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40m Log |
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Tue Apr 19 18:10:10 2022, Paco, Update, BHD, Part V of BHR upgrade - POX11 path, LO path, and ITMX Oplev  
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Wed Apr 20 08:20:22 2022, Paco, Update, BHD, Part V of BHR upgrade - PR2 weirdness
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Wed Apr 20 18:50:03 2022, Koji, Update, BHD, Part V of BHR upgrade - PR2 weirdness
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Thu Apr 21 16:49:01 2022, Paco, Update, BHD, Part V of BHR upgrade - BS Oplev + LO1 offset
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Thu Apr 21 18:42:47 2022, Tega, Update, BHD, Part V of BHR upgrade - Align LO and AS beams to BHD BS
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Thu Apr 21 20:33:31 2022, Koji, Update, BHD, AS1 UR OSEM problem localized in the chamber
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Fri Apr 22 12:03:09 2022, Tega, Update, BHD, AS1 UR OSEM problem localized in the chamber
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Fri Apr 22 12:15:08 2022, Anchal, Update, BHD, Cable post installation
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Mon Apr 25 16:57:57 2022, Anchal, Update, BHD, Cable post installation
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Message ID: 16789
Entry time: Wed Apr 20 08:20:22 2022
In reply to: 16788
Reply to this: 16792
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Author: |
Paco |
Type: |
Update |
Category: |
BHD |
Subject: |
Part V of BHR upgrade - PR2 weirdness |
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Yesterday, I tried tuning the PR2 damping gains by increasing the gain until the damping gave the ~5 oscillations (by watching the damped motion using StripTool, and keeping an eye on the PD var). I noticed that often when I changed the gain, some OSEM sensors shifted (gained an offset!!) and the PD var values changed, typically increasing at higher damping gains. I reverted the changes until the PD var looked "normal" again (~ 2 mV) but it is hard to imagine that the damping filters can have such a "DC" effect, given the shape comprises single zero at 0 Hz (and pole at 30 Hz). |