Testing the Precision of Optical Tweezers

A highly focused laser beam can be used to trap, move and monitor microscopic particles, creating what is known as an ‘optical tweezer’. This effect is extremely useful, as it allows very small objects to be held and moved during microscopic study. Optical tweezers have many applications, ranging from medical diagnosis, to investigating the intricate processes occurring inside cells, to trapping and transporting single atoms.

Because the technology is relatively new, many fundamental issues still remain to be addressed. Not only do techniques for producing the highly focused light beams need to be developed, but also methods for adapting them to forms that are useful for particular applications.

Dr Warwick Bowen from the University of Otago has been awarded a Fast-Start Marsden grant, to investigate and develop the science and technology behind optical tweezers. The Fast-Start programme is an initiative to give emerging researchers an opportunity to explore an innovative idea, developing their capabilities and helping them establish their research career.

Many of the applications of optical tweezers are due to their ability to monitor the position of particles with extremely high resolution. This means that very tiny particles can be trapped and monitored – much smaller than other more traditional instruments. But what is the ultimate resolution limit of these devices? Just how small can they go? Dr Bowen will investigate just this issue. First, he will determine the theoretical precision in which the position of a particle held in an optical tweezer can be measured. Then, he will find out whether this can actually be achieved in a practical experiment.

Ultimately, Dr Bowen’s research could see this very useful technology extended to a much wider range of applications.

Total Funding:    $140,000 Fast-Start
Researchers:    Dr Warwick Bowen, Department of Physics, University of Otago, Dunedin.