We have designed and fabricated a new type of focusing multilayer mirror, capable of reflecting a divergent beam over a large energy band around 9 keV. A flat energy response about 10% wide and providing a reflectivity of 50% has been achieved by a non-periodic bi-layer sequence while a lateral thickness gradient follows the varying Bragg condition over the whole mirror length. The focusing setup is based on a simple one-point bender and a pre-shaped substrate. A focal spot size of about 8 micrometers has been obtained at a distance of 285 mm from the center of the mirror using synchrotron radiation from an undulator source. Energy dependent scans have shown that this device enables focusing experiments with fixed geometry at variable energies.

In the hard x-ray range, optics based only on refraction, as in the case of visible optics, require extremely small (a few microns) bending radii of the crystal monochromators, since the deviation of the refraction index (δ = 1-n) from unity is of the order of 10^-6. Based on the principle of a series of N refractive lenses, compound refractive lenses provide an appreciable focus at a reasonable distance, but the photon flux is limited by absorption because of the generally high value of N required. As the effect of refraction is very weak, x-rays deviate considerably when diffraction occurs in a crystal in Bragg geometry: this is the base of many crystal optics devices. Focusing with crystal optics is generally achieved bending the crystals to modify the orientation of the lattices planes or modulating the entrance surface of a flat or curved crystal, the so-called Bragg-Fresnel lens. Sagittal focusing can be also obtained using asymmetrically cut crystals. From a general point of view the focusing by means of bent crystals in Laue geometry is interesting when high energies are used, because the absorption due to the transmission in the crystals is very limited. The use of bent crystals has two big advantages: it allows to accept a great divergence of the incoming radiation, thus increasing the flux of the focused radiation and allowing at the same time to select its frequencies, owing to the Darwin width of the considered reflection. Indeed, the crystal bending enables the diffracting planes to be crossed at the Bragg angle corresponding to each ray of the incident beam and, at the same time, the diffraction process produces a monochromatic beam. Actually, a small Bragg angle implies a rather long beam path in the crystal in the case of Bragg geometry, whereas in Laue geometry the incidence is almost normal: the absorption is therefore minimized upon using a suitably thin crystal. We suggest here a method allowing to improve the quality of high energy polychromatic focusing by bent crystals in Laue geometry.

Compound refractive lenses printed in Al and Be are becoming the key X-ray focusing and imaging components of beamline optical layouts at the 3^rd generation synchrotron radiation sources. Recently proposed planar optical elements based on Si, diamond etc. may substantially broaden the spectrum of the refractive optics applicability. Planar optics has focal distances ranging from millimeters to tens of meters offering nano- and micro-focusing lenses, as well as beam condensers and collimators. Here we promote deep X-ray lithography and LIGA-type techniques to create high aspect-ratio lens structures for different optical geometries. Planar X-ray refractive lenses were manufactured in 1 mm thick SU-8 negative resist layer by means of deep synchrotron radiation lithography. The focusing properties of lenses were studied at ID18F and BM5 beamlines at the ESRF using monochromatic radiation in the energy range of 10 - 25 keV. By optimizing lens layout, mask making and resist processing, lenses of good quality were fabricated. The resolution of about 270 nm (FWHM) with gain in the order of 300 was measured at 14 keV. In-line holography of B-fiber was realized in imaging and projection mode with a magnification of 3 and 20, respectively. Submicron features of the fiber were clearly resolved. A radiation stability test proved that the fabricated lenses don't change focusing characteristics after dose of absorbed X-ray radiation of about 2 MJ/cm³. The unique radiation stability along with the high effficiency of SU8 lenses opens wide range of their synchrotron radiation applications such as microfocusing elements, condensers and collimators.

Focusing properties of Si planar refractive lenses including experimental tests and theoretical analysis have been studied. Computer simulations of the X-ray wave field distribution near the focal plane have been performed for different lens designs. Comparison of the experimental results with the computer simulation allows establishing the reasons for deviation of focusing from ideal performance. The deviation of the lens vertical sidewall profile was minimized by additional correction in the lens design and special efforts in optimization of etching process. Optimized lenses were manufactured, tested at the ESRF and brought out the dramatic enhancement in focusing properties.

Two approaches have been explored to cover existing gap in energy resolution between traditional multilayers (1 to 2%) and perfect crystals (0.01%). The first approach is based on low contrast (Al₂O₃/B₄C) multilayers where we measured the width of the reflectivity curve as low as 17 arc sec, a spectral resolution of 0.27% and a reflectivity of 40% from a 26 Å d-spacing multilayer with 800 bi-layers. The second approach is based on using structures with small d-spacing using traditional W/B₄C and Mo/B₄C materials. A W/B₄C multilayer with 14.8Å d-spacing showed a resolution of 0.5% and a reflectivity of 58.5%. Two Mo/B₄C samples with d-spacings of 15Å and 20Å showed energy resolutions of 0.25% and 0.52% with corresponding reflectivities of 39% and 66% correspondingly.

With the advent of high brilliance, third generation synchrotron radiation sources, the spatial resolution of non-destructive X-ray tomographic investigations can be scaled down to the micrometer or even submicrometer range while the coherent nature of the radiation extends the traditional absorption imaging techniques towards edge-enhanced or phase-sensitive measurements. The performance of the presently used detectors is limited by scintillation properties, optical light coupling and charge coupled device granularity which impose a practical limit of about 1 micrometer spatial resolution with efficiencies of a few percent. We developed a detector called Bragg magnifier which exploits double asymmetrical Bragg diffraction from flat crystals to efficiently produce distortion- and aberrations-free X-ray images with magnification factors up to 150x150 and pixel sizes of less than 100x100nm².

Compound refractive lenses (CRLs) are effective for collimating or focusing high-energy x-ray beams (50 - 100 keV) and can be used in conjunction with crystal optics in a variety of configurations, as demonstrated at the 1-ID undulator beamline of the Advanced Photon Source. As a primary example, this article describes the quadrupling of the output flux when a collimating CRL, composed of cylindrical holes in aluminum, is inserted in between two successive monochromators -- a modest energy resolution premonochromator followed by a high-resolution monochromator. The premonochromator is a cryogenically cooled, divergence-preserving, bent double-Laue Si(111) crystal device delivering an energy width ΔE/E ~10^-3, sufficient for most experiments. The high-resolution monochromator is a four-reflection, flat Si(111) crystal system resembling two channel-cuts in a dispersive arrangement, reducing the bandwidth to ΔE/E < 10^-4, as required for some applications. Tests with 67 keV and 81 keV photon energies show that the high-resolution monochromator, having a narrow angular acceptance of a few μrad, exhibits, a four-fold throughput enhancement due to the insertion of a CRL which reduces the premonochromatized beam's vertical divergence from 29 μrad to a few μrad. The ability to focus high-energy x-rays with CRLs having long focal lengths (tens of meters) is also shown by creating a line focus of 70 - 90 μm beam height in the beamline end-station with both the modest-energy-resolution and high-energy- resolution monochromatic x-rays.

X-ray phase-retarder systems to compensate for aberrations which arise from angular divergence and energy spread of x rays, have been developed. The two-quadrant x-ray phase-retarder system consists of two diamond crystals of almost identical thickness. It can compensate for off-axis aberration (phase-shift inhomogeneity due to angular divergence of incident x rays). The four-quadrant x-ray phase-retarder system consists of four diamond crystals of almost identical thickness. The scattering planes of four phase retarders were set to be inclined by 45 deg, 135 deg (= 45 deg + 90 deg), 225 deg (= 45 deg + 180 deg) and 315 deg (= 45 deg + 270 deg), respectively, with respect to the direction of incident polarization. It can compensate for not only the off-axis aberration but also chromatic aberration (phase-shift inhomogeneity due to energy spread of incident x rays). The principles and applications of the two-quadrant and four-quadrant phase-retarder systems will be described.

In the present work the lattice plane curvature of a nearly dislocation free S:doped InP and a semi-insulating GaAs wafer crystals has been investigated using the method of X-ray rocking curve imaging based on the FRELON CCD area detector with a pixel resolution from 10 to 40 μm at the ID19 ESRF beamline. The geometry of the experiment is based on a vertical Si (111) monochromator and a horizontal sample scattering planes in the Bragg geometry (σ-π geometry). To determine the local lattice inclination, the effect of such dispersive setup on the measured local diffraction peak position has been accurately determined and the equations to determine the lattice plane curvature of the crystals under the condition of isotropic distribution of dislocation Burgers vectors are obtained. The analysis of the data showed that the shift of the Bragg condition is almost completely due to the lattice tilt rather than to the lattice parameter variation. Lattice displacements from the ideal lattice as large as 200 μm are found at the edges of the InP crystal. Non random distributions of dislocation Burgers vectors are observed in both samples.

The stability of synchrotron beamline optics is required in experiments using x-ray coherence. Especially the stability of a monochromator is important in considering a high heat load due to exposure to intense polychromatic x-rays. We developed MOSTAB (monochromator stabilization) modules and carried out performance tests using SPring-8 beamlines. We succeeded in the simultaneous stabilization of the monochromatic x-ray beam intensity and position with MOSTAB. An attempt was also made to stabilize the x-ray beam at the 1 km experimental station at SPring-8.

The high resolution, high asymmetric diffractive-refractive x-ray lens was tested at BM5 beamline in ESRF. The lens consists of two Si (111) channel-cut crystals in dispersive arrangement with the angle of asymmetry of 12.7°. The channels have a circular profile with the diameter of 22 mm. The test was performed for the energy of 7.8 - 8.1 keV and the focusing distance of 19 - 20 m. At the place of the focus the beam was squeezed horizontally from 8.8 mm (unfocused beam) to 0.4 mm, i.e. more than 20 times. To get a good reflectivity in such a highly asymmetric diffraction, the cylindrical surface had to be mechanically-chemically polished.

One of the factors influencing the focus size in diffractive-refractive optics is the quality of diffracting surface. If the surface is uneven, then the diffraction at each point of the surface is a combination of an asymmetric and inclined diffraction (general asymmetric diffraction). This somewhat deviates and spreads the diffracted beam. The integration over the surface hit by an incident beam gives the angular spread of the diffracted beam. It is shown that in some cases (highly asymmetric, highly inclined cut) the etched surface may create the spread of the diffracted beam, such that it causes a significant broadening of the focus. In this case a mechanical-chemical polishing is necessary.

A double-reflection multilayer monochromator is being developed at BM5 in order to fulfill two different functions. As a primary monochromator, it provides higher bandpass and higher photon flux than the Si(111) Bragg crystal monochromator. In combination with the crystal monochromator, it rejects the harmonics and the beam exit can be kept fixed. An additional aim is to preserve the beam coherence. Design issues and performances evaluated on the beamline are presented.

X-ray diffraction imaging with micrometer resolution was performed on type Ib and IIa diamond crystals. Experiments were carried out using 8 keV x-rays and a double-crystal diffractometer equipped with a CCD detector (pixel size 60 μm x 60 μm). Diamond samples were rotated about the horizontal axis collinear with a given reciprocal lattice vector. Local rocking curves (LRCs) were extracted from sequences of topographs taken at various angles along the global rocking curves measured at different azimuth positions of the specimen. Based on the angular positions of these LRCs, maps of local tilt and strain were produced. Results demonstrate that local misorientations play a more important role than do lattice parameter variations in broadening of total crystal rocking curves.