Catching up on issues since computer restarts, lvea temp drifts, and bringing SHG powers back to normal. IFO was lightly thermalizing its last 5kW in the course of these measurements, taken ~2.5-3 hours after reaching NLN. I think increasing generated SQZ levels from about 9 dB --> 14dB (NLG 4-->9) increased high-frequency squeezing by ~0.3-0.6dB.
- no sqz 1368329184 - 1368329794 (10 min)
- Took this time to reset our SQZ AS42 no-sqz offsets (had been reset last week in computer restarts), offload all our FC+SQZ ASC outputs to the ZM+FC slider P/Ys, and accepted all this in Observe.snap SDF. Also accepted SQZ-ASC_WFS_SWITCH = OFF in safe.snap SDF of ASCSQZIFO, hope this resolves LHO:69674 so computer restarts don't rail ZMs.
- re-inject sqz. First, I walked the ZM4 sliders from ZM4 P/Y = -900,900 to ZM4 P/Y = -120,-170, with SQZ-ASC running to keep ZM5/6 aligned. Updated slider values saved in SDF, both observe and safe .snaps.
- These were values I found from when we first opened gate values in Nov. 2022, when maybe the ZM4 --> ZM5 centering was more reasonable? Unsure, we can also try walking ZM4 around, to vary the beam spot over ZM5's surface, and see if anything happens. I had previously tried to offload ZM6 sliders to ZM4, not thinking about the beam spot on ZM5. I had already un-done this big offload 1-2 weeks ago, but last week's computer restarts reset them, so now I'm again bringing ZM4 sliders closer to in-chamber centered values. Recent LLO:64886 saw there was possibly a bad spot to hit ZM5.
- NLG = 3.9, Gen SQZ = 9.2 dB, same OPO TRANS as before, so same NLG uncertainties. Sqz levels below are measured using DTT cursors at 1.4kHz.
- anti-sqz ~ +6.7 dB at NLG = 3.9, Gen SQZ = 9.2 dB, 1368330725 (angle @ +276).
- sqz ~ -3.0 dB, 1368328338 (200s, angle @ +161 deg)
- turned up NLG = 9.7, Gen SQZ = 14 dB. Tuned OPO temp to maximize CLF_RF6_DEMOD_RFMON.
- asqz ~ +11.5 dB. 1368331155 - 1368331177 (angle @ +276)
- sqz ~ -3.4 dB sqz (angle @ +172.56 deg)
- Re-conciled SDF's so they can proceed to observing. See total trends of this time and the DTT here. More analysis of these sqz/asqz levels to come.
Lockloss a while after. While IFO was down, I re-aligned fiber polarizations given the recent LVEA temp drifts:
- opo pump fiber (OPO GRD 'LOCKED_CLF_DUAL_NO_ISS', minimize in-vac rejected power H1:SQZ-SHG_FIBR_REJECTED_DC_POWER)
- clf fiber (CLF GRD 'DOWN', maximize CLF_REFL_LF_OUT_DQ)
- fcgs fiber (doesn't matter GRD state, I minimized in-vac rejected power H1:SQZ-FC_FIBR_REJECTED_DC_POWER. This one was pretty close.)
Maybe sometime we can check the SQZ ASC gain / time constant and make sure it makes sense, since its outputs seem to move a lot very quickly? Also, since IFO was still thermalizing, if we have no-sqz time with a very thermalized IFO, it might be worth re-setting the AS42 no-sqz offsets again then.
