Reports until 17:37, Friday 22 November 2024
H1 SUS
jenne.driggers@LIGO.ORG - posted 17:37, Friday 22 November 2024 (81423)
TMSY slider or OSEM readbacks backwards

While the PSL team finishes up their work, I wanted to get a jump start on alignment, so I moved the ITMs, ETMs, and TMSs back to where their top mass OSEMs said that they were, the last time that we had good transmission for both ALSX and ALSY while trying to lock.  This indeed got somewhat okay flashes on both ALSs, so will be a fine place to start from, once the reference cavity is locked again.

However, I found that TMSY's pitch slider has a minus sign with respect to the OSEM readbacks for pitch.  This is the only slider (out of pit or yaw, for all 6 optics that affect ALS alignment for either arm) that seems to have this issue. 

In the attached screenshot, when I try to move the TMS up the OSEM readbacks say it went down, and vice versa. 

Not any kind of urgent matter, but may make it more challenging for ALS auto-alignment scripts to do their work.

Images attached to this report