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Entry  Wed May 30 15:51:22 2012, yuta, Update, IOO, MC beam spot oscillation specMC3_onoff_localdamping.pdf
    Reply  Wed May 30 19:27:38 2012, yuta, Update, IOO, MC beam spot oscillation 
       Reply  Wed May 30 20:12:15 2012, rana, Update, IOO, MC beam spot oscillation 
          Reply  Thu May 31 10:31:19 2012, Jamie, Update, IOO, MC beam spot oscillation 
Message ID: 6718     Entry time: Wed May 30 19:27:38 2012     In reply to: 6715     Reply to this: 6719
Author: yuta 
Type: Update 
Category: IOO 
Subject: MC beam spot oscillation 

[Koji, Yuta]

We found that C1:SUS-MC{1,2,3}_TO_COIL_3_4_GAIN was somehow changed to -1, and feedback signal for SIDE was fedback to LLCOIL, which is apparently not correct.
We checked the snapshots on May 25 and confirmed that it was used to be 0, so we fixed it.
We suspect that it happened during the beam spot measurement, because the measurement changes the TO_COIL matrix gains.

Now, we don't see any MC beam spot oscillation.

Quote:

[Koji, Suresh, Jenne, Yuta]

Background:
  We noticed that the beam spots on MC mirrors are oscillating in ~ 1 Hz yesterday. It means MC mirrors are actually oscillating. This was observable even if the WFS servo is off.

 

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