The coherence requirements for efficient operation of an X-ray grating interferometer are discussed. It is shown how a Talbot–Lau geometry, in which an array of equidistant secondary sources is used, can be used to decouple fringe visibility in the interferometer (and thus, its efficiency) from the total size of the X-ray source. This principle can be used for phase-contrast radiography and tomography with sources of low brilliance, such as X-ray tubes.

Tomography with grating interferometers at low-brilliance sources

We present an interferometric method to measure the shape of a hard-x-ray wavefront. The interferometer consists of a phase grating as a beam splitter and an absorption grating as a transmission mask for the detector. The device can be used to measure wavefront shape gradients corresponding to radii of curvature as large as several dozens of meters, with a lateral resolution of a few microns. This corresponds to detected wavefront distortions of approximately 10−12m or λ∕100. The device was used with 12.4 keV x rays to measure the slope error and height profile of an x-ray mirror. Surface slope variations with periods ranging from less than 1 mm to more than 1 m can be detected with an accuracy better than 0.1μrad.

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X-ray wavefront analysis and optics characterization with a grating interferometer

Summary

We used hard X-ray scanning microscopy with ptychographic coherent diffraction contrast to image a front-end processed passivated microchip fabricated in 80 nm technology. No sample preparation was needed to image buried interconnects and contact layers with a spatial resolution of slightly better than 40 nm. The phase shift in the sample is obtained quantitatively. With the additional knowledge of the elemental composition determined in parallel by X-ray fluorescence mapping, quantitative information about specific nanostructures is obtained. A significant enhancement in signal-to-noise ratio and spatial resolution is achieved compared to conventional hard X-ray scanning microscopy.

Non‐destructive and quantitative imaging of a nano‐structured microchip by ptychographic hard X‐ray scanning microscopy

Functional characterisation of the genes regulating metal(loid) homeostasis in plants is a major focus for phytoremediation, crop biofortification and food security research. Recent advances in X-ray focussing optics and fluorescence detection have greatly improved the potential to use synchrotron techniques in plant science research. With use of methods such as micro X-ray fluorescence mapping, micro computed tomography and micro X-ray absorption near edge spectroscopy, metal(loids) can be imaged in vivo in hydrated plant tissues at submicron resolution, and laterally resolved metal(loid) speciation can also be determined under physiologically relevant conditions. This article focuses on the benefits of combining molecular biology and synchrotron-based techniques. By using molecular techniques to probe the location of gene expression and protein production in combination with laterally resolved synchrotron techniques, one can effectively and efficiently assign functional information to specific genes. A review of the state of the art in this field is presented, together with examples as to how synchrotron-based methods can be combined with molecular techniques to facilitate functional characterisation of genes in planta. The article concludes with a summary of the technical challenges still remaining for synchrotron-based hard X-ray plant science research, particularly those relating to subcellular level research.

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Functional Characterisation of Metal(loid) Processes in Planta Through the Integration of Synchrotron Techniques and Plant Molecular Biology

A basic prerequisite for in vivo X-ray imaging of the lung is the exact determination of radiation dose. Achieving resolutions of the order of micrometres may become particularly challenging owing to increased dose, which in the worst case can be lethal for the imaged animal model. A framework for linking image quality to radiation dose in order to optimize experimental parameters with respect to dose reduction is presented. The approach may find application for current and future in vivo studies to facilitate proper experiment planning and radiation risk assessment on the one hand and exploit imaging capabilities on the other.

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Dose optimization approach to fast X-ray microtomography of the lung alveoli

This volume compiles the contributions to the International Conference on X-Ray Microscopy (XRM2008) held on 20–25 July 2008 in Zurich, Switzerland. The conference was the ninth in a series which started in Gottingen in 1984. Over the years the XRM conference series has served as a forum bringing together all relevant players working on the development of methods, building instrumentation, and applying x-ray microscopy to challenging issues in materials science, condensed matter research, environmental science and biology. XRM2008 was attended by about 300 participants who followed 44 oral presentations and presented 220 posters. Figure 1: Participants of the XRM2008 conference gathered in front of the main building of the ETH-Zurich. The conference showed that x-ray microscopy has become a mature field resting on three pillars. The first are workhorse instruments available even to non-specialist users. These exist at synchrotron sources world-wide as well as in laboratories. They allow the application of established microscopy methods to solve scientific projects in areas as diverse as soil science, the investigation of cometary dust particles, magnetic materials, and the analysis of ancient parchments. Examples of all of these projects can be found in this volume. These instruments have become so well understood that now they are also commercially available. The second pillar is the continued development of methods. Methods like stroboscopic imaging, wet cells or high and low temperature environments add versatility to the experiments. Methods like phase retrieval and ptychographic imaging allow the retrieval of information which hitero was thought to be inaccessible. The third pillar is the extension of such instruments and methods to new photon sources. With x-ray free electron lasers on the horizon the XRM community is working to transfer their know-how to these novel sources which will offer unprecedented brightness and time structure, but which at the same time require unprecedented effort to perform the experiment and to extract meaningful information from the data. Resting on these three pillars, the XRM community seems well prepared to solve the scientific questions of today and to help solve even more challenging scientific questions in the future. Many people contributed to the success of XRM2008, first and foremost were the participants with their excellent contributions and through their lively discussions. Organizing the event was made possible due to many helping hands and brains at the organizing institution, the Paul Scherrer Institut. It is our pleasure to thank all of these people. Financial support was given by the Gold Sponsor, XRADIA, by the European Round Table for Synchrotrons and Free Electron Lasers, the Center for Imaging Science and Technology at Zurich, and by the Swiss National Science Foundation. The conference was kindly hosted by ETH Zurich which provided a perfect setting for this venue. We thank all the participants of XRM2008, everybody who helped in the organization and all financial supporters and are looking forward to hearing about further progress during XRM2010 which will be organized by Argonne National Laboratory in Chicago. C Quitmann, C David, F Nolting, F Pfeiffer and M Stampanoni Proceedings Editors Figure 2 View over Zurich and into the alps from the terrace of the ETHZ main building during the XRM2008 reception. Figure 3 Flag tosser and Alphorn blowers in front of the ETH Zurich main building during the XRM2008 opening reception. Figure 4 Industry exhibition in the entrance hall of the ETHZ main building. Figure 5 Lively discussions amongst the conference participants took place during the two poster sessions. Figure 6 Lecture hall with the participants busily discussing between talks. Figure 7 Past and present winners of the Werner Meyer-Ilse Award are joined by Andrea Meyer-Ilse, the wife of the deceased x-ray microscopy pioneer Werner Meyer-Ilse. From left to right: Weilun Chao (winner 2005), Ann Sakdinawat (winner 2008), Piere Thibault (winner 2008), Andrea Meyer-Ilse and M Feser (winner 2002). Figure 8 Reception in the court of Schloss Rapperswil during the XRM2008 conference excursion. Figure 9 Conference participants walking towards the castle of Rapperswil during the conference excursion. Figure 10 Accompanying persons group gathered in the port of Lucerne.

9th International Conference on X-Ray Microscopy

We derive mathematical relations for hard X-ray moire wavefront analysis with a grating interferometer. In particular, the first derivative of the wavefront phase profile and the local radius of curvature of the wavefront are related to the position and inclination of the observed moire fringes.

Marco Stampanoni

Papers

9th International Conference on X-Ray Microscopy

Moiré interferometry formulas for hard x-ray wavefront sensing