Research in my group focuses on colloidal suspensions and light. Colloidal suspensions, such as paint, consist of small particles (typically, at least 10 times smaller than the diameter of a human hair!) suspended in a fluid. The particles are large enough, however, to interact strongly with light and can often be seen under a microscope.
Optical tweezers use a focused laser beam to exert and measure forces on colloidal particles -- like tractor beams in science fiction movies, albeit on a microscopic scale. Optical tweezers can be used to measure the forces exerted by biological molecules, assemble objects at the nanoscale, and study how colloidal particles interact with each other. While the behavior of spherical particles in optical tweezers is well-understood, the behavior of non-spherical particles in optical tweezers (or in even more complicated optical beams) is not.
We have a custom, home-built optical tweezers microscope in the lab that can create multiple optical traps. We're using this setup to explore how non-spherical particles such as clusters of spheres can be manipulated using light.