While doing the things below we accidentally misaligned the PSL laser. Thanks to Suresh and Jenne for realigning!!
There are a lot of strange features in MC_F (see for example http://nodus.ligo.caltech.edu:8080/40m/5738 )
To get some better understanding of the signals in the control loop we looked some more into what happens to the MC feedback signal after it exits the MC servo board (D040180 see DCC).
The MC_F signal is actually the servo signal: http://nodus.ligo.caltech.edu:8080/40m/5695
The Thorlabs temperature controller is actually used in the PZT path!
We measured the LP filter in the PZT path (that is kind of mislabeled as temp.)
We looked into the FB going into the temp. and PZT parts of the FB.
We also looked at the signal in just in front of the FSS box No idea why the elog doesn't preview these pdfs.
Lots of extra noise there. We will check out where that comes from.