Optical Forces, Trapping and Manipulation

Abstract

The development of optical tweezers led to optical trapping becoming a widely used practical tool, with many applications in biology, biophysics, and other fields. The fundamental theory that one can use to describe optical tweezers is classical electromagnetic theory. This chapter presents a brief review of the relevant basic elements of electromagnetic theory, largely as a reminder about basic concepts and terminology. It presents a detailed discussion on the theory of optical forces and optical torques and the measurement of forces and torques. The force acting on a trapped particle can be calculated if the electromagnetic field is known, via the Maxwell stress tensor, or the Poynting vector in the far field. Therefore, calculation of optical forces is a task in computational light scattering.