Reports until 13:10, Friday 24 July 2026
H1 AOS
sheila.dwyer@LIGO.ORG - posted 13:10, Friday 24 July 2026 - last comment - 16:57, Friday 24 July 2026(91235)
electronics problems time line

Summary:

JAC PZT outputs were turned off, this lead to hours of confusion.  It shows up in HAM1 suspensions because light was sparying all over HAM1.

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keita.kawabe@LIGO.ORG - 15:44, Friday 24 July 2026 (91244)

After turning the PSL PZT back on with the same offsets before, JM1 was brought back to the position right before the problem started according to OSEM.

This didn't bring back the beam on JAC REFL diode so I steered PZT until JAC REFL see some light, and refined from there.  In the end, JM1 didn't move that much

  before problem after recovery difference
H1:SUS-JM1_M1_DAMP_P_INMON -668 -680 -12
H1:SUS-JM1_M1_DAMP_Y_INMON -920 -917 +3
H1:SUS-JM1_M1_OPTICALIGN_P_OFFSET -537 -634 -97
H1:SUS-JM1_M1_OPTICALIGN_Y_OFFSET -1471 -1434 +37

JM1 OSEMs are drifting as I write this but it seems to be consistent with diurnal changes.

PZT output changed mostly in PIT, much larger than I expected from hysterisis. I don't know why but I leave it as is for now. Note that JAC-PZT_PIT_OFFSET and YAW_OFFSET  move the beam in PIT and YAW in JAC basis, in the PSL room coordinate it is YAW and PIT.

  before problem after recovery difference
H1:JAC-PZT_PIT_OFFSET 6407.5 2546 -3861.5
H1:JAC-PZT_YAW_OFFSET 26025 26605 +580

 

jennifer.wright@LIGO.ORG - 16:34, Friday 24 July 2026 (91245)

I looked at the time we had to re-align PZT offsets after the power cut last Thursday and this was a much smaller change:

about + 500 counts on PZT YAW ( 1.9 % increase) and +100 counts on PZT PITCH (1.5% increase).

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jennifer.wright@LIGO.ORG - 16:57, Friday 24 July 2026 (91246)OpsInfo

Jennie W

 

The offsets to the PZT were turned off because I turned off the ASC outputs on the JAC WFS screen and forgot that these were the buttons for the filter banks JAC-PZT_PIT_OFFSET and JAC_PZT_YAW_OFFSET that send static alignment offsets to the PZT mirror pre-periscope. It also is before the PD that the rotation stage uses for power adjustment and so that led to the rotation stage not taking us to the requested power.

 

I have now removed these output off/on buttons from the front of the JAC WFS MASTER screen. I have circled where they were in the medm screen. I left the buttons for the JM1 suspension as these do not control the DC alignment for the suspension, those are in the JM1 model itself.

 

In future I (and anyone else seeking to kill the JAC ASC outputs) should just turn the loop gain to 0 or turn the output from the JAC-DOF1_P, JAC_DOF1_Y, JAC-DOF2_P, JAC_DOF2_Y filter banks off.

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