Berlin 2008 – scientific programme

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DD: Fachverband Didaktik der Physik

DD 31: Praktika III (moderne Experimente)

DD 31.3: Talk

Thursday, February 28, 2008, 15:00–15:20, EW 015

Light motion - optical tweezers for students — •Antje Bergmann, Ursula Kroll, Gülhan Wogh-Deveoglu, and Kurt Busch — Institut für Theoretische Festkörperphysik, Universität Karlsruhe

Optical tweezers are devices with which objects can be manipulated solely via a focussed light beam. It is possible to trap and move small polarisable particles or cells by using a laser which is coupled into a microscope. Not only is it a highly fascinating thing to experience, but there are numerous applications in various research and application fields apart from physics: e.g. medicine (in vitro fertilisation,...), biology (manipulation of DNA, bacteria,...), microtechnology (microgears,...) and many more. The motivating and multidisciplinary character of such tweezers experiments as well as their importance in modern science makes them worth teaching.

Thus, we designed a low cost setup which is supposed to be the pioneer project for a new school laboratory at the Physics Department of the Universität Karlsruhe. We show how easy it is to design a properly working optical tweezers assembly, we describe the setup in detail and explain how it works. Furthermore, we introduce certain suitable experiments for students, e.g. evaluation of the trapping forces of micron size particles via Stokes‘ Law or the evaluation of the Brownian motion with and without an optical trap.