Theoretical Characterisation of Microbubbles Paper

As part of the NPL/UCL/Oxford microbubble trapping collaborative project a paper Theoretical characterisation of the radial and translational motion of coated microbubbles under acoustic excitation has been published as C. J. Harfield et al, J. Phys.: Conf. Ser 457 012001 (2013).

From the abstract: Ultrasound contrast agents, in the form of coated microbubbles, are a powerful tool in current diagnostic imaging. Given their sensitive dynamic response they also have the potential to be used for quantitative measurements of the properties of the surrounding tissue (e.g. percentage perfusion or blood pressure). For this potential to be realised, however, the theoretical descriptions of bubble behaviour, in particular the constitutive equations for the microbubble shell, need to be improved and a method needs to be developed for the accurate characterisation of individual bubbles. In this paper the first steps are taken towards deriving a complete model for the coupled radial and translational motion of a coated bubble. It is then shown that with this model the bubble can be characterised by a unique set of parameters describing the bubble shell corresponding to its viscous and elastic response. This uniqueness will enable the model to be used to interpret experimental data and quantify these parameters for which accurate values are currently lacking but which are critical to predicting bubble response and hence enabling advanced diagnostic applications.

Visit by Prof Jixiong Pu

We are pleased to welcome Prof Jixiong Pu (Huaqiao University) to the group as a distinguished visiting scholar.  Prof Pu is Professor of Physics and Dean of the College of Information Science and Engineering, Huaqiao University.  He has been awarded a visiting scholarship to come to UCL and will be staying with us from 25 July - 08 September 2013,  His research interests include the generation of partially coherent light beams and their focusing and propagation, vortex beams, tight focusing of stochastic electromagnetic beams, applications of surface plasmon polaritons (SPP), and optical manipulation

Konnect: The smart lecture experience

UCL Physics students Adam & Nat have entered their idea Konnect - The smart lecture experience into the JISC Summer of Student Innovation competition. 

Learning works best with participation. However, lectures are typically highly passive experiences. For the students, lectures are more akin to watching a performance than expanding their knowledge and understanding of a particular topic. This is especially true for students in their first year of university who have become accustomed to relatively small classes at school and college.

We propose a platform that provides a real time connection between students and their lecturer. We aim to make the lecture environment one that promotes engagement; students will start to question their understanding for themselves. Essentially, our platform is comprised of a website, which acts as the hub of the service, and a smart phone app for students. Using these, a connection can be formed between a lecturer and his/her students.

Vote for Adam & Nat's idea with the JISC Elevator Vote button opposite.

MSci Projects 2013

This year we have had two MSci students working in the group for their final year projects.  Chris Richards used Mie scattering theory to calculate optical forces experiences by microscopic particles in optical trapping experiments.  In particular he was interested in finding the range of parameters for which an optical pulling force or 'tractor beam' was possible. By finding the fields scattered by a dielectric sphere and evaluating the Maxwell Stress Tensor to find the distribution of optical stress over a sphere he was able to determine the combination of beam and particle properties that would lead to the strongest 'backward' directed scattering force.  Above you can see some of Chris' calculated stress distributions on the sphere surface in the forward- and backward scattering directions.

Zhi Hao Wong also worked with us to investigate the optical properties of metallic nanoparticles. Opposite you can see the calculated extinction spectra for gold and silver spherical nanoparticles as a function of size and optical wavelength which clearly show the enhancement of optical scattering arising from their plasmonic properties.  Zhi Hao then went on to investigate how these properties could be used to control the dynamics of metallic nanoparticles in optical fields.

More MSci projects will be available for Physics and Natural Science students in the year 2013-14.  Contact Dr Phil Jones for details of available projects.

PHOTOPTICS 2014

The 2nd International Conference on Photonics, Optics and Laser Technology (PHOTOPTICS2014) will be held in Lisbon, Portugal, 07-09 Jan 14.  The conference will feature three different tracks on Optics, Photonics and Lasers, covering both theoretical and practical aspects, and the Keynote Speaker is Prof David Andrews of the University of East Anglia.

Big Bang Science Fair

POP! The Sound of Bubbles was at the Big Bang Science Fair in the ExCeL Centre in Docklands 14 - 17 March.  Members of the NPL/UCL/Oxford microbubble project together with colleagues from NPL, Glasgow University and King's College demonstrated bubble science to over 63,000 visitors in four days.
Among the visitors to our stand was the Secretary of State for Business, Innovation and Skills, Vince Cable, here being shown our Kundt Tube demonstration of acoustic resonance by Ian Butterwoth of the NPL.

Susan Skelton PhD viva

Congratulations to Optical Tweezers PhD student Susan Skelton who has successfully defended her PhD thesis on Applications of cylindrical vector beams for optical micromanipulation.  Susan will be leaving the group to start a postdoc at the University of Osaka, Japan, in the Laboratory for Scientific Instrumentation and Engineering (LaSIE) under the supervision of Prof Satoshi Kawata.  Many thanks to Dr Stephen Hogan (UCL) and Dr David McGloin (Dundee University) for acting as examiners.

Well done Dr Skelton, and good luck in Japan!