Optical manipulation and the angular momentum of light

Abstract

This thesis consists primarily of an investigation into the action of laser light on particles held within optical tweezers. I present work on a dynamic method of measuring both the axial and lateral efficiencies of optical tweezers using Laguerre-Gaussian laser modes. I have developed a new and straight¬ forward way of using an aperture within optical tweezers to rotate particles. I demonstrate a new method for trapping metal particles which is interesting for the insight it gives into the fundamental properties of light. Finally, I show the different ways spin and orbital angular momentum interact with a particle placed off-axis in a Laguerre-Gaussian beam. In addition to the work on optical tweezers I also explain a novel method for producing any type of pure laser mode from a Hermite-Gaussian laser mode. A summary of my conclusions together with some ideas for future work is included.