Mr Andrew Morgan
School of Physics
University of Melbourne
Research Group: Theoretical Condensed Matter Physics
Phone: 03 8344 7404
Fax: 03 9347 4783
Current Research ActivitiesDuring the early part of my PhD I was involved in calculating the effect of spatial incoherence (mainly the finite width of the source of imaging electrons) and temporal incoherence (the fluctuation in energy of the source of imaging electrons) on Scanning Transmission Electron Microscope (STEM) images. In addition methods were developed to mitigate the damage due to incoherence for the purposes of sample reconstruction.
This was followed by theoretical work for the Confocal Electron Microscope geometry. This work (along with experimental results) were subsequently published.
Expanding on previous results within the Theoretical Condensed Matter Physics (TCMP) group, an algorithm to deterministically solve the phase problem, we generalized the algorithm to the Fresnel diffraction regime. This had the advantage (among others) of reducing the restrictions on the illumination for which the algorithm was applicable, such as allowing for plane-wave illumination. The algorithm was then used to reconstruct the scattering amplitude and phase of a micro-fibre illuminated by laser. This has been submitted for publication in Ultramicroscopy.
The general algorithm (applicable for both far-field and near-field images of nano particles) was further improved. Additional analysis revealed that the residual of the linear equations used to solve the phase problem also served as an excellent error metric in more traditional iterative phase retrieval techniques. This work along with a high fidelity reconstruction, using experimental data, has been submitted for publication in Physical Review Letters.