Vicky, Jenne, Jennie W, TJ

Today we got the PSL beam back after the vent work and the new OMC has been installed so we tried to do some 'single bounce' mode scans of the OMC where we bounce the PSL beam off one ITM (in this case X).

We can see flashes in OMC transmission on the DCPDs.

The beam going into the OMC can be centred on ASC_AS_A,B WFS using the DC centering loops. Once this in done flashes can be seen on the DCPD_SUM_OUPUT meaning the cavity is going through some modes. Vicky also tried aligning the OMC and OM3 suspensions. After trying hand alignment, we realised that the OMC trans camera was not showing any flashes, despite seeing them on the PD.

According to Camilla it is perfectly possible this camera was not aligned to the OMC transmitted beam after the OMC swap, but it is plugged in.

As this would require laser hazard (and therefore WP) we proceeded with other efforts from the control room first.

We tried turning on the OMC ASC loops. This makes several of the ADCs on the OMC suspension output rail before the loops converge. They tried offloading the alignment onto the DC centering loops but the YAW degree of freedom in the ASC loops does not converge.

We also reset the offsets in the QPDs to the nominal ones used during the run and changed them till there was no offset at the output. When the servo is switched back on we expect the loops to drive the outputs to zero but the yaw degree of freedom still diverges away.

We reverted the OMC servo changes we made before leaving.

On Monday we will re-align the camera to check which modes we are aligning to and check more into the OMC loops to figure out what is going wrong.