Jennie W, Jeff K, Josh F
On Monday Betsy, Jeff and Josh got the light aligned from the ISIK breadboarrd in HAM3 to the ISIJ receiver in HAM2 manually while the HAM2/3 ISIs were locked (alog #90621). Then the ISI in HAM2 was unlocked (alog #90620).
This morning pitch was off on QPD A.
This morning Jeff recentred onto optical lever QPD A in HAM2 using M_M1 picomotor mirror. See pic. The SUM_OUT of the QPD was around 23.9V at 16:45 UTC.
Then we attempted to do the same for the optical lever QPD B in HAM3 using the ISIJ picomotor. See pic.
Jeff and Fil relocated the IOT2L picomotor driver in order to drive the ISIJ picomotor in this alog.
We were not finding a good point where we could center the beam solely with the picomotors so Jeff went in chamber and we were near the edge of the M_M5 pericope mirror.
I used the ISIJ picomotor to center on the first periscope mirror M_M5, but the alignment downstream from the periscope is still ongoing.
We could not center the beam on the QPD B so that it was equally on all four quadrants and we saw clipping on the beamsplitter in front of the QPD B, M_B4.
Picomotor is now functional but now we need to do the correct thing; center the beam on M_M5, then use M_M5 to center on QPD B.
Centering on M_M5 with the picomotor was simple. Some notes for next time: moving left on the ISIJ picomotor moves the beam in +Y on the QPD and moving down on the picomotor moves up (or +Z) . Use the speed 'jog' on the picomotor and steps of 100 counts to see motion, finer steps of 10 are needed to do fine adjustment.
Eventually Jeff realised we needed to roll the periscope mount in RZ to change the pitch alignment in the QPD B local coordinates which is hard to get fine adjustment on as the whole mount must be moved and then the set screw re-tightened which can then again move the alignment. Yaw adjustment is done with the alignment screws on the mount so once we get pitch adjusted we can improve yaw.
Conclusions:
- Picomotors are alive, exactly what we need, plenty of range and coordinate system transformations all make sense
- We *need* a re-design of the periscope mount for the future – need to design a periscope mount that has 3-axis rotation capability (pitch, yaw, *and* roll of the mount)
- Likely need to reduce the transimpedance on the QPDB segments channels as each segment seems to saturate at 20V in the moves we were doing.
