Michael Brown

Position: Research Fellow (EPSRC Doctoral Prize)
Email: michael.brown.13@ucl.ac.uk
Room: Malet Place Engineering Building, 3.18
Address: Department of Medical Physics and Biomedical Engineering
University College London
Malet Place Engineering Building
Gower Street, London, WC1E 6BT


I joined the Department of Medical Physics and Biomedical Engineering on the Medical and Biomedical Imaging DTP in September 2013 after completing a MSci in Physics at the University of Bristol. This was motivated by a desire to study in a more applied and multidisciplinary field.

My research is focused on the optical generation of ultrasound (OGUS) using the photoacoustic effect. In particular I have been exploring several new approaches by which spatial and spectral properties of optically generated acoustic fields can be manipulated using a mixture of numerical modelling with the k-Wave toolbox and laboratory experiments.

The first approach involves modulating the spatial pattern and temporal shape of the light incident on a planar absorber. This enables control of both the acoustic spectra and the spatial pattern of the initially generated pressure. These combined allow the use of photoacoustic holography to control where the resulting acoustic field constructively and destructively interferes enabling the generation of a number of novel acoustic fields.

The second approach involves creating ‘3-D holograms’. These are structures made up of several optically absorbing layers each separated by a transparent spacer of a known thickness. Each absorbing layer is patterned so that when it is optically excited an acoustic signal is generated only from portions of the layer. The patterns are calculated so that the acoustic signal generated from each layer arrives simultaneously at a set of targeted focal points. These enable the generation of patterned acoustic fields with a single pulsed optical source.

Finally, I have begun exploring whether chaotic cavities and time reversal can be used to generate patterned acoustic fields using a single pulsed source and a single patterned optically absorbing layer.

Journal Publications

1.M. D. Brown, B. T. Cox, B. E. Treeby (2017): Design of multi-frequency acoustic kinoforms. In: Appl. Phys. Lett., 111 (24), pp. 244101, 2017. (Type: Journal Article | Links | BibTeX)
2.M. D. Brown, D. I. Nikitichev, B. E. Treeby, B. T. Cox (2017): Generating arbitrary ultrasound fields with tailored optoacoustic surface profiles. In: Appl. Phys. Lett., 110 (9), pp. 094102, 2017. (Type: Journal Article | Links | BibTeX)
3.M. D. Brown, J. Jaros, B. T. Cox, B. E. Treeby (2016): Control of broadband optically generated ultrasound pulses using binary amplitude holograms. In: J. Acoust. Soc. Am., 139 (4), pp. 1637–1467, 2016. (Type: Journal Article | Links | BibTeX)

Conference Publications

1.M. D. Brown, B. T. Cox, B. E. Treeby (2017): Investigating the effect of thickness and frequency spacing on multi-frequency acoustic kinoforms. IEEE International Ultrasonics Symposium, 2017. (Type: Conference | Links | BibTeX)
2.M. D. Brown, E. Martin, B. T. Cox, B. E. Treeby (2016): Single pulse illumination of multi-layer photoacoustic holograms for patterned ultrasound field generation. IEEE International Ultrasonics Symposium, 2016. (Type: Conference | Links | BibTeX)
3.M. D. Brown, T. J. Allen, B. T. Cox, B. E. Treeby (2014): Control of optically generated ultrasound fields using binary amplitude holograms. IEEE International Ultrasonics Symposium, 2014. (Type: Conference | Links | BibTeX)