A University of Sheffield professor whose research has radically transformed the capabilities of microscopic imaging has been honoured with one of the highest accolades in science and engineering.
Professor John Rodenburg from the University’s Department of Electronic and Electrical Engineering has been elected a Fellow of the Royal Society – an award given to scientists and engineers by the Royal Society of London in recognition of their exceptional contribution to the fields.
Professor Rodenburg is internationally renowned for developing computational imaging methods that have radically improved the capabilities of light, X-ray and electron transmission microscopes.
Microscopes have traditionally used lenses to form a magnified image of an object, however lenses have some serious limitations, particularly in X-ray and electron microscopy when the radiation that is being used has an atomic-scale wavelength.
Lenses have aberrations, which means the image is blurred or distorted. X-ray and electron lenses also have a very small useable lens aperture size, which seriously limits resolution.
Finally, the image itself contains no information at all if the specimen is perfectly transparent, which is often the case for many types of specimen that are examined using light, X-ray and electron transmission microscopes.
Professor Rodenburg was the first to propose a radically new approach to overcome all of these issues.
He realised that if an object is lit by radiation at many different places, and the radiation scattered from the object is recorded some distance away, then it would be possible to invert this data – to work out backwards using a powerful computer – to produce a picture of the object without using any lenses at all.
The technique – called ptychography – processes huge quantities of measurements, but can compute a near-perfect image of the specimen. It can also calculate the phase of the waves that have passed through the object, which means transparent objects can be seen with very high contrast.
His more recent work at the University of Sheffield has greatly reduced the computational requirements of ptychography, and has brought about other key innovations, such as its ability to account for multiple scattering effects in thick specimens.
Ptychography is now adopted at most X-ray synchrotrons around the world and is having a growing impact in electron microscopy. Its ability to generate very high contrast phase images is also used in conventional lens-based optical microscopes to image living biological cells.
Professor Rodenburg said: “I am absolutely delighted with this news. Throughout my career, I have had an enormous respect for the Royal Society: it has been a fixed point of excellence in the international world of science for over 350 years.
“I am deeply honoured to have my work on computational microscopy recognised in this way.”
Venki Ramakrishnan, President of the Royal Society, said: “Over the course of the Royal Society’s vast history, it is our Fellowship that has remained a constant thread and the substance from which our purpose has been realised: to use science for the benefit of humanity.
“This year’s newly elected Fellows and Foreign Members of the Royal Society embody this, being drawn from diverse fields of enquiry—epidemiology, geometry, climatology—at once disparate, but also aligned in their pursuit and contributions of knowledge about the world in which we live, and it is with great honour that I welcome them as Fellows of the Royal Society.”