-dimensional focusing. The single lens is composed of two large prisms of millimetre size, which touch each other at one of the tips, like an old sand clock. Each large prism contains a highly regular structure of essentially identical prism-like smaller segments. The first lens prototypes focused an X-ray beam with a vertical size of 500 microm and a photon energy of 8 keV to a line with a width of only 2.8 microm. This is only slightly worse than the line width of 1.73 microm expected for its focal length of f = 2.18 m. The photon density enhancement in the focus was 25, but could have been larger as the lens can intercept a beam height of 2.6 mm.

Prisms deflect and disperse X-rays due to refraction very similar to visible light. As X-rays are always attenuated while traversing material, the intensity distribution in the transmitted beam carries information about the prism transmission function. This study will show that sufficient information is contained in a single digitally registered radiograph from a rectangular prism, for deriving both the refractive index of the material and its attenuation length. The measured data can be prepared such that neither intensity fluctuations nor false light content in the incident beam will introduce systematic errors into the result. The strategy is thus very adapted, when single shot pictures are taken at X-ray sources with limited shot reproducibility. This technique is favourably be used at very grazing angles of incidence of the order of the critical angle for the prism material, when the beam deflection becomes significant. In such a geometry dimensional parameters, like sample thickness, do not affect the data analysis, which is particularly insensitive to even significant errors in the tip angle. (C) 2011 Elsevier B.V. All rights reserved.

Synchrotron radiation induced TXRF allows the nondestructive investigation of low Z contaminations on Si wafer surfaces at trace levels required by the semiconductor industry. The PTB (Physikalisch Technische Bundesanstalt) U180 undulator beamline at BESSY II, equipped with a plane grating monochromator ensuring an energy resolving power E /Δ E between 500 and 5000, can be operated either in wiggler mode for photon energies up to 1.7 keV to excite Al, Mg and Na efficiently, or in undulator mode, i.e. using one of the first odd U180 harmonics, to obtain intensive low energy radiation below 0.7 keV to excite carbon, nitrogen and oxygen. The specific feature of the beamline is its high spectral purity that allows for fundamental investigations. The TXRF wafer chamber of the Atominstitut was used for the experiments with a sidelooking Si(Li) detector with the wafer arranged vertically to take advantage of the linear polarization for background reduction. The energy dependence of the resonant Raman scattering, which is a limiter for the determination of Al at ultra trace levels excited with energies just below the Si absorption edge was studied as well as the influence of the incidence angle on the Raman peak. Droplet samples containing boron were measured and the detection limit of 3 ng determined. A single Carbon layer (5 nm) and a C–Ni–C multilayer sample on a Si wafer were characterized and it was shown that the thickness and density of these layers could be determined.

We present angle-, energy- and polarization-dependent magneto-optical properties of Gd/Fe and Gd/Co multilayers with periods of the order of 1 nm for the photon energy range of 700–1230 eV. In the vicinity of the 2p absorption edge of transition metals (TM) and the 3d edge of the rare earth elements (RE), the X ray magnetic circular dichroism (XMCD) was measured in transmission and the X ray resonant magnetic scattering (XRMS) was investigated in L-MOKE geometry. The magnetic state of Gd could be realized at room temperature. Based on these data a calibrated detector of the polarization state of synchrotron radiation has been developed.

Prisms deflect and disperse x-rays due to refraction very similarly to visible light. However, as the refractive index for X-rays is only very slightly different from unity and as it is even smaller than unity, the dispersion is found in the opposite direction compared to the visible range and it is observable only at very grazing incidence onto the refracting interface. Absorption will then limit the geometrical aperture of the prism to rather small dimensions. When the prism is further limited in length the aperture can be even smaller. In this case one will observe a small beam being refracted at the interface and as a result of this in the straight-through direction a small shadow. Both can easily be separated. It is proposed that this latter shadow can be used as a “negative” pinhole camera. Experimental data is presented for this application. It is discussed, that the quality of the refracting interface does not affect the shadow image and thus such device is well suited for the use at high power X-ray sources.

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.

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.

When an x-ray beam passes through the tip of a triangular prism, i.e., an edge, it undergoes two consecutive refraction processes. This will also happen when the incident beam is not perpendicular to the tip but when the beam progresses at a very small inclination to it. It will be shown that in such a condition, when both interfaces adjacent to the tip have concave surfaces, decoupled focusing in two orthogonal directions can be introduced in the transmitted x-ray beam. The limitations for this application are discussed, and focusing of x rays to spots with diffraction limited sizes of the order of 100 nanometers is found to be feasible. The feasibility of bidimensional focusing by use of such a device was experimentally verified. (C) 2014 Optical Society of America

Magnetic Gd/Fe and Gd/Co multilayer structures with d-spacing of about 1 nm were probed with elliptically polarized synchrotron radiation (SR). The intensity dependence of the magnetic circular dichroism (MCD) around the 3d absorption edge of Gd at room temperature was measured as a function of the degree of circular polarization in order to utilize the MCD effect for quantitative polarization analysis of SR in soft X-ray range.

We present here a novel X-ray diffraction imaging method which allows the determination of local structural properties with spatial resolution (in one dimension) of about 100 nm. The method is based on an X-ray microscope whose main element is a waveguide producing a divergent and coherent X-ray beam with vertical dimension below 100 nm. Applications for microelectronics materials and processes are presented.

Fresnel X-ray zone plates, which have been extensively developed for the last 20 years, are widely used for X-ray imaging in the hard part of the X-ray spectrum. In this paper zone plates based on the SPCVD (Surface Plasma Chemical Vacuum Deposition) technology are proposed and their optical properties in the hard X-ray range 10–30 keV are discussed. It will be shown that this technology enables production of zone plates working in the 10–30 keV range based on SiO2/GeO2 multilayer structures. The first zone plate samples based on SPCVD technology have been fabricated and tested. The parameters of the zone plates are: diameter 0.1–2.5 mm, number of zones 1000–2000, focal distance 1–5 m. The X-ray zone plates suggested here, if successful, will dramatically reduce the cost of imaging experiments in the hard X-ray spectral region, while maintaining spatial resolution high enough to be useful for the X-ray microanalysis, X-ray microscopy and focusing of the X-ray radiation.

This report discusses standing X-ray waves in thin films and their application for the determination of the position of a thin marker layer in a 100-nm-thick carbon layer. The position of 0.3–0.5-nm-thick titanium layers could be determined with an accuracy of 1% of the total film thickness. As the standing X-ray wave is a standing wave only in the direction parallel to the surface normal, it is travelling in the direction parallel to the surface. In the present study the properties of such a waveguided beam are studied when the beam exits from the waveguide end. Such a beam is of particular interest as it has dimensions of the order of 100–200 nm in one direction. Data will be presented for the shape of the beam, the energy tunability and the obtainable gain. The beam is found to be highly coherent and divergent. With the latter properties, an interesting application in microdiffraction experiments will be discussed in more detail. In a magnifying projection scheme the strain development in semiconductor crystalline material under oxidised lines of submicron width size could be studied with submicron lateral resolution and high sensitivity.

(1999). The elettra circular polarization beamline and electromagnetic elliptical wiggler insertion device. Synchrotron Radiation News: Vol. 12, No. 4, pp. 34-38.

This report discusses the latest performance data for X-ray waveguides applied in the production of hard X-ray micro-spots. It is possible to compress an X-ray radiation beam in a thin film waveguide in one direction down to the level of about 0.1 μm, a value which has not been achieved routinely with any other device. A gain factor of about 5 could be achieved in this case for a photon energy of 17 keV. The thin film waveguides were found to provide increasing transmission from 11 keV to 25 keV. As the exiting beam is not only of small size but also highly coherent and divergent it can be used in a number of microscopic techniques: e.g. micro-diffraction, micro-fluorescence, Gabor-holography, phase contrast microscopy.

Clessidra (hour-glass) X-ray lenses have an overall shape of an old hour glass, in which two opposing larger triangular prisms are formed of smaller identical prisms or prism-like objects. In these lenses, absorbing and otherwise optically inactive material was removed with a material-removal strategy similar to that used by Fresnel in the lighthouse lens construction. It is verified that when the single prism rows are incoherently illuminated they can be operated as independent micro-lenses with coinciding image positions for efficient X-ray beam concentration. Experimental data for the line width and the refraction efficiency in one-dimensional focusing are consistent with the expectations. Imperfections in the structures produced by state-of-the-art deep X-ray lithography directed only 35% of the incident intensity away from the image and widened it by just 10% to 125 microm. An array of micro-lenses with easily feasible prism sizes is proposed as an efficient retrofit for the refocusing optics in an existing beamline, where it would provide seven-fold flux enhancement.

The refractive index for matter in the hard X-ray range changes rather rapidly with increasing photon energy. In fact away from absorption edges the refractive index decrement varies with the square of the photon energy. As the photon energy dispersion depends on the refractive index decrement, prisms, as used in the visible spectral range, can also be used in the X-ray range for monochromatising or dispersing an incident polychromatic X-ray beam. The dispersion in a single prism is rather small and it is thus mandatory to use ensembles of many prisms for the dispersion process. A particular prism assembly is the Clessidra X-ray lens. The name of the lens, which is Italian for hourglass, describes its appearance as many tiny prisms form two larger prisms with opposing areas. In this form the device can focus an incident plane X-ray wave by refraction. Then the dispersion will make the focusing suffer from chromatic aberrations. The latter can be used in order to operate the structure as a monochromator in combination with an exit slit. For this operation it was found to be advantageous to use a central obstruction in the lens. As the prism array focuses only onedimensionally the object rotation around an axis, which is perpendicular to the incident X-ray beam and which lies in the dispersion plane, is now an available degree of freedom. In a monochromator one can make good use of it, as it permits us to tune the photon energy in a fixed slit. This contribution will discuss the limits for such an operation in terms of achievable spectral resolution and in terms of rapid tuning.

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.

This chapter deals with the fundamental properties of X-ray waveguides (WGs), whose development is a logical consequence of the theoretical and experimental work on X-ray standing waves. The different coupling modes and the formation of the wavefield inside the WG are reviewed. Some fabrication procedures and relevant applications are also briefly described.

This report discusses the properties of a 13‐keV submicrometer x‐ray beam exiting from a waveguide. Waveguides for this spectral regime can be constructed by enclosing a low‐absorbing material between highly absorbant metals. Best performance is found for about 0.1 μm guiding layer thickness. Measurements of the photon beam size close to the exit and of the intensity distribution far from the exit will be presented. From these data one derives a beam size at the exit which is identical to the guiding layer thickness. This number being in the submicrometer range offers interesting perspectives for microscopy experiments in the hard x‐ray range.

A technique for the determination of the total film thickness and the position of a marker layer in an amorphous graphite film by means of grazing incidence X-ray reflectometry and X-ray fluorescence is presented. This technique makes use of a strong resonance effect in the electric field intensity distribution measured in the graphite film. Angularly dependent fluorescence measurements on samples with different positions of a Ti marker showed that independent, non-destructive determination of the total graphite thickness and of the Ti position can be achieved with a relative accuracy of the order of 1%. The presented measurements were performed using a standard laboratory X-ray source and equipment.

The glancing-angle reflectivity profiles in samples containing an X-ray waveguide layer are studied. Oscillations observed at angles within the region of resonance and above, are interpreted by angle dependent interference of the monochromatic X-ray beam in thin layer. The discussion is extended to the structures composed of more than one layer. Experimental reflectivity spectra recorded with Cu Kα radiation are compared with the theoretical calculations. It leads to the model of oscillations in reflectivity consistent both for the resonant and non-resonant regions, and clarifies interpretation of oscillations in the region above the resonances. A brief discussion of potential applications of the reflectivity spectra to the studies of structure of thin layers is done. PACS numbers: 68.65.+g, 78.20.Ci

Several ways of tuning a higher asymmetry factor (>10) in V-channel X-ray monochromators, for metrological and imaging applications, were analysed. A more than sixfold intensity increase for compositionally and thermally tuned cases was achieved., While channel-cut crystals, in which the diffracting surfaces in an asymmetric cut are kept parallel, can provide beam collimation and spectral beam shaping, they can in addition provide beam compression or expansion if the cut is V-shaped. The compression/expansion ratio depends in this case on the total asymmetry factor. If the Ge(220) diffraction planes and a total asymmetry factor in excess of 10 are used, the rocking curves of two diffractors will have a sufficient overlap only if the second diffractor is tuned slightly with respect to the first one. This study compares and analyses several ways of overcoming this mismatch, which is due to refraction, when the Cu Kα1 beam is compressed 21-fold in a V21 monochromator. A more than sixfold intensity increase was obtained if the matching was improved either by a compositional variation or by a thermal deformation. This provided an intensity gain compared with the use of a simple slit in a symmetrical channel-cut monochromator. The first attempt to overcome the mismatch by introducing different types of X-ray prisms for the required beam deflection is described as well. The performance of the V-shaped monochromators is demonstrated in two applications. A narrow collimated monochromatic beam obtained in the beam compressing mode was used for high-resolution grazing-incidence small-angle X-ray scattering measurements of a silicon sample with corrupted surface. In addition, a two-dimensional Bragg magnifier, based on two crossed V15 channel monochromators in beam expansion mode and tuned by means of unequal asymmetries, was successfully applied to high-resolution imaging of test structures in combination with a Medipix detector.

International audience; Diamond is a promising material for the production of semitransparent in situ photon beam monitors which can withstand the high dose rates occurring in new generation synchrotron radiation storage rings and in free electron lasers. We report on the development of a 500 mu m thick freestanding, single crystal chemical vapor deposited diamond detector with segmented electrodes. Performances in both low and radio frequency beam monitoring are presented as well. By using charge integration techniques at a frame rate of 6.5 kHz in combination with a needle synchrotron radiation beam and mesh scans, the inhomogeneity of the sensor was found to be of the order of 2%; with a measured electronics noise of 2 pA / root Hz a 0.05% relative precision in the intensity measurements (at 1 mu A) and a 0.1 mu m resolution in the position encoding have been estimated. Moreover, the high electron-hole mobility of diamond compared with other active materials enables very fast charge collection characterized by rise-times below 1 ns; this allowed us to utilize single pulse integration to simultaneously detect the intensity and the position of each synchrotron radiation photon bunch generated by a bending magnet

The article describes the ESCA microscopy beamline dedicated to high spatial resolution quantitative and qualitative analysis on surfaces and interfaces. The scanning microscope is constructed to work both in transmission and photoemission within the photon energy range from 200 to 1200 eV with a spatial resolution of ∼0.1 μm. A Fresnel zone plate demagnifies the photon beam to submicrometer dimensions with 109–1010 photons/s in the focus spot. A photodiode and a hemispherical electron energy analyzer are used as detectors for recording the transmitted x‐rays and emitted photoelectrons, respectively. The operation modes in photoemission give the opportunity to obtain conventional energy distribution curve spectra from a microspot or a two‐dimensional micrograph of the spatial distribution and local concentration of a selected element as the sample is mechanically scanned. For conductive specimen topography measurements of a selected surface area probed by SPEM are possible using a scanning tunnelling microscope. The first test images of a zone plate and an e‐beam written specimen with 1 μm2 Au squares on Si have shown a spatial resolution better than 0.2 μm.

Metrology requirements for optical components for third‐generation synchrotron sources are taxing the state of the art in manufacturing technology. We have investigated a number of error sources in a commercial figure measurement instrument, the Long‐Trace‐Profiler II, and have demonstrated that, with some simple modifications, we can significantly reduce the effect of error sources and improve the accuracy and reliability of the measurement. By keeping the optical head stationary and moving a penta prism along the translation stage, as in the original pencil‐beam interferometer design of von Bieren, the stability of the optical system is greatly improved, and the remaining error signals can be corrected by a simple reference beam subtraction. We illustrate the performance of the modified system by investigating the distortion produced by gravity on a typical synchrotron mirror and demonstrate the repeatability of the instrument despite relaxed tolerances on the translation stage.

X ray microscopy excels on high‐brightness sources, such as the Advanced Light Source and ELETTRA, where there is a good match between the source and optics phase spaces. In these conditions, diffraction‐limited operation becomes possible with large flux. We will discuss the development of a second‐generation x ray scanning spectromicroscope; an evolution of the MAXIMUM project at the University of Wisconsin. The new tool is called SuperMAXIMUM and will be installed on ELETTRA in Trieste, Italy.

The concept of variation of the angle of deflection in a spherical grating monochromator allows to keep the defocus aberration at zero while keeping the entrance and the exit slit distances fixed. This report presents the optimization of this concept for different applications in which one would always like to work with maximum resolving power and photon flux while keeping the exit slit at a fixed position. Three designs are presented for medium resolution (E/ΔE = 3000) soft x‐ray microscopy studies in the photon energy range 200–1200 eV and 20–300 eV and for high‐resolution spectroscopy (E/ΔE≳10 000) in the larger range 20–800 eV.

New generation Synchrotron Radiation (SR) sources and Free Electron Lasers (FEL) require novel concepts of beam diagnostics to keep photon beams under surveillance, asking for simultaneous position and intensity monitoring. To deal with high power load and short time pulses provided by these sources, novel materials and methods are needed for the next generation BPMs. Diamond is a promising material for the production of semitransparent in situ X-ray BPMs withstanding the high dose rates of SR rings and high energy FELs. We report on the development of freestanding, single crystal CVD diamond detectors. Performances in both low and radio frequency SR beam monitoring are presented. For the former, sensitivity deviation was found to be approximately 2%; a 0.05% relative precision in the intensity measurements and a 0.1-μm precision in the position encoding have been estimated. For the latter, single-shot characterizations revealed sub-nanosecond rise-times and spatial precisions below 6 μm, which allowed bunch-by-bunch monitoring in multi-bunch operation. Preliminary measurements at the Fermi FEL have been performed with this detector, extracting quantitative intensity and position information for FEL pulses (~ 100 fs, energy 12 ÷ 60 eV), with a long-term spatial precision of about 85 μm; results on FEL radiation damages are also reported. Due to their direct, low-energy band gap, InGaAs quantum well devices too may be used as fast detectors for photons ranging from visible to X-ray. Results are reported which show the capability of a novel InGaAs/InAlAs device to detect intensity and position of 100-fs-wide laser pulses.