[Yokozawa, Enomoto, GGG, Nakano]
We aligned all of the mirrors except for the ETMY. The details are as follows:
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Alignment of the PR mirrors
1. Aligned the IOO mirrors by using the oplev signals
2. Misaligned the PRM by using the IFI camera so that the beam injects the high power beam damp. I put the offset of 9000 on the OPTICALIGN with the ramp time of 60 sec
3. Aligned the PR2 and PR3 by using the oplev signals.
4. Aligned the PR3 finely so that the IR get reached to the EXA PDA. The PD signal got reached up to around 1000.
Alignment of the ITMs and the BS
1. Aligned the ITMs by using the oplev signal, and then we could see the reflected beam from the ITMX on the IFO REFL.
2. Aligned the BS by using the oplev signal. Then, the reflected beam from the ITMY and the ITMX could be seen on the POS camera.
3. Aligned the BS finely by looking the fringe of the reflected beams from the ITMs
Alignment of SR3
1. Went to the Yend and checked the PD on the TMSY for GRY. The gain of the PDA was set to 70 dB. Also, we turned the light of the Yend and the offset of the PD signal is almost zero.
2. Aligned the SR3 so that the GRY reached up to the TMSY PD. This was the toughest part of today's alignment. Even after we bring the SR3 back to the good position two weeks ago, we could not find any signal on the PD. So, we tried to sweep in the area of ~400 urad^2, but even then we could not. We went back to the center area and check the beam on the viewport between the BS and the ITMY, and we found that the GRY was clipped on that. However, the reflected beam from the ITMY came back to the POS table. This means that the beam position on the SR3 is not good, so we decided to touch the POS_POM pico-motor. I moved the POS_POM in-vac pico by ~2000 steps in the direction of yaw so that the beam goes through the center of the viewport. Then, the SR3 was aligned so that the reflection beam comes back to the POS table.
3. Swept the SR3. After the sweeping was started, immediately we found the beam on the TMSY PD. The PD output was saturated up to ~17000 cnts.
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Remaining
The ETMY alignment has not been done yet. This is because the IP of the ETMY is at a different position from the position where we aligned last time. So, the oplev is not good reference anymore. I would like to ask type-A team to bring back it.