Jenne D, Ryan S, Camilla C, TJ S

Today in a single bounce 10W configuration we set SR2 to center AS_C with the SRC2 ASC loops via the ALIGN_IFO guardian in the SR2_ALIGN state, then moved SR3 in steps to see how our AS_C power would change in different positions. We found that there is an area, or spot, that we lose significant throughput to AS_C, but moving around this spot in any direction recovers our nominal single bounce power. This is followup from Jenne Driggers SR3/2 move (alog77388) to bring back our power at the AS port on April 24th, and Jennie Wright, Minhyo, and Sheila's efforts searching in yaw to find where we are losing the power (alog77513). This time we went further than Jennie W and team went and managed to get back almost all of the AS_C sum back. Almost all because just before we got there we starting running into a different, perhaps clipping, issue that changed the shape of the AS air camera in a much different way than when around this spot.

More details:

We started out by reverting the alignment to a time during DRMI locking from the Tuesday morning of April 23. We then brought up tried to move SR2 and SR3 as was done previously, then Jenne suggested that we turn on SRC2 to have SR2 follow our SR3 moves and keep AS_C centered. This worked great along with a little extra SRC2 gain to help move things along faster. Moving in pitch in either direction yielded fairly quick power gains (trends SR3 -P move & SR3 +P move). Jenne suggested that we try to go further in yaw than the Jennie W. team did to see if it ever improves, and we were able to get AS_C almost back after ~550urad in SR3 (trend SR3 -Y move today, and SR3 +Y move April 24 ). If I had the time I'd love to make a nice graphic to show where we can't go but we'll have to deal with this table for now.