Kokeyama, Sato, Nakano(remote), Kenta

Today, We looked into the ghost beams by reflected beam from PRM in IFI chamber. We found the 2 ghosts (rGB1, 16) and the some beams that we don't understand where they come from.

What we did

• We set the power of input beam 5 W, and aligned PRM, we investigated the ghost beam by reflected beam from PRM based on Tanioka-san's data as yesterday investigation. 
• As a result, we found two ghost beams (rGB 1, 16). We confirmed that they were indeed the ghost beams from the reflected beam, by blocking the beam reflected from the PRM only.
• We also found some ghost beams between the MCF and IFI chambers, but we could not determine where they were coming from .
• I attached a paint that summarizes the ghost beams we've found in our research so far.

Todo

• investigate where the unknown ghost beams come from again.
• In particular, we are somewhat concerned about the shape of the transmitted beam from the STM2, so we will re-examine the area around the STM2. In some cases, the STM2 may be replaced.
• Also, we found that the clamping of some optical instruments is not good, so we re-clamp them.