Naoki, Camilla.
After SQZ laser was turned on laser week, today we locked PMC and SHG with no issues. We struggled with OPO locking (CLF dual). In the end Naoki could lock by hand but the trigger wasn't triggering. We will continue to troubleshoot tomorrow. The OPO dither lock worked well but only after we swapped H1:SQZ-OPO_IR_LSC_SERVO_GAIN sign from -10 to 10: strange!
I put ZM4/5 PSAMS and ZM4/5/6, ZM2/3 and FC1 alignments back to the same values as in alog79193. Todays plot and July 17th plot attached. There was only around 0.3mW on the IR trans, when we expect 1mW. So may need some more alignment moved. We have the SQZT7 iris to help if needed.
CLF input power was lower than before. After I increased CLF input power, OPO can be locked by guardian.
After Camilla changed ZM2 PSAMS in 79625, we can see 1.3mW seed trans in SQZT7 with 75mW seed. However, seed dither lock did not work. It seems that the OPO PZT offset after scan by guardian does not match well with the seed resonance. I found that there is an intentional PZT offset for hysteresis in line 728 of OPO guardian as follows.
ezca['SQZ-OPO_SERVO_SLOWOUTOFS'] += 0.08 # hysteresis
I flipped the sign of this offset from 0.08 to -0.08 and the dither lock works. I am not sure if this is a correct way to fix this issue, but I tested the dither lock several times and all worked.
The dither lock gain needs to be reverted to -10.