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Entry  Thu Feb 28 02:43:49 2013, yuta, Update, LSC, some qualitative evidence of PRMI sideband lock PRMIsideband.png
    Reply  Thu Feb 28 03:25:27 2013, yuta, Update, LSC, PR gain ~ 25 from PRMI carrier lock PRMIcarrier.png
       Reply  Thu Feb 28 03:41:31 2013, Koji, Update, LSC, PR gain ~ 25 from PRMI carrier lock 
       Reply  Sat Mar 2 05:53:15 2013, yuta, Update, LSC, stable lock of PRMI LSCMICHOLTF_PRMI.pngLSCPRCLOLTF_PRMI.pngPRMtoAS55REFL55.png
          Reply  Sat Mar 2 14:52:02 2013, rana, Update, LSC, stable lock of PRMI 
             Reply  Sun Mar 3 22:16:46 2013, Jenne, Update, LSC, LSC whitening triggering started 
                Reply  Mon Mar 4 09:55:33 2013, rana, Update, LSC, LSC whitening triggering started 
                Reply  Tue Mar 5 18:36:27 2013, Jenne, Update, LSC, LSC whitening triggering started 
Message ID: 8196     Entry time: Thu Feb 28 02:43:49 2013     Reply to this: 8197
Author: yuta 
Type: Update 
Category: LSC 
Subject: some qualitative evidence of PRMI sideband lock 

[Manasa, Yuta]

Since we have setup POP22 PD now(elog #8192), we could confirm that sideband power builds up when PRMI is sideband locked.

Plot:
  Here's some plot of PRC intra-cavity powers and MICH,PRCL error signals. As you can see from POP22, we locked at the peak of 11MHz sideband. There was oscillation at ~500 Hz, but we couldn't optimize the gain yet.
PRMIsideband.png


Movie:
  Here's 30 sec movie of AS, POP, REFL when acquiring (and losing) PRMI sideband lock. It was pretty hard to take a movie because it locks pretty seldom (~1 lock / 10 min).



Locking details:
  For MICH lock, we used ITMs instead of BS for reducing coupling between PRCL.
  Also, AS55 phase rotation angle was coarsely optimized by minimizing MICH signal in I.
  For PRCL lock, we used REFL55_I_ERR instead of REFL33_I_ERR. It had better PDH signal and we coarsely optimized phase rotation angle by minimizing PRCL PDH signal in Q.

 == PRMI sideband ==
  MICH: AS55_Q_ERR, AS55_PHASE_R = -12 deg,  MICH_GAIN = -0.1, feedback to ITMX(-1),ITMY(+1)
  PRCL: REFL55_I_ERR, REFL55_PHASE_R = 70 deg, PRCL_GAIN = -15, feedback to PRM

  We set POP22_PHASE_R = -170 deg by minimizing Q.

Issues:
 - We tried to use REFL55_Q_ERR to lock MICH, but couldn't. It looks like REFL error signals are bad.
 - We tried to use POP22_I_ERR to trigger PRCL lock, but it didn't work.

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