From Paul Scherrer Institute [Paul Scherrer Institut] (CH) : “X-ray microscopy with 1000 tomograms per second” 

From Paul Scherrer Institute [Paul Scherrer Institut] (CH)

24 September 2021

Dr. Christian Schlepütz
X-ray Tomography Group
Paul Scherrer Institute
+41 56 310 40 95
christian.schlepuetz@psi.ch [German, English]

1
Christian Schlepütz at the Tomcat beamline of the Swiss Light Source SLS, where a team of scientists have developed a 3D imaging method capable of recording 1,000 tomograms per second.
(Photo: Mahir Dzambegovic/Paul Scherrer Institute.

Tomoscopy is an imaging method in which three-dimensional images of the inside of materials are reconstructed in rapid succession. A new world record has now been set at the Swiss Light Source at the Paul Scherrer Institute: with 1000 tomograms per second, it is now possible to non-destructively capture very fast processes and structural changes in materials on the micrometre scale, such as the burning of a sparkler or the foaming of a metal alloy for the production of stable lightweight materials.

Most people are familiar with computed tomography from medicine: a part of the body is X-rayed from all sides and a three-dimensional image is then calculated, from which any sectional images can be created for diagnosis.

This method is also very useful for material analysis, non-destructive quality testing or in the development of new functional materials. However, to examine such materials with high spatial resolution and in the shortest possible time, the particularly intense X-ray light of a synchrotron light source is required. In the synchrotron light, even rapid changes and processes in material samples can be visualised if it is possible to capture 3-dimensional images in a very short time sequence.

A team led by Francisco García Moreno from the Berlin Helmholtz Center for Materials and Energy [Helmholtz-Zentrum für Materialien und Energie] (HZB) (DE) is working on this, together with researchers from the Swiss Light Source SLS at the Paul Scherrer Institute (PSI).

Two years ago, they managed a record 200 tomograms per second, calling the method of fast imaging “tomoscopy”. Now the team has achieved a new world record: with 1000 tomograms per second, they can now record even faster processes in materials or during the manufacturing process. This is achieved without any major compromises in the other parameters: the spatial resolution is still very good at several micrometres, the field of view is several square millimetres and continuous recording periods of up to several minutes are possible.

Special table reaches 500 rotations per second

For the X-ray images, the sample is placed on a high-speed rotary table developed in-house, whose angular speed can be perfectly synchronised with the camera’s acquisition speed. “We used particularly lightweight components for this rotary table so that it can turn around its axis 500 times per second and still remain stable,” García Moreno explains.

Creating a 3D image from 40 projections per millisecond

At the Tomcat beamline at the SLS, which is specialised in time-resolved X-ray imaging, PSI physicist Christian Schlepütz used a new high-speed camera and special optics. “This increases the sensitivity very significantly, so that we can take 40 2D projections in one millisecond, from which we create a tomogram,” Schlepütz explains. One 3D image is therefore created every millisecond, in other words 1,000 3D images per second. With the planned SLS2.0 upgrade, even faster measurements with higher spatial resolution should be possible from 2025.

The team demonstrated the power of tomoscopy with various examples from materials research: the images show the extremely rapid changes during the burning of a sparkler, the formation of dendrites during the solidification of casting alloys or the growth and coalescence of bubbles in a liquid metal foam. Such metal foams based on aluminium alloys are being investigated as lightweight materials, for example for the construction of electric cars. The morphology, size and cross-linking of the bubbles are important to achieve the desired mechanical properties such as strength and stiffness in large components.

“This method opens a door for the non-destructive study of fast processes in materials, which is what many research groups and also industry have been waiting for,” says García Moreno.

See the full article here.

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The Paul Scherrer Institute [Paul Scherrer Institut] (CH) is the largest research institute for natural and engineering sciences within Switzerland. We perform world-class research in three main subject areas: Matter and Material; Energy and the Environment; and Human Health. By conducting fundamental and applied research, we work on long-term solutions for major challenges facing society, industry and science.

The Paul Scherrer Institute (PSI) is a multi-disciplinary research institute for natural and engineering sciences in Switzerland. It is located in the Canton of Aargau in the municipalities Villigen and Würenlingen on either side of the River Aare, and covers an area over 35 hectares in size. Like ETH Zurich [Swiss Federal Institute of Technology ETH Zürich [Eidgenössische Technische Hochschule Zürich)](CH) and EPFL [EPFL (Swiss Federal Institute of Technology in Lausanne) [École polytechnique fédérale de Lausanne](CH)], PSI belongs to the Swiss Federal Institutes of Technology Domain of the Swiss Confederation [https://www.sbfi.admin.ch/sbfi/en/home/ihe/higher-education/domain-of-the-federal-institutes-of-technology/bodies-and-institutes-within-the-eth-domain.html]. The PSI employs around 2100 people. It conducts basic and applied research in the fields of matter and materials, human health, and energy and the environment. About 37% of PSI’s research activities focus on material sciences, 24% on life sciences, 19% on general energy, 11% on nuclear energy and safety, and 9% on particle physics.

PSI develops, builds and operates large and complex research facilities and makes them available to the national and international scientific communities. In 2017, for example, more than 2500 researchers from 60 different countries came to PSI to take advantage of the concentration of large-scale research facilities in the same location, which is unique worldwide. About 1900 experiments are conducted each year at the approximately 40 measuring stations in these facilities.

In recent years, the institute has been one of the largest recipients of money from the Swiss lottery fund.

Research and specialist areas

PSI develops, builds and operates several accelerator facilities, e. g. a 590 MeV high-current cyclotron, which in normal operation supplies a beam current of about 2.2 mA. PSI also operates four large-scale research facilities: a synchrotron light source (SLS), which is particularly brilliant and stable, a spallation neutron source (SINQ), a muon source (SμS) and an X-ray free-electron laser (SwissFEL). This makes PSI currently (2020) the only institute in the world to provide the four most important probes for researching the structure and dynamics of condensed matter (neutrons, muons and synchrotron radiation) on a campus for the international user community. In addition, HIPA’s target facilities also produce pions that feed the muon source and the Ultracold Neutron source UCN produces very slow, ultracold neutrons. All these particle types are used for research in particle physics.