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| 40m Log |
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 Tue Dec 10 15:13:55 2013, Koji, Update, IOO, IMC servo inspection
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 Thu Dec 12 14:57:01 2013, Koji, Update, IOO, IMC servo inspection 
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Fri Dec 13 18:03:00 2013, Den, Update, IOO, common mode servo
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Fri Dec 13 23:07:04 2013, Koji, Update, IOO, common mode servo
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Sat Dec 14 11:56:54 2013, rana, Update, LSC, common mode servo
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Sat Dec 14 14:21:46 2013, Den, Update, LSC, common mode servo
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Message ID: 9472
Entry time: Sat Dec 14 11:56:54 2013
In reply to: 9468
Reply to this: 9474
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| Author: |
rana |
| Type: |
Update |
| Category: |
LSC |
| Subject: |
common mode servo |
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| Quote: |
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It seems to me that current design of the common mode servo is already fine. Attached plots show common mode open and closed loop transfer function.
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These seem like pretty terrible loop shapes. Can you give us a plot with the breakdown of several of the TFs and some .m file?
We should be able to estimate the noise coming out of the MC using the single arm and then make a guess for the CM loop gain requirement. There's no reason to keep the old Boost shapes; those were used in the old MC configuration which had a RefCav. In addition to minimizing the EOM range, we should also minimize the AO signal as Koji has pointed out. In practice, I've seen that using ~300 Hz of offset makes no harm with 4 kHz MC pole. |