James Flewellen

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James Flewellen

Academic Visitor

I commenced doctoral studies under Dr Richard Berry in October 2008. My work was funded by an EPSRC Basic Technology Studentship and a Sims Scholarship from my alma mater the University of Canterbury, New Zealand. My work focused on indirect methods of detecting bacterial motion and thesis - Digital Holographic Microscopy for Three-Dimensional Studies of Bacteria - was completed in 2012. I subsequently secured a BBSRC Tools and Research Development Fund grant and a John Fell Fund award to develop commercial applications of holographic microscopy. I am currently working on portable digital holographic microscopes for clinical diagnostic and other research applications, along with novel optical innovations for use in off-axis holographic microscopy.

I was a member of Lincoln College during my doctoral studies, rowing for the College and serving on the MCR committee. Outside of my research I tutor undergraduate and secondary school students, am involved in choral singing and am an award-winning wine writer. I run wine and food tastings courses in Oxford and around the world.

Holographic Microscopy

For my doctoral research I developed a multi-mode digital holographic microscope to study the behaviour of swimming bacteria. My microscope is capable of operating in both inline and off-axis imaging modalities and I developed novel methods of combining off-axis holographic microscopy with dark field imaging. The microscope acquires high-speed video holograms and can operate at a range of magnifications up to 225x.

A conventional image (such as a photograph or the image received by our retinas) is a record of the intensity of the light (amplitude squared) reflected from (or transmitted through) an object. Holography uses the interference properties of light to generate images (holograms) from which both the amplitude and phase of the object can be reconstructed.

Holographic imaging has the advantage over conventional microscopy in that one is not limited by typical depth of field restrictions. This allows for a full, isotropic 3D volume to be imaged at a framerate limited only by the recording camera. A 3D approach is crucial for understanding the swimming behaviour of microorganisms, which, of course, exist in a 3D world.

More recently, I have been exploring commercial applications of this technology. A hologram has embedded in it a full 3D record of the captured scene. This scene can be interrogated by advanced machine learning protocols to identify automatically the 3D shape, size and number of particles in the sample. Digital holographic microscopy can thus be used for automated diagnoses of biomedical samples as well as other industrial and research applications. As part of this project, I have developed a prototype portable holographic microscope suitable for benchtop applications in research labs, medical clinics or field testing locations.