We describe an experiment in which a laser beam is sent into a high-finesse optical cavity with a mirror coated on a mechanical resonator. We show that the reflected light is very sensitive to small mirror displacements. We have observed the Brownian motion of the resonator with a very high sensitivity.
@article{arxiv.quant-ph/9901056,
title = {High-sensitivity optical measurement of mechanical Brownian motion},
author = {Y. Hadjar and P. F. Cohadon and C. G. Aminoff and M. Pinard and A. Heidmann},
journal= {arXiv preprint arXiv:quant-ph/9901056},
year = {2010}
}