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40m Log |
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Tue May 3 21:05:23 2022, yuta, Update, BHD, AS path alignment, removing a lot of green stuff 7x
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Wed May 4 13:09:42 2022, Anchal, Update, BHD, IMC table balanced again, IMC is locking, YARM is locking
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Wed May 4 15:08:59 2022, Tega, Update, BHD, XARM alignment to get flashing
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Wed May 4 18:52:43 2022, Tega, Update, BHD, POP beam too high at POP SM4 on the ITMX chamber
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Thu May 5 14:46:22 2022, Anchal, Update, BHD, POP beam height lowered, POP_SM4 raised
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Thu May 5 17:05:31 2022, Tega, Update, BHD, IMC & X/Y-arm alignment
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Mon May 9 18:43:03 2022, Anchal, Update, BHD, ITMX table layout corrected
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Mon May 9 18:49:05 2022, Tega, Update, BHD, Relocate green TRX and TRY PDs/cams/optics from PSL table to BS table 
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Tue May 10 15:46:38 2022, JC, Update, BHD, Relocate green TRX and TRY components from PSL table to BS table 
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Tue May 10 18:25:43 2022, Paco, Update, BHD, Green Transmission path
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Tue May 10 16:31:14 2022, Tega, Update, BHD, ITMX optlev return beam steered to QPD
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Fri May 6 13:48:34 2022, Anchal, Update, BHD, WFS loop instability fixed
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Thu May 12 19:55:01 2022, Tega, Update, BHD, AS path alignment 
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Thu May 12 20:11:18 2022, Anchal, Update, BHD, BHDBS Output beams steered out to ITMY table
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Thu May 12 20:24:29 2022, yuta, Update, BHD, POX and POY investigation
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Mon May 16 13:22:59 2022, yuta, Update, BHD, REFL and AS paths aligned at AP table 
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Mon May 16 19:14:17 2022, Anchal, Update, BHD, Camera set on AS path and BHDBS output path
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Tue May 17 18:43:38 2022, Anchal, Update, BHD, Placed SRM in ITMY Chamber
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Wed May 18 08:30:29 2022, Paco, Update, BHD, SRM OpLev
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Thu May 19 08:51:40 2022, Paco, Update, BHD, SRM OpLev
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Wed May 18 09:02:52 2022, Anchal, Update, BHD, WFS1 PD centered
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Wed May 18 17:23:15 2022, Anchal, Update, BHD, Placed PRM in BS Chamber
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Thu May 19 18:56:08 2022, yuta, Update, BHD, Current OSEM sensor values with all the suspensions aligned
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Thu May 19 19:05:59 2022, Anchal, Update, BHD, BS Chamber all work finished, BHD path setup
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Fri May 20 20:03:48 2022, Paco, Update, BHD, ITMY chamber work finished - LO and AS overlapped 
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Mon May 23 13:16:59 2022, Paco, Update, BHD, End of vent - checks  
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Tue May 24 15:21:13 2022, Anchal, Update, BHD, Freeswing tests of new SOS started
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Message ID: 16831
Entry time: Wed May 4 18:52:43 2022
In reply to: 16830
Reply to this: 16832
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Author: |
Tega |
Type: |
Update |
Category: |
BHD |
Subject: |
POP beam too high at POP SM4 on the ITMX chamber |
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[Yuta, Tega]
We needed to sort out the POXDC signal so we could work on X-arm alignment. Given that POXDC channel value was approx 6 compared to POYDC value of approx. 180, we decided to open the ITMX chamber to see if we could improve the situation. We worked on the alignment of POX beam but could not improve the DC level which suggests that this was already optimized for. As an aside, we also noticed some stray IR beam from the BS chamber, just above the POX beam which we cold not identify.
Next we moved on to the POP beam alignment, where we noticed that the beam level on LO1 and POP_SM4 was a bit on the high side. Basically, the beam was completely missing the 1" POP_SM4 mirror and was close to the top edge of LO1. So we changed TT2 pitch value from 0.0143 to -0.2357 in order to move the beam position on POP_SM4 mirror. This changed the input alignment, so we compensated using PR2 (0.0 -> 49.0) and PR3 (-5976.560 -> -5689.800). This did not get back the alignment as anticipated, so we moved ITMY pitch from 0.9297 to 0.9107. All of these alignment changes moved the POP beam down by approx 1/5 of an inch from outside the mirro to the edge of POP_SM4 mirror, where about half of the beam is clipped.
Next Steps:
We need to repeat these aligment procedures with say 1.5 time the change in TT2 pitch to center the beam on POP_SM4 mirror. |
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