There looks some activity at around MC2 on Wednesday afternoon.
It caused the misalignment of MC2. Misalignment was not found in MC1/3.
It seems that the incident beam on the MC was aligned in the evening.
This increased the MC transmission but it is vibible that the spot on MC2 is shifted from the center.
We need an action on this issue tomorrow in the daytime.
I am working on fixing this. You might some strange stuff going on in the control room screens. Pls ignore it till I am done.
I have realigned the MC by recentering the spots on all the MC optics. The current spot positions (in mm) are:
MC1P MC2P MC3P MC1Y MC2Y MC3Y
0.2245 0.3364 -0.2801 -1.8891 0.1631 -1.744
Initially the lockins 2 and 5 showed very small outputs. This was traced to the fact that we have recently switched on a 28Hz ELP filter module in the MC2 ASC filter bank which introduces an extra phase of about 75deg.. See this elog.
When the MC ASS lockins were initially setup, the phase was set with this filter module switched off. Since quite some time has passed since the last calibration of these phases, I readjusted the phases to minimise the Q_OUTPUT and I also adjusted the GAINs in the SIG filter banks of all the six lockins so that their I_OUT's drop by the calibration value of -2.65 when an offset of 0.1 is introduced into the MC suspension output matrices. Two short scripts in the $scripts$/ASS/ directory help in setting and removing these offsets. They are called MCxoffsetOn and MCxoffsetOff. They have to be edited appropriately to address each DoF of the MC.
The $scripts$/ASS/mcassUp script., which sets up everything to make the MC spot decentering measurement, has been edited to set these new phases and gains. The old settings have been commented out.
I then centered the spots on the WFS sensors and the MC_TRANS QPD. We are now ready to make the MC WFS output matrix transfer coef measurement again, but this time with the WFS loops closed.