Control of the double pendulum optics suspension system of a 30 m triangular Fabry-Pérot cavity
Résumé
We present a technique for the control of a double pendulum suspension system used to carry the optical elements of a 30 m long Fabry-Pérot cavity, a prototype for the mode cleaner of the VIRGO experiment. The movement of the payload is sensed with a charge coupled device camera, and the feedback forces are applied to the intermediate stage of the suspension via coil-magnet systems. The control strategy is explained and the application of the system for the longitudinal locking of the cavity is demonstrated.