An optical levitation system for a physics teaching laboratory
Journal article, 2018

We describe an experimental system based on optical levitation of an oil droplet. When combined with an applied electric field and a source of ionizing radiation, the setup permits the investigation of physical phenomena such as radiation pressure, light diffraction, the motion of a charged particle in an oscillating electric field, and the interaction of ionizing radiation with matter. The trapping occurs by creating an equilibrium between a radiation pressure force and the force of gravity. We have found that an oil droplet can be trapped for at least nine hours. The system can be used to measure the size and total electric charge on the trapped droplet. The intensity of the light from the trapping laser that is scattered by the droplet is sufficient to allow the droplet to be easily seen with the naked eye, covered by laser alignment goggles. When oscillating under the influence of an ac electric field, the motion of the droplet can be described as that of a driven, damped harmonic oscillator. The magnitude and polarity of the charge can be altered by exposing the droplet to ionizing radiation from a low-activity radioactive source. Our goal was to design a hands-on setup that allows undergraduate and graduate students to observe and better understand fundamental physical processes.

Author

Oscar Isaksson

University of Gothenburg

Magnus Karlsteen

Chalmers, Physics, Condensed Matter Physics

Mats Rostedt

University of Gothenburg

Dag Hanstorp

University of Gothenburg

American Journal of Physics

0002-9505 (ISSN)

Vol. 86 2 135-142

Subject Categories

Accelerator Physics and Instrumentation

Atom and Molecular Physics and Optics

Other Physics Topics

DOI

10.1119/1.5007738

More information

Latest update

9/2/2019 6