Optical Tweezers: Techniques and Applications

Dr. David McGloin
School of Physics and Astronomy
University of St. Andrews, Scotland

In this talk I will discuss optical tweezers, a technique that allows the non-contact
manipulation of micro and nano scale objects using a focused laser beam. I will give an 
overview of the work carried out in my group which focuses on the use of novel light beams 
to manipulate matter. In particular I will discuss the use of holographic optical tweezers, 
using computer controlled holograms, which are able to shape a laser beam to form many 
simultaneous trap sites. Our work in this area concentrates on the manipulation, control 
and characterization of airborne particles, such as aerosols and on the optical control of 
the growth of biological organisms such as fungi. The aerosol work allows us to look at 
optically controlled digital microfluidics systems whereby droplets can be coagulated and 
rotated with the aim of producing chemical microreactors and particle composition 
diagnostic tools. The biological work focuses on using holographically generated patterns 
to dictate how photoresponsive organisms grow. I will also discuss our work using 
non-diffracting beams such as Bessel beams and their applications in particle guidance, 
studies of Brownian motion and orbital angular momentum. I will conclude with a brief 
overview of some of the related optical manipulation work from the Optical Trapping Group 
in St. Andrews.