This optical bench houses photodiodes and cameras used to control the interferometer and to detect passing gravitational waves. Lenses and mirrors are used to guide the laser beam to the sensors. The Advanced Virgo benches are suspended to an attenuator and placed in vacuum in order to isolate them from vibrations from the ground and from environmental sounds. In this picture, a researcher is closing the "hat" of the vacuum enclosure. where the attenuation system can be seen.
Credits: Cyril Frésillon/Virgo/Photothèque CNRS