After Rahul was done with his transfer function for OM2, I started searching for the beam on OMC QPDs. Eventually I was able to align the OMC path in the following order. We still need to mechanically relieve OM2 alignment offset (both PIT and YAW).

• Found the beam by manually tweaking OM2 alignment slider.
  • More P adjustment was necessary than Y.
• OMCS alignment sliders were totally zeroed.
  • Our usual OMC ASC scheme of feeding back to OM3 and OMCS works OK except when OMCS rails as it doesn't have a lot of range. We need to relieve OMCS by first zero-ing all OMCS alignment offsets, then aligning the beam into OMC using some combination of OM1, OM2 and OM3, then pico-ing WFSs and ASC-AS_C. That's what I'm trying to do.
• Used OM1 and OM3 for OMC QPD centering.
  • Setting change: Disabled H1:OMC-ASC_QPD_A_PIT_OFFSET, H1:OMC-ASC_QPD_B_PIT_OFFSET, H1:OMC-ASC_QPD_A_YAW_OFFSET, H1:OMC-ASC_QPD_B_YAW_OFFSET though B_YAW offset was zero. Disabled H1:ASC-OMC_A_PIT_OFFSET, H1:ASC-OMC_A_YAW_OFFSET. B offsets were off.
  • Setting change: OMC ASC output matrix from our usual one (1st attachment) to a temporary one to feed back to OM1 and OM3 (2nd attachment).
  • It worked though very slow.
• Moved OM2 alignment slider by hand while QPD centering was ON to relieve ASC output to OM3.
  • OM3 coil outputs were OK but larger than I'd like (~15k), so I tilted OM2 mostly up all the way to relieve OM3 PIT. See 3rd attachment for the results.
• Tomorrow we still need to mechanically relieve OM2 both in YAW and PIT.
• Other notes:
  • We put a foil over the HAM5-HAM6 septum viewport adapter, otherwise the purge air coming from the corner volume directly blows on OM2 and the alignment is almost hopeless. This is why things were moving badly on Friday. Foil is OK as we also have a purge port for HAM6 and the air moves from HAM6 to outside.
  • At first I thought that the alignment was totally off as the OMC QPD level was an order of magnitude smaller than what I saw on Friday, but eventually convinced myself that I'm looking at the right beam because the QPDs responded sensibly. Then I thought that the laser was dying, went to the floor to measure the power, and somehow the power came back even though I did nothing. This is the reason why everything was slow today.
  • Aux laser was turned off.