Profile on Professor Tony Wilson: Imaging hidden depths
Image: Professor Tony Wilson has been pursuing research into microscopy, imaging and applied optics for more than twenty years.
Long before Professor Tony Wilson had discovered microscopy, he was very passionate about Mathematics and the Arts. Torn between which of the two disciplines to focus on, he opted for the former, concluding you could always read a book at home.
"Chemistry books were too thick and seemed to contain too much to remember," he adds. "But I realised Mathematics was a beautiful language which you could use to express concepts that were terribly difficult to express in words."
Still, it wasn't just about the language. Wilson also wanted to apply Mathematics to real world problems, so on completing A' Levels in Pure and Applied Mathematics, and Physics, he decided to study Engineering Science at the University of Oxford.
"The advantage of this course was it included bits of everything. We were using Maths to describe the real world and were applying this science to engineering," he recalls.
Wilson completed his degree in 1976, and by this time, had discovered optics. He started a Doctorate based on integrated optics, including waveguides and using optical fibres, at the University Oxford but limited funding thwarted experimental work.
However, at around the same time, he met Austrian-born physicist Rudolf Kompfner. Known for inventing the travelling wave tube, Kompfner was exploring scanning acoustic microscopy, prompting Wilson to ditch integrated optics and pursue scanning optical microscopy.
With a fresh focus, Wilson teamed up with several Oxford University researchers, including Colin Sheppard, a fellow optics pioneer now at the Italian Institute of Technology, Genoa, and set forth establishing the theory and practicalities of scanning optical microscopy including the confocal optical arrangement.
"It was a great time, we didn't have a formal education in optics so didn't know what you could do and what you couldn't do," says Wilson. "Looking back we were pretty green, not that we thought that at the time."
The principle of confocal microscopy has been established by American cognitive scientist Marvin Minsky as early as 1957. The MIT Professor had suggested confocal imaging to overcome the limitations of the traditional wide-field fluorescence microscope when imaging deep inside the brain but crucial components, including the laser, had not yet been developed.
However, in the years to follow, researchers around the world would build on the concept. And come 1978 Wilson, Sheppard and colleagues at Oxford University had developed a confocal set-up with laser illumination, stage scanning and photomultiplier tubes as detectors.
Brine shrimp captured using an Aurox structured illumination/detection system. [Aurox]
"People had tried to build scanning microscopes in the past but didn't have sufficiently bright light sources," points out Wilson. "We were lucky, the commercially affordable laser had arrived and this was one of its early applications; without this we wouldn't have been able to get sufficient signal [to generate an image]."
Crucially, the young researchers had also designed a system which allowed an optically-sectioned image to be obtained at a particular depth. According to Wilson, it was then straightforward to record a through-focus series of thin, high resolution, images from which a 3D image of the specimen could be created.
"Our whole idea had been to simply get better resolution but this set-up also gave us the optical sectioning. And that eventually led to 3D imaging," he adds.
Commercialising confocal imaging
Wilson completed his doctorate in 1979 and moved to Brasenose College, University of Oxford, as a junior research fellow, while also launching Oxford Optoelectronics with Colin Sheppard.
The researchers had won funding from several sources, including the Prince of Wales Innovation Award. And as Wilson says: "We thought enough people were interested in confocal scanning microscopy by now, so why not set up a company to manufacture the thing?"
As Wilson points out, this was an unusual time to spin out a company from the University, but the venture worked, and come 1982 Oxford Optoelectronics had sold the first commercial laser scanning microscope, the stage-scanner SOM-100.
However by this time, Wilson was keen to explore new avenues. An opportunity to work at Bell Labs came up, and the researcher accepted.
"This wasn't scanning optical microscopy but I wanted to see this research lab," he says. "It was an amazing place and was the only place in the world that had the mantra, 'spend money to save time'."
Still two years later, the future of Bell Labs had become uncertain and Wilson returned to the University of Oxford and the world of microscopy, taking the position of tutorial fellow at Hertford College in 1984.
Wilson had realised, as had the rest of the world he jokes, that biology was critically important. Prior to heading out to Bell Labs, Wilson and Colin Sheppard, had developed the theory for a direct-view confocal microscope for optical sectioning. This, they believed, combined the resolution and depth discrimination of confocal microscopy with the ease of operation of a conventional microscope.
Labelled fluorescent image of brassica flower bud. [Aurox]
"We wrote a paper about this and our referees told us to take a look at a similar concept that we hadn't heard of then, tandem scanning microscopy," he says.
Years later, Wilson and his colleagues realised that they could build on this. Tandem scanning microscopy designed by researchers at Charles University in Prague and Yale, used a perforated spinning disk placed in front of the microscope aperture, to generate multiple emission pin-holes and obtain real-time confocal images.
But as Wilson highlights: "This method was very light inefficient as it threw away almost 99% of the light available for imaging. So we had this idea to modify the conventional microscope while providing optical sectioning, and this was the birth of structured illumination."
As part of this development, Wilson had been keen to dispense with laser light and reverted to using a simple white light excitation source with a patterned spinning disc for optical sectioning.
"We patterned the disc in a defined geometrical grid and projected the light pattern onto the specimen," explains Wilson. "By processing a series of images, we achieved optical sectioning."
Concept to practical instrument took years of development. But by the late-1990s, Wilson and colleagues had published several high profile papers on how to use structured illumination to obtain optical sectioning and 3D imaging in a wide-field microscope.
They went onto develop light demodulation algorithms to extract optical sections from raw data images. Meanwhile other key developments included the developments in CCD camera technology along with new disc designs and optical architectures to optimise optical sectioning.
Then, in 2004, Wilson, alongside fellow researchers, Rimas Juskaitis, Mark Neil and Martin Booth, launched 'Aurox', to market spinning disk confocal microscopy system, SD62.
Labelled fluorescent image of fibroblasts in muntjac skin. [Aurox]
In the years that followed, Carl Zeiss and Andor Technology would come on board to distribute the systems, the company would win the Queen's award for Enterprise and Innovation, and the company would earn more than £1 million in revenue thanks to the system's development.
Beyond spinning optical microscopy
But while Wilson is perhaps most well known for his pioneering development of confocal imaging and widefield sectioning microscopy, today he heads up the Scanning Optical Microscopy group within the Department of Engineering Science at the University of Oxford.
Here, he and colleagues also develop multi-photon and non-linear microscopy methods, as well as use adaptive optics to overcome the unavoidable aberrations associated with focusing deep within a specimen.
And, importantly, the team has developed a remote focusing technique to allow the user to image along planes, curbed surfaces and arbitrary 3D trajectories.
More than ever, Wilson is collaborating closely with biologists from Oxford University, Guy's Hospital, London, and elsewhere to develop techniques to image cardiac tissue, mouse embryos and more.
Looking to the future, Wilson will continue to develop instruments and believes the next big imaging breakthrough could centre around axial resolution.
While lateral resolution in confocal microscopy can reach around 180 nm, thanks to spherical aberration, axial resolution is limited to around 500 nm.
"I have this gut feeling that if we could improve axial resolution of both brightfield and fluorscence microscopes in an elegantly simple manner, that would be a really good thing to do," he says. "I don't yet know how to do this, and perhaps you can't, but if we could crack this, well that would be very neat."
In short: Tony Wilson
Professor Wilson graduated from the University of Oxford in 1976 and completed his DPhil in 1979. He was appointed as a Tutorial Fellow in Engineering Science at Hertford in 1984.
His work has led to the formation of Oxford Optoelectronics and Aurox, and resulted in many awards including the 2012 Institute of Physics innovation Award and a Queen’s Award for Enterprise.
He was President of the Royal Microscopical Society from 2010 to 2013, Master of the Worshipful Company of Scientific Instrument Makers from 2014 to 2015 and is also Thousand Talents Professor at the Harbin institute of Technology, China. Wilson is also editor of the Journal of Microscopy, currently celebrating its 175th year.