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X-ray phase/dark-field tomography by using an X-ray grating interferometer and white synchrotron radiation has been demonstrated to observe dynamics in materials consisting of light elements, because it is available with X-rays of a broad energy bandwidth. In this work, we combined X-ray phase/dark-field tomography with a stroboscopic technique, which synchronizes image acquisitions with repetitive tension applied to a sample. Snapshot images with a 200 μs temporal resolution are measured to reconstruct phase/dark-field tomograms. A result of stroboscopic X-ray dark-field tomography is described, which was obtained for a rubber sample under a 24 Hz repetitive compression-stretch motion of a 10 mm amplitude.

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.

When applying phase shifting interferometry to practical phase measurement, the wave may become non-sinusoidal, and could include some phase shift errors. Prior phase shift algorithms are primarily used for sinusoidal cases, and can cause system errors when used for these non-sinusoidal interference. We propose two phase recovery methods for non-sinusoidal interference fringes: specifically, a least-squares-based fitting algorithm that eliminates system errors using a sufficient number of measured images, and a Fourier transform-based method that effectively suppresses system errors using a lower (or insufficient) number of images. Simulation and experimental results verify the efficacy of the proposed methods.

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.

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.

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 .

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.

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.

X-ray microbeam generated by a Kirkpatrik-Baez (KB) mirror optics with a set of two parabolic-shaped reflective surfaces was tested at an undulator beamline BL47XU of SPring-8. The KB mirror used in the experiment was fabricated by numerically-controlled polishing technique at Cannon Co. Ltd. Measured focal spot size at the x-ray energy of 8 keV in the vertical and the horizontal were 0.75 μm and 0.32 μm, respectively. The photon flux of the focal spot was 2 x 10'° [photons / s / 100 mA ring current]. Tantalum test pattern of the 0.2 μm line width was clearly observed with raster scan.

A wave-front dividing interferometer was devised in which half of a highly spatially coherent beam deflected by an x-ray prism is overlapped with another half. By placing the samples in the two beams and the x-ray imaging detector closely downstream of the sample, the differential phase of the sample is recorded on the imaging detector. The separation of the two paths at the sample plane, the amount of shear, was approximately 2 pm in the present experiment. This is easily controllable by changing the distance between the sample and the imaging detector. Phase retrieval using the fringe scanning method was successfully demonstrated for various kinds of weakly absorbing samples.

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.

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 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.

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.

In our previous papers we reported that La 3+ , Gd 3+ , Y 3+ , and Lu 3+ dopings significantly improve the optical and scintillation characteristics, including radiation hardness, of PbWO 4 single crystals. The hypothesis of Pb 2+ deficiency in the grown crystals and its charge compensation by the mentioned trivalent ions occupying the Pb 2+ sites has been proposed to explain the observed improvement. Under such assumption, tetravalent-ion doping may be as efficient as or even more efficient than trivalent-ion doping in improving PbWO 4 scintillator. Recently we extended the dopant ions to stable tetravalent ions (Th 4+ , Zr 4+ ) and some other ions (Ce 3+,4+ , Sb 3+,5+ , Mn 2+ ). We have found that the tetravalent-ion (Th 4+ ) doping gives similar improvement compared with the trivalent-ion doping in consistency with the expectation mentioned above. The ions with two different possible charge states (Ce 3+,4+ , Sb 3+,5+ ) gave finite but much less improvement than the trivalent and tetravalent ions. Ce 3+,4+ doping reduced the light yield significantly. Annealing of undoped PWO in PbO vapour was also studied to examine the possibility of reducing the Pb 2+ deficiency

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.

Doping by different trivalent ions (La3+, Lu3+, Gd3+, Y3+, Sc3+) was systematically studied in PbWO4 crystals in the same way, using raw material from the same source. The result was compared with an undoped sample (actually a Pb-rich one) and samples doped with divalent (Cd2+) and pentavalent (Nb5+) ions. All the trivalent ions but Sc3+ gave a significant improvement in transmittance in the short wavelength region (330–450 nm) and in radiation hardness. Among all the tested dopants, Y3+ and Gd3+ showed the best result; these dopants may be worth further studies, since they have another advantage of the segregation coefficient close to unity.

We have investigated applications of cerium-doped GSO (Gd2SiO5:Ce or GSO:Ce) scintillating crystals to high-precision electromagnetic calorimeters in high-energy physics experiments. Basic properties of GSO:Ce such as the decay time, light yield and radiation hardness were measured using small ( ∼ 4 cm long) sample crystals. The radiation hardness tests include the scintillator stability under 60Co exposure. The characteristics of the observed residual phosphorescence due to radiation were studied in detail. These properties are dependent on the Ce concentration. Between the two concentrations we tested, 0.5 and 1.5 mol%, GSO:Ce scintillator with 1.5 mol% Ce is better in various aspects. Recently, large ingots with 1.5 mol% Ce concentration have been grown successfully. We report optical properties of 2.5 × 2.5 × 26 cm3 crystals. We discuss the feasibility of GSO:Ce scintillator-based calorimeters in operating under high radiation such as at future hadron collider experiments.

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.

Tristan Main Ring (MR) at KEK in Japan was temporarily operated as a synchrotron radiation source from September to December in 1995. The machine was operated at 8Gev and the beam current was several mA during our experiment. Although our machine time was limited to only five days, the results were very useful. A quasi-monochromatic beam from the undulator was monochromatized by two silicon parallel crystals. An 8.5keV monochromatic X-ray beam was focused by the Wolter-type grazing incidence mirror which consists of paraboloidal and hyperboloidal inner surfaces. The distance between the undulator and the mirror was 100m, which gave rise to a relatively large coherent area (vertical ∼ 50 μm, horizontal-30μm) at the entrance plane of the mirror. A highly collimated beam (vertical divergence∼3μrad, horizontal∼5μrad) was so sensitive to the mirror surface undulation that several focal spots were produced. The shape of the spots were nearly elliptical. The smallest diameter of the spots was less than 1 μm.

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 wave front dividing interferometer was devised in which half of a highly spatially coherent beam deflected by an x-ray prism is overlapped with another half. By placing the samples in the two beams and the x-ray imaging detector closely downstream of the sample, the differential phase of the sample is recorded on the imaging detector. The separation of the two paths at the sample plane, the amount of shear, was 2.2 μm in the present experiment. This is easily controllable by changing the distance between the sample and the imaging detector. Phase retrieval using the fringe scanning method was successfully demonstrated for various kinds of weakly absorbing samples.

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 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.

A total reflection x‐ray mirror is fabricated with a new method called as “bent‐polishing”. Focusing properties of a microbeam are evaluated at undulator beamline BL47XU of SPring‐8. The measured focal spot size is 0.16 μm at an x‐ray energy of 8 keV. Spot size of smaller than 0.5 μm is kept at the x‐ray energy up to 28 keV.

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.

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.

Point spread functions (PSF) of some kinds of x-ray imaging detectors are directly measured using x-ray microbeam. The experiment has been performed at bending magnet beamline BL20B2 and undulator beamline BL2oXU of Spring-9. The microbeam is focused using a Fresnel zone plate (FZP) with coherent illumination to 0.3micrometers (almost outermost zone width of the FZP). The imaging detectors are put at the focal plane and directly detect the microbeam. Two types of high spatial resolving detectors are tested. One is x-ray- electron conversion type with electro-magnetic lens, and spatial resolution is estimated to 0.7micrometers . The other is x-ray-visible light conversion type with optical lens and the spatial resolution is estimated to 1.0micrometers .

The first result is presented of an X-ray fluorescence microscope with a Wolter mirror in combination with a CCD camera used as an energy-resolved two-dimensional detector in photon-counting mode. Two-dimensional elemental maps of metallic wires, such as Fe, Co, Ni and Cu, and inclusions of a synthesized diamond could be obtained with an energy resolution of 350 eV.

A soft x-ray dark-field imaging microscope with Wolter-type mirrors was constructed in a laboratory scale. An annular aperture stop was used to cut off the undeviated beam, which satisfied the dark-field condition. The image was formed with only scattered x-rays from the object. It provides not only absorption but also phase shift information. Especially, the x-rays that have particular diffraction angle form the dark-field images in this system because Wolter mirror has a thin annular aperture. And the structures of 110∼460 nm in the object was emphasized for 5.2 nm x-rays.

A Zernike-type one-dimensional phase-contrast x-ray microscope with a Wolter mirror was developed and tested. A Cu wire or an Al phase plate was placed at the back focal plane of the Wolter mirror objective. A dark-field image of a Cu mesh could be obtained at 9.00 keV by using the Cu wire as a direct beam stop, and a phase-contrast image could be obtained at 8.97 keV by using the same optics. A polyethylene telephthalate (PET) fiber of 9 μm in diameter could be obtained at 8.97 keV by using the Al phase plate, which could seldom be observed without the phase plate. These results agreed fairly well with simulated images.

A simple hard X-ray imaging method achieving a high spatial resolution is proposed. Images are obtained by scanning a metal wire through the wave field to be measured and rotating the sample to collect data for back projection calculations; the local diffraction occurring at the edges of the metal wire operates as a narrow line probe. In-line holograms of a test sample were obtained with a spatial resolution of better than 100 nm. The potential high spatial resolution of this method is shown by calculations using diffraction theory.

An experiment to focus 82 keV x rays with a sputtered-sliced Fresnel zone plate (SS-FZP) optics was performed at an x-ray undulator beamline 20XU of SPring-8. The achieved beam size was 1.1 μm in vertical and 1.3 μm in horizontal directions. The measured flux density was 7×105 (photons/s/μm2).

A new total reflection double-slit for hard X-ray region was developed. It consists of Au narrow stripes deposited on a SiO2 substrate and can function equivalently as a conventional Young's interferometer by operating with a small grazing incident angle. The Young's interferometer using the total reflection double-slit was constructed at Hyogo-ID BL of SPring-8, and the spatial coherence at 10 keV X-rays was evaluated by analyzing the interference fringes.

Fast X-ray computed tomography (CT) system with sub-second order measurement for single CT acquisition has been developed. The system, consisting of a high-speed sample rotation stage and a high-speed X-ray camera, is constructed at synchrotron radiation beamline in order to utilize fully intense X-rays. A time-resolving CT movie (i.e. 4D CT) can be available by operating the fast CT system continuously. Real-time observation of water absorbing process of super-absorbent polymer (SAP) has been successfully performed with the 4D CT operation.

A microfocusing experiment for hard X-rays has been performed to evaluate the performance of Fresnel zone plate optics. A tantalum Fresnel zone plate with an outermost zone width of 50 nm and a thickness of 0.5 µm has been fabricated by electron-beam lithography. The focused beam size measured by a knife-edge scan is 58 nm in full-width at half-maximum for the first-order diffraction at an X-ray energy of 8 keV. It can be concluded that this zone plate has nearly diffraction-limited resolution in the hard X-ray region. The measured diffraction efficiency is 5% at 8 keV. The spot size using the third-order focus of the zone plate is measured to be approximately 30 nm.

A soft X-ray dark-field imaging microscope with Wolter-type mirrors was constructed on a laboratory scale. An annular aperture stop was used to cut off the direct beam, which satisfied the dark-field condition. The image is formed only with scattered X-rays from the object. It provides not only absorption but also phase shift information with high contrast. In the dark field, fine particles and defects of the sample that had not been seen in the bright-field image, could be observed. The image formation was analyzed by computer simulation. The dark-field images of organic specimens were also observed and compared with the bright-field images.