Ushiba, Tanaka

### Abstract

We confirmed each beam position on POM1(fig.1), POM2(fig.2), and STM1(fig.3). They hit on each center which is their nominal position.

### What we did

• We rotated the PSL HWP from 11 degrees to 0 degrees to reduce the PSL output power. We removed the HWP in front of the last PSL periscope to change the polarization from p-pol to s-pol, and we removed the aluminum foils around the IMC, IFI, and PRM chambers to allow the beam to pass to the PRM.
• We attempted to confirm the beam position, but the power was too low (PSL output with s-pol was 0.2 W). Therefore, we restored the PSL HWP to 11 degrees. The PSL output power with s-pol in this state was approximately 2 W.
• We verified the position of each beam on POM1 (fig. 1), POM2 (fig. 2), and STM1 (fig. 3), and we observed that they were hitting their nominal center positions.
• After confirmation, we rotated the PSL HWP back to 0 degrees. We closed the beam shutter and then sealed each chamber with aluminum foils. Finally, we placed the HWP in front of the last periscope again.