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17 Jun 2002
A compact, low cost, optical trapping microscope has been developed by scientists at the University of Hertfordshire in the UK by adapting a standard optical microscope using a laser diode.
The developers of the microscope, Zbigniew Ulanowski and Ian Ludlow, say that it makes optical trapping technology accessible for education and research purposes for the first time.
"We are aiming for a low-cost system, so its main use could be in education, for example, in demonstrations that take advantage of video microscopy. This is an unexplored area, due to the high cost of commercially available systems," said Ulanowski.
The system is based on a microscope that is focused by shifting the microscope limb with the objective nose piece instead of adjusting the sample stage.
An unusual beam-deflection scheme moves the collimated diode-laser output. Only two singlet lenses are used to achieve the laser-beam expansion, steering and confocality. This means that the laser-beam spot can be positioned in two or three dimensions without any change in the diameter of the beam at the microscope objective, which ensures that optimum trapping conditions are maintained.
Only two singlet lenses are required, so the system design and construction is simplified and power losses are reduced.
"The system also has a short optical path, making it compact," said Ulanowski. "At the same time optical aberrations can be kept below the diffraction limit, despite using only singlet lenses."The researchers have built a prototype system in which the trapping spot can be positioned using a computer mouse or trackerball. They are also looking for an industrial partner to commercialize their product.
Contact Zbigniew Ulanowski, University of Hertfordshire, tel. +44 1707 284604, e-mail "zulanowski@herts.ac.uk".
Story courtesy of Opto and Laser Europe magazine.
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