MZ and GRMC

Lock was recovered with the nominal level of stabilized output power (power meter in transmission of GRMC says 26.5 mW green to OPO at 4.2 on the MZ offset dial, which is our usual setting).

I tried mode matching on each arm - 
PZT arm: 384 mV TEM00, 8 mV HOM, 96.9%
Non PZT arm: 364 mV TEMO00, 33.2 mV total HOMs, 91.6 %
 

After adjusting them together, then maximising the mode cleaner transmission using the MZ HVD offset (different control knob to the above), I get:
GRMC: 1.5 V TEM00, 68 mV HOMs, 95.76%
but one other time I got 720 mV, 72.4 HOMs, 90.9%
 

The power meter autoranging should be off. Maybe I am just a bit confused about the MZ scan. A bit of explanation for people not familiar, the MZ is not locked using PDH since it is not a cavity, rather it is just locked to some reference voltage controlled by MZ offset dial. When the LOCK switches are turned on, the GRMC scans across the free spectral range quickly and acquires lock first using the PDH sideband signal from GRMC reflection PD, then the MZ scans slowly and locks second using the signal from GRMC transmission PD to keep the transmitted green power at a stable level. Also, the interference condition of MZ using the HVD offset can be changed to reflect or transmit TEM00/HOM - we want it to transmit mostly TEM00 and reflect HOM into a rejected port. Anyway, I don't remember how slow is "slow" scan, but I don't think it should be causing the slow change of MZ mode matching on the timescale I saw. Either way, that is only an issue for measuring mode matching when not locked. The system locks and sends stabilized power to OPO so we can fix it later.

BAB to OPO

I recovered bright alignment beam mode matching to about the level it was during Yuhang's last visit, which is to say, ok but not great (~ 60%). I measured using power meter in transmission of OPO - it is quite hard to see the BAB transmission with OPO unlocked since it is injected from the HR side of the OPO, but there was a conveniently placed holder at just the right spot for the power meter. I tried to measure with homodyne but the IRMC started having some issue where it wouldn't lock to the correct point. We have been having issue with SHG and IRMC mutual lock ever since we switched to the single 88 MHz EOM to do all of the squeezer table modulations. We should decouple these two signals some time.

FC green lock

I turned on the FC length control servo inside the clean room and then tried to lock FC on green but was not successful.