DOUBLE-BALANCED BELLOWS FOR VIBRATION ISOLATION BETWEEN THE INSIDE AND OUTSIDE OF A VACUUM - APPLICATION TO GRAVITATIONAL-WAVE EXPERIMENT

In recent precise experiments, such as optical measurements with inter ferometry, physical quantities sometimes need to be observed in a 'qui et' vacuum, where all of the instruments in the vacuum are well isolat ed from the vibration of the vacuum tank including the vacuum-pumping system and, sometimes, from the seismic noise of the earth. We have de veloped a new technique for vibration isolation between the inside and outside of a vacuum (e.g. an optical bench and a tank), which involve s a double-balanced bellows (DBB) to compensate for the atmospheric pr essure. Both the detailed structure and the DBB mechanism as well as t he results of measurements of the vibration characteristics are presen ted, showing the validity of using the DBB, especially in gravitationa l-wave experiments.