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Entry  Tue Feb 25 00:00:01 2014, rana, jenne, Update, LSC, reasons that the REFL signals may be degenerate now 
    Reply  Tue Feb 25 02:46:38 2014, rana, jenne, Update, LSC, Changing PRCL offset changes REFL 165 degeneracy PRC_offsetCheck_24Feb2014.pdf
       Reply  Tue Feb 25 14:48:49 2014, ericq, Update, LSC, Changing PRCL offset changes REFL 165 degeneracy MICHvPRCLangle_wOffset.pdfSBprclPeaks.pdf
          Reply  Tue Feb 25 16:07:33 2014, ericq, Update, LSC, Changing PRCL offset changes REFL 165 degeneracy MICHvPRCLangle_wOffset.pdfMICHvPRCLangle_wOffset_fullscale.pdf
             Reply  Wed Feb 26 01:49:08 2014, Jenne, Update, LSC, Changing PRCL offset changes REFL 165 degeneracy DemodPhaseSeparation.pdfPOP_AS_PDvalues.pdf
Message ID: 9669     Entry time: Tue Feb 25 02:46:38 2014     In reply to: 9668     Reply to this: 9670
Author: rana, jenne 
Type: Update 
Category: LSC 
Subject: Changing PRCL offset changes REFL 165 degeneracy 

[Jenne, Rana]

We put offsets in the PRCL and MICH loops, and measured sensing matrices for each condition. 

What we found was that PRCL offsets of order 1/20th a linewidth (calibration to be checked tomorrow) would give significant changes in the angles of the REFL signal sensing matrix elements.  We broke MICH lock before we were able to put in a significant enough offset to see the demod phases change.

Because there are so many plots, I've put them together in a pdf. Each page has a set of radar plots for sensing matrix elements.  On the bottom of each page I note what our MICH and PRCL offset values were, and where the data is saved (in the 40m scripts directory). To see the differences, make sure your pdf viewer is set to single-page, not scrolling.

PRC_offsetCheck_24Feb2014.pdf

One major thing that we noted was that putting in a PRCL offset also changed the MICH offset.  When we increased the PRCL offset, we saw the AS port get brighter (but not as bright as when we were putting in large MICH offsets). 

Tomorrow, I need to check the calibrations we were using, to see how many meters we were moving the optics.  Also, Q, Gabriele and I need to meditate and do some modelling to figure out why the length offset could be affecting the degeneracy so strongly. 

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