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Entry  Fri Oct 10 03:05:09 2014, ericq, Update, LSC, Which side of optical spring are we on? comparison.pdf
    Reply  Fri Oct 10 03:25:11 2014, Jenne, Update, LSC, Which side of optical spring are we on (simulation) 10x
    Reply  Mon Oct 13 12:01:28 2014, ericq, Update, LSC, Which side of optical spring are we on? AOInjection_SqrtInv_REFLDC.pngAOinjection_SqrtInv_REFLDC.xml.zip
       Reply  Mon Oct 13 21:20:56 2014, Jenne, Update, LSC, Which side of optical spring are we on? (No progress) 
          Reply  Mon Oct 13 21:59:47 2014, rana, Update, Computer Scripts / Programs, Which side of optical spring are we on? (No progress) 
             Reply  Tue Oct 14 17:38:31 2014, ericq, Update, Computer Scripts / Programs, Rossa and Allegra wiped, Ubuntu 12.04 installed 
                Reply  Tue Oct 14 23:44:42 2014, diego, Update, Computer Scripts / Programs, Rossa and Allegra wiped, Ubuntu 12.04 installed 
                   Reply  Wed Oct 15 17:18:10 2014, Jenne, Update, Computer Scripts / Programs, Dataviewer fix with Ubuntu 12.04 
          Reply  Wed Oct 15 02:58:03 2014, Jenne, Update, LSC, Which side of optical spring are we on?  PRFPMI_MC2injection_PosCARMoffset_REFLDC_TRX_response_14Oct2014_TRX.pdfPRFPMI_MC2injection_PosCARMoffset_REFLDC_TRX_response_14Oct2014_REFLDC.pdfPRFPMI_MC2injection_NegCARMoffset_REFLDC_TRX_response_14Oct2014_TRX.pdfPRFPMI_MC2injection_NegCARMoffset_REFLDC_TRX_response_14Oct2014_REFLDC.pdf
             Reply  Wed Oct 15 19:56:38 2014, Jenne, Update, LSC, Which side of optical spring are we on? Meas vs Model AntispringModel_NegOffsetMeas_comparison.pdfSpringModel_NegOffsetMeas_comparison.pdf
Message ID: 10594     Entry time: Fri Oct 10 03:05:09 2014     Reply to this: 10595   10598
Author: ericq 
Type: Update 
Category: LSC 
Subject: Which side of optical spring are we on? 

 I made some measurements to try and see if any difference could be seen with different CARM offset signs. 

Specifically, at various offsets, I used a spare DAC channel to drive IN1 of the CM board, as an "AO Exciter." I used CM_SLOW to monitor the signal that was actually on the board. I used the CARM_IN1 error signal to see how the optical plant responded to the AO excitation. Rather than a swept sine, I used a noise injection kind of TF measurement. 

Here are plots of CARM_IN1 / CM_SLOW at different CARM FM offsets; I chose to plot this in an attempt to divide out some of the common things like AA and delays and make the detuned CARM pole more evident). The offsets chosen correspond roughly to powers of 2, 2.5, and 3. I tried to go higher than that, but didn't remain locked for long enough to measure the TF. 

comparison.pdf

By eye, I don't see much of a difference. We can zpk fit the data, and see what happens. 

 

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