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40m Log |
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Tue Jun 12 02:07:42 2012, Jenne, Update, SUS, PRM oplevs left off
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Tue Jun 12 16:33:32 2012, steve, Update, SUS, PRM oplevs servo ON for confirmation
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Tue Jun 12 17:04:55 2012, steve, Update, SUS, PRM oplevs servo is still bad
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Tue Jul 10 17:47:55 2012, yuta, Update, SUS, PRM oplevs fixed  
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Mon Aug 6 07:59:33 2012, steve, Update, SUS, PRM oplevs servo is still bad
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Mon Aug 6 23:05:22 2012, Jenne, Update, SUS, PRM oplevs servo is fine
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Mon Oct 15 08:08:33 2012, steve, Update, SUS, PRM damping restored
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Message ID: 6952
Entry time: Tue Jul 10 17:47:55 2012
In reply to: 6805
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Author: |
yuta |
Type: |
Update |
Category: |
SUS |
Subject: |
PRM oplevs fixed |
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I centetered PRM oplev, lowered gain and PRM oplev servo is not oscillating any more.
It is OK for more than a softball practice.
C1:SUS-PRM_OLPIT_GAIN = 0.15 (was 0.5)
C1:SUS-PRM_OLYAW_GAIN = -0.3 (was 0.7)
Openloop transfer function:
Oplev Pitch: gain ~ 12 at 0.69 Hz resonance
Oplev Yaw: gain ~ 18 at 0.83 Hz resonance
 
I adjusted the gain so that oplev damps resonance as much as possible, but not introduce additional noise. I did no calculation, but just measured OSEM spectra (SUSPIT and SUSYAW). Below, you can see the noise reduces at resonance when oplev servo is on, and not increasing at other frequencies. It was introducing noise before. Someone should do more systematic adjustment of oplev servos for all the optics.

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