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Entry  Tue May 12 17:26:56 2009, pete, Update, oplevs, etmy oplev quad was bad bad_oplev_quad.pdf
    Reply  Wed May 13 03:05:13 2009, pete, Update, oplevs, etmy oplev quad was bad 
Message ID: 1580     Entry time: Wed May 13 03:05:13 2009     In reply to: 1578
Author: pete 
Type: Update 
Category: oplevs 
Subject: etmy oplev quad was bad 


Pete, Rob

After looking at some oplev noise spectra in DTT, we discovered that the ETMY quad (serial number 115)  was noisy.  Particularly, in the XX_OUT and XX_IN1 channels, quadrants 2 (by a bit more than an order of magnitude over the ETMX ref) and 4 (by a bit less than an order of mag).  We went out and looked at the signals coming out of the oplev interface board; again, channels 2 and 4 were noise compared to 1 and 3 by about these same amounts.  I popped in the ETMX quad and everything looked fine.  I put the ETMX quad back at ETMX, and popped in Steve's scatterometer quad (serial number 121 or possibly 151, it's not terribly legible), and it looks fine.  We zeroed via the offsets in the control room, and I went out and centered both the ETMX and ETMY quads. 

Attached is a plot.  The reference curves are with the faulty quad (115).  The others are with the 121.


 I adjusted the ETMY quad gains up by a factor of 10 so that the SUM is similar to what it was before.

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