[Sheila, Georgia]

After Ed/Corey/Sheila locked the y-arm in green, Sheila and I went out to end-y to check the phasing of the green WFS (A and B), as mentioned in the to-do list in alog-42925.

We injected a 31 Hz sine wave from the SR785 into the excitation port of the common-ALS-laser-to-Y-arm PDH servo board. While the arm was locked we saw this signal in I and Q quadratures, and tuned the phasing quadrant-by-quadrant to minimise the signal in Q. Both sensors did not require a dramatic re-phasing, i.e. they were still close to optimal.

We have left the SR785 hooked up to the excitation channel for now.