Professor Jem Hebden is former head of the UCL Department of Medical Physics & Biomedical Engineering (2008-2019), and director of the UCL Biomedical Optics Research Laboratory (BORL), which represents a federation of four research groups, each involved in internationally-leading research. I joined the UCL Department of Medical Physics & Bioengineering in 1992 when I vacated a tenure-track position at the University of Utah to take up a 5-year Wellcome Trust Senior Fellowship (later renewed for a further 5 years). I immediately established my own group devoted to the development of clinical prototypes for optical imaging of human subjects, with particular emphasis on the study of the premature infant brain at risk of damage resulting from hypoxia-ischaemia. I have pioneered the technique of time-resolved diffuse optical imaging, and (with Wellcome Trust and industrial support) developed a prototype which is widely regarded as the most sophisticated clinical instrument in optical tomography, utilising unique, ground-breaking technology. My group has published the first (and so far the only) three-dimensional (3D) optical images of the entire infant brain, including 3D functional images. We have also developed a novel optical topography system for real-time display of functional activity in the cortex of adults and children.