With Washimi-san.

Pictures at SR3 remedying work after O3.

Alignment recovery

• The IP and F0 are locked since last week. We don't need them unlocked for the adjustment of the ballast masses.
• I moved IM-P from -640 urad to -342 urad (the aim was -339 urad per the commented klog entry)
• I moved IM-Y to approximately zero. We will use the F0 yaw motor to adjust the mirror yaw.
• We moved the position in which F0 is locked to -834 um, which is the current setpoint.
• With certain amount of coil-magnet actuation we set BF and F1 close to their setpoints.
• We moved the oplev collimator a few millimeters towards the -X direction.
• Then, by adjusting the tip and tilt of the collimator the beam reached the tilt QPD but not to the center yet.
• For the length sensing beam, we adjusted the lens holder sideways from the base to make the beam go through the centre of the lens; we used a ground glass alignment disk. See this picture.
• Then we tilted the second folding mirror to make the beam reach the centre of the length sensing QPD.
• Finally we adjusted the yaw of the suspension using the F0 yaw motor to bring the beam to the center of the tilt QPD.
• The temperature was 22.8 degrees, which is a bit low. See entry 15949. Heaters were added. During our work we used the Koach filters and the temperature raised to 23 degrees. After our work it went down back to 22.8 degrees.

I measured transfer functions in IM-P, IM-Y and IM-R and the system looks healthy.

As preparation to the adjustment of the IM ballast mass I checked the BF fishing rod is not jammed, and I left it at the upper limit of its moving range.