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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: 8446     Entry time: Fri Apr 12 02:56:34 2013     Reply to this: 8447
Author: Den 
Type: Update 
Category: Locking 
Subject: prcl angular motion 

I compared PCRL and XARM angular motions by misaligning the cavities and measuring power RIN. Divergence angles for both cavities I calculated to be 100 urad.

XARM pointing noise sums from input steering TTs, PR2 and PR3 TTs, BS, ITMX, ETMY.

PRCL noise - from input TT, PRM, PR2 and PR3 TT, BS, ITMX, ITMY.

I would expect these noises to be the same as angular motion of different optics measured by oplves is simular. We do not have oplves on TT but they are present in both passes.

I measured RIN and converted to angle. Sharp 1 Hz resonance at XARM pointing spectrum is due to EMTX, it is not seen by PRCL. Other then that XARM is much quiter, especially at 3 - 30 Hz.

As PRM  is the main difference in two passes, I checked its spectrum. When PRCL was locked I excited PRM in pitch and yaw. I could see this excitation at RIN only when the peak was 100 times higher then background seismic noise measured by oplev.

pointing.png

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