Colloidal interactions with optical fields: Optical tweezers

This chapter reviews the basic physics and design of an optical tweezers system. It shows how the optical tweezers can be used in a range of studies, with emphasis on colloidal systems. The chapter examines how modern optical tweezers are able to take advantage of the ability to shape optical beams into near arbitrary shapes through a range of technological innovations from the acousto-optical modulator to the spatial light modulator. It also discusses other optical techniques that make use of radiation pressure to manipulate particles that are typically dual-beam traps and can offer some flexibility over optical tweezers for certain applications. The chapter explores the developing fields of nanoparticle manipulation, and aerosol trapping and analysis. The use of optical tweezers in colloidal science is particularly useful for the measurement of interaction forces, as opposed to adhesion, binding, or structural forces involved in biological processes.