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Entry  Fri Jul 24 21:02:46 2009, Alberto, Update, PSL, Aligning the beam to the Faraday 
    Reply  Sat Jul 25 16:04:32 2009, rob, Update, PSL, Aligning the beam to the Faraday 
       Reply  Sat Jul 25 19:04:01 2009, Koji, Update, PSL, Aligning the beam to the Faraday MC2_Cam.jpg
          Reply  Sun Jul 26 13:19:54 2009, rana, Update, PSL, Aligning the mode cleaner Untitled.png
             Reply  Sun Jul 26 16:05:17 2009, Alberto, Update, PSL, Aligning the mode cleaner 
             Reply  Mon Jul 27 09:34:07 2009, steve, Summary, IOO, Aligning the mode cleaner 20dtrend.jpg
Message ID: 1791     Entry time: Sat Jul 25 16:04:32 2009     In reply to: 1788     Reply to this: 1792
Author: rob 
Type: Update 
Category: PSL 
Subject: Aligning the beam to the Faraday 

Quote:

When I turned them on, the control signal in Pitch from WFS2 started going up with no stop. It was like the integrator in the loop was fed with a DC bias. The effect of that was to misalign the MC cavity from the good state in which it was with the only length control on (that is, transmission ~2.7, reflection ~ 0.4).

I don't know why that is happening. To exclude that it was due to a computer problem I first burtrestored C1IOO to July the 18th, but since that did not help, I even restarted it. Also that didn't solve the problem.

 

 

At least one problem is the mis-centering of the resonant spot on MC2, which can be viewed with the video monitors.  It's very far from the center of the optic, which causes length-to-angle coupling that makes the mulitple servos which actuate on MC2 (MCL, WFS, local damping) fight each other and go unstable.

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