J. Kissel, S. Dwyer, D. Sigg, E. Hall, N. Mavalvala After performing all of the usual alignment position checks (SUS, SEI, MC TRANs QPD, IM4 TRANS QPD), after the RCG 2.9 upgrade (see LHO aLOG 16040) we've confirmed that the IMC REFL path has jumped down in pitch again as it has done several times in the past after major computer reboots or SEI/SUS events (see Integration Issue 854, LHO aLOGs 10335, 11481, and 15650). We didn't preserve camera views prior to the reboot, and I didn't get the chance to capture an UNLOCKED camera view in which the REFL path was similarly low, but I attach the misaligned views after the RCG, then SEI and SUS recovery before realigning the path, and the realigned views after Evan, Sheila, and Nergis have realigned the whole path. We've also confirmed that the MC WS are running happily now as well. Note that the IMC REFL L RFPD and trigger PD are on different image planes and lens focal points than the MC WFSA and MC WFSB and MC REFL GIGE Camera (see D0902284), so it's to be expected that they're differently affected by a misalignment of the MC REFL path. In other words, the IMC LSC path is much less sensitive to misalignments than the IMC ASC path (which contains the MC REFL GIGE Camera View). Finally, for future reference, I attach a screenshot of all of the relevant camera views and screens I can for the IMCASC and surrounding sensors, with 2015-01-13_H1IMC_Status_ScreensandCamera.png
We added an iris to the IMC refl path on IOT2L, in front of the calcite polarizer, in the hopes that we can use this next time to recover the alignment.
Keita, Brett and I also noticed that HAM2 HEPI moved between before and after the bootfest, as can be seen both on the oplevs and the IPSs. (RY, which is pitch, was different by about 15 urad before and after the bootfest) We have restored HAM2 RY, but I didn't finish checking this for the rest of the chambers since the schnupp crew want the michelson locked for now. In the morning we will have to go through the rest of the chambers and redo the alignment procedure.
This isn't a big enough shift to explain why we had to realign on IOT2L earlier, but restoring this did bring the IM4 trans QPD back to almost the same position it was at before the bootfest.
