Holographic endo-microscopy based on multimode waveguides

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Date 07.05.2015
Hour 10:00
Speaker Dr. Tomas Cizmar, University of Dundee, Scotland
Location
Category Conferences - Seminars
Small, fibre-based endoscopes have already improved our ability to image deep within the humanbody. Current fibre-based devices consist of fibre-bundles in which individual fibres represent single pixels of the transmitted image. A novel approach introduced recently1 utilized disordered light within a standard multimode optical fibre for lensless imaging. Importantly, this approach brought very significant reduction of the instrument’s footprint to dimensions below 100μm. Such device may be used for imaging of structures deep inside living organisms directly through centimeters of living tissues without bringing about their extended collateral damage. In Neuroscience, this technology may assist to address important unanswered questions related to formation and recall of memories as well as onset and progression of severe neuronal disorders such as Alzheimer’s disease.The two most important limitations of this exciting technology are (i) the lack of bending flexibility (imaging is only possible as long as the fibre remains stationary) and (ii) high demands on computational power, making the performance of such systems slow.We discuss routes to allow flexibility of such endoscopes by broader understanding of light transport processes within. We show that typical fibers retain highly ordered propagation of light over remarkably large distances, which allows correction operators to be introduced in imaging geometries in order to maintain high-quality performance even in such flexible micro-endoscopes. Separately, we introduce a GPU toolbox2 to make these technique faster and accessible to researchers. The toolbox optimizes acquisition time of the transformation matrix of the fibre by synchronous operation of CCD and SLM.Further, it uses the acquired transformation matrix retained within the GPUmemory to generate any desired holographic mask for on-the-fly modulation of the output light fields. We demonstrate the functionality of the toolbox bydisplaying an on-demand oriented cube, at the distal end of the fibre with refresh-rate of 20ms.

Bio: Though my scientific background is Physics, throughout my scientific career I took part in a variety of inter-disciplinary projects in Bio-Medical Photonics, mostly related to optical manipulation, digital holography, microscopy and cell biology.
My recent research activities are focused on Photonics in random environments and highly turbid media such as biological tissues or multimode waveguides.
·         2003 - 2006 - PhD at the Institute of Scientific Instruments & Masaryk University, Brno, Czechia

·         2007 - 2010 - PDRA at School of Physics and Astronomy, University of St Andrews, Scotland, UK

·         2010 - 2013 - Academic research fellow at School of Medicine, University of St Andrews, Scotland, UK

·         2013 onwards - Reader in Physics & Life Sciences, University of Dundee, Scotland, UK

Practical information

  • General public
  • Free

Organizer

  • Carole Berthet

Contact

  • Carole Berthet

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