We aligned Y arm to Y green and tweaked TT1/TT2 to get IR locked in Y arm.
1. Align ETMY/ITMY to maximize TEM00 green transmission to PSL table. We reached ~240 uW.
2. Aligned PRM and TT2 so that PRM reflected beam go through FI and get ITMY-PRM cavity flashing. This is to coarsely align input pointing to Y arm. After this alignment, we got tiny Y arm flash. Input pointing to IPANG QPD was lost.
3. Aligned TT1/TT2 to maximize TRY in TEM00. We reached ~0.92.
I was struggling with finding Y arm flash. I was using IPPOS/IPANG as input pointing reference, and slider values (C1:SUS-(ITMY|ETMY)_(PIT|YAW)_COMM) or OSEM values (C1:SUS-(ITMY|ETMY)_SUS(PIT|YAW)_IN1) before pumping for Y arm alignment reference. But it was a lot more easier if Y arm is aligned to green and having Yarm cavity axis assured.
- X arm flash in IR
- Steer X end green
- If X arm or AS looks bad, adjust IR input pointing and Y arm alignment. We have to steer Y end green afterwards.