Manipulating particles with light: radiation and gradient forces

David S. Bradshaw, David L. Andrews

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)
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Abstract

The manipulation of matter with electromagnetic radiation is a capacity that has been known for over a century. However, the prominence of such optical effects only grew rapidly following the invention of optical tweezers in the 1980s. While both the original theory and the early trapping techniques are based on the radiation force, optical tweezing uses the gradient force. This paper aims to differentiate between these two clearly distinct types of optical forces, which are sometimes confused in the literature. We also discuss three completely separate forms of optical torque that can be applied to a particle, also due to an electromagnetic field. These involve the transfer of either spin or orbital angular momentum from the beam to the particle, depending on the character of the light, or the often overlooked alignment effect that can act on a cylindrical particle due to a gradient force.
Original languageEnglish
Article number034008
Number of pages17
JournalEuropean Journal of Physics
Volume38
Issue number3
DOIs
Publication statusPublished - 8 Mar 2017

Keywords

  • optical trap
  • optical tweezers
  • optical force

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