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Entry  Wed Apr 24 00:42:07 2013, Jenne, Update, SUS, PRMI locked, ITMX pitch OpLev ringing up PRMI_locked_ITMXpitOpLevRingingUp.pdf
    Reply  Wed Apr 24 00:44:33 2013, Koji, Update, SUS, PRMI locked, ITMX pitch OpLev ringing up 
Message ID: 8481     Entry time: Wed Apr 24 00:42:07 2013     Reply to this: 8482
Author: Jenne 
Type: Update 
Category: SUS 
Subject: PRMI locked, ITMX pitch OpLev ringing up 

Koji is working on PRMI locking, and while he was doing that I glanced at the oplevs' spectra for the ITMs and PRM.

I found that when the PRMI was locked (for only 1 second or so max lock time) on the 55MHz sideband, and the error signals show a big peak around 400Hz (definitely audible in the control room), the only OpLev that I see a similar peak in is ITMX pitch. 

In the plot below, I have grabbed a time when the PRMI was flashing as the black reference traces, and then a time when the PRMI was locked as the active traces.  You can see that there is a similar peak in both REFL55I and ITMX_OL_PIT when the cavity is locked. 

PRMI_locked_ITMXpitOpLevRingingUp.pdf

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