IFO is in LOCKING at FIND_IR
I got called at 03:11 AM because ALSY Guardian went into fault during initial alignment and stayed there for an hour at which point IFO Notify was triggered to call the OWL Ops. I couldn't see anything immediately wrong with Y-ARM other than it got itself into a weird state. Long story short, the ALSY IR DC Power is low, and around the threshold for ALSY guardian faulting.
I went into init to try another initial alignment but ALSY got into the same state. Upon further investigaiton, this was due to the ALS Guardian detecting an error in the locking relating to the ALS_Y_LASER_IR_DC. I noticed that ALSY would only fault if the power went below 4.5 mW, which I later realized to be on the boarder, fluctuating between "too low" and over 4.5. I set the threshold on the same page (attached pic) to 4.48 (lower by 0.02mW), which seems to have fixed the issue. I waited until ALS Locked in both INITIAL_ALIGNMENT and LOCKING_ARMS_GREEN to ensure that the fix worked. I waited a bit more and can confirm we can lock DRMI (we lost lock a few minutes thereafter though).
I have accepted and screenshoted the SDF corresponding to the power change in SAFE.SNAP just in case we lose lock on the way to NLN (since this gets reset with each LL). I will likely get called again and need to accept the SDF in OBSERVE later, though that may be during DAY OPS time. Other screenshots have been attached, including the screen where I made the power threshold change. I've re-set my OWL and will stay logged in to expect a call for potential SDF confirmation.
Accepted ALSY IR DC Power Change in OBSERVE (attached). H1 is now OBSERVING.
Ryan Short, Sheila
Last November the power out of this laser dropped 13% after the current was reduced to get it operating in a more stable region during the PSL NPRO difficulties, 81117. Daniel lowered some thresholds and raised some gains at the time, but not the ALS Y LASER IR threshold. It has been close to the limit since but only drifted below last night, due to it's normal long slow drift. I've lowered the threshold to 4 mW now, so that we have a similar level of headroom for this error as we did before the laser current drop. I've accepted this in safe.snap but not in observe
Ryan Short also has been looking at some of our other ALS locking problems. He noticed that sometimes the ALS PLL beckhoff gives an error based on the reference cavity transmission. This is leftover from when the ALS pick off was in transmission of the reference cavity, but it has been moved so this error check isn't helpful anymore. We've set the threshold to -1 for ALS X and Y H1:ALS-Y_FIBR_LOCK_REFCAV_TRANSLIM, and also accepted these in safe.snap, but not observe.
