Sheila, Ryan S, Jennie, Jenne, Control Room...
Ryan started with green initial alignment and got PRX locked 69467.
Sheila continued yesterdays work looking for signals in the REFL path. Could again get signal on ASC REFL B but not A. She measured PRX OLG, see attached, it's a bit below the reference.
Sheila reset the LSC POP A 45 dark offsets that are hard coded in ALIGN_IFO PREP XARM state.
Sheila set up some sine oscillations on PM1 and RM2 to try to find the beam on the POP diodes in HAM1.
Jennie/e and I then reset IM1,2,3,4 to a November time 2025/11/16 15:34:24 UTC (ndscope on cdsws44 had some issues with this yesterday). And then we walked IM3 and IM4 to get IM4_TRANS and ASC-POP_A back to this time which was quite different IM3/4 alignments. ASC-POP_B ended up not too far off. Plot of now and November attached. In particular, IM3 and IM4 PIT OSEMs are 200 and 400urad different than November.
Ryan and Jenne improved Xarm IR transmission via PR2.
Jennie, Jenne, Sheila, Daniel, Ryan S, Corey,
Summary: We can align the x-arm with IR but not get good signals on several of our HAM1 in-vac sensors, even after several rounds of RM, IM and PR mirrors moves.
We tried going back to the baffle align scripts and this brought us to a different X-arm alignment. In this new alignment we still could not see reasonable signals on LSC-POP_A PD (factor of 10 too small) or ASC-REFL_A and B (signals were a factor of 1000 too small). By 'reasonable' I mean compared to the level at our reference time of 15:32:00 UTC on November 16th. We chose this instead of the time on December 12th that we used as a reference in yesterday's locking efforts as it is before the site power outage which happened on December 4th.
Some things we ruled out:
- Moving PM1 around the whole range of pitch and yaw adjustment does not help us get signals on LSC-POP_A. So even if this somehow moved during the vent (since to reach JAC path optics one must lean over it) this makes that seem unlikely. The close out transfer functions for PM1 were also within nominal parameters so we think its unlikely the BOSEM swap out or any of the coil driver problem solving that happened for that suspension.
- HAM1 periscope that delivers the POP and ALS beams to HAM1. Since we can get good beat notes for ALS signals on ISCT1 it seems unlikely this moved during the vent when stiffeners were added to it.
- On the REFL side of the table (-Y) side. It seems weird that we can get good signals on LSC-REFL PD but not on the WFS (these are a factor of 1000 too small). These share most of the path from HAM3. Corey ran some injections on both RMs tonight which we can check in the morning to see if there is some alignment of them that makes ASC-REFL A and B signals go back to reasonable levels.
- Yesterday Jenne found if she mis-aligned PRM we could get reasonable signal levels on ASC-REFL_B. So we don't think it is an electronics issue.
- Just to double check - Jenne, Daniel and I went to the racks by ther PSL to check that the WFS electronics chassis were turned on. Everything looks good and Daniel checked the power connection to each box was not falling out.
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LSC rack r4, u37 holds the DC refl and pops wfs electronics, this seems fine and is powered.
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We also checked R1 and R2 racks that hold the RF and everything seems powered and plugged in.
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Daniel also checked that none of the HAM1/3 pico motors had been used since the vent started. This is pico controller A. The only use was earlier today when we tried to improve the pointing from hAM3 to the LSC POP diode but Sheila already undid this.
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Jenne also checked the uncontrolled degree of freedom in the mode cleaner (MC2 + MC3) by moving MC1 to its old position from November and letting the WFS move MC2 and MC3. This also did not help.
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I checked with Jim (who unlocked HAM1 HEPI earlier today) that HAM1 and 3 should not have moved since November. Both of these should be fine as HAM3 HEPI was never locked during the vent and HAM1 HEPI has not moved appreciably in the DOFs that would affect alignment.
In the afternoon we observed that with PRX fringing, we can see a signal on LSC POP A RF45 that is about 1/10 of what it was in this state in November. We saw that this amplitude did not change when we moved PM1 acros it's full acutation range. We used the PR2 spot move guardian state to keep PRX aligned while we moved PR3 by several microradians, and this also did not change the amplitude on LSC POP RF45. We then redid the baffle PD scripts, which resulted in ITM alignments different by 3-4urad at most, and realinged the vertex to those ITMs. This didn't change the situation of missing signals in the in vacuum pop or the REFL WFS. We do see that we have 3-4 counts on both REFL ASC sensors with 2W incident on PRM now, compared to 3-4 thousand counts in November.
These various efforts leave me thinking that the problem isn't an interferometer alingment problem, but could be an issue with the PDs or electronics, or alignment in HAM1.
We can see the expected light level on both LSC refl diodes for most of these alignments, and we can see clear signals in the POP air diodes, although we haven't aligned those and the signal levels seem a bit small compared to November. While we could proceed with locking with the reflair and popair diodes, we also need to figure out what is happening with the in vacuum diodes.