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40m Log |
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Sat Sep 19 01:49:52 2020, Koji, Update, General, M4.5 EQ in LA
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Sat Sep 19 11:27:04 2020, rana, Update, General, M4.5 EQ in LA
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Sat Sep 19 18:08:34 2020, rana, Update, General, M4.5 EQ in LA
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Sat Sep 19 19:14:59 2020, Koji, Update, General, ITMX released / ETMY UR magnet knocked off
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Sun Sep 20 11:41:54 2020, gautam, Update, General, IMC re-locked
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Mon Sep 21 12:40:58 2020, gautam, Update, General, Workable IFO recovery 
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Message ID: 15590
Entry time: Mon Sep 21 12:40:58 2020
In reply to: 15585
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Author: |
gautam |
Type: |
Update |
Category: |
General |
Subject: |
Workable IFO recovery |
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See Attachment #1.
- The original ETMY actuation matrix was the naive one so I simply retuned everything by adding the butterfly mode appropriately.
- The cross coupling between the DOFs has not been characterized, but the local damping, Oplev loops, POX/POY locking, simpel Michelson locking, and ASS dither alignemnt all seem to work so I'm thinking this is good enough for now.
- A copy of the ETMYaux.db file was made, and the slow bias voltage was redistributed among the three available face OSEMs - note that the magnet polarity has to be taken into account.
- The series resistance on the slow path was reduced from 430 ohms, 1W to 100 ohms, 3W, to allow DC alignment of the cavity axis to the beam axis.
- Vertex Oplevs were re-centered on their respective QPDs after locking POX/POY and running the ASS dither alignment.
- The AS spot was a little low on the camera - presumably the SR2/SR3 got macroscopically misaligned. I re-centered the beam on the camera on the AS table (by moving the camera, the beam path was not disturbed).
The beam spot on ETMY looks weird (looks almost like a TEM10 mode), but the one on ITMY seems fine, see Attachment #2. Wonder what's going on there, maybe just a focusing problem?
Quote: |
We need a vent to fix the suspension, but until then what we can do is to redistribute the POS/PIT/YAW actuations to the three coils.
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