cheryl.vorvick@LIGO.ORG - posted 06:42, Friday 15 December 2017 (39774)
IO work 14 Dec 2017
- IMC flashing
- recovery of IM1 to IM2 beam path was not possible
- the reflected beam from IM1 is not centered on two apertures that have historically been centered, and the beam is noticeably miscentered on IM2
- moving IM1 within it's cage did not correct the beam path
- IM1 recentered (as close as possible to it's alignment at install in 2012) within it's cage did not correct the beam path
- verified beams on MC1, MC2, MC3, and MC3 Trans irises
- verified MC3 iris placement, measured to be 0.2mm off in Y direction from my images (iris base and ruler)
- options for cause:
- IM1 placement (explored, doesn't correct)
- IM1 changes with the bolt torque were 300urad and less, alog 38808
- beam path is wrong (current evidence shows the irises and beam are aligned as they were when IMC was last flashed)
- HAM3 refloated/rebalanced (this is the first time flashing the IMC since HAM3 was refloated/rebalanced)
- Hugh's alog 39453 indicates some change in alignment of HAM3
- I looked at the HAM3 ISI CPS changes, Nov. 14th (last flashing before HAM rebalanced) to now and see some changes
- for reference, at the beginning of the vent, the beam from the IMC made it through the IMs and IO faraday, with no IM alignment biases