sheila.dwyer@LIGO.ORG - posted 12:59, Monday 13 April 2026 (89875)
comparison of FC1, SRM, SR3 changes when mega cleanroom turned on and off
This is a follow up on the FC1 alingment confusion described in 89751 (also FRS ticket 37555).
I compared what happened to FC1 and FC2 during the mega cleanroom temperature swings.
The vertical shift is seen just about equally from the three top mass osesms on FC1, consistent with the blade springs getting warmer, not an individual osem problem. At this time both HAM5 + HAM7 were under vacuum.
| FC1 | SRM | SR3 | |
| M1 V | -34 um | -48 um | -23 um |
| M1 P | -160 urad | +114 urad | -8 urad |
| M3 P | +48 urad | +76 urad | less than 2 urad |
Images attached to this report
