Abstract
Three-dimensional (3D) x-ray microscopy by ptychographic tomography requires elaborate numerical reconstructions. We describe a coupled ptychography-tomography reconstruction algorithm and apply it to an experimental ptychographic x-ray computed tomography data set of a catalyst particle. Compared to the traditional sequential algorithm, in which ptychographic projections are reconstructed to serve as input for subsequent tomographic reconstruction, the coupled ptychography-tomography algorithm reconstructs the 3D volume with higher spatial resolution over a larger field of view. Coupling the data from different projections improves the overall reconstruction, and the ptychographic sampling in individual projections can be coarsened beyond the point of overlap between neighboring scan points, still leading to stable reconstructions.
Highlights
Knowing the structure of nanomaterials and nano-objects is key to understanding their properties and function
The reconstructed probe function was subsequently used as an initial probe estimate for all upcoming reconstructions. This is sensible, as no Ptychographic x-ray computed tomography (PXCT) measurement will be performed without having tested the successful reconstruction of a single projection first
Corrections for projected phase shifts and absorption coefficients are added to the current object estimate sequentially from one projection angle to the. We refer to this tomography algorithm as simultaneous algebraic reconstruction technique (SART)
Summary
Knowing the structure of nanomaterials and nano-objects is key to understanding their properties and function. X rays are an ideal probe to study their three-dimensional (3D) nanostructure. Due to their large penetration depth and short wavelength, x rays make nondestructive 3D imaging at the nanoscale possible. Ptychographic x-ray computed tomography (PXCT) is an emerging microscopy technique that uniquely offers high spatial resolution and sensitivity among contemporary x-ray imaging methods, producing 3D quantitative maps of the complex index of refraction of the sample [1]. In this way, it yields quantitative information on the local electron density. PXCT has been established as a method at multiple synchrotron-radiation facilities around the world [2,3,4,5,6,7,8]
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