Seeing through obscuration

Opaque materials, including most living tissues, scatter the light that propagates through them. This scattering prevents the direct formation of images, obscuring our ability to see objects behind or inside the scatterer. However, the light passing through these materials has not been absorbed and lost – just redirected. The last decade has seen the emergence of remarkable techniques to overcome scattering and reconstruct images in situations previously considered intractable. These techniques are providing a range of powerful new imaging systems, capable of seeing deep inside the human body using visible light, imaging around corners using backscatter from rough surfaces, through hair-thin optical fibres, and ultimately seeing through rapidly changing scattering environments such as mist and fog.

Driving these advances has been new insights into optical scattering, fluorescence, optical ranging, combined with the development of advanced computational imaging processing, sophisticated digital light shaping and ultra-sensitive, time-resolved cameras. Although progress has been swift, significant challenges remain in taking these technologies from laboratory benches to revolutionise medical clinics, telescopes, weather stations, and numerous other applications worldwide.

This symposium reunited a community that first met during COVID lock-down, exchanging the on-line meeting format for the face-to-face format of the unique RANK experience, supported by Samantha Walker from the Rank Prize. With experts in laser beam shaping, sensor technology, imaging processing and various types of algorithm development, the community learnt much about each other’s domains and established a shared vocabulary with which to exchange ideas, identify solutions and gain an insight to future avenues.

International keynote speakers included Prof. Hui Cao from Yale University (USA), an expert in wavefront shaping to control light within diffusive media; Prof. Vivek Goyal from Boston University (USA), an expert in computational imaging and inverse problems; Prof. Alexander Jesacher from the Medical University of Innsbruck (Austria), an expert in biomedical microscopy; and Prof. Tomás Čižmár from the Leibniz Institute of Photonic Technology, Jena, (Germany), an expert in micro-endoscopy through hair thin optical fibres. Invited speakers joined from all corners of the UK, including Glasgow, Strathclyde, Dundee, Nottingham, Oxford, Imperial, UCL and Exeter.

The quality of talks given by the early career researchers in attendance was exceptionally high. In the end, talk prizes were awarded to three early career researchers:

• Graduate student Rohin McIntosh, University of Yale (USA), who told us about the delivery of broadband light deep inside diffusive media using spatio-spectral beam shaping.
• Dr Unė Būtaitė, University of Exeter (UK), who gave a talk about optimising the interaction of light and matter for ultra strong optical tweezers.
• Dr André Gomes, Leibniz Institute of Photonic Technology, Jena, (Germany), who spoke about funnelling super-resolution STED microscopy through hair-thin strands of optical fibre.

Dr Amanda Foust, Imperial College London

Professor David Phillips, University of Exeter

Professor Miles Padgett, University of Glasgow