Virgo Logbook

We realigned the beam by moving the last mirror on the PSL laser bench (LB_M14) (the misalignment was maybe caused to a drift of the entire laser bench). The beam is now better passing through the EOMs, and the IMC cavity has been realigned.
After the intervention we noticed that the reflection from the IMC cavity has a better shape (look at fig. 1 and 2) and we also obtained more power transmitted (third plot). We finally closed the loops and let the IMC cavity properly locked (last plot). There could be a side effect in the ITF locking sequence since we have now approximately 7% more light transmitted by the IMC cavity and thus injected in the ITF. To be checked by locking experts.