Mårten Selin

Title: 3D X-ray microscopy: image formation, tomography and instrumentation
Candidate: Mårten Selin
Time: Friday April 22, 2016, at 13:00
Location:  Room FD5, Albanova, Roslagstullsbacken 21, KTH, Stockholm
Opponent: Professor Chris J. Jacobsen, Argonne National Laboratory, Argonne, USA
Supervisor: Prof. Hans Hertz
Abstract: Tomography in soft X-ray microscopy is an emerging technique for obtaining quantitative 3D structural information about cells. One of its strengths, compared with other techniques, is that it can image intact cells in their near-native state at a few 10 nm’s resolution, without staining. However, the methods for reconstructing 3D-data rely on algorithms that assume projection data, which the images are generally not due to the imaging systems’ limited depth of focus. To bring out the full potential of tomography in soft X-ray microscopy an improved understanding of the image formation is desired.

This Thesis reviews zone plate-based X-ray microscopy for biological imaging and the theory necessary for a numerical implementation of a 3D image formation model. Furthermore, a novel reconstruction approach is proposed that improves the overall resolution in a reconstruction of a tomographically imaged object. This is demonstrated by simulations and experiments. Finally, this Thesis covers work on the Stockholm X-ray microscope, including an upgrade of the X-ray source yielding unprecedented brightness for a compact system. With this upgrade it was possible to do high-quality imaging of cells in their near-native state with only 10 second exposures.