Diffraction Analysis for Particle Sizing

Company: 
Malvern Instruments Ltd
Academic Supervisor: 
Dr Michael Mazilu
University: 
Email: 
mm17@st-andrews.ac.uk

The use of laser diffraction to measure a particle size distribution (PSD) is a mature technique that relies on the solution of an ill-posed problem.  To calculate a PSD, an m x n scattering matrix A is generated using an appropriate scattering theory.  The measured scattering data provides the right hand side b of an ill-posed problem Ax = b, the solution x gives the PSD.  The calculation of x in the next generation of instrument requires two areas of study.  Firstly, the suppression of background artifacts in b will help calculate a more accurate PSD.  A recent development at Malvern has suggested that scattering pattern symmetry holds information which can allow scattering source identification.  Methods for leveraging this information to both suppress unwanted artifacts and correct the parameters used in the matrix generating approximations should be developed.  Secondly, the approximations by which A is generated will be investigated.  Currently, Mie’s solution or the Fraunhofer approximation are used.  Investigating novel modeling methods to expand the applicability of the diffraction sizing technique would be necessary.  Finally, knowledge gained in these areas should be applied to solve problems with the current generation of sizing instrument and inform novel optical designs in the next.

The ideal candidate would have a first degree in physics and an interest in computational or theoretical aspects of the topic would be good for this project.  A candidate with a first degree in mathematics may also be acceptable.

Skills and Knowledge required

  • Numerical programming experience with scripted and compiled languages.  For example, at Malvern Instruments we use either Matlab or Python’s numerical libraries for modeling and our numerical software is written with C++ and C#, though it is not essential that candidate is familiar with these languages.
  • Some familiarity with mathematical modelling of electrodynamic systems would be required.  Experience with solving scattering problems would be useful, perhaps a project of this type as part of a first degree.
  • Some optics experience would be beneficial but not required.
  • The ability to communicate sophisticate specialist ides to a technical audience with a wide variety of specialisms.