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Entry  Mon Jan 12 18:11:25 2015, ericq, Update, ASC, Test Mass -> Transmon QPD TFs measured Jan12_singleArmSensing.pdfJan12_singleArmSensing.xml.zip
    Reply  Thu Jan 15 18:57:41 2015, ericq, Update, ASC, Transmon QPD loops live loopDesign.pdf
       Reply  Fri Jan 16 04:14:38 2015, ericq, Update, CDS, Unexpected CDS behavior digitalProblem.pdf
Message ID: 10886     Entry time: Mon Jan 12 18:11:25 2015     Reply to this: 10908
Author: ericq 
Type: Update 
Category: ASC 
Subject: Test Mass -> Transmon QPD TFs measured 

We want to have some angular control of the arms during lock acquistion. 

In single arm lock, Diego and I shook the TMs and measured how the QPDs responded. (I would've liked to do a swept sine in DTT, but the user envelope function still isnt' working!)

For now, we can close simple loops with QPD sensor and ITM actuator, but, as Rana pointed out to Diego and me today, this will drive some amount of the angular cavity degree of freedom that the QPD doesn't sense. So, ideally, we want to come up with the right combination of ITM and ETM motion that lies entirely within the DoF that the QPD senses.

I created a rudimentary loop for Yarm yaw, was able to get ~20Hz for the upper UGF, a few mHz for the lower, but it was starting to leak into the length error signal. Further tweaking will be neccesary...

Attachment 1: Jan12_singleArmSensing.pdf  80 kB  Uploaded Tue Jan 13 01:13:32 2015  | Hide | Hide all
Attachment 2: Jan12_singleArmSensing.xml.zip  72 kB  Uploaded Tue Jan 13 01:14:03 2015
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