X-ray microscopy at a speed of 1000 tomograms per second
Most people are familiar with computed tomography from medicine: part of the body is x-rayed from all sides, and a three-dimensional image is then calculated, from which all sectional images can be created for diagnosis.
This method is also very useful for material analysis, non-destructive quality checks or in the development of new functional materials. However, to examine such materials with high spatial resolution and in the shortest possible time, particularly intense X-light from a synchrotron radiation source is needed. In the synchrotron beam, even rapid changes and processes in material samples can be imaged if it is possible to acquire three-dimensional images in a very short time sequence.
From 200 to 1000 tomograms per second
An HZB team led by Dr Francisco Garcia Moreno is working on this with colleagues from the Swiss Light Source SLS at the Paul Scherrer Institute (PSI), Switzerland. Two years ago, they achieved a record 200 tomograms per second, calling for the rapid imaging tomoscopy method. Today the team has set a new world record: with a speed of 1000 tomograms per second, they can now record even faster processes in materials or during the manufacturing process. This is achieved without major compromise on other parameters: the spatial resolution is still very good at a few micrometers, the field of view is several square millimeters and continuous recording periods of up to several minutes are possible.
Rotary table and high speed camera
For X-ray images, the sample is placed on an in-house developed high-speed rotary table, the angular speed of which can be perfectly synchronized with the acquisition speed of the camera. “We have used particularly light components for this rotary table so that it can reach a rotation speed of 500 Hertz in a stable manner”, explains García Moreno.
On SLS’s TOMCAT beamline, which specializes 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 a millisecond, from which we create a tomogram,” says Schlepütz. With the planned upgrade to SLS2.0, even faster measurements with higher spatial resolution should be possible from 2025.
Data flow processing
Acquiring 1000 sets of three-dimensional data per second – over a period of a few minutes – generated a huge data stream, which was initially stored at PSI. Finally, Dr Paul Kamm from HZB was responsible for further processing and quantitative evaluation of the data. The reconstruction of the raw data into 3D images was performed remotely from HZB on PSI’s high performance computers, and the results were then transferred to HZB for further analysis.
Sparklers, dendrites and bubbles
The team demonstrated the power of tomoscopy with various examples from materials research: The images show the extremely rapid changes during the combustion of a sparkler, the formation of dendrites during the solidification of alloys of casting or growth and coalescence of bubbles in a liquid metal foam. Such metallic foams based on aluminum alloys are being studied as lightweight materials, for example for the construction of electric cars. Bubble morphology, size and crosslinking are important to achieve desired mechanical properties such as strength and stiffness in large components.
“This method opens the door to the non-destructive study of rapid processes in materials, which many research groups and also industry expected”, explains García Moreno.
Thanks to a world record in tomography, synchrotron radiation can be used to observe the formation of metal foam
Tomoscopy: Time resolved tomography for dynamic processes in materials, Advanced materials (2021). DOI: 10.1002 / adma.202104659
Quote: New world record in materials research: X-ray microscopy at a speed of 1000 tomograms per second (2021, September 27) retrieved September 27, 2021 from https://phys.org/news/2021-09 -world-materials-x -ray-microscopy-tomogrammes.html
This document is subject to copyright. Other than fair use for private study or research purposes, no part may be reproduced without written permission. The content is provided for information only.