Ushiba, Takano, Hirata, Aso

Following the work on SR3, we continued to check and align the beam spot on SR2.

We first reconnected the picomotors of the SR2 in-vac steering mirror to the driver.
The cables were poorly labeled, so we checked which cable corresponds to which degree of freedom by looking at the motion of the picomotors by eyes.
Now the cables are nicely labeled by Hirata-san.

From the yesterday's work, we knew that pitching SR3 down by 100urad roughly centers the IR beam on SR2.
So we checked the IR beam spot with this state.

It was slightly higher than the center. So we pitched down the SR3 by 30urad.
The result looks nicely centered.

Now we know the target orientation of the SR3.
Then, starting from the SR3 orientation where the green-Y reaches the EYA PD, we moved the SR3 little by little to the target orientation, while keeping the green-Y alignment by moving the in-vac picomotors. This way, we were able center the IR beam spot on SR2 with green-Y reaching the Y-end.

Then, we checked the green beam spot on SR2.

It was obviously higher than the center.
We moved a picomotor on the POS table and the in-vac picomotor to center the green beam spot on SR2 while keeping the green-Y alignment.
The result is the following.

We wanted to continue to align the beam spot on the center of SRM by moving SR2.
However, the momentary power outage and following DGS failures did not allow us to work on this today.