Brilliant future for WhiteLase

A collaboration of four UK partners could boost laser manufacturing and biomedical imaging technology within the UK. The Technology Strategy Board is spending part of its £7m fund for lighting, lasers and displays on a research project to improve the systems used for imaging biomedical samples.

The WhiteLase project addresses the need for high- brightness, efficient visible laser illumination sources by developing advanced white light (super- continuum) fibre lasers and their applications within biomedical imaging.

It is being led by Fianium, a fibre laser company from Southampton which focuses on the manufacture and development of ultra-fast, high-power laser systems covering a wavelength range from the UV (240nm) to infrared (2500nm).

Lasers within the visible region of the spectrum are used in microscopy and flow cytometry for imaging biomedical samples whose components have been labelled with fluorescent dyes. However, different dyes are excited by different wavelengths so up to 10 discrete lasers can be required to get a comprehensive image of a single sample.

Such a system may cost up to £600,000, putting them beyond the budget of most research facilities. Usually they are located only at core centres, which can slow up the processing of samples.

To overcome these drawbacks, the WhiteLase project aims to produce a single laser that can generate a wide band of wavelengths of sufficient brightness.

If produced successfully, the white laser will offer any colour of light and therefore provide additional functionality over the existing discrete lasers but at a fraction of the cost. The result could make high-end imaging systems affordable to many medical centres and research institutes, allowing processing and research to accelerate.

'The WhiteLase goals are extremely challenging, but by forming a technology partnership between Fianium and the Centre for Photonics and Photonic Materials at Bath University, the chances of success are high,' said John Clowes, R&D head at Fianium. 'We are being driven by the need of end users, so the goals are commercially driven.'

In this case Fianium is working with Genetix of New Milton, Hampshire, which supplies equipment for cell identification, and Edinburgh Instruments, manufacturers of steady state and time resolved fluorescence spectrometers.

Supercontinuum lasers were first developed in the 1970s and use an ultrafast pulse of high intensity at a single wavelength within the infrared spectrum. Work in the 1990s showed that when the pulse is injected into a photonic crystal fibre it spreads further into the infrared and also into the visible region due to the high intensity of the pulse interacting with the silica of the fibre. So a one-micron wavelength pulse can be used to generate a whole spectrum from 400nm to 2.5 micron.

With such a broad spectrum of wavelengths available, the theory is that, by applying the right filters, a single supercontinuum laser could provide all the wavelengths needed to excite all the dyes within a biomedical sample. This would obviate the need for different lasers that are now required for the job, cutting costs dramatically.

To approach this solution, Fianium and its partners are focusing on specific objectives. 'The project has two main goals,' said Clowes. 'The first is to scale the power of the supercontinuum in the visible region, to approach a 10-fold increase in spectral brightness on the current state-of-art.

'The second is to push the wavelength down even further. At the moment we cover the spectrum from 400nm to 2.5 micron. We want to get down to 300nm in the ultra violet region.'

The hope is that this will be achieved with new photonic crystal fibres from Bath and new ultrafast laser sources from Fianium. Clowes regards the support of the Technology Strategy Board as crucial to such progress.

'We're a relatively young company,' he said. 'The laser industry is highly dynamic and we can't afford long-term projects, nor could we afford the half a million pounds it would cost to fund such high-quality research at Bath, especially when there is no guarantee of a successful outcome for the research.'

The Technology Strategy Board's support means that Fianium needs only fund about 25 per cent of the university costs.

'We couldn't embark on a project like this without the TSB funding,' said Clowes. 'Likewise Genetix and Edinburgh Instruments would otherwise just have to wait for this research to occur but now they can influence the direction and gain access to early prototypes to help them get a couple of years ahead of their competitors.'

Max Glaskin