Nowadays, thanks to the high brilliance available at modern, third generation synchrotron facilities and recent
developments in detector technology, it is possible to record volumetric information at the micrometer scale within few
minutes. High signal-to-noise ratio, quantitative information on very complex structures like the brain micro vessel
architecture, lung airways or fuel cells can be obtained thanks to the combination of dedicated sample preparation
protocols, in-situ acquisition schemes and cutting-edge imaging analysis instruments. In this work we report on recent
experiments carried out at the TOMCAT beamline of the Swiss Light Source  where synchrotron-based tomographic
microscopy has been successfully used to obtain fundamental information on preliminary models for cerebral fluid flow
, to provide an accurate mesh for 3D finite-element simulation of the alveolar structure of the pulmonary acinus 
and to investigate the complex functional mechanism of fuel cells . Further, we introduce preliminary results on the
combination of absorption and phase contrast microscopy for the visualization of high-Z nanoparticles in soft tissues, a
fundamental information when designing modern drug delivery systems . As an outlook we briefly discuss the new
possibilities offered by high sensitivity, high resolution grating interferomtery as well as Zernike Phase contrast
Highly brilliant X-rays delivered by third generation synchrotron facilities coupled with modern detector technology
permit routinely acquisition of high resolution tomograms in few minutes, making high throughput experiments a reality
and bringing real-time tomography closer. New solutions for fast post-processing of such large amount of data are
mandatory to fully exploit advantages provided by the high acquisition speed enabling new experiments until recently
The TOMCAT beamline<sup>1</sup> is well equipped for fast and high throughput experiments<sup>2, 3</sup>. Here, we will focus on our
solutions regarding the reconstruction process and discuss a fast reconstruction algorithm<sup>4</sup>, based on the Fourier
Transform method as opposed to slower standard Filtered Back-Projection routines. We perform the critical step of such
method, the polar-to-Cartesian mapping in the Fourier space, by convolution with the Fourier transform of functions with
particular characteristics. This convolution approach combines speed with accuracy, making real-time data postprocessing
closer to reality.
This fast reconstruction algorithm implemented at TOMCAT also features several plug-ins, aimed at taming
reconstruction artifacts. Here, we will discuss a new approach for removing rings from reconstructed datasets arising
from defective detector pixels and/or damaged scintillator screens. This new method is based on a combined wavelet-
FFT decomposition<sup>5</sup>. Another important feature of the presented reconstruction algorithm deals with local tomographic
datasets, characterized by incomplete data. We show here that ad-hoc padding of the sinograms prior to reconstruction
significantly reduces typical artifacts related to data incompleteness, making local tomography a valuable acquisition
mode when small volumes in relatively large samples are of interest.
Synchrotron based X-ray microtomography is a novel way to examine paint samples. The three
dimensional distribution of pigment particles, binding media and their deterioration products as well as
other features such as voids, are made visible in their original context through a computing
environment without the need of physical sectioning. This avoids manipulation related artefacts.
Experiments on paint chips (approximately 500 micron wide) were done on the TOMCAT beam line
(TOmographic Microscopy and Coherent rAdiology experimenTs) at the Paul Scherrer Institute in
Villigen, CH, using an x-ray energy of up to 40 keV. The x-ray absorption images are obtained at a
resolution of 350 nm. The 3D dataset was analysed using the commercial 3D imaging software Avizo
5.1. Through this process, virtual sections of the paint sample can be obtained in any orientation.
One of the topics currently under research are the ground layers of paintings by Cuno Amiet (1868-
1961), one of the most important Swiss painters of classical modernism, whose early work is currently
the focus of research at the Swiss Institute for Art Research (SIK-ISEA). This technique gives access
to information such as sample surface morphology, porosity, particle size distribution and even particle
identification. In the case of calcium carbonate grounds for example, features like microfossils present
in natural chalks, can be reconstructed and their species identified, thus potentially providing
information towards the mineral origin. One further elegant feature of this technique is that a target
section can be selected within the 3D data set, before exposing it to obtain chemical data. Virtual
sections can then be compared with cross sections of the same samples made in the traditional way.
Synchrotron-based X-ray Tomographic Microscopy is a powerful technique for fast, non-destructive, high resolution quantitative volumetric investigations on diverse samples. At the TOMCAT (TOmographic Microscopy and Coherent radiology experimenTs) beamline at the Swiss Light Source (SLS), synchrotron light is delivered by a 2.9 T superbend. The main optical component, a Double Crystal Multilayer Monochromator, covers an energy range between 8 and 45
keV. The standard TOMCAT detector offers field of views ranging from 0.75x0.75 mm<sup>2</sup> up to 12.1x12.1mm<sup>2</sup> with a theoretical resolution of 0.37 μm and 5.92 μm, respectively. The beamline design and flexible endstation setup make a large range of investigations possible. In addition to routine measurements, which exploit the absorption contrast, the high coherence of the source also enables phase contrast tomography, implemented with two complementary techniques. Differential Phase Contrast (DPC) imaging has been fully integrated in terms of fast acquisition and data reconstruction. Scans of samples within an aqueous environment are also feasible. The second phase contrast method is a Modified Transport of Intensity approach that yields a good approximation of the 3D phase distribution of a weakly absorbing object from a single tomographic dataset. Typical acquisition times for a tomogram are in the order of few minutes, ensuring high throughput and allowing for semi-dynamical investigations and in-situ experiments. Raw data are automatically post-processed online and full reconstructed volumes are available shortly after a scan with minimal user intervention. In addition to a beamline overview, a selection of high-impact tomographic applications will be presented.
Over the last decade, synchrotron-based X-ray tomographic microscopy has established itself as a fundamental tool for non-invasive, quantitative investigations of a broad variety of samples, with application ranging from space research and materials science to biology and medicine. Thanks to the brilliance of modern third generation sources, voxel sizes in the micrometer range are routinely achieved by the major X-ray microtomography devices around the world, while the isotropic 100 nm barrier is reached and trespassed only by few instruments. The beamline for TOmographic Microscopy and Coherent rAdiology experiments (TOMCAT) of the Swiss Light Source at the Paul Scherrer Institut, operates a multimodal endstation which offers tomographic capabilities in the micrometer range in absorption contrast - of course - as well as phase contrast imaging. Recently, the beamline has been equipped with a full field, hard X-rays microscope with a theoretical pixel size down to 30 nm and a field of view of 50 microns. The nanoscope performs well at X-ray
energies between 8 and 12 keV, selected from the white beam of a 2.9 T superbend by a [Ru/C]<sub>100</sub> fixed exit multilayer monochromator. In this work we illustrate the experimental setup dedicated to the nanoscope, in particular the ad-hoc designed X-ray optics needed to produce a homogeneous, square illumination of the sample imaging plane as well as the magnifying zone plate. Tomographic reconstructions at 60 nm voxel size will be shown and discussed.