Upper image: A dielectric bead trapped between two optical fibers, 125 μm in diameter. Lower image: the microfluidic chamber mounted with optical fibers.

Optical manipulation is a versatile tool in both atomic physics (where it is used for cooling of atoms) and in biological physics.  At the Department of Physics, we recently constructed a two-beam optical trap with light from two optical fibers that may be used for stretching of biological cells. In the project, you will learn to use the trap both to trap and stretch single cells but also for quantitative force determination by trapping dielectric beads. The measurements should be compared to numerical calculations of forces, calculations that you are to perform as well.