We found that the MC REFL image was no longer round and that the MCWFS DC quadrant spots were mostly
in one quadrant. So we re-centered the MCWFS beams in the following way:
1) We unlocked the MZ and adjusted the PZT voltage to keep the beam on the WFS from saturating.
2) Re-aligned the black hole beam dump to center its beam in its aperture.
3) centered the beam on the MCWFS optics and MCWFS QPD displays.
4) Relocked MC.
Below is the image of the IOO Strip tool. You can see that the MC REFL DC is now more flat. The
MC pointing has also been changed (see the MC TRANS HOR & VERT channels). The MC transmitted
light is also now more stable and higher.
We tried to center the QPD, and we found that there were a few hundred mV of dark offset for each
quadrant of QPD. We adjusted them with this scripts: