camilla.compton@LIGO.ORG - posted 10:08, Thursday 14 August 2025 - last comment - 13:03, Thursday 14 August 2025(86361)
Mid SQZ Data for 5kHz HOM Spacing with ZM4 Yaw alignment changes
Sheila, Camilla
We saved H1:OMC-DCPD_524K_A2_IN1 data with the PD sum after Sheila changed the matrix as in 85937. DTT saved as
/ligo/home/camilla.compton/Documents/sqz/templates/dtt/20250814higher_order_modes.xml screenshot attached.Interestingly we could reduce the size of the 5kHz modes by changing ZM4 YAW alignment, at the nominal alignment and the alignment that reduced the 5kHz modes most, we also took mean sqz data, the nominal alignment had a slightly better mean SQZ.
Starting angle is (-)133, took SQZ_ANG SERVO to DOWN. After each step of ZM, we changed SQZ angle to get level back to 4dB ASQZ, as our 5kHz modes look clearest here.
To get mean sqz, pause SQZ_MANAGER, SQZ_LO_LR to DOWN and ADF off. Should have misaligned the FC but we didn't.
| Type | Time (UTC) | Angle | DTT Ref | Notes |
| SQZ | 15:54:00 - 15:59:00 | (-)133 | ref 0 | While taking CAL measurements |
| FDS Mid - SQZ | 16:01:30 - 16:04:00 | (-)105 | ref 1 | |
| FDS Mid SQZ, -50urad pit +3deg | 16:07:30 - 16:09:30 | (-)109 | ref 2 | |
| FDS Mid - SQZ | 16:10:30- 16:12:30 | (-)111 | ref 3 | Redid at 4dB ASQZ |
| FDS Mid SQZ, -50urad yaw | 16:14:30 - 16:16:30 | (-)114 | ref 4 | |
| FDS Mid SQZ, +50urad yaw | 16:17:45 - 16:19:45 | (-)109 | ref 5 | |
| FDS Mid SQZ, +100urad yaw | 16:21:30 - 16:23:30 | (-)106 | ref 6 | |
| FDS Mean SQZ, +100urad yaw | 16:26:00 - 16:28:00 | N/A | ref 7 | |
| FDS Mean SQZ, | 16:29:00 - 16:31:00 | N/A | ref 8 | |
|
No SQZ
|
16:37:00 - 16:57:00
|
N/A
|
ref 9
|
took 1500 avg (~10mins)
|
Took above data at NLG of 16.4, checked the NLG 76542, it's a lot better since we adjusted the pump alignment on Tuesday 86323. Then increased NLG to 37 to see if this will improve SQZ.
| OPO Setpoint | Amplified Max | Amplified Min | UnAmp | Dark | NLG | Note |
| 80 | 0.1121155 | 0.001849 | 0.0068192 | -1.16e-5 | 16.4 | Without Optimizing Temp |
| 90 | 0.257827 | 0.001813 | 37.7 |
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Sheila, Elenna, Camilla
Tested if SQZ was any better with the higher NLG, see attached, it wasn't although we did have good ASQZ of 19dB. We will revert OPO setpoint to 80uW
| Type | Time (UTC) | Angle | DTT Ref | SQZ |
|
No SQZ
|
16:37:00 - 16:57:00
|
N/A
|
ref 0
|
|
| ASQZ NLG 37 | 17:43:30-17:46:30 | (-)81 | ref 1, 10 | 19dB |
| SQZ NLG 37 | 17:51:00-17:54:00 | (-)141 | ref 2, 11 | -4.5dB |
Took more 5kHz/10kHz data with the NLG at 37 (effects of HOM easier to see). DTT saved as /ligo/home/camilla.compton/Documents/sqz/templates/dtt/20250814higher_order_modes.xml
In the first set of data, Elenna added an offset to DHARD, we didn't see a change at 5kHz but there was a change at 10kHz that was debatably repeatable.
In the second set of data, Sheila added an offset to SRCL1, we saw a big change at 5kHz but no change at 10kHz, see attached at 5kHz and 10kHz.
| Type | Time (UTC) | Angle | DTT Ref | Notes |
|
No SQZ
|
16:37:00 - 16:57:00
|
N/A
|
ref 0
|
|
| ASQZ NLG 37 | 17:43:30-17:46:30 | (-)81 | ref 1, 10 | |
| SQZ NLG 37 | 17:51:00-17:54:00 | (-)141 | ref 2, 11 | |
| Mid SQZ | 18:00:30 - 18:02:30 | (-)118 | ref 12 | |
| Mid SQZ +4cts DHARD PIT | 18:06:30 - 18:08:30 | (-)118 | ref 13 | Difference only at 10k? Repeat |
| Mid SQZ | 18:09:30 - 18:11:30 | (-)118 | ref 14 | |
| Mid SQZ +4cts DHARD PIT | 18:12:30 - 18:14:30 | (-)118 | ref 15 | |
| Mid SQZ -4cts DHARD PIT | 18:15:45- 18:17:45 | (-)118 | ref 16 | |
| Mid SQZ +4cts DHARD YAW | 18:19:30 - 18:21:30 | (-)118 | ref 17 | No difference seen |
| Mid SQZ SRM YAW 1urad (offset 0.3) | 18:28:00 - 18:30:00 | (-)120 | ref 18 | Big difference at 5kHz, none at 10kHz |
| Mid SQZ SRM YAW -1urad (offset -0.3) | 18:33:30 - 18:35:50 | (-)114 | ref 19 | Got better |
| Mid SQZ SRM YAW -2urad (offset -0.6) | 18:41:30 - 18:43:30 | (-)108 | ref 20 | Overshot, got worse, mode didn't flip |
| Mid SQZ SRM YAW -1.5urad (offset -0.45) | 18:46:30 - 18:48:30 | (-)108 | ref 21 | |
| Mid SQZ | 18:52:00 - 18:52:00 | (-)118 | ref 22 | Back to nominal |
Took OPO setpoint back to 80uW and remeasured NLG to be 22.4. It is interesting that before the SQZT0 pump alignment 86323 we had much worse NLG even with the same OPO trans setpoint and spot on the crystal. This doesn't make sense to us.
| OPO Setpoint | Amplified Max | Amplified Min | UnAmp | Dark | NLG | Note |
| 80 | 0.153078 | 0.002067 | 0.0068192 | -1.16e-5 | 22.4 | With Optimizing Temp |
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