Development Of X-ray Optics Research Articles

Silicon micro-pore X-ray optics

We present our development of novel light-weight and low-cost micro-pore X-ray optics based on the Micro Electro Mechanical Systems (MEMS) technologies. We successfully fabricated X-ray mirror chips with surface roughness less than several nm and an accurately defined optic mount. Our studies suggest this type of optics is a promising device for X-ray optics in many research fields such as space research, nuclear physics, and microanalysis.

X-ray fluorescence microscopy reveals large-scale relocalization and extracellular translocation of cellular copper during angiogenesis

Although copper has been reported to influence numerous proteins known to be important for angiogenesis, the enhanced sensitivity of this developmental process to copper bioavailability has remained an enigma, because copper metalloproteins are prevalent and essential throughout all cells. Recent developments in x-ray optics at third-generation synchrotron sources have provided a resource for highly sensitive visualization and quantitation of metalloproteins in biological samples. Here, we report the application of x-ray fluorescence microscopy (XFM) toin vitro models of angiogenesis and neurogenesis, revealing a surprisingly dramatic spatial relocalization specific to capillary formation of 80-90% of endogenous cellular copper stores from intracellular compartments to the tips of nascent endothelial cell filopodia and across the cell membrane. Although copper chelation had no effect on process formation, an almost complete ablation of network formation was observed. XFM of highly vascularized ductal carcinomas showed copper clustering in putative neoangiogenic areas. This use of XFM for the study of a dynamic developmental process not only sheds light on the copper requirement for endothelial tube formation but highlights the value of synchrotron-based facilities in biological research.

Residual stress analysis in micro- and nano-structured materials by X-ray diffraction

Micro- and nano-structured materials often exhibit high level of residual stresses which may affect the reliability of electronic devices. Stress control is, therefore, essential for improving device lifetime. X-ray diffraction is one of the most widely used techniques for stress analysis. It is essentially non destructive and allows for the study of both the microstructural and elastic properties of all the diffracting phases in complex materials. With the advent of third generation synchrotrons and the development of new X-ray optics and detectors as well as enhanced data analysis capabilities, measurements of specific stress features such as local stresses, stress gradients and stress heterogeneities are now within reach. This paper reviews the state of the art in that field illustrated with a few examples.

X-Ray Resonance in Crystal Cavities: Realization of Fabry-Perot Resonator for Hard X Rays

X-ray back diffraction from monolithic two silicon crystal plates of 25-150 microm thickness and a 40-150 microm gap using synchrotron radiation of energy resolution DeltaE = 0.36 meV at 14.4388 keV clearly show resonance fringes inside the energy gap and the total-reflection range for the (12 4 0) reflection. This cavity resonance results from the coherent interaction between the x-ray wave fields generated by the two plates with a gap smaller than the x-ray coherence length. This finding opens up new opportunities for high-resolution and phase-contrast x-ray studies, and may lead to new developments in x-ray optics.

Normal-incidence reflectance of optimized W/B_4C x-ray multilayers in the range 14 nm < λ < 24 nm

We have fabricated W/B(4)C multilayers having periods in the range d = 0.8-1.2 nm and measured their soft-x-ray performance near normal incidence in the wavelength range 1.4<l<2.4 nm . By adjusting the fractional layer thickness of W we have produced structures having interface widths ó ~ 0.29 nm (i.e., as determined from normal-incidence reflectometry), thus having optimal soft-x-ray performance. We describe our results and discuss their implications, particularly with regard to the development of short-wavelength normal-incidence x-ray optics.

High resolution coronal imaging with multilayers

Since the 1960s, when on-disk coronal imaging became possible, progress in the field has consisted largely in improving the spectral spatial and temporal resolution of the observations. With the development of normal-incidence, soft X-ray and XUV multilayer optics in the 1980s, a dramatic improvement in the first two of these occurred, and with the development of better detectors the temporal resolution (along with the sensitivity) also improved. In this paper we discuss recent results from The Transition Region and Coronal Explorer ( TRACE), which is providing observations of the solar outer atmosphere with unprecedented spatial and temporal resolution. The new views of coronal structure and dynamics being obtained indicate that: (i) the corona is filled with flows of both hot and cool material, (ii) instead of “loops,” the basic coronal structures are threads, and (iii) threads of hot plasma appear to form as parallel bundles on surfaces, which may correspond to dissipation at quasi-separatrix layers. We conclude with a discussion of the possible next generation of high resolution missions.

Construction and commissioning of a 215-m-long beamline at SPring-8

The 215-m-long beamline has been constructed as the first medium-length beamline of SPring-8 for the purpose of R&D of imaging techniques, development of X-ray optics, computed tomography for mineral science, medical imaging, and X-ray topography. By using the long beamline, large field and spatially coherent beam can be obtained. Advantage of long beamline is successfully demonstrated by the preliminary experiment such as one-shot topograph of 300-mm-diameter silicon crystal.

Hard X-ray microbeam production with synchrotron radiation: application to microanalysis

The advent of synchrotron radiation and the recent development of x-ray optics have rendered possible the realization of x-ray fluorescence microprobes. Various arrangements allow one to obtain micrometer-size hard x-ray beams with sufficient flux to undertake elemental mapping of trace elements. Associated with micro-diffraction or with extended x-ray absorption fine structure studies, these microprobes are becoming very powerful tools for material characterization.

Electronic and optical moiré interference with microchannel plates: artifacts and benefits

The spatial resolution of position-sensitive detectors that use stacks of microchannel plates (MCP's) with high-resolution anodes can be better than 20-microm FWHM [Proc. SPIE 3114, 283-294 (1997)]. At this level of accuracy, channel misalignments of the MCP's in the stack can cause observable moiré interference patterns. We show that the flat-field detector response can have moiré beat pattern modulations of as great as approximately 27% with periods from as small as a few channel diameters to as great as the size of a MCP multifiber. These modulations, however, may be essentially eliminated by rotation of the MCP's or by a mismatch of the channel sizes. We also discuss how the modulation phenomena can be a useful tool for mapping the metric nonlinearities of MCP detector readout systems. Employing the optical moiré effect, we demonstrate a simple, but effective, technique for evaluation of geometrical deformations simultaneously over a large MCP area. For a typical MCP, with a 60-channel-wide multifiber, we can obtain accuracies of 1.2 mrad for multifiber rotations and twists and 35/(L/p) mrad for channel-long axis distortions (where L/p is MCP thickness to interchannel distance ratio). This technique may be used for the development of MCP x-ray optics, which impose tight limitations on geometrical distortions, which in turn are not otherwise easily measurable with high accuracy.

X-ray Optics Developments at the APS for the Third Generation of High-Energy Synchrotron Radiation Sources

Third-generation hard-X-ray synchrotron radiation sources simultaneously provide both a need and an opportunity for the development of new short-wavelength optical components. The high power and power densities of the insertion-device-produced X-ray beams have forced researchers to consider what may seem like exotic approaches, such as cryogenically cooled silicon and highly perfect diamond crystals, to mitigate thermal distortions in the first optical components. Once the power has been successfully filtered while maintaining the high beam brilliance, additional specialized optical components can be inserted into the monochromatic beam that take advantage of that brilliance. This paper reviews the performance of such optical components that have been designed, fabricated and tested at the Advanced Photon Source, starting with high-heat-load components and followed by examples of several specialized devices, such as an meV resolution (in-line) monochromator, a high-energy X-ray phase retarder and a phase-zone plate with submicrometer focusing capability.

Performance of x-ray optics at the European Synchrotron Radiation Facility

This paper gives an overview of the challenges, the strategies, and the solutions in x-ray optics research and development at the European Synchrotron Radiation Facility (ESRF), followed by an account of the practical experience gathered on the beamlines. The performances of state-of-the-art mirrors, single-crystal monochromators, and multilayer structures are given. Amongst the topics are: adaptive optics and cryogenic cooling to cope with the heat load problem, Bragg-Fresnel optics for microfocusing, x-ray phase plates for polarization production and analysis, and the use of diamond crystals. It is shown that today’s optical elements at the ESRF are capable of preserving the high quality of the present x-ray beams to a large extent.

X-ray microprobes

The advent of synchrotron radiation and the recent development of X-ray optics have rendered possible the realization of X-ray fluorescence microprobes. Various arrangements allow to obtain micrometer size hard X-ray beams with enough flux to undertake elemental mapping of trace elements. Associated with microdiffraction or with extended X-ray absorption fine structure studies, these microprobes will become a very interesting tool for material characterization.

Fixed-Exit Monochromators for High-Energy Synchrotron Radiation

Current developments in X-ray optics for synchrotron radiation beamlines are briefly reviewed. Reference is made to recent work on adaptive mirrors, cryogenic cooling of monochromators, use of thin diamond crystals, and active correction of the crystal shape for distortions caused by beam heating. The use of bent Si crystals as monochromators is discussed in detail. At high energies Si crystals become transparent to X-rays allowing new monochromator constructions. Bending of the crystal increases the energy bandpass and allows focusing. Different combinations of bent crystals that provide a fixed exit beam are discussed. These include vertically diffracting meridionally focusing Laue-Laue crystals, a Laue crystal combined with a sagittally focusing Bragg crystal, and a Laue-Bragg pair of crystals which provides meridional focusing at two stages.

High heat load X-ray optics research and development at the advanced photon source — An overview

Insertion devices at third-generation synchrotron radiation sources are capable of producing X-ray beams with total power in excess of 7 kW or power densities of 150 W/mm 2 at a typical location of the optical components. Optical elements subjected to these heat fluxes will suffer considerably unless carefully designed to withstand such unprecedented power loadings. At the Advanced Photon Source (APS), we have an aggressive program aimed at investigating possible methods to mitigate thermal distortions. The approaches being studied include improved heat exchangers, use of liquid gallium and liquid nitrogen as coolants, novel crystal geometries, power filtering, and replacement of silicon with diamond for crystal monochromators. This paper provides an overview of the high heat load X-ray optics program at the APS.

New Opportunities at Soft-X-Ray Wavelengths

A once dark region of the electromagnetic spectrum is now becoming very bright. The soft-x-ray spectral region, nominally extending from wavelengths of several angstroms to several hundred angstroms and including photon energies from tens of electron volts to several thousand electron volts, is providing many new research and development opportunities in the physical and life sciences and in industry. The move toward shorter wavelengths is driven in part by the desire to see and write smaller features. But the numerous and distinct atomic resonances in this region of the spectrum also provide for elemental identification and, in some cases, chemical sensitivity. (See the article by Bernd Crasemann and Francois Wuilleumier in PHYSICS TODAY, June 1984, page 34.) Developments in x-ray optics and new sources of highbrightness, partially coherent radiation make it possible to study materials and biological samples with feature sizes of several hundred angstroms.

Synchrotron radiation applications of charge coupled device detectors (invited)

Scientific charge coupled devices (CCDs) offer many opportunities for high brightness synchrotron radiation applications where good spatial resolution and fast data acquisition are important. We describe the use of virtual-phase CCD pixel arrays as two-dimensional area detectors illustrating the techniques with results from recent x-ray scattering, imaging, and absorption spectroscopy studies at NSLS, CHESS, SRC, and LURE DCI. The virtual phase architecture allows direct frontside illumination of the CCD detector chips giving advantages in the speed and sensitivity of the detector. Combining developments in x-ray optics (dispersive geometry), position sensitive area detectors (CCDs), and fast data acquisition, we have been able to perform time-resolved measurements at the microsecond level. Current developments include faster data transfer rates so that the single bunch timing structure of third generation synchrotron sources can be exploited.

Synchrotron X-ray topographic studies on minute strain fields in as-grown silicon single crystals

Recent developments in X-ray optics for imaging minute strain fields in as-grown silicon single crystals using synchrotron radiation are described. One means of obtaining higher strain sensitivity is to reduce both angular and energy spread of the incident beam (pre-processing of the incident beam). Another is kinematical imaging using an analyzer crystal downstream of the sample in order to mask the strong dynamically diffracted X-rays from perfect regions (post-processing of the diffracted beam).

A high energy X-ray scattering beamline for the ESRF

High energy photon or gamma-ray scattering ( E > 100 keV) is a widely recognised technique in condensed matter physics which has specific advantages. For instance, when performing diffraction experiments the low absorption, the small Bragg angles and the small wavelengths substantially reduce or eliminate corrections for absorption, polarisation and extinction, and facilitate sample environment control. A major shortcoming of both elastic and Compton scattering using high energy photons is the relatively weak intensity produced by the nuclear gamma-ray sources which have mainly been used until now. The availability of bright high energy synchrotron radiation sources and the development of adequate X-ray optics will permit a gain of several orders of magnitude in flux and open up new experimental possibilities, for instance high Q scattering and studies of anharmonicities. While designed mainly for diffraction experiments, the instrument recently proposed for the European Synchrotron Radiation Facility in Grenoble also provides the possibility of Compton scattering studies [1].

Advances in transmission x-ray optics

Recent developments in X-ray optics are reviewed. Specific advances in coded aperture imaging, zone plate lens fabrication, time and space resolved spectroscopy and CCD X-ray detection are discussed.

New Methods in Development of X-Ray Optics for Plasma Diagnostics of Laser - Produced Plasma

A new technology was developed for manufacturing of precise and low-cost X-ray grazing incidence microscopic optics.Imaging experiments represent one of the main directions in the Czechoslovak X-ray astronomy program. The Space Research Department of the Astronomical Institute of the Czechoslovak Academy of Sciences in Ondřejov has been active in the development of X-ray mirrors since 1970. We have participated in 7 space X-ray imaging experiments. 6 experiments were flown onboard the Vertical 8, 9 and 11 rockets in the years 1979, 1981 and 1983 (Hudec et al. 1984a), one experiment was flown onboard the Soviet orbital station Salyut 7 in the year 1982 (Valníček et al. 1983 and Hudec et al. 1984b). The experiments represent both small solar X-ray imaging telescopes and big stellar X-ray telescope.