Yesterday evening the laser was shut down due to a lid violation error. During the attempt to install the rf-summation box inside the 35W front-end box, we had made a mistake in the activation of the lid-overwrite, which is required to safely open the FE box. As we did not completely understood what happened we decided to leave the laser in the off state overnight.
Today the laser was restarted and run the full day without any problems. The currents of the HPL diode boxes were adjusted to the following values:
DB1: 50.5A
DB2: 49.1A
DB3: 48.9A
DB4: 49.2A

We installed and tested the water flow sensors for the water cooled power meters. All three flow sensors were set to switch at 1.5 l/min. If the flow is too low , the shutter of the high power lasers is automatically closed. With this system in place we can now operate the PMC overnight.

We continued to work on the beam path from the PMC pickoff port to the reference cavity. With the PMC transmitting 142W at the IO interface we get 387mW in the FSS beam path (measured directly infront of the FSS-AOM). The AOM is aligned to a double path efficiency of 59% such that 225mW are measured directly after the PBS downstream of the double passed AOM. (VCO_MOD_LEVEL 32000 in FSS MEDM screen, all power levels measure with an OPHIR 10A-V2-SH power head). A WinCam scan of the single path pattern is attached. The modematching was adjusted to give a 75% dip in the reflected light while scanning over the TEM00 mode of the cavity. The transmitted peak of the largest higher order mode has about 10% of the peak heigth of the TEM00.