Characterization of Acoustic Standing Waves Surrounding A Cylindrical Inertia Block in an Ultra-Low Vibration Facility

In facilities working with scanning tunneling microscopes (STM), it has been found that the vibrations of the surface on which the STM is placed can significantly alter results. To mitigate this issue, more research is being done into low-vibration laboratories. The low-vibration facility at Harvard University employs a massive cylindrical inertia block mounted on pneumatic isolators. The block has been made cylindrical to avoid coupling of acoustic standing waves between the walls of the room and the inertial block. We have used COMSOL Multiphysics to perform finite element analysis to simulate coupling of the acoustic standing waves in the room to the resonant modes of the inertial block. To check the results of the simulation, a speaker is used to generate a range of frequencies in order to excite the block. We then measure the acoustic standing waves using a microphone.