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Entry  Fri Apr 12 02:56:34 2013, Den, Update, Locking, prcl angular motion pointing.pngoplev_exc.pdf
    Reply  Fri Apr 12 09:20:32 2013, rana, Update, Locking, prcl angular motion 
       Reply  Fri Apr 12 13:21:34 2013, Den, Update, Locking, prcl angular motion 
          Reply  Sat Apr 13 03:45:51 2013, rana, Update, Locking, prcl angular motion 
             Reply  Sat Apr 13 23:11:04 2013, Den, Update, Locking, prcl angular motion pointing.pdf
                Reply  Sun Apr 14 17:56:03 2013, rana, Update, Locking, prcl angular motion 
                Reply  Mon May 13 18:44:04 2013, Jenne, Update, Locking, prcl angular motion TT_Q_measurements.pdf
Message ID: 8451     Entry time: Sat Apr 13 23:11:04 2013     In reply to: 8450     Reply to this: 8454   8564
Author: Den 
Type: Update 
Category: Locking 
Subject: prcl angular motion 

Quote:

For the PRM, it is also a mostly translation effect as calculated at the PRC waist position (ITM face).

I made another estimation assuming that PRCL RIN is caused by translation of the cavity axis:

  • calibrated RIN to translation, beam waist = 4mm
  • measured PRM yaw motion using oplev
  • estimated PR3 TT yaw motion: measured BS yaw spectrum with oplev OFF, divided it by pendulum TF with f0=0.9 Hz, Q=100 (BS TF), multiplied it by pendulum TF with f0 = 1.5 Hz, Q = 2 (TT TF with eddy current damping), accounted for BS local damping that reduces Q down to 10.

PRM and TT angular motion to cavity axis translation I estimated as 0.11 mm/urad and 0.22 mm/urad assuming that TTs are flat. We can make a more detailed analysis to account for curvature.

I think beam motion is caused by PR3 and PR2 TT angular motion. I guess yaw motion is larger because horizontal g-factor is closer to unity then vertical.

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