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Owing to the development of X‐ray focusing optics during the past decades, synchrotron‐based X‐ray microscopy techniques allow the study of specimens with unprecedented spatial resolution, down to 10 nm, using soft and medium X‐ray photon energies, though at the expense of the field of view (FOV). One of the approaches to increase the FOV to square millimetres is raster‐scanning of the specimen using a single nanoprobe; however, this results in a long data acquisition time. This work employs an array of inclined biconcave parabolic refractive multi‐lenses (RMLs), fabricated by deep X‐ray lithography and electroplating to generate a large number of long X‐ray foci. Since the FOV is limited by the pattern height if a single RML is used by impinging X‐rays parallel to the substrate, many RMLs at regular intervals in the orthogonal direction were fabricated by tilted exposure. By inclining the substrate correspondingly to the tilted exposure, 378000 X‐ray line foci were generated with a length in the centimetre range and constant intervals in the sub‐micrometre range. The capability of this new X‐ray focusing device was first confirmed using ray‐tracing simulations and then using synchrotron radiation at BL20B2 of SPring‐8, Japan. Taking account of the fact that the refractive lens is effective for focusing high‐energy X‐rays, the experiment was performed with 35 keV X‐rays. Next, by scanning a specimen through the line foci, this device was used to perform large FOV pixel super‐resolution scanning transmission hard X‐ray microscopy (PSR‐STHXM) with a 780 ± 40 nm spatial resolution within an FOV of 1.64 cm × 1.64 cm (limited by the detector area) and a total scanning time of 4 min. Biomedical implant abutments fabricated via selective laser melting using Ti–6Al–4V medical alloy were measured by PSR‐STHXM, suggesting its unique potential for studying extended and thick specimens. Although the super‐resolution function was realized in one dimension in this study, it can be expanded to two dimensions by aligning a pair of presented devices orthogonally., A new X‐ray focusing device generates hundreds of thousands of line foci, periodically spaced in the sub‐micrometre range, with centimetre length. It enables to achieve large FOV pixel super‐resolution scanning transmission hard X‐ray microscopy. image

Quantitative measurements of the phase shift of X-rays passing through a matter allow us to perform X-ray phase tomography for visualization of soft materials. Combination of an X-ray microscope and a grating interferometer is a promising approach to realize quantitative phase measurements with a microscopic spatial resolution. A Lau interferometer consisting of a source grating and a phase grating is available for this purpose with an incoherent laboratory X-ray source. We installed a Lau interferometer into a laboratory-based X-ray microscope adopting a copper rotating anode source and Fresnel zone plates (ZEISS Xradia 800 Ultra). A “twin-phase image”, which consists of positive and negative phase images overlaid with a certain separation, is generated through a fringe-scanning measurement with this microscope. A step for generating a quantitative phase image from the twin phase image should be developed to perform phase tomography. However, conventional deconvolution operations are not suitable because of artifacts and noise remained in resultant phase images. To reduce the artifacts and noise, an iterative calculation algorithm has been developed. The evaluation of the algorithm shows that the artifacts and noise are suppressed and quantitative phase images are obtained. Finally, results of phase tomography obtained for soft materials are demonstrated.

An x-ray phase tomographic microscope has been developed by optimizing the optical system for 9-keV synchrotron x rays at BL37XU, SPring-8, Japan. The system consists of a full-field x-ray imaging microscope and a Talbot interferometer. In contrast with our previous system, a Fresnel zone plate for the microscope objective and transmission gratings of the interferometer was designed to improve the refraction sensitivity, with a larger field of view and a higher spatial resolution, utilizing a 28-m space available at BL37XU. An x-ray phase tomographic microscope with a field of view of 375 µm and a spatial resolution of 560 nm was thus constructed, even with a considerably low x-ray dosage. By applying this tomographic microscope to auditory bone specimens of young mice, it was shown that soft tissues in addition to bone tissue could be observed simultaneously without serious radiation damage.

This paper review the configurations of grating-based X-ray interferometry for X-ray phase imaging/tomography and describes recent activities for four-dimensional X-ray phase tomography and nanoscopic X-ray phase tomog- raphy. A multilayer mirror to produce a 10% bandwidth pink beam at 25 keV has been installed at SPring-8 for four-dimensional X-ray phase tomography, and an application to polymer laser ablation is presented. A 100-fold full-field X-ray microscope employing a Fresnel zone plate has been used successfully in combination with a Talbot interferometer to perform nanoscopic phase tomography for a malleal processus brevis of a mouse nine days after birth. Another development using a laboratory-based full-field X-ray microscope in combination with a Lau interferometer is also described.

An X-ray phase tomographic microscope that can quantitatively measure the refractive index of a sample in three dimensions with a high spatial resolution was developed by installing a Lau interferometer consisting of an absorption grating and a π/2 phase grating into the optics of an X-ray microscope. The optics comprises a Cu rotating anode X-ray source, capillary condenser optics, and a Fresnel zone plate for the objective. The microscope has two optical modes: a large-field-of-view mode (field of view: 65 μm x 65 μm) and a high-resolution mode (spatial resolution: 50 nm). Optimizing the parameters of the interferometer yields a self-image of the phase grating with ~60% visibility. Through the normal fringe-scanning measurement, a twin phase image, which has an overlap of two phase image of opposite contrast with a shear distance much larger than system resolution, is generated. Although artifacts remain to some extent currently when a phase image is calculated from the twin phase image, this system can obtain high-spatial-resolution images resolving 50-nm structures. Phase tomography with this system has also been demonstrated using a phase object.

X-ray phase contrast imaging offers a complementary modality next to conventional absorption. To reveal internal structures of soft materials in high resolution, an X-ray phase imaging microscope has been developed by installing a Lau interferometer into a commercially available ZEISS Xradia 800 Ultra-nano computed tomography X-ray microscope. On this system, a twin phase image is once generated through measurements of interference fringes. In order to produce a quantitative X-ray phase map, the twin phase image should be treated by deconvolution. However, conventional deconvolution results showed a reduction in image quality due to noise and artifacts. Therefore, we propose and evaluate the performance of an iterative deconvolution method. The results show that the proposed deconvolution method does not affect spatial resolution, increases the signal to noise ratio compared to that of the twin phase image, and is capable of imaging complex structures.

We have launched a project to promote grating-based X-ray phase imaging/tomography extensively. Here, two main activities are presented for enabling dynamic, or four-dimensional, X-ray phase tomography and nanoscopic X-ray phase tomography by grating interferometry. For the former, while some demonstrations in this direction were performed with white synchrotron radiation, improvement in image quality by spectrum tuning is described. A preliminary result by a total reflection mirror is presented, and as a next step, preparation of a 10% bandpass filter by a multilayer mirror is reported. For the latter, X-ray microscopes available both at synchrotron radiation facilities and laboratories equipped with a Fresnel zone plate are combined with grating interferometry. Here, a preliminary result with a combination of a Lau interferometer and a laboratory-based X-ray microscope is presented.

Multilayer zone plate (MZP) technology for hard X-ray focusing was upgraded and its focusing performance was evaluated using 20-keV X-rays at the synchrotron beamline (BL24XU) of SPring-8. The MZP consists of MoSi2 and Si layers alternately deposited on a glass fiber by magnetron sputtering so that all zone boundaries satisfy the Fresnel zone configuration. The focused beam was evaluated using knife-edge scanning in which the measured intensity distribution is identical to the line spread function (LSF) in the focal plane. The focused beamsize of about 30 nm was estimated by oscillation peaks observed in the measured LSF according to Rayleigh’s criterion.

A total-reflection zone plate (TRZP), which is a reflective grating that generates a line focus of hard X-rays, was developed. Newly designed TRZPs, introducing a laminar grating concept, were fabricated with various zone parameters. The focusing performances with regard to the beam size and the diffraction efficiency were evaluated using synchrotron radiation X-rays of 10 keV energy. Although the beam sizes measured are insufficient in comparison with the ideal value, the maximum diffraction efficiency, measured at 20%, exceeds the limitations of conventional TRZPs based on a binary grating.

The experimental procedure for obtaining the point spread function (PSF) of a focusing beam generated using an X-ray multilayer zone plate (MZP) with a narrow annular aperture has been developed. It was possible to reconstruct the PSF by applying the tomographic process to the measured dataset consisting of line spread functions (LSFs) in every radial direction on the focal plane. The LSFs were measured by a knife-edge scanning method of detecting scattered intensity. In the experimental work, quasi-monochromatic undulator radiation with a first harmonic energy of 20 keV was directly focused without a monochromator by the MZP, and the PSF was measured using this procedure. As a result, a near diffraction-limited focused beam size of 46 nm full width at half-maximum was obtained.

A grating interferometer (GI) system has been installed in an X-ray microscope equipped with a Zernike phase contrast (ZPC) system and a Cu rotating anode X-ray source. The GI and ZPC systems are switchable, and their performances of phase information extraction have been compared. The GI system is based on a Lau interferometer consisting of an absorption grating and a π/2 phase grating, which extracts a magnified phase shift map of a sample via a phase-stepping measurement. The ZPC system generates a phase contrast image by using a phase plate and a corresponding condenser device. The ZPC system and the GI system are compared in terms of detectability of phase objects. By the Fourier analysis of images of a logarithmic ruler pattern, the spatial resolution was found to be identical between the two systems. Although the sensitivity depends on the sample size, the signal-to-noise ratio of polystyrene spheres with a few microns in diameter was used for sensitivity comparison, showing the superior sensitivity of the GI system to that of the ZPC system. The quantitativeness of the GI system with the phase-stepping measurement was also demonstrated over the ZPC system, which generates halo and shade-off artifacts. The GI system exhibits twin image artifacts that need to be resolved for practical applications of the technique.

We have investigated the crystallinity of compositionally graded SiGe layers of strained Si (s-Si) wafers in the growth direction by irradiating a synchrotron X-ray microbeam with a high parallelism on a cross section of s-Si wafers. As a result, we can confirm the presence of surface parallel SiGe lattice rotation and lattice rotation distribution (LRD). The surface parallel LRD and relaxation ratio of SiGe start to decrease in the depth direction below approximately 3 ?m from the wafer surface. It is inferred that the insufficient relaxation of SiGe near the wafer surface is caused by the characteristics of the free wafer surface. Furthermore, such characteristics are thought to lead to a reduction in LRD near the wafer surface.

The time-lapse observation of the electrodeposition of copper in copper sulfate solution was performed by imaging X-ray fluorescence from the copper deposition. The X-ray fluorescence was directly imaged with a full-field Wolter mirror microscope, which was constructed at the Photon Factory. Controlling the electric current in the solution from 0 to 71.7 µA, the deposition of copper on a Pt cathode was directly observed by imaging its X-ray fluorescence. One exposure time for obtaining an X-ray fluorescence image was 80 s. Then, it was 17 min later from the beginning of the electrolysis when the X-ray fluorescence image of the electrodeposition is observed for the first time. At this exposure time, the detection limit of the mass of copper was estimated to be 0.60 pg/image, which was calculated using test samples of 1.00×10-3–1.00 mol/l copper sulfate solutions.

Tomographic quantitative phase measurement has been carried out by using a hard X-ray micro-interferometer in Hyogo-ID at SPring-8. The micro-interferometer combines an imaging microscope and a wavefront-division-type interferometer by using a novel optical element called a “twin zone plate.” A three-dimensional quantitative phase distribution of a glass capillary with an outer diameter of 6 μm was successfully obtained with the tomographic technique. The measured refractive index corresponded to the ideal value. The spatial resolution of the tomographic image was estimated to be 250 nm and the density resolution was estimated to be 0.6 g/cm 3 .

A multilayer (sputtered-sliced) Fresnel zone plate (FZP) is one of the promising focusing optics with high spatial resolution for the high-energy X-ray region. This is because a large “aspect ratio” can be realized easily. In addition, it is important that the kinoform FZP (theoretical diffraction efficiency=100%) can be fabricated by the sputtered-sliced method. This paper presents the experimental results of two new approaches for fabrication of a multilayer FZP for X-rays. (1) To achieve higher diffraction efficiency, a multilevel-type (4-step: quasi-kinoform type) FZP was fabricated. This FZP was composed of concentric multilayers of alternating high-Z, low-Z, and composite materials. The composite material layer was deposited by co-sputtering of high-Z and low-Z materials. (2) To achieve smoother zones (multilayer interfaces) at the conventional-type FZP, each target of a sputtering apparatus with two DC-sputtering guns was surrounded by a cover with an aperture, and Ar gas was supplied inside the cover, which led to the deposition at lower Ar gas pressure. As a result, for the former, the efficiency was improved markedly as compared with conventional FZP, and for the latter, the zone roughness was reduced, which has resulted in the improvement of the spatial resolution of the FZP.

Microfocusing of 100 keV x ray with a sputtered-sliced Fresnel zone plate (ss-FZP) has been performed at the 250-m-long beamline (20XU) of SPring-8. The ss-FZP with an outermost zone width 0.16 μm which is composed of 70 layers of alternating Cu and Al layers and having thickness ∼180 μm was fabricated and characterized. The minimum focal spot size attained for the first order focal beam was 0.5 μm with a focal distance 900 mm at a photon energy 100 keV. The total flux of the microprobe was ∼2×106 photons s−1 μm−2.

Zemike phase-contrast microscopy was realized using a micro-capillary X-ray refractive lens. Using a gold N4-phase plate, positive phase contrast images were successfully taken. The microscope system was designed so that the ID & 2D phase contrast images can be taken with various sizes of the phase plates and the absorption contrast images, switchable by moving the phase plate. Thc profiles of the observed images are compared with the theoretically expected ones and they qualitatively agreed with each other. The sensitivity of the system was checked by detecting weakly absorbing materials, such as the SiC particles with the diameter of less than 5 micrometer.

Development of microfocusing optics for scanning microscopy and image forming optics for imaging microscopy are now in progress in SPring-8 by using varieties of optical devices: refractive lens, total reflection mirrors. Fresnel zone plates, and sputtered-sliced Fresnel zone plates. Spatial resolution of 100 nm has been achieved in scanning microscopy using highly coherent X-ray beam at a 248 m-long beamline 20XU and F2P' focusing optics. Recent results on development of optical systems are described.

High-sensitive differential phase imaging has been performed with hard x-ray scanning transmission microscope optics and an imaging detector. A microbeam with the size of 60 nm at 8 keV x ray is generated by highly-coherent illuminated beam at x-ray undulalor beamline BL20XU of SPring-8. The differential phase image is reconstructed by data set consists of diffraction images of each scan position. Advantages for absorption imaging are shown with some objects.

Present status of our developments of x-ray holographic microscopes at SPring-8 BL20XU is described. A combination of the x-ray undulator and a zone plate enabled us to make a coherent x-ray source of around 0.1 μm size. Using this secondary source, two types of x-ray holographic microscopes were investigated. First, a Gabor microscope in point-projection geometry was tested. A tantalum 0.2 μm line-and-space pattern could be resolved. Second, using a zone plate as a beam splitter, a Fourier transform holographic microscope was tested. A tantalum 0.2 μm line-and-space pattern could be observed. Polystyrene beads of 2.8 μmand 0.8 μm in diameter could be observed. In Fourier transform holography, a reconstructed image of a specimen that is located out of the plane of the reference source is blurred. Numerical focusing of such an x-ray hologram could be successfully demonstrated.

We are planning to develop a kinoform zone plate (ZP) for hard X-ray using a sputtered-sliced (SS) method with two materials (Cu/Al). The SS kinoform ZP is composed of a Cu/Al multilayer that is based on radial modulation of the refractive indices of deposition materials. The X-ray through the zones interferes constructively at the focal point. The kinoform ZP, therefore, has an advantage of high focusing efficiency. According to the our theoretical calculation, the focusing efficiency of the Cu/Al kinoform PZP is up to 86% in the 0-30 keV X-ray energy region, while one of the conventional Cu/Al multilayer Fresnel zone plate is up to 38%.

An x-ray microtomography method combined with hard x-ray imaging microscopy was developed that has a potential spatial resolution of the order of 10–100 nm. The system consists of a high-brilliance undulator source of SPring-8, a beam diffuser plate to reduce the coherence of the illumination, a high-precision rotating sample stage, a Fresnel zone plate objective, and a high-resolution x-ray imaging detector. The three-dimensional images of several samples were observed and successfully reconstructed with a pitch pattern of 0.6 μm.

A hard X-ray microbeam is a key technology for third-generation high-brilliance synchrotron radiation sources such as SPring-8. A Fresnel zone plate (FZP) is one of the promising focusing elements for X-rays. A multilayer (sputtered–sliced) FZP is suitable for use in hard X-ray region, because large thickness can be available. Zone (multilayer interface) roughness is inevitable to the multilayer FZP, which results in the inferior-focusing characteristic. Some Cu/Al concentric multilayers were fabricated by DC sputtering deposition. In order to reduce the oblique incidence of sputtered atoms on the wire substrate, a cylindrical slit was placed between the target and the wire substrate. As a result, the interface roughness was improved with very good repeatability.

Full-field x-ray scattering microscopic images were obtained with a Wolter mirror (×10 magnification). A synchrotron radiation white beam (4–20 keV) from a bending magnet beamline at the Photon Factory was used to obtain x-ray scattering images. The system was available for multi-kilo-electron-volt x-ray range (4–12 keV) with the Wolter mirror. The image was formed only with scattered x rays from the object, which is kind of a dark-field image. Very low absorptive materials could be imaged with this microscope. Sensitivity of the system was evaluated and also the detection limit was estimated.

The performance of a Fresnel zone plate has been tested by observing the focusing property of higher-order diffraction. The Fresnel zone plate was fabricated by the electron-beam lithography technique. The zone material was made from 1 µm-thick tantalum and the outermost zone width was 0.25 µm. The third-order focused spot size measured by the knife-edge scan method was 0.1 µm full width at half-maximum at an X-ray energy of 8 keV, which is exactly equal to one-third of the first-order focal spot size.

The intensity distribution in phase space of an X-ray synchrotron radiation beamline was measured using a pinhole camera method, in order to verify astigmatism compensation by a Fresnel zone plate focusing optical system. The beamline is equipped with a silicon double crystal monochromator. The beam size and divergence at an arbitrary distance were estimated. It was found that the virtual source point was largely different between the vertical and horizontal directions, which is probably caused by thermal distortion of the monochromator crystal. The result is consistent with our astigmatism compensation by inclining a Fresnel zone plate.

We have improved the performance of a previously reported multilayer zone plate by reducing its outermost zone width, using the same multilayer materials (MoSi2 and Si) and fabrication technique. The focusing performance was evaluated at the BL24XU of SPring-8 using 20-keV X-rays. The line spread function (LSF) in the focal plane was measured using a dark-field knife-edge scan method, and the point spread function was obtained from the LSF through a tomographic reconstruction principle. The spatial resolution was estimated to be 30 nm, which is in relatively good agreement with the calculated diffraction-limited value of 25 nm, while the measured diffraction efficiency of the +1st order was 24%.

An X-ray fluorescence imaging microscope with a Wolter-type grazing-incidence mirror objective was constructed at beamline 39XU of SPring-8. Monochromatic X-rays in the energy range 6–10 keV were used for X-ray fluorescence excitation of the specimens. Recording X-ray fluorescence images of a test specimen (Cu, Ni and Fe wires) from 50 different angles of view, three-dimensional tomographic reconstructions were obtained. These wires could be reconstructed selectively by changing the energy of the excitation X-rays. A synthetic diamond could also be imaged three-dimensionally.

X-ray imaging microscopy with a sputtered-sliced Fresnel zone plate (SS-FZP) has been developed at an X-ray energy of 25keV. Objects were imaged in transmission with the SS-FZP as an objective with a magnification of 10.2 times, and detected with a X-ray image sensor. The performance of the imaging microscope has been tested with a gold mesh and a resolution test pattern at an undulator beamline 47XU of SPring-8. The resolution test patterns up to 0.5mm line-and-space structures have been resolved. # 2001 Elsevier Science B.V. All rights reserved.

X線集光素子の1つである多層膜フレネルゾーンプレート (FZP) の作製方法, 開発したFZPを利用した集光実験の成果および関連分野の世界の研究動向を紹介した.大型放射光施設SPring-8における集光実験ではトップレベルのデータが得られ, 多層膜FZPは特に高エネルギー領域 (>25keV) の集光にも有効であることがわかった.FZPは連続100時間以上の使用の間, 放射線損傷は観察されなかった.このことから, 高輝度放射光を利用した硬X線顕微鏡の実用化に大きく前進したと言える.測定された性能値を理論値に限りなく近づけるためには, 成膜工程を中心に一層の工夫が必要である.今後, ゾーン (多層膜界面) の平滑性を改善するために成膜条件の検討, 成膜装置の改良を引き続き行うと共に, 多層膜FZPの結像特性の理論的考察も行いたい.また, マイクロビームを利用して微小領域の元素マッピング, 化学状態のイメージングなどを行う予定である.本報告で紹介した以外にも注目すべき新しい硬X線領域用の集光素子が最近相次いで発表され, 今後の進展が期待される.集光テストを行ったSPring-8での利用研究課題の課題番号は, 1999A0091-NM-np, 1999B0080-CM-np, 1999B0103-NM-np, 2000AO160-NM-npである.

Full-field x-ray fluorescence (XRF) and transmission x-ray microscopic images were obtained with a Wolter-type mirror (10× magnification). A synchrotron radiation white beam (4–20 keV) from a bending magnet beamline at the Photon Factory was used to obtain XRF images and a conventional laboratory x-ray source (8.04 keV) was used to obtain transmission x-ray images. The effects of the coherent and the incoherent scattering x rays on the contrast of an XRF image were estimated. The scattering angle between the incidence x ray and the optical axis of the XRF microscope should be 90° to obtain the highest contrast image when the incidence x ray is horizontally polarized. Observation of small metallic inclusions in the synthesized diamond showed that the contrast of the XRF image was better than that of the transmission x-ray image.

An X-ray fluorescence imaging microscope with a Wolter-type objective mirror (magnification: 13) has been constructed at beamline 39XU of SPring-8. Monochromatic X-rays (DeltaE/E approximately 10(-4)) in the energy range 6-10 keV were used for X-ray fluorescence excitation of the specimens. Using two monochromatic X-rays above and below the absorption edge of a particular element, a two-dimensional image of the element could be obtained. As a result, two-dimensional element mapping of the test specimens (Cu, Co, Ni, Fe and Ti wires) and constituent minerals (Fe, Mn and Ti) of a rock specimen (a piemontite-quartz schist) became possible.

In this paper we report the crystal growth of lead tungstate crystals by the vertical Bridgman method with a flat-bottom crucible. The crystals were grown with different melt compositions. Other parameters such as effect of crucible thickness and growth orientation were also studied. Measurement of lattice parameters and phase analysis was carried out by X-ray diffraction method at different stages of crystallization and the region of congruent composition is investigated. Electron probe micro analyzer was used to image the eutectic flux mixture at the end of crystallization. It is concluded that the stoichiometric composition of PbWO 4 is congruent.

We constructed a soft X-ray imaging microscope on a laboratory scale by using a laser produced plasma source. Two different soft X-rays (wavelength: 3.2 nm and 5.2 nm) were obtained by using a Nd-YAG laser with a power of 1.2 J and a pulse width of 8 ns. Wolter mirrors were used as a condenser and an objective. A back-illuminated CCD camera was introduced as an X-ray imaging detector. Spatial resolution was estimated to be about 60 nm with a transmission grating object. An X-ray micrograph of a stoma at epidermis of vincia faba L. was obtained. A human red blood cell in a solution was also observed and it showed that the soft X-ray microscope is available for living specimens in a wet state.

A hard X-ray nano-interferometer using two types of zone plate has been developed. One is an ordinary zone plate for a microscope objective, and the other is a newly designed zone plate called an "annular zone plate" for configuring reference waves. We have succeeded in producing interference fringes with variable periods up to a fringeless pattern. The phase-shift distribution of polystyrene microparticles could be imaged clearly with a spatial resolution of 60 nm and a phase sensitivity of λ/40 at a photon energy of 8 keV. Furthermore, this interferometer was applied to phase tomography for high-spatial-resolution three-dimensional observation.

An imaging microscopy experiment in a hard x-ray region has been performed at the undulator beamline 40XU of SPring-8. The helical undulator at the BL40XU provides quasimonochromatic radiation with a bandwidth of 1.2% at 8.34 keV. A Fresnel zone plate with an outermost zone width of 0.25 μm and a Fresnel zone number of 100 is used as an objective. The natural bandwidth of the undulator radiation of BL40XU is nearly equal to the monochromaticity required for the zone plate objective. Therefore, compared with conventional beamlines with a crystal monochromator, the available photon flux is higher by two orders. Fine structure of test patterns with 0.25 μm line and space was clearly observed at an x-ray energy of 8.34 keV within an exposure time of 1.5 ms.

X-ray topographs are taken for a sapphire wafer with the [0001] surface normal, as an example, by forward transmitted synchrotron x-ray beams combined with two-dimensional electronic arrays in the x-ray detector having a spatial resolution of 1 μm. They exhibit no shape deformation and no position shift of the dislocation lines on the topographs. Since the topography is performed under multiple-beam diffraction conditions, the topographic images of a single diffraction (two-wave approximation condition) or plural diffractions (six-wave approximation condition) can be recorded without large specimen position changes. As usual Lang topographs, it is possible to determine the Burgers vector of each dislocation line. Because of high parallelism of the incoming x-rays and linear sensitivity of the electronic arrays to the incident x-rays, the present technique can be used to visualize individual dislocations in single crystals of the dislocation density as high as 1 × 10(5) cm(-2).

A hard X-ray focusing test of a Fresnel zone plate has been performed with a synchrotron radiation source at the undulator beamline 20XU of SPring-8. A Fresnel zone plate with a radius of 150 µm, and an outermost zone width of 100 nm was used for the X-ray focusing device. The 248-m-long beamline provides fully coherent illumination for the focusing device. The focused beam was evaluated by the knife-edge-scan method and scanning microscope test using test charts. Nearly diffraction-limited focusing with a size of 120 nm was achieved for the first-order diffraction at 10 keV X-ray. Evaluation for the third-order diffraction was also performed at 8 keV X-ray, and a focal size of 50 nm has been obtained.

A circular multilayer zone plate (MZP) was fabricated and its focusing performance was evaluated using 20-keV x-rays. MoSi(2) and Si layers were alternately deposited by DC magnetron sputtering on a wire core; all the interfaces satisfied the Fresnel zone condition. The measured line spread function was converted to a point spread function by tomographic reconstruction. The results suggest that the MZP has the potential to realize the diffraction-limited resolving power, which is calculated to be 35 nm using the diffraction integral. Furthermore, scanning transmission microscopy using the MZP could resolve a 50-nm line-and-space pattern.

A Zernike-type phase-contrast X-ray microscope with a zone plate and a phase plate was constructed at the Photon Factory BL3C2. Parallel monochromatic X-rays of 8.97 keV were incident on a specimen and a direct beam transmitted through the specimen was focused on the back focal plane of the zone plate, where an aluminium phase plate was placed. Tantalum line patterns as fine as 0.3 µm could be imaged. Phase-contrast images of polypropylene wires and polystyrene latex beads were obtained, which showed better contrast than that of their bright field images.

X-ray nanofocusing devices are capable of focusing X-rays down to sizes of about 10 nm. We have developed a new nanofocusing device, known as total-reflection zone plates (TRZPs), for focusing high-brilliance synchrotron radiation in the hard x-ray region. This device consists of a reflective zone pattern on a flat substrate. It has the potential to focus hard x-rays down to sub-10-nm dimensions. Furthermore, it is considerably easier to fabricate than other hard x-ray nanofocusing devices since it is used with a very small grazing incidence angle. We have focused 10-keV x-rays to sub-15 nm dimensions using a TRZP that was fabricated by conventional electron-beam lithography. In addition, we present designs for more efficient devices that have a target focus size of 5 nm. We propose and discuss a new approach for achieving point focusing with nanometer dimensions.

Strain in silicon on insulator (SOI) and strained-silicon(s-Si)/silicon–germanium (SiGe)/Si-substrate crystals is analysed by means of synchrotron X-ray microbeam diffraction. It is found that strain features of the s-Si/SiGe/Si crystals are much different from those of SOI crystals from the lattice tilt and lattice parameter distribution points of view. The two-dimensional lattice tilt maps obtained by scanning the synchrotron X-ray microbeam of about 1 μm in size on the sample surface are useful to study local strain distribution in those materials.

A high spatial resolution X-ray microscope was constructed using an X-ray refractive lens as an objective. The spatial resolution was tested using 18 keV X-ray. A 0.4 mm line and 0.4 mm space tantalum test pattern was successfully resolved. Using the similar setup with the addition of a phase plate, a Zernike type phase-contrast microscopy experiment was carried out for the phase retrieval of the samples. Two-dimensional phase-contrast images were successfully taken for the first time in the hard X-ray region. Images of a gold mesh sample were analyzed and the validity of this method was indicated. An improvement of the lens, however, is required for the precise phase retrieval of the samples. # 2001 Elsevier Science B.V. All rights reserved.

A hard X-ray microbeam created from a sputtered-sliced Fresnel zone plate has been tested at SPring-8 undulator beamline. Focusing properties are evaluated in the X-ray wavelength regions of 0.15– 1.5 A . The measured focal beam size is about 0.6 μm at an X-ray wavelength of 1.4 A . In a scanning microscopy experiment, resolution-test-patterns with 0.2 μm structure are resolved at an X-ray wavelength of 0.45 A .

A medium‐length beamline with undulator source, BL20XU at SPring‐8, was constructed, and opened to public use. The distance from source point to the end of the beamline is 248 m. By utilizing the long beam transport path, the beamline has advantages for experiment that requires high spatial coherence in hard X‐ray regions.

Using two zone plates, a hard x‐ray lens‐less Fourier transform holographic microscope with cone‐beam illumination was investigated at SPring‐8 BL20XU. One zone plate was placed on the optical axis, and another zone plate was placed 16 mm downstream and 9 μm off the optical axis. The diverging x‐rays from the focus of the upstream zone plate illuminated a specimen where the focus of the downstream zone plate was placed. A hologram of a copper mesh of 12.7 μm pitch could be obtained. The intensity and the phase could be successfully reconstructed with sub‐micron resolution.

New small angle X‐ray dispersion speckle method by the condensing optical system using FZP (Fresnel zone plate) was performed. And single crystal diffraction spot image was observed using this optical system. High photon flux with the FZP of 100‐micron‐diameter is obtained than that with a 5‐micron‐diameter pinhole. S/N ratio of data improved and measurement time also became short. The minimum beam size focused with the FZP was 0.25 μm. The speckle image resulting from the non‐ordering structure and periodic structure of 10nm order is successfully observed. This optical system was applicable also to diffraction spot image observation. We show a possibility that the information of the periodic and/or random structural analysis with sub‐μm order which were unsuitable with the conventional single crystal x‐ray diffraction analysis.

Microfocusing experiments of high‐brilliance, high‐energy X‐ray by using a multilayer Fresnel zone plates were performed at SPring‐8. It is proved that the multilayer FZPs can be used as focusing elements with high spatial resolution in a wide range X‐ray wavelength domain up to 100 keV. A Cu/Al FZP with the thickness of 40 micron has attained the spatial resolution of 0.7 ∼ 1.8 micron in a wide range X‐ray wavelength domain of 18.6 ∼ 113 keV. Three types of microscopic image of an Au mesh with 1500 lines per inch were taken by a X‐ray microscopy experiment by using the multilayer FZP at 82 keV: a scanning microscopic transmission image, a scanning microscopic fluorescent one and an imaging microscopic one with the spatial resolution of ∼ 0.7 micron. High‐energy X‐ray microprobe by using the multilayer FZP will be powerful tool for non‐destructive various analyses of thick materials (bulk, IC, etc) with submicron spatial resolution.

Resolving power of high spatial resolution X‐ray computed tomography (CT) system was evaluated by taking CT images of artificial test patterns at BL47XU in SPring‐8 (SP‐μCT BL47XU). The system consists of an in‐vacuum type undulator, a double crystal monochromator cooled with liquid nitrogen, a high precision sample stages and a high spatial resolution X‐ray detector. For the precise measurement of the resolving power, the artificial test patterns of Cu/Al concentric multilayer were fabricated by DC sputtering deposition at AIST Kansai. 7 or 5 layers of Cu/Al are deposited by period of 2 μm and 1 μm. Therefore the resolving power could be measured at 4 μm and 2 μm with each test pattern. It was confirmed that the system had a resolving power of 2 μm at 15keV from the CT images of test patterns. The resolution is not independent on the used energy. At 30keV, the resolving power was slightly poorer than 2 μm. The result was consistent with the point spread functions of the high resolution detector measured by focused micro‐beam.