We redid the PSL measurements from alog 61623.
Everything seems ready for locking.
PMC UGF: 1.8 kHz
ISS first loop UGF: 32.2 kHz
FSS UGF: 465.6 kHz
The IMC should be the same as it was in alog 61623,
and the ISS second loop should be set the same as it was in 61721.
IMC UGF: 60 kHz
ISS second loop UGF: 25.6 kHz
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We also checked the FSS fast gain settings, similar to alog 43479.
Our current settings for the gain sliders on the FSS are:
Common gain: 15 dB
Fast gain: 11 dB
We start to see bad PZT/EOM crossover behavior when the Fast gain hits ~14 dB, and things get really bad by 17 dB (see PDF 4).
Our current settings have been saved in SDF.
One comment on the PMC UGF. It should be around 1.0 kHz, but is currently at 1.8 kHz with the PMC MEDM gain slider at 0. This is due to the trigger issue that we noted here. Recall that to solve the trigger issue we had to increase the light level on the PMC locking PD so there was enough light incident when the PMC was locked to stay within our trigger thresholds. The consequence here is that this increases the optical gain in the control loop, and we do not have enough range in the electrical gain to compensate for it. We'll have a think about this, and may have to go in and see if we can carefully adjust the light level on the PD to both make the control loop happy and meet the trigger conditions.
In other news, the PMC REFL signal (PMC reflected power) still cannot be trusted. At all. We're still looking for a suitable ~50/50 beam splitter (if %R is a little higher than 50% that's OK as well) so we can install the PD we want to monitor PMC REFL (the first BS I found had fingerprints all over it. I mean, really? *sigh*). Hopefully we can find one by next Tuesday's maintenance window so we can go in, install the correct PD, and get it calibrated so we have a reliable reading on PMC REFL.