[Sato, Miyakawa, Hirose]

In preparation for changing the length of the IMC, we installed an HWP after the IR shutter in the PSL room in order to switch the incident light from S-polarisation to P-polarisation. (The current optical setup is shown in Fig1.)

1. Unlocked the IMC.

2. Installed a PBS and confirmed that most of the light was reflected using a sensor card.

3. Installed an HWP and placed a PBS immediately after it. Confirmed that most of the light was transmitted using a sensor card.

4. Removed the PBS after the confirmation.