A very strange thing is going on.
The REFL11 and REFL55 demod signals show high frequency noise depending on how big signals go to the POS actuator of PRM.
This noise shows up even when the beam is single-bounced back from PRM ( the rest of the suspensions are misaligned) and it's very repeatable.
Any idea ?? Am I crazy ?? Is PRM making some fringes with some other optics ??
(Glitch is related to the PRM POS actuation)
We tried to figure out what is causing spikes in the REFL33 signal, which is used to lock PRCL.
No useful information was obtained tonight and it is still under investigation.