This afternoon the rebalance of PSL power discarding has been performed by lowering the power sent to the PMC and increasing the transmission of IPC1 in order to keep the same power transmitted by IMC.

The power transmitted by the PMC has been reduced by roughly 18% by acting on the HWP/polarizers just upstream of the PSTAB AOM. We measured the beam profile coming out of the PMC before and after the power variation (results in a separate entry), and realigned the PMC by suing the steering mirrors after the AOM and before the PMC. This had the effect of improving the mismatch to the IMC cavity while delivering the same power from IMC.

Also, the reduced power sent into the AOM seemed to be beneficial to the PSTAB loop. We maanged to engage the PSTAB loop without seeing the glitches which wwere there during the past days - no gain tuning was deemed to be necessary at this moment.

Unfortunately, the drawback was that the IMC linear alignment works for the moment in drift control, a check of the working point and possibly the alignment matrix will be done as soon as possible. For the time being the engagement of full bandwidth linear alignment has been left commented in metatron.

The interferometer was locked up to carm_null_1f after the work, and left to the TCS measurements.