Project 1: Optical Clamp

Designers:

François Treussart and Marie-Pierre Adam

Optical trapping uses light to manipulate micrometer-scale objects. In fact, if a laser beam is highly focused—for example, using a microscope objective with a large numerical aperture—the photons transfer part of their momentum to the object, thereby trapping it. This makes it possible to manipulate micrometer- or even nanometer-scale particles, such as viruses, bacteria, and cells in biology.

The goal of this experimental project is to develop an optical tweezers using a He-Ne laser beam and to use it to trap micrometer-sized dielectric beads. Students will be required to assemble the experimental setup and optimize the parameters for maximum trapping efficiency. They will compare the trap’s effect on beads made of different materials dispersed in a liquid.

Depending on the project’s progress, a method for calibrating the trap based on the study of the Brownian motion of the trapped bead may be implemented.