[Takahashi, Miyamoto, Kawakami, Fujimoto, Komori]

We prepared for the MCE displacement planned for tomorrow.

First, we brought the mechanical parts that will be used to move the MCE, such as pushers and side clamps to prevent lateral slipping, into the MCE clean booth.

Next, we checked the beam path of the optical lever (oplev).
We did not find any potential clipping points around the MCE suspension.
At the output viewport for the oplev, the beam currently passes close to the edge of the aperture, but this situation should improve after moving the MCE toward the MCF.

We also visually confirmed that the oplev beam is hitting close to the center of the MCE.
Although the exact position is somewhat uncertain, the photo in Fig. 1 indicates that the oplev beam spot is approximately at the center, as shown by the red point inside the yellow dotted circle.

Tomorrow, we will start by realigning the IMC immediately before moving the MCE and recording the alignment conditions as a reference.
After moving the MCE by -10.26 mm, we will tilt the MCI/MCO by 3.69 µrad, which is the geometrically required change in angle.
We will then search for the optimal alignment by adjusting the MCE angle.
Finally, we will center the MCE oplev beam on the QPD by moving the QPD stage and/or adjusting the position of the entire QPD assembly.