Keywords:Fabry-Perot interferometer, Microcantilever, Zero-point motion
The ultimate target of our research is to measure the zero-point motion of microcantilever as a macroscopic object. In order to achieve the target, it is necessary to remove the thermal vibration which is the limit of measurement. Up to now, we have been using the Michelson interferometer for the feedback cooling of the thermal vibration of microcantilever. We decided to use Fabry-Pérot (FP) interferometer which has higher finesse to improve S/N, because the noise level of the detection system determines the limit of suppression of thermal vibration. We developed a micro FP interferometer at Rayleigh range with a mirror and a microcantilever which will be used for the measurement of the thermal vibration. We have succeeded in the measurement the thermal vibration of microcantilever and reducing the noise level about hundredfold using FP interferometer.