stillingsbetegnelse:
PhD scholarship in Nano-scale 3D reconstruction of phase contrast X-ray projections

jobbeskrivelse:
DTU Energy seek a ph.d student to improve algorithms for 3D reconstruction of phase contrast X-ray projections. The highly penetrating power of X-rays make them ideal for probing the dynamic structure of realistic, functioning devices for energy conversion and storage, but this is an application that is largely unexplored. With the advances in imaging techniques which by combination of better optics for hard X-ray focusing and new measuring schemes and algorithms taking advantage of coherent X-ray illumination, the potential for sub-nm resolution is within reach. Because of the hard X-ray penetration, complementary analysis techniques and non-ambient sample environments are relatively easy to integrate with the X-ray experiment for in situ studies, and we have considerable experience with such applications at DTU Energy. Our expertise in the application of these methods will be applied to real devices for resolving problems relating to up-scaled processing of nano-structured devices, among which fuel cells and 3rd generation solar cells are specific focus areas. The in situ experiments will be applied to advance the fundamental understanding of charge generation and transport in complex 3D nanostructures. Progress in this field constitutes an important part of bridging current advances at the microscale level in the Strategic Research Alliance, CINEMA with the upcoming endeavors into the nano domain. Responsibilities and tasks The ph.d will work with improving algorithms for 3D reconstruction of phase contrast X-ray projections, typically from ptychographic tomography. Ptychography is a form of phase contrast imaging, where the sample is illuminated with coherent X-rays in a fine raster pattern with a large degree of overlap between illuminated points. By exploiting the large data redundancy, the iterative phase reconstruction is ensured a fast and robust convergence. In this manner, projections of X-ray phase shift across the sample are retrieved with nanometer resolution. 3D resolution depends on X-ray beam and sample positioning stability, and not least, on the algorithms for aligning projections and reconstructing the phase tomogram. The standard way of reconstructing tomograms from 2D ptychography projections is the well-established filtered back projection, reconstructing the tomogram slice by slice, but much more advanced algorithms for 3D reconstructions have been developed, and research is still in advance in this direction. Under the auspice of CINEMA and in collaboration with DTU Compute, we will explore the possibilities for implementing these methods for reconstruction of ptychographic phase projections. Methods include 3D reconstruction by Total Variation Regularization (TVReg) and other regularized reconstruction algorithms, including methods employing a priori information. We will also explore the possibilities of integrating 3D projection alignment with the reconstruction algorithms and the prospect of reconstructing the phase distribution directly from the 3D array of aligned diffraction data. Qualifications Candidates should have a master's degree in engineering or a similar degree with an academic level equivalent to the master's degree in engineering. Approval and Enrolment The scholarships for the PhD degree are subject to academic approval, and the candidates will be enrolled in one of the general degree programmes of DTU. For information about the general requirements for enrolment and the general planning of the scholarship studies, please see the DTU PhD Guide. Assessment •Excellent performance in both bachelor and graduate studies Further qualifications: •It is expected that the candidate has a background in mathematics or physics and have skills in programming (matlab, python, C). •Experience with computational imaging analysis is particularly welcome. We offer We offer an interesting and challenging job in an international environment focusing on education, research, public-sector consultancy

Arbejdsgiver Navn: Danmarks Tekniske Universitet

Arbejdsgiver telefonnummer: 45252525

Arbejdsgiver faxnummer: 45881799

Job kort beskrivelse:
Undervisning og forskning på universiteter og højere læreranstalter

land: Danmark

region: Hovedstaden

krævede uddannelse: Ikke angivet

Kilde til jobtilbud: AMS, Offentlige arbejdsformidlinger, Danmark