No abstract

We present performance measurements of a three-stage low-frequency vibration isolation chain which will form the low-frequency isolation part of an advanced isolator design developed for the Australian International Gravitational Observatory (AIGO). Each stage is a combination of a vertical Euler-spring stage and a self-damped pendulum. Experimental results demonstrate all horizontal normal modes including the fundamental pendulum mode to be strongly damped. Measurements below 10 Hz show vertical and horizontal performance close to theoretical expectations without extraneous normal mode peaks.