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FRINATEK-Fri prosj.st. mat.,naturv.,tek

4D Computed Tomography of Porous Materials

Alternative title: 4D tomografi av porøse materialer

Awarded: NOK 9.0 mill.

The 4D-CT project is centered around making 3D images of systems that evolve over time. A good example is multiphase flow in porous materials like rocks and soil. To achieve a high resolution in both space and time, there is a need for good measurement methods and algorithms. In the 4D-CT project, a main goal is to develop improved experimental methods based on X-ray radiation and visual light to make quantitative imaging. This implies that numerical information about for example density distributions can be extracted from the microscopy images. Experimental methods that can contribute to understanding complex electronic, mechanical and thermal material properties are in high demand. 4D microscopy (3D + time) is increasingly used in many scientific fields. Storage of CO2 in abandoned petroleum reservoirs is considered one of the most promising technologies for reducing the massive climate challenges with CO2 accumulation in the atmosphere. In 2020 we succeeded in monitoring the carbonation process in cement exposed to CO2 under high temperature and pressure by using CT in a bespoke sample cell (Chavez et al, Env. Sci. Tech., 2022), a study that has received considerable international attention. A highlight from 2021 was a series of 3D CT studies with diffraction contrast, applied to both geological and biological materials. An example of the latter is a study of the transition zone between bone and cartilage in knee joints (Mürer et al, Scientific Reports, 2021). Diffraction contrast gives 3D images with nano scale information about both the local spatial orientation of the fibrous tissue and the mineral distribution within the bone. In 2022 we had considerable progress in developing Fourier ptychographic microscopy (FPM) based on visible light. Several articles were published on this topic, with Optics Express (Gholamimayani et al, 2022) as a highlight. Polarization control is also incorporated into the microscope, which gives additional information about oriented structures in the sample. In 2023 we have used quantitative phase contrast imaging to study microscopic defects in glass, motivated by antiterrorism and general safety. This work has been published in Applied Physics Letters (Tekseth et al, 2023). Another prioritized theme has been CT studies of liquids in porous media, which has huge implications to climate and pollution. With new algorithms, we have been able to reduce the measurement times for CT scans at our home laboratory from about one hour to less than one minute, which opens for new scientific discoveries. We have also performed drainage experiments of porous media at ESRF, with highly interesting results, that now are accepted for publication. Last, but not least, we have studied 3D order in liquid crystals – an original study that we are looking forward to publishing. We are still working on developing our phase contrast X-ray microscope at NTNU. A particularly positive aspect of the 4D-CT project is the many resulting activities we have with external partners, including new projects, industrial collaborations, and new scientific and technological developments. Important milestones in 2024 will be novel experiments, a seminar with industry, and several good articles that will be published.

Computational microscopy is a hot topic in optics, promising to revolutionize the image forming process by actively employing sophisticated computer algorithms. High-resolution microscopy has until recently been synonymous with expensive, heavy and bulky hardware. In the X-ray regime, the lack of high-quality objective lenses has during the last decade prompted the development of lens-less imaging, based on retrieving images from coherent diffraction patterns. In this project, we shall further develop Fourier Ptychography (FP), which is a coherent imaging method relying on synthesizing a high-bandwidth image from a series of low-bandwidth images. Reflection-mode FP microscopy in the visual optical range will established - including a smartphone compatible demonstrator. We further aim to construct the world's first X-ray FP microscope, which we hypothesize will prove superior to competing coherent X-ray diffractive imaging (CXDI) schemes in terms of high resolution and fast reliable operation, because of the robustness introduced by the physical objective lens. High-performance computing and artificial intelligence will be integral parts of these efforts. An exceptional team with internationally leading competence within the fields of X-ray physics, optics and high-performance computing has been assembled. The project is of high relevance to the upcoming X-ray free electron lasers (XFELs), but also to the advanced study of porous and other functional materials. An overarching theme in the project is quite literally to illuminate the subtle interplay between optical hardware and clever software with the aim of obtaining new fundamental insights as well as readily applicable new microscopy schemes - a topic with profound scientific and societal consequences.

Publications from Cristin

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FRINATEK-Fri prosj.st. mat.,naturv.,tek