Measuring the mechanical motion of a mirror. The light in the cavity interacts with the oscillating mirror, and the reflected light bears information about the mirror position. {Figure taken from Science 321, 1172 (2008)}

Aim

The objective of this project is to measure the position of a mirror using a cavity and a feedback loop.

Background

Macroscopic gravitational wave detectors as well as microscopic cantilevers in atomic force microscopes are based on the ultrasensitive measurements of a mechanical displacement. Usually the displacement is measured by coupling the mechanical degree of freedom with the optical degree of freedom of a light beam. By means of such techniques it is envisaged that a mechanical displacement as small as 10^-19 meter can be measured!

In the present project we plan to measure the displacement of a mirror by coupling its mechanical motion to a light beam. In order to enhance the sensitivity of the measurement, we want to build the mirror into a cavity and stabilize it via an electro-optical feedback loop. The project therefore involves the construction of a high-finesse cavity combined with a state-of-the-art feedback system.