TRIPLE-PENDULUM VIBRATION ISOLATION SYSTEM FOR A LASER INTERFEROMETER

We have developed a triple-pendulum vibration isolation system for sus pended mirrors used in a laser interferometer for gravitational wave d etection. Owing to the passive damping method using high-performance p ermanent magnets, the system has a very simple, compact structure. We measured the isolation ratio for vibration below 40 Hz and confirmed t hat the observed and calculated values are in good agreement. The stab ility of the system has been demonstrated by operating a Michelson las er interferometer incorporated with a mirror mounted on the vibration isolation system.