BS fluctuation

This time, Ushiba-kun tried to cancel the DC alignment shift from the wind by feeding back to the IM to avoid the saturation of the TM coils.
The BS fluctuation was still large (+/-50urad or so), but at least the fluctuation was centered around the good orientation.
50urad rotation of the BS induces about 1mm beam position shift at the mirrors.

SR3

Green-X

Green-Y

IR beam
https://www.dropbox.com/s/ferwdudp2sfwts9/SR3_from%20-X%20flange.MP4?dl=0

Both Green-X and Green-Y seem to be at the center.

IR beam seems to be largely off centered in +X and upper directions. However, this is deceptive. The beam is clipped in the bottom right part by the GV window. Therefore, the true center of the beam cannot be properly identified.
In fact, we believe that Green-X and IR are hitting the same position on the SR3 mirror. This is because IR and Green-X are aligned well to the same cavity (X-arm) and the beam spots on the SR2 overlap well.
With these conditions satisfied, the beam spot positions on the SR3 cannot be different.

SR2

Green-X

Green-Y

IR
https://www.dropbox.com/s/6c4bfg0akesk59y/SR2_from%20%2BX%20flange.MP4?dl=0

Green-Y is well centered.
Green-X and IR are off-centered in the +X direction by about the same amount (~5mm).

Checking the beam clipping by the mid-sized baffle

We also checked the IR beam position at the mid-sized baffle. Both forward and reflected beams are not clipped as far as we can see with a sensor card.

What shall we do?

The IR beam is not hitting right at the center of SR2. However, the offset is small (less than 5mm).

Since the main beam is not clipped by the baffle, we may just leave it as is.