Ibrahim, Elenna

In summary, we can make it to CARM to REFL!

Here are some notes about recovering lock. I am bolding the ones that I think are urgent/should be read by anybody who next attempts to lock this IFO.

• Before we even started this process, I set all DRMI and PRMI ASC to false except MICH ASC.
• Locking green arms is a very "smooth" process (read: ALSY sucks a normal amount)
• Locking ALS proceeded without any hitch, as well as the find and check IR states.
• I first had problems with acquiring DRMI, even though at first glance the POPAIR flashes looked good. I tried PRMI, with good flashes, still no luck. I eventually had to go through MICH fringes, even though we had just run a successful initial alignment.
• Any state where the power needs to change requires manualing in one or more guardians- the laser power guardian stalls because it gets stuck in some "10W idle" state.
  • This is likely due to miscalibration in the rotation stage. If you get stuck, just manual to the power you need!
• After MICH fringes I went back to PRMI, and moved the PRM endlessly with no luck until I nudged the beamsplitter and everything immediately locked. Puzzling, because we had run at least two different MICH alignments at this point.
• Even with PRC1 disabled in PRMI ASC, the guardian still runs WFS centering on ALL WFS, which means it will error because the WFS centering isn't working well on the REFL WFS right now. I again had to manual around the WFS centering stage so it could offload MICH alignment.
  • this ended up being an SDF error which I fixed, see further notes
• Manualing around in ISC_DRMI seemed to stall things out, and since I was playing fast and loose with the guardian, caused a lockloss when I clicked "init" (I was trying to remanage guardians).
• Next lock went fine and I went straight to DRMI lock. (no need for PRMI or MICH fringes)
• when DRMI caught lock, the AS AIR camera started shaking. Ibrahim saw that it was the beamsplitter, specifically F2 and F3 osems seemed to briefly saturate. I averted this problem by turning the LSC MICH gain down by 10% (MICH2 gain from 1 to 0.9).
• Guardian got stuck in acquire DRMI 1f because the WFS centering on REFL failed again. I manualed over again to avoid it.
• Everything proceeded very well, the alignment looked great, I ran all the way to "CARM to REFL" and something started shaking.
  • At lockloss, there was a beamsplitter saturation warning, so I think something is funky in either the MICH LSC or ASC loop.
• Next two lock attempts still required reduction of MICH LSC gain to get through DRMI.
• However, through the CARM offset reduction, Ibrahim and I could see a small oscillation in POP90. It seemed to go away when I put the LSC MICH gain back up to nominal. However, still a lockloss at CARM to REFL, but much faster this time.
• The FSS got stuck in an oscillation again and I toggled the autolock to get out of it.
• The WFS centering keeps saturating the RMs and I am not sure why. I tried to move the RMs to center on REFL A and B but got saturation warnings as I got the beam closer to center on the diodes.
  • This turned out to be because the input matrix values were flipped! Keita had changed the DC1 and DC2 input matrix values about two weeks ago, since REFL A and REFL B had been flipped in the electronics.
  • However, it appears this was never SDFed, and got reverted. Once I re-flipped the matrix, the WFS centering worked perfectly. SDF screenshot attached
• When relocking DRMI after I fixed the WFS centering problem, there was no more MICH LSC oscillation. The reason for this is not immediately obvious to me, since the WFS centering only effects the REFL WFS (not in loop at this time)
• One more time, I tried going through CARM to REFL. I stepped through the state by hand and found that the lockloss occurs at the last step, where the input matrix is loaded
  • # Transition between TRXY and REFLAIR

    ISC_library.intrix['REFLBIAS', 'TR_REFL9'] = 2.0 #put back from 3.0 to 2.0 on 09/10/2018

    ISC_library.intrix['REFLBIAS', 'TR_CARM'] = 0.0

    ezca['LSC-PD_DOF_MTRX_TRAMP'] = 0.2

    time.sleep(0.1)

    ISC_library.intrix.load()