J. Kissel, L. Dartez

I'm attaching a plot of the DARM UGF that compares two measurements taken ~3.5 months apart. The blue trace is taken from the calibration sweep that Ryan C. took a few days ago (LHO:72392) and the orange trace is from a similar sweep taken back in May (20230506T170817Z). 

The DARM loop UGF has moved from ~58Hz to ~66.4Hz and the phase margin has increased by about a degree since May. 

There is no immediate need to adjust the DARM open loop gain (DRIVEALIGN_L2L gain, as mentioned in LHO:72416).


The fact that we don't see the loop dip near 20Hz is a rough indicator that the [actuation stage] crossovers are stable. I'll be following up with a more in-depth look at that.


The script used to generate the attached plot lives at: /ligo/home/louis.dartez/projects/20230825/plot_olg/plot_olg_meas.py