[Sheila, Karmeng]
FC1 alignment was adjusted to account for the buoyancy, and we coaligned the FC1 green/IR beam. We managed to recover the FC refl green on SQZT7 periscope, but not on the photodiode.
The OPO IR transmission is misaligned, and we managed to recover the IR on SQZT7 PD. As we recovered the IR refl (top) on SQZT7, we saw an improvement from ~600 to ~1680 (we may have been clipping on the refl PD previously).
By changing the setting on ZM2, we managed to improve the IR trans (bottom).
Old setting ZM2 PIT: 424 ; YAW: -235
New setting ZM2 PIT: 444 ; YAW: -315
Will need to check on the iris tomorrow, to make sure we did not deviate from the original path.
Some additional information:
In december we checked that the alignment sliders on FC1 had not moved since the observing run. Noting that the red and green co-alignment were off, this morning I trended osems as well and saw that FC1 had a shift of +200urad in pitch at the time of the vent. The ZMs all had similar shifts. When I moved FC1 to make sure the osem values matched the observing run pitch, the beam was then clipped on B:P1. We adjusted B:M1 to clear the VIP, then adjusted B:M4 to recenter the beam on the ZM4 iris. Then Kar Meng adjusted ZM4 alignment to match the irises on SQZT7 in the homodyne path. After this we saw that the beams were still on the QPDs in HAM6, but not well centered. We will have to return to that tomorow.
After that we turned our attention to the co-alignment of the FC green sensing with the squeezed beam. The shift in the FC1 pitch wasn't enough to make a difference in the large misalingment of these two. We became confused for a while looking at the FC green beam in the SK path. The old HAM7 layout shows the SK path on the -X side of the three beams leaving the chamber toward the green periscope, this is correct but the two beams cross as they travel down the periscope so that the FC green refl path is on the -X side by the time it reaches the bottom, and looking at the SQZT7 layout shows the SK path located on the table in the area where the FC green refl path is.
Once we understood this path, we were able to walk H:M1 to coalign red and green right after A:DC2, and using H:M2 to co-align them at the iris after ZM3. Then we adjusted the pointing to the periscope using H:M4.
While we were in laser safe, I unlocked the OPO suspension, since we hope that we are finished with the alignment work on the VIP. This caused enough of a shift that the reflected seed beam was clipping on its way to the diode, perhaps on the lens in HAM7. We moved this beam so that it is still mis centered on the lens but not close to the edge.