1,5,6,6,3- 1School of Earth and Atmospheric Sciences, Planetary Surface Exploration, & Centre for Data Science, QUT, Brisbane, Australia (schrankce@gmail.com)
- 2School of Chemistry and Physics, Planetary Surface Exploration Group, & Central Analytical Research Facility, QUT, Brisbane, QLD, Australia
- 3Australian Synchrotron, Australian Nuclear Science and Technology Organisation, Clayton, VIC, Australia
- 4Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
- 5Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
- 6Institut für Geologie, University of Bern, Bern, Switzerland
X-ray ptychography is a lensless, coherent-diffraction imaging technique developed over the last 20 years that affords 10-nm resolution for optically thick specimens1. It reconstructs the optical transmission function (OTF) of a sample from raster-scanned overlapping 2D transmission diffraction patterns through iterative phase retrieval algorithms1,2. The OTF projects the refractive index of the sample along the incident beam and thus quantifies the phase shift and amplitude attenuation of the transmitted beam2, which in turn relate to the projected electron density of the specimen. X-ray ptychography is therefore an ultramicroscopy technique that is very well suited to mapping nano- and micron-sized objects with significant density differences relative to the bulk such as pores and dense accessory minerals.
In this contribution, we present a primer for the application of X-ray ptychography to nano- and micro-scale studies of rocks. First, we illustrate the underlying physical principles that guide the data processing and interpretation of ptychographs. Then, we show exemplary applications to a wide range of rock samples (e.g., seismogenic brittle fault rocks, mylonites, veins, shale, and micrite) imaged at the XFM beamline of the Australian Synchrotron3 over the last 5 years4,5. Application examples include the measurement of sample surface roughness, imaging of cracks and pores, 3D porosity measurements, and the detection of buried accessory phases.
References
1 Pfeiffer, F. X-ray ptychography. Nature Photonics 12, 9-17, doi:10.1038/s41566-017-0072-5 (2018).
2 Wittwer, F., Hagemann, J., Brückner, D., Flenner, S. & Schroer, C. G. Phase retrieval framework for direct reconstruction of the projected refractive index applied to ptychography and holography. Optica 9, 295-302, doi:10.1364/OPTICA.447021 (2022).
3 Howard, D. L. et al. The XFM beamline at the Australian Synchrotron. Journal of Synchrotron Radiation 27, 1447-1458, doi:doi:10.1107/S1600577520010152 (2020).
4 Jones, M. W. M. et al. High-speed free-run ptychography at the Australian Synchrotron. Journal of Synchrotron Radiation 29, 480-487, doi:https://doi.org/10.1107/S1600577521012856 (2022).
5 Schrank, C. E. et al. Micro-scale dissolution seams mobilise carbon in deep-sea limestones. Communications Earth & Environment 2, 174, doi:10.1038/s43247-021-00257-w (2021).
How to cite: Schrank, C. E., Jones, M. W. M., Kewish, C. M., van Riessen, G. A., Hinsley, G., Berger, A., Herwegh, M., Schwichtenberg, B., Bishop, N. D., Howard, D., Langendam, A. D., and Paterson, D. J.: Nano- and micro-scale imaging of rocks with X-ray ptychography, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8362, https://doi.org/10.5194/egusphere-egu26-8362, 2026.
