[Tanaka, Yano, Ushiba]

Abstract:
We checked the beam position at several places.
The misalignment is about 5 mm at IMMT1 trans QPDA1 and clipped by 1 inch beam splitter in fornt of that QPD.
It seems that the misalignment can be recovered by only moving STM2 and centered the beam to IMMT1 trans QPDA1 (not yet done).

Detail:
We checked the beam from IMC to IMMT1 trans at several places.
Fig1: beam on STM1, hit almost center of the mirror.
Fig2: beam on STM2, hit slightly right side of the center, which is nominal after the work reported in klog19489 if I remembered correctly.
Fig3: beam after IFI, seems no clipping.
Fig4: beam on the steering mirror on IMMT1 trans table, the beam seems to be slightly shifted to left side from the last beam position check (klog20124).
Fig5: beam on the beam splitter in front of IMMT1 trans QPDA1 and QPDA2.
Fig6: beam on IMMT1 trans QPDA2, the beam is inside the QPD effective area.
Fig7: beam on IMMT1 trans QPDA1, clipped by BS.

Since the beam position on STM1 and STM2 seem good and there is no clipping at IFI, situation seems not so terrible.
Also, the amount of beam shift at IMMT1 trans table is not so large (the beam is in the QPD effective area).
So, just moving STM2 and centering the IR beam to IMMT1 trans QPDA1 could recover the alignment without large troubles.

Note:
During the work, we found IMC trans beam has ghost beams around the main beam (fig8).
We are not sure they existed from long time ago...