The X arm was also aligned for the IR by hand and ASS. Also the X end green PZT was aligned to make the TEM00 mode reasonably locked.
What I did:
- Looked at the ITMXF camera. It seemed that the green beam was hitting the mirror.
- Went to the end. Looked at the X end green REFL. Tuned coarse alignment of the ETMX so that the beam was (retro-)reflected to the Faraday and the REFL PD.
- Looked at the ETMX face from the view port. Tried to locate the spot from the ITMX by shaking the ITMX alignment with 0.1 and then 0.01 increments.
- After some struggle with the ETMX and ITMX alignment, resonant fringes were found on the ETMY face while I still looked at the ETMX.
- Once the ITMX/ETMX were aligned, the BS needed to be aligned. But of course there was no IR fringe.
- Returned to the original alignment of the ITMX to find the ITMX spot on the AS camera.
Then gradually moved the ITMX to the aligned value for the green while tracking the michelson alignment with the BS.
This made the AS spots at the upper left edge of the AS video image.
- This was enough to find the IR spikes at TRX. Then the ETMX was touched to maximize the transmission.
- Lock the cavity. Use the ASS to optimize the alignement.
- Once the arm mirrors were aligned, the Xend PZT was also adjusted to have TEM00 for the green beam.
Now I leave the IFO with ITMX/Y, ETMX/Y and BS aligned. As I wrote above, the AS spot is very high at the AS camera.
We need to revisit the AS steering (SR TTs?) to ensure the AS beam unclipped.