A. Heidmann

We performed an experiment to study the thermal noise of mirrors and the effects of radiation pressure in interferometric measurements. A laser beam is sent in a high-finesse optical cavity with a mirror coated on a mechanical resonator. The phase of the reflected field reproduces the motion of the mirror and we have observed its Brownian motion with a very high sensitivity. We have also cooled the mirror by the radiation pressure of light. We have finally examined the possible application of this cooling mechanism to control the thermal noise in gravitational-wave interferometers.