As a part of trying to diagnose the mode cleaner locking issues, I ran a transfer function of MC2 M3 to M3 to see if everything looked normal. Unfortunately, there is nothing in the sus svn to provide a reference, so we don't know what it is supposed to look like.
I immediately noticed strange behavior above 10 Hz that is related to the BIO state. I thought I was on to something, however, I found out that this is a long known problem that comes from coil driver coupling to the osem. Nonetheless, here is a measurement, in case anything else jumps out as strange to anyone.
I took two transfer functions in BIO state 4 - Acq On LP On, and one in BIO state 3 (nominal)- Acq Off LP On.
I also measured SR2 when I was investigating the BIO state issue. I toggled between state 3 and four. I noticed that the high frequency response changes like MC2 M3, but much less so.
