Sheila, Camilla
As we were re-locking before commissioning time, we paused with ISC_LOCK in IDLE to check the alignment of SQZ and the IFO on AS_C.
Changed SQZ alignment, unsure if better or worse until we lock.
Checking SQZ:
- Single bounce ITMX, OM centering loops on and frozen (turn off inputs)
- Increased SEED injected power from 0.2mW to 76mW (same as April 16th 19:19UTC as in 77518 and 77518 plot)
- SQZ Manager LOCKED SEED DITHER
- ALIGN SRM, misaligned ITMs
- Previously injecting 1.28mW into HAM6 (OPO_IR_PD_LF with BeamDiv closed), now 1.25mW to 1.29mW, so similar power to before.
- Started with ~360 on AS_C NSUM
- Kept centered on AS_C with ZM4 while moving ZM5 to increase power on AS_C.
- Power was fluctuating a lot and it seems like we were mainly on a plateau.
- Accepted new alignments (scattering in IFO will tell us if they are better or worse, hard to tell if AS_C power really increased), attached in two sdfs, mainly pitch move then yaw.
- Got peaks of 384 on AS_C_SUM, average was 370 (want 380). Still loosing 2-3% from what’s expected.
- Similar power on AS_A and AS_B ~75.
- Plot attached.
Checking IFO:
- Single bounce ITMX 10W in, previously had 762e-2 on AS_C_NSUM. Today had 750e-2.
- With similar power into IMC 9.60W today, 9.61W prevoiulsy.
- Sheila checked the alignment sliders, we are ~15urad off in SR2 PIT witness channel. Everything else looks good (DC centering not on at time). Plot attached.
- Didn't change IFO alignment, started locking.