Hirata, Nishino, Miyazaki, Akutsu, Ushiba, Matteo, Tamaki and Aso

As reported here, the IR beam spot on SR2 was off-centered.
In order to fix this, we did the followings.

Y-green alignment with SR3 and the SR2 in-vac steering mirror

While, SR3 was dithered to maximize the green transmission of Y-arm, the picomotors on the in-vac steering mirror in the SR2 chamber was moved to further maximize the green transmission.
With this, we were able to significantly reduce the TEM01/10 components. The TEM00 transmission increase from 0.45 to 0.55(arbitrary unit). We now see that the dominant higher-order mode is LG01.
More details may be reported separately.

Checking the IR beam spot on SR2.

After the above alignment work, the IR and green-Y beams should be co-aligned. Therefore, we can expect that they overlap well on SR2.
We put the target plate on SR2 and checked the beam spots.

Green-Y spot was slightly off-centered (1-2mm?).

IR beam seemed to be well-centered.

So we decided that no-further adjustment was necessary for the orientation of SR3.

Centering the beam on SRM

Since the orientation of SR3 was changed, the IR beam spot on SRM was off-centered.
We put the target plate before SRM and centered the beam using SR2 rotation.

After this, we also needed to align the beam again through the OFI. This work is reported here.