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Entry  Wed Mar 10 00:32:03 2021, gautam, Update, LSC, PRFPMi PRMI3f_ALSsensMat.pdf
    Reply  Thu Mar 11 01:45:42 2021, gautam, Update, LSC, PRFPMi 
Message ID: 15892     Entry time: Wed Mar 10 00:32:03 2021     Reply to this: 15900
Author: gautam 
Type: Update 
Category: LSC 
Subject: PRFPMi 

The interferometer can nearly be locked again. I was unable to fully hand off control from ALS-->RF, I suspect I may be using the wrong sign on the AO path (or some such other sub-optimal CM board settings). I'll hook up the SR785 and take some TFs tomorrow, that should give more insight into what's what. With the arms held off resonance, the PRMI acquires lock nearly instantly (REFL165 I for PRCL, REFL165 Q for MICH), and can stay locked nearly indefinitely, which is what I need so I can get the RF lock going. However the sensing matrix (for vertex DoFs, arms held off resonance) still makes no sense to me. The MICH loop has ~50 Hz UGF and the PRCL loop ~150 Hz. I think the MICH loop shape can be optimized a little for better low frequency suppression, but this isn't the show-stopper at the moment. For record-keeping, the ALS performance was excellent and other subsystems were nominal tonight.

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