On Monday morning we started to investigate the possibility to change the input power towards the ITF with INJ (and the ITF ) locked. The idea is to check wether we can change the power on IPC1 keeping constant the other signals used by the injections loops to maintain the lock unperturbed.

In the first part of the shift, we re-tuned the working point of the injection. Indeed, we had to apply only minor changes, in particular we changed a bit the offsets of the AA galvo, the AA matrix was then recalculated accordingly (very similar to the previous though).

We also checked the OLTF of both IMC (fig. 1) and PSTAB (fig. 2) loops as references for the standard input power.

Then, we configured the remote connection to the other important IPC for the IMC_REFL and PSTAB photodiodes (used for the IMC ramp-auto trigger for the lock) and the IMC_REFL quadrant. BCP and RFC do not have remotely controllable IPC.

At the end of the shift, we also tried to change the power of the PSTAB photodiodes (on the suspended bench) by decreasing at the maximum the step and speed of the rotator, and with both RFC or SSFS locked, but in all the cases the Injection unlocked, probably due to an excess of frequency noise produced by the shaking of the dihedron.