We locked Xarm/Yarm and manually alignmed ITMX/ITMY/BS/ETMX/ETMY/PZT1/PZT2.
ITMY OPLEV was largely misaligned ==> The beam was centered on the QPD.
Then we aligned PRM using SB locking PRMI.
We noticed that OPLEV servo does not work. It made the PRM just noiser.
We went into the PRM table and found that the OPLEV beam was clipped in the vacuum chamber.
We tried to maximize the reflected beam from the window by touching the steering mirrors at the injection side.
Then the reflected beam was introduced to the center of the QPD.
After the alignment, the OPLEV QPD SUM increased to 4000ish from 200ish.
According to the OPLEV trend data, this is a nominal value of the QPD SUM.
Now the OPLEV servo does not go crazy.
BS OPLEV beam was centered on the QPD.